Littérature scientifique sur le sujet « Effetto SNARC »

Space is markedly involved in numerical processing, both explicitly in instrumental learning and implicitly in mental operations on numbers. Besides action decisions, action generations, and attention, the response-related effect of numerical magnitude or ordinality on space is well documented in the Spatial-Numerical Associations of Response Codes (SNARC) effect. Here, right- over left-hand responses become relatively faster with increasing magnitude positions. However, SNARC-like behavioral signatures in non-numerical tasks with ordinal information were also observed and inspired new models integrating seemingly spatial effects of ordinal and numerical metrics. To examine this issue further, we report a comparison between numerical SNARC and ordinal SNARC-like effects to investigate group-level characteristics and individual-level deductions from generalized views, i.e., convergent validity. Participants solved order-relevant (before/after classification) and order-irrelevant tasks (font color classification) with numerical stimuli 1-5, comprising both magnitude and order information, and with weekday stimuli, comprising only ordinal information. A small correlation between magnitude- and order-related SNARCs was observed, but effects are not pronounced in order-irrelevant color judgments. On the group level, order-relevant spatial-numerical associations were best accounted for by a linear magnitude predictor, whereas the SNARC effect for weekdays was categorical. Limited by the representativeness of these tasks and analyses, results are inconsistent with a single amodal cognitive mechanism that activates space in mental processing of cardinal and ordinal information alike. A possible resolution to maintain a generalized view is proposed by discriminating different spatial activations, possibly mediated by visuospatial and verbal working memory, and by relating results to findings from embodied numerical cognition.

Bimanual parity judgments of numerically small (large) digits are faster with the left (right) hand (the SNARC effect; Dehaene, Bossini, & Giraux, 1993 ). According to one explanation, this effect is culturally derived and reflects ontogenetic influences such as the direction of written language; it might therefore be limited to, or at least be larger with, pairs of lateralized effectors which are instrumental to the production and comprehension of written language. We report two experiments which test for SNARC effects with pedal responses, and compare these effects to manual results. Pedal responses yielded highly systematic SNARC effects; furthermore, these effects did not differ from manual SNARC effects. These results argue against accounts in which the SNARC effect is specific for effectors that are habitually associated with the production or comprehension of written language.

The present study investigated the effects of left hemispatial neglect on two tasks activating the mental number line (MNL). Six patients with left neglect performed a mental number bisection task and a modified version of the Spatial Numerical Association of Response Codes (SNARC) task. Effects of left neglect were observed in the number bisection task, but not in the SNARC task. We argue that the dissociation between number bisection and SNARC resembles, in the representational space of the MNL, previously reported dissociations on neglect between explicit knowledge (assessed by direct tasks) and implicit knowledge (assessed by indirect tasks).

Congruency sequence effects are observed when the congruency effects following incongruent trials are smaller than those following congruent trials. It is typically assumed that such flexible adjustments are evidence of cognitively controlled dynamic modulations. The present study investigated whether cognitive control acts locally or globally when implicit and explicit conflicts exist simultaneously within a system. The implicit SNARC task and explicit Simon task were combined in a single task. The results showed that congruency effects of one type (e.g., SNARC effect) were only smaller following an incongruent trial of the same type (e.g., SNARC effect), but not when following an incongruent trial of the other type (e.g., Simon effect). These results indicate the operation of local control mechanisms triggered by implicit and explicit conflicts.

The SNARC (spatial–numerical association of response codes) effect is the finding that people are generally faster to respond to smaller numbers with left-sided responses and larger numbers with right-sided responses. The SNARC effect has been widely reported for responses to symbolic representations of number such as digits. However, there is mixed evidence as to whether it occurs for non-symbolic representations of number, particularly when magnitude is irrelevant to the task. Mitchell et al. reported a SNARC effect when participants were asked to make orientation decisions to arrays of one-to-nine triangles (pointing upwards vs. pointing downwards) and concluded that SNARC effects occur for non-symbolic, non-canonical representations of number. They additionally reported that this effect was stronger in the subitising range. However, here we report four experiments that do not replicate either of these findings. Participants made upwards/inverted decisions to one-to-nine triangles where total surface area was either controlled across numerosities (Experiments 1, 2, and 4) or increased congruently with numerosity (Experiment 3). There was no evidence of a SNARC effect either across the full range or within the subset of the subitising range. The results of Experiment 4 (in which we presented the original stimuli of Mitchell et al.) suggested that visual properties of non-symbolic displays can prompt SNARC-like effects driven by visual cues rather than numerosity. Taken in the context of other recent findings, we argue that non-symbolic representations of number do not offer a direct and automatic route to numerical–spatial associations.

Directional response biases due to a conceptual link between space and number, such as a left-to-right hand bias for increasing numerical magnitude, are known as the SNARC (Spatial-Numerical Association of Response Codes) effect. We investigated how the SNARC effect for numerosities would be influenced by reading-writing direction, task instructions, and ambient visual environment in four literate populations exemplifying opposite reading-writing cultures—namely, Arabic (right-to-left script) and English (left-to-right script). Monoliterates and biliterates in Jordan and the U.S. completed a speeded numerosity comparison task to assess the directionality and magnitude of a SNARC effect in their numerosity processing. Monoliterates’ results replicated previously documented effects of reading-writing direction and task instructions: the SNARC effect found in left-to-right readers was weakened in right-to-left readers, and the left-to-right group exhibited a task-dependency effect (SNARC effect in the smaller condition, reverse SNARC effect in the larger condition). Biliterates’ results did not show a clear effect of environment; instead, both biliterate groups resembled English monoliterates in showing a left-to-right, task-dependent SNARC effect, albeit weaker than English monoliterates’. The absence of significant biases in all Arabic-reading groups (biliterates and Arabic monoliterates) points to a potential conflict between distinct spatial-numerical mapping codes. This view is explained in terms of the proposed Multiple Competing Codes Theory (MCCT), which posits three distinct spatial-numerical mapping codes (innate, cardinal, ordinal) during numerical processing—each involved at varying levels depending on individual and task factors.

Spatial–Numerical Association of Response Codes (SNARC) and Spatial–Quantity Association of Response Codes (SQARC) effects are evident when people produce faster left-sided responses to smaller numbers, sizes, and durations and faster right-sided responses to larger numbers, sizes, and durations. SQARC effects have typically been demonstrated in paradigms where the explicit processing of quantity information is required for successful task completion. The current study tested whether the implicit presentation of task-irrelevant magnitude information could trigger a SQARC effect as has been demonstrated previously when task-irrelevant information triggers a SNARC effect. In Experiment 1, participants ( n = 20) made orientation judgements for triangles varying in numerosity and physical extent. In Experiment 2, participants ( n = 20) made orientation judgements for triangles varying in numerosity and for a triangle preceded by a delay of varying duration. SNARC effects were observed for the numerosity conditions of Experiments 1 and 2 replicating Mitchell et al. SQARC effects were also demonstrated for physical extent and for duration. These findings demonstrate that SQARC effects can be implicitly triggered by the presentation of the task-irrelevant magnitude.

Our directional reading habit seems to contribute to the widely reported association of small numbers with left space and larger numbers with right space (the spatial-numerical association of response codes, SNARC, effect). But how can this association be so flexible when reading habits are not? To address this question, we asked bilingual Russian-Hebrew readers to classify numbers by parity and alternated the number format from trial to trial between written words and Arabic digits. The number words were randomly printed in either Cyrillic or Hebrew script, thus inducing left-to-right or right-to-left reading, respectively. Classification performance indicated that the digits were spatially mapped when they followed a Russian word but not when they followed a Hebrew word. An auditory control experiment revealed left-to-right SNARC effects with different strengths in both languages. These results suggest that the SNARC effect reflects recent spatial experiences, cross-modal associations, and long-standing directional habits but not an attribute of the number concepts themselves.

The Spatial-Musical Association of Response Codes (SMARC) effect consists in faster and more accurate responses to low (vs. high) pitched tones when they are executed in the bottom/left (vs. top/right) space. This phenomenon has many similarities with the Spatial-Numerical Association of Response Codes (SNARC) effect which, however, has been more extensively investigated and theoretically debated. The first theoretical account of the SNARC effect suggests the existence of a direct mapping between the position of a number on a mental number line and the external space of response execution. Conversely, following accounts claim that numbers are automatically categorized in two opposing categories (e.g., small vs. large) and then associated to response alternatives (left vs. right). A modified task, consisting in unimanual close/far responses relative to a reference key, has been employed to disentangle between the opposite theoretical accounts of the SNARC effect. However, this modified task has never been applied to pitch height and currently there are no specific theoretical accounts for the SMARC effect. The aim of this study is to fill this gap of knowledge. Contrary to what has been found for numbers, our data are more in line with the "direct mapping" account and suggests a linear representation of pitch height. Our data suggest that SNARC and SMARC effects might have different origins and might require different theoretical accounts.

Zusammenfassung: Hintergrund: Die Repräsentation der Größe von Zahlen in einem von links nach rechts orientierten mentalen Zahlenstrahl wurde bei Erwachsenen mit dem SNARC-Effektes dargestellt (Spatial Numerical Association of Response Codes: schnellere Reaktion linke Hand bei kleinen Zahlen und rechte Hand bei großen Zahlen; Dehaene, Bossini & Giraux; 1993 ). Fragestellung: Die Studie untersucht die Frage, ob SNARC-Effekte (SE) schon bei Kindern der 2. Klasse nachweisbar sind und welche Zusammenhänge zu Rechenleistungen bestehen. Methode: Untersucht wurden N = 113 Kinder aus einer repräsentativen Stichprobe aus dem Kanton Zürich. Die Überprüfung von Fertigkeiten der Zahlenverarbeitung erfolgte longitudinal im Kindergarten und in der 2. Klasse. Ebenfalls zum zweiten Testzeitpunkt erfolgte die Durchführung des computergestützten SNARC-Paradigmas. Ergebnisse/Diskussion: Etwa ein Drittel der Kinder zeigten einen SE. Über die gesamte Stichprobe ließ sich kein signifikanter Einfluss des SE auf die Testleistung nachweisen, es besteht jedoch eine signifikante Wechselwirkung mit dem Geschlecht. Bei Knaben korreliert der SE positiv, bei Mädchen negativ mit der Testleistung. Die Ergebnisse werden in Hinblick auf geschlechtsspezifische Aspekte der Entwicklung kognitiver Denkstile diskutiert.

Negli ultimi decenni, molte ricerche sono state dedicate all'indagine degli effetti di congruenza spaziale in diversi ambiti e diversi studi hanno dimostrato che gli esseri umani elaborano le informazioni relative al tempo e alla grandezza rappresentandole in termini spaziali. Alla luce dei risultati degli studi di associazione spaziale sono stati proposti i concetti di Mental Number Line (MNL) e di Mental Time Line (MTL). La MNL e la MTL nel loro formato orizzontale sono continua spaziali su cui i numeri piccoli e gli eventi passati sono rappresentati a sinistra e i numeri grandi e gli eventi futuri sono rappresentati a destra della linea. Da un punto di vista psicolinguistico, ci sono altri tipi di informazioni relative alla grandezza e al tempo che possono essere esplorate in termini di spazialità. In questa tesi di dottorato, intendo studiare l'associazione spaziale di input linguistici, esplorando due fenomeni che non sono stati considerati in termini spaziali: i quantificatori vaghi e suffissi verbali. Ho indagato se i quantificatori vaghi presentati come parole isolate (Capitoli 2-4), e inseriti all’interno di frasi (Capitolo 3) possono essere rappresentati spazialmente. Nel Capitolo 5 ho indagato se le stringhe sub-lessicali, ovvero i suffissi verbali, attivano informazioni concettuali sul tempo e sono quindi in grado di attivare la MTL. I risultati hanno mostrato che i quantificatori vaghi sono soggetti a un effetto di compatibilità spaziale, che ho definito effetto SLARC, secondo il quale i quantificatori che si riferiscono a set relativamente piccoli, come pochi o alcuni, ricevono risposte più rapide con la mano sinistra e i quantificatori che denotano set relativamente più grandi, come molti o parecchi, ricevono risposte più veloci con la mano destra (Capitolo 2). Ho poi dimostrato che la grandezza dei quantificatori può essere manipolata tramite il contesto linguistico in cui compaiono e che l'effetto SLARC può essere sfumato da un effetto di working memory (Capitolo 3). I risultati del Capitolo 4 hanno mostrato che i quantificatori possono essere ordinati mentalmente, anche se non in maniera assolutamente rigida, secondo la loro grandezza. Nel Capitolo 5 ho mostrato che i suffissi verbali attivano con successo la MTL e che l'effetto di congruenza spazio-temporale emerge chiaramente sia quando il tempo degli stimoli è rilevante, sia quando non è rilevante per il completamento del compito sperimentale, suggerendo un automatismo del fenomeno. I risultati di questa tesi di dottorato forniscono nuove intuizioni sulle rappresentazioni spaziali degli stimoli linguistici, sia relative alla grandezza, attraverso l'esplorazione dei quantificatori vaghi, sia relative al tempo, attraverso l'esplorazione dei suffissi verbali che esprimono informazione temporale. Nel complesso, questi risultati sostengono l'idea che ci sia una tendenza generale a trasformare anche la conoscenza linguistica termini di rappresentazioni spaziali.
In the last decades, much research across different domains has been devoted to the investigation of spatial-congruity effects and various research showed that humans process information related to time and magnitude by representing it in spatial terms. As a result, the concepts of Mental Number Line (MNL) and of Mental Time Line (MTL) have been proposed. The horizontal MNL and MTL are spatial continua on which small numbers and earlier events are represented on the left and larger numbers and later events are represented on the right of the line. From a psycholinguistic perspective, there are other types of information related to magnitude and time that can be explored in spatial terms. In this doctoral dissertation, I investigate spatial association of linguistic inputs by exploring two phenomena which have not been considered in spatial terms: vague quantifiers and sub-lexical verb endings. I investigated whether vague quantifiers both presented in isolation (Chapters 2-4) and embedded in sentences (Chapter 3), were spatially represented. In Chapter 5 I investigated whether sub-lexical strings, namely verb endings, carry conceptual information about time and are able to activate the Mental Time Line. Results showed that vague quantifiers are subjected to a response-side compatibility effect, that I defined as SLARC effect, according to which Low-Magnitude quantifiers, such as pochi (“few”) or alcuni (“some”), were responded to faster with the left hand and High-Magnitude quantifiers, such as molti (“many”) or parecchi (“several”), were responded to faster with the right hand (Chapter 2). I then demonstrate that quantifiers’ magnitude can be successfully manipulated by the linguistic context and that the spatial-association effect can be blurred by a working-memory effect (Chapter 3). Results from Chapter 4 showed that quantifiers can be mentally ordered, although in a flexible format, according to their magnitude. In Chapter 5 I showed that verb-endings successfully activate the MTL and that the spatial temporal congruency effect strongly emerged both when the tense of the stimuli was relevant and when it was not relevant to the task. The results of this dissertation provide novel insights about spatial representations of linguistic stimuli related to magnitude, through the exploration of vague quantifiers, and to time, through the exploration of tensed verbs and tense-related sub-strings. Overall, these findings support the idea that there is a general tendency to transform also linguistic knowledge into spatial representations.

Two event-related potential (ERP) experiments were conducted to investigate spatial-numeric associations of response codes (SNARC) and attentional cuing (SNAAC). In the SNARC effect, people respond faster when making a left-hand response to report that a number is small, and when making a right-hand response to report that a number is large. Experiment 1 examined effects of SNARC-compatibility and prior response-probability in a number comparison task. Lateralized readiness potentials (LRPs) showed that SNARC-compatibility influenced an intermediate stage of response-selection, and prior response-probability influenced both earlier and later stages. The P300 ERP component was also modulated by SNARC-compatibility and prior response-probability, suggesting parietal involvement in the SNARC effect. In the SNAAC effect, attention is directed to left-side regions of space upon viewing small-magnitude numbers, and to right-side regions of space upon viewing large-magnitude numbers. Experiment 2 investigated whether ERPs evoked by peripheral visual probes would be enhanced when probes appeared in the left hemifield after small-magnitude digits and when they appeared in the right hemifield after large-magnitude digits. ERPs to peripheral probes were not modulated by numerical magnitude of digit pre-cues.

The present thesis deals with the mental representation of numbers in space. Generally it is assumed that numbers are mentally represented on a mental number line along which they ordered in a continuous and analogical manner. Dehaene, Bossini and Giraux (1993) found that the mental number line is spatially oriented from left­-to­-right. Using a parity­-judgment task they observed faster left-hand responses for smaller numbers and faster right-hand responses for larger numbers. This effect has been labelled as Spatial Numerical Association of Response Codes (SNARC) effect. The first study of the present thesis deals with the question whether the spatial orientation of the mental number line derives from the writing system participants are adapted to. According to a strong ontogenetic interpretation the SNARC effect should only obtain for effectors closely related to the comprehension and production of written language (hands and eyes). We asked participants to indicate the parity status of digits by pressing a pedal with their left or right foot. In contrast to the strong ontogenetic view we observed a pedal SNARC effect which did not differ from the manual SNARC effect. In the second study we evaluated whether the SNARC effect reflects an association of numbers and extracorporal space or an association of numbers and hands. To do so we varied the spatial arrangement of the response buttons (vertical vs. horizontal) and the instruction (hand­related vs. button­-related). For vertically arranged buttons and a button­related instruction we found a button-­related SNARC effect. In contrast, for a hand-­related instruction we obtained a hand­-related SNARC effect. For horizontally arranged buttons and a hand­related instruction, however, we found a button­related SNARC effect. The results of the first to studies were interpreted in terms of weak ontogenetic view. In the third study we aimed to examine the functional locus of the SNARC effect. We used the psychological refractory period paradigm. In the first experiment participants first indicated the pitch of a tone and then the parity status of a digit (locus­-of-­slack paradigma). In a second experiment the order of stimulus presentation and thus tasks changed (effect­-propagation paradigm). The results led us conclude that the SNARC effect arises while the response is centrally selected. In our fourth study we test for an association of numbers and time. We asked participants to compare two serially presented digits. Participants were faster to compare ascending digit pairs (e.g., 2-­3) than descending pairs (e.g., 3-­2). The pattern of our results was interpreted in terms of forward­associations (“1­-2-­3”) as formed by our ubiquitous cognitive routines to count of objects or events.
Die vorliegende Arbeit beschäftigt sich mit der räumlichen Repräsentation von Zahlen. Generell wird angenommen, dass Zahlen in einer kontinuierlichen und analogen Art und Weise auf einem mentalen Zahlenstrahl repräsentiert werden. Dehaene, Bossini und Giraux (1993) zeigten, dass der mentale Zahlenstrahl eine räumliche Orientierung von links­-nach­-rechts aufweist. In einer Paritätsaufgabe fanden sie schnellere Links-hand­ Antworten auf kleine Zahlen und schnellere Rechts-hand Antworten auf große Zahlen. Dieser Effekt wurde Spatial Numerical Association of Response Codes (SNARC) Effekt genannt. In der ersten Studie der vorliegenden Arbeit ging es um den Einfluss der Schriftrichtung auf den SNARC Effekt. Eine strenge ontogenetische Sichtweise sagt vorher, dass der SNARC Effekt nur mit Effektoren, die unmittelbar in die Produktion und das Verstehen von Schriftsprache involviert sind, auftreten sollte (Hände und Augen). Um dies zu überprüfen, forderten wir Versuchspersonen auf, die Parität dargestellter Ziffern durch Tastendruck mit ihrem rechten oder linken Fuß anzuzeigen. Entgegen der strengen ontogenetischen Hypothese fanden wir den SNARC Effekt auch für Fußantworten, welcher sich in seiner Charakteristik nicht von dem manuellen SNARC Effekt unterschied. In der zweiten Studie gingen wir der Frage nach, ob dem SNARC Effekt eine Assoziation des nicht-­körperbezogenen Raumes und Zahlen oder der Hände und Zahlen zugrunde liegt. Um dies zu untersuchen, variierten wir die räumliche Orientierung der Tasten zueinander (vertikal vs. horizontal) als auch die Instruktionen (hand-­bezogen vs. knopf­-bezogen). Bei einer vertikalen Knopfanordnung und einer knopf-­bezogenen Instruktion fanden wir einen knopf­bezogenen SNARC Effekt. Bei einer hand-­bezogenen Instruktion fanden wir einen hand-­bezogenen SNARC Effekt. Mit horizontal angeordneten Knöpfen gab es unabhängig von der Instruktion einen knopf-­bezogenen SNARC Effekt. Die Ergebnisse dieser beiden ersten Studien wurden im Sinne einer schwachen ontogenetischen Sichtweise interpretiert. In der dritten Studie befassten wir uns mit dem funktionalen Ursprung des SNARC Effekts. Hierfür nutzten wir das Psychological Refractory Period (PRP) Paradigma. In einem ersten Experiment hörten Versuchspersonen zuerst einen Ton nach welchem eine Ziffer visuell präsentiert wurde (locus-­of-­slack Paradigma). In einem zweiten Experiment wurde die Reihenfolge der Stimuluspräsentation/Aufgaben umgedreht (effect­-propagation Paradigma). Unsere Ergebnisse lassen vermuten, dass der SNARC Effekt während der zentralen Antwortselektion generiert wird. In unserer vierten Studie überprüften wir, ob Zahlen auch mit Zeit assoziiert werden. Wir forderten Versuchspersonen auf zwei seriell dargebotene Zahlen miteinander zu vergleichen. Versuchspersonen waren schneller zeitlich aufsteigende Zahlen (z.B. erst 2 dann 3) als zeitlich abfolgenden Zahlen (z.B. erst 3 dann 2) miteinander zu vergleichen. Unsere Ergebnisse wurden im Sinne unseres vorwärtsgerichteten Mechanismus des Zählens („1-­2-­3“) interpretiert.

This study is an investigation into the relationship between numeric cognition and aging. Specifically, older and younger adults engaged in an experimental protocol that allowed observation of number comparison accuracy and response time latencies associated with the SNARC effect, the distance effect, and number format. The experimental protocol featured a computerized magnitude comparison task wherein the participants were prompted to identify the larger of two numbers. Half of the trials featured whole numbers and half featured fractions. The number stimuli were consistently mapped such that half of all trials were at near distance (i.e., difference of 2) or far distance (i.e., difference of 4) and half of all trials had the larger numerosity on the left side of space and the other half with the larger numerosity on the right side of space. Older adults were significantly slower and less accurate than young adults. Both age groups were significantly slower and less accurate when comparing fractions as opposed to comparing whole numbers. The SNARC effect impaired accuracy in both age groups but did not significantly impact response times. The distance effect impacted both age cohorts in accuracy but differentially impacted older adult response times more than young adult response times. The results of this study support the model of numeric cognition as an automatic process when comparing whole numbers at a far distance and this process is not disrupted by the SNARC effect but is when comparing whole numbers at near distance. The results also indicate that fraction comparison is a controlled process even when the fraction stimuli are consistently mapped. Further investigation is necessary to understand the amount of cognitive resources necessitated by fraction processing and if training can improve fraction comparison.

How do we represent numbers and make mathematical calculations? This question is the main focus of the present work and it falls in the domain of mathematical cognition, the field of knowledge concerned with the cognitive and neurological processes that underline mathematical abilities. The mental number line, with its analogue left-to-right orientation of growing numerical values, is often regarded as the best candidate to the role of mental representation of numbers. Many studies have examined the so-called mental number line taking the Spatial-Numerical Association of Response Codes (SNARC) effect as evidence for a unique connection between space and number. However, left-to-right orientation has been shown to extend to other dimensions, including duration and physical size. Such observations converge with the notion of a general magnitude system, where different magnitudes share neural and conceptual resources. This rise an important question about the nature of the information represented along the mental number line: is it exclusive to number or not? The present work is divided in 4 chapters. Chapter 1 addresses several issues in mental representations of numbers. Research in mathematical cognition has a long history and has made considerable progress over the last decades; sometimes this big volume of data makes it difficult to gain a global view of what the state-of-the-art is. For this reason, Chapter 1 will offer an overview of the different mental representations of numbers, whether innate or acquired, precise or approximate, symbolic or non symbolic. On the one hand, the most important insight gained on mental representations of numbers are listed; on the other, literature on the representation of time, space, number and intensity, related with number representation, are revised to show the similarities between these domains, and how those are indicative of common processing mechanisms. The theoretical background specific for the present work is introduced. A great body of evidences point out that the representation and processing of numbers is associated to an activation of spatial codes. One of the classical view of numerical cognition on this subject states that spatial codes are an imprescindible component of the long-term representation of numerical magnitude information. According to this idea, refereed to as number mental line hypothesis, numbers are systematically associated to spatial codes, as if numerical magnitudes were represented along a spatial continuum with small numbers to the left and large numbers to the right. Nevertheless, the origin of the association between numbers and space is not completely clear to date. Studies will be presented showing that the spatial coding of numbers is not stable and is not necessarily the result of long-term memory associations but, on the contrary, a flexible type of representation built during cognitive processing as the result of task demands and spatial coding preferences. Moreover, studies on the association of numbers with others, non-spatial, magnitudes will be reviewed. In Chapter 2 a series of three studies are presented, in all of them a numerosity production method of response was used. Participants performed approximate arithmetic task on symbolically presented numbers, they were instructed to respond by the production of a dot pattern, the set size of which was controlled by a rotating knob. Study 1 shows two experiments in which participants judged the average numerosity between two sequentially presented dot patterns. In Experiment 1, the response was given on a 0–20 numerical scale (categorical scaling), and in Experiment 2, the response was given by the production of a dot pattern of the desired numerosity numerosity production). Data showed that responses were shaped according to an averaging integration model. This suggests the linearity in the response scale of both of the response methods in the approximate arithmetic task. More important, the two operands were found to have the same influence in determining the result. These two experiments served as a validation tool of the numerosity production method of response to be applied in the sequent studies. Study 2 proposes one experiment using the numerosity production method of response to test the influence of the force required to respond on the Operational Momentum (OM) effect. The OM effect is the finding of a systematic tendency to overestimate the results of addition problems and underestimate the results of subtraction problems under conditions that prevent exact calculation. In this experiment the force required to turn the knob has been manipulated in three between subjects blocks. It has been suggested that the OM effect depend on the spatial representation of numbers; by showing that the elimination of psycho-motor feedback nullifies the difference between addition and subtraction, evidence are provided that the OM effect is modulated by information from a magnitude different from space (required force), even when such information is entirely task-irrelevant. Study 3 proposes an experiment on the comparison of four different effects classically considered examples of the automatic spatial organization of numerical information. The spatial-numerical association of response codes (SNARC), that is, the tendency to be faster in responding to small numbers on the left and to bigger number on the right. The distance effect, that is, close numbers are more difficult to compare than numbers far apart. The size congruency effect, that is, numbers are identified more rapidly as bigger or smaller than 5 if their physical size is congruent with the correct answer. And last but not least, the OM effect. Those effects have been tested together to investigate the relationship among them with an inter-individual differences approach. The presence of all the effects object of this study was verified in the participants set. Linear regression have been used to calculate the coefficient of each subject for each effect in order to test the correlation between all the effects this study take into consideration. The result of this study, even if not conclusive, point in the direction of a common representational mechanism underling the tested numerical effects (SNARC, size congruency, distance ). Moreover, the operational bias seem to have a negative correlation only with the SNARC effect, suggesting a connection between the two, but weekending the mental number line account of those effects. In Chapter 3 conclusions are drawn upon the presented experimental work taking into account different explanatory frameworks. The present research work use a relatively unknown method of response to numerical tasks; the numerosity production method of response. This method shows a wide range of applications and opens new scenarios in mathematical cognition, providing a good instrument to understand in detail the implications of action in mathematical cognition. Moreover, the experiments here presented provide clear indications for a role of non-spatial psycho-motor feedback in arithmetical calculations carried out with the numerosity production method of response, thus challenging the classical interpretation of OM as an effect derived from a purely spatial representation of numbers. Moreover, considering that the force information was presented haptically but numerical information visually, such integration across sensory modalities is consistent with the General magnitude system hypothesis suggesting that representations of magnitudes are multimodal. Study 3 comparing, at our knowledge for the first time, different effects connected to the mental number line hypothesis, provide new insight on the shared processing undergoing these classical findings of mathematical cognition. Our findings, although not conclusive, renew the question on the nature of the representation of numbers.
Come possiamo rappresentare i numeri e fare calcoli matematici? Questa domanda è l'obiettivo principale del presente lavoro e cade nel campo della cognizione matematica, il quale si interessa dei processi cognitivi e neurologici che sottendono le abilità matematiche. L'ipotesi della linea numerica mentale (MNL) prevede che i numeri siano rappresentati mentalmente sottoforma di una misura continua (analogica) con valori numerici crescenti da sinistra a destra. La MNL viene considerata uno dei migliori modelli per la rappresentazione mentale dei numeri. Molti studi hanno esaminato la MNL considerando l’effetto SNARC (Spatial-Numerical Association of Response Codes) come prova per una connessione univoca tra spazio e numero. Tuttavia, è stato dimostrato che la rappresentazione mentale di valori piccoli a sinistra e di valori più grandi esiste anche per grandezze diverse dalla numerosità, compresa la durata temporale e la grandezza fisica. Queste osservazioni convergono con l'idea di un sistema dove diverse grandezze (ad esempio tempo, spazio e numerosità) condividono risorse neurali e concettuali, definito sistema generale di elaborazione delle grandezze (GMS). Questo solleva un'importante domanda sulla natura delle informazioni rappresentate lungo la MNL: si tratta esclusivamente di informazioni numeriche? Il presente lavoro è diviso in 4 capitoli. Il capitolo 1 affronta diversi problemi riguardanti la rappresentazione mentale dei numeri. La ricerca nel campo della cognizione matematica ha una lunga storia e ha fatto notevoli progressi negli ultimi decenni; a volte questo grande volume di dati rende difficile ottenere una visione globale di quello che è lo stato dell'arte. Per questo motivo il Capitolo 1 offrirà una 1panoramica dei diversi modelli di rappresentazione mentale dei numeri, sia innati che acquisiti, precisi o approssimati, simbolici o non simbolici. Prima di tutto sono elencate le principali scoperte sulla rappresentazione mentale dei numeri; in secondo luogo verrà presentata una carrellata sulla letteratura che mostra come le rappresentazioni di tempo, spazio, intensità e numero interagiscano tra loro e probabilmente condividano meccanismi di elaborazione; questo fornirà un adeguato contesto teorico necessario alla chiara comprensione dei lavori sperimentali presentati nei capitoli successivi. Una gran quantità di risultati scientifici dimostra che la rappresentazione e l'elaborazione dei numeri siano associate all'attivazione di una rappresentazione di natura spaziale. Una delle posizioni canoniche della cognizione numerica a tal riguardo afferma che la codifica spaziale è una componente imprescindibile della rappresentazione mentale a lungo termine dei numeri. Secondo questa idea, che porta il nome di ipotesi della linea numerica mentale, i numeri sarebbero rappresentati come una linea continua con i numeri più piccoli a sinistra e quelli più grandi a destra. Tuttavia l'origine dell'associazione tra numeri e spazio non è stata ancora totalmente chiarita. Verranno presentati degli studi che dimostrano come la codifica spaziale dei numeri non sia, in effetti, stabile nè necessariamente il risultato di un'associazione a lungo termine, ma al contrario sia una rappresentazione flessibile costruita a partire dalle necessità di elaborazione delle informazioni specifiche per i compiti che ogniuno di noi si trova a svolgere quotidianamente. Inoltre saranno presi in considerazione studi sull'associazione dei numeri con grandezze prive di caratteristiche spaziali. Nel Capitolo 2 viene presentata una serie di tre studi sperimentali ed in ognuno di essi è stato impiegato un metodo di risposta basato sulla produzione di numerosità. I partecipanti hanno eseguito un compito di aritmetica approssimata su numeri presentati, a seconda dello studio, in notazione simbolica o non simbolica. In tutti gli studi presentati i partecipanti sono stati istruiti ad utilizzare un metodo di risposta caratterizzato dalla produzione di numerosità non simboliche, essi infatti fornivano la risposta al compito specifico nel quale erano impegnati attraverso la produzione, sullo schermo di un computer, di un insieme di punti la cui numerosità era controllata dalla rotazione di una manopola posta davanti ai partecipanti e connessa al computer. Un apposito programma si occupava di registrare il grado di rotazione della manopola ed aggiornare il numero di punti presentati sullo schermo. Lo studio 1 presenta due esperimenti in cui i partecipanti giudicavano la numerosità media tra due insiemi di punti presentati in sequenza. Nell'Esperimento 1 di questo studio, i partecipanti utilizzavano una scala di numerica di risposta da 0 a20 (scala categorica), mentre nell'Esperimento 2 la risposta è stata data attraverso il metodo di risposta basato sulla produzione di numerosità. I risultati di questo studio hanno mostrato come le risposte siano state fornite secondo un modello di integrazione Average. Questo suggerisce una linearità nella scala risposta per entrambi i metodi usati nel compito di aritmetica approssimativa. Più importante, i due operandi mostravano di esercitare la stessa influenza sulla risposta fornita dai partecipanti, il che esclude un effetto sequenza o recenza legata ai compiti impiegati. Questi due esperimenti sono serviti come strumento di validazione del metodo di risposta basato sulla produzione di numerosità al fine della sua applicazione negli studi successivi. Lo Studio 2 presenta un esperimento in cui il metodo di risposta basato sulla produzione di numerosità è stato utilizzato per testare l'effetto della forza necessaria a ruotare la manopola usata per portare a termine un compito di aritmetica mentale. In particolare si è verificata l'influenza della variabile Forza sull'effetto denominato Operational Momentum (OM). L'effetto OM è la tendenza sistematica a sovrastimare i risultati di addizione e a sottovalutare i risultati di sottrazioni in condizioni che impediscono un esatto conteggio. In questo esperimento la forza necessaria per ruotare la manopola è stata manipolata in tre blocchi tra i soggetti. La letteratura ha suggerito che l'effetto OM possa dipendere da una rappresentazione spaziale dei numeri; tuttavia i risultati di questo studio dimostrano che l'eliminazione di un feedback psicomotorio quale la forza richiesta per ruotare la manopola, porta all'annullamento della differenza tra addizioni e sottrazioni. I risultati di questo studio forniscono evidenze sperimentali dell'influenza di una grandezza priva di connotazioni spaziali quale la Forza su un fenomeno di aritmetica mentale come l'effetto OM. Questo risultato è particolarmente interessante considerando che la Forza fosse una variabile interamente irrilevante per lo svolgimento del compito. Lo Studio 3 presenta un esperimento sul confronto tra quattro diversi effetti classicamente considerati esempi dell'automaticità dell'attivazione di codici spaziali durante l'elaborazione di informazioni numeriche. Gli effetti che sono stati considerati in questo studio sono l'effetto SNARC, l'effetto distanza, l'effetto di congruenza delle dimensioni e l'effetto OM. L'effetto SNARC: la tendenza ad essere più veloci nel rispondere a numeri piccoli sulla sinistra e a numeri più grandi a destra. L'effetto distanza: il fatto per cui numeri vicini tra loro sono piu difficili da discriminare rispetto a numeri distanti tra loro. L'effetto di congruenza delle dimensioni: il fatto che i numeri sono identificati come maggiori o minori di 5 più rapidamente se la loro dimensione fisica è congruente con la loro grandezza numerica. Ultimo ma non meno importante, l'effetto OM. Tali effetti sono stati testati insieme per indagare i rapporti che li legano con un approccio basato sulle differenze individuali. La presenza di ognuno degli effetti è stata verificata. Al fine di valutare la correlazione tra i vari effetti in esame, è stato calcolato il coefficiente di regressione lineare di ciascun effetto su ognuno dei partecipanti. I risultati di questo studio, anche se non conclusivi, puntano in direzione di una rappresentazione mentale comune tra gli effetti numerici testati (effetto SNARC, effetto di congruenza della dimensione, effetto distanza). L'effetto OM, inoltre, sembra correlare negativamente con l'effetto SNARC, suggerendo una connessione tra i due, ma contraddicendo la teoria della linea numerica mentale. Nel capitolo 3 si traggono conclusioni sul lavoro sperimentale presentato tenendo conto di diversi quadri esplicativi. Il presente lavoro di ricerca utilizza un metodo di risposta per compiti numerici relativamente poco noto: il metodo di risposta basato sulla produzione di numerosità. Questo metodo presenta una vasta gamma di applicazioni e apre nuovi scenari nel campo della cognizione matematica, fornendo un valido strumento per comprendere nel dettaglio le implicazioni dell'azione nella cognizione matematica. Gli esperimenti qui presentati, inoltre, forniscono indicazioni chiare rispetto al ruolo del feedback psicomotorio con caratteristiche non spaziali in compiti di aritmetica mentale portati a termine attraverso un metodi di risposta basato sulla produzione di numerosità, mettendo così in discussione l'interpretazione classica dell'effetto OM come effetto derivato da una rappresentazione puramente spaziale dei numeri. Considerando che le informazioni riguardanti la forza sono state presentate attraverso un feedback tattile mentre le informazioni numeriche sono state presentate visivamente, tale integrazione tra modalità sensoriali diverse è coerente con l'ipotesi di un sistema generale per le grandezze. Lo studio 3 confrontando, a nostra conoscenza per la prima volta, diversi effetti legati all'ipotesi della linea numerica mentale, fornisce nuove informazioni sui meccanismi di elaborazioni condivisi a questi classici effetti nel campo della cognizione matematica. I nostri risultati, anche se non conclusivi, rinnovano la domanda sulla natura della rappresentazione mentale dei numeri.

Abstract concepts seem to be related to space dimension. Evidence of this relation refers to the domain of numerical cognition. An example is the SNARC effect (Spatial Numerical Association of Response Codes, Dehaene, Bossini, and Giraux 1993), which consists in the observation that people react faster to small number with the left hand and to large number with the right hand. This number-space interaction has been explained according to the mental number line hypothesis (e.g. Restle 1970; Dehaene, Bossini, and Giraux 1993), which claims that the representation of numbers has the form of a horizontal line upon which numbers are represented from left to right. Recently, an alternative account suggests that the association between numbers and space results from a decision process to categorize numbers as “small” and “large” before being associated with space dimension (e.g. Gevers et al. 2006b, 2010; Van Opstal and Verguts 2013). The first goal of this thesis is investigating the spatial coding of numbers. In a first study, magnitude concepts such as “small” and “large” were observed to be spatially organized like numbers. In a second study, these magnitude concepts were intermixed with numbers in a reversal design (e.g. Notebaert et al. 2006). In this study, responding as incompatible to magnitude concepts with hand or foot was observed to reverse the spatial mapping of numbers, supporting the idea that the congruency between numbers and space results from conceptual coding of magnitude (e.g. Gevers et al. 2006b, 2010; see also Van Opstal and Verguts 2013). Further evidence of association between abstract concepts and space has been provided also in the domain of emotion. On one hand, Casasanto (2009a) demonstrated that people spontaneously associate positive valence with the side of space congruent to the dominant hand. On the other hand, Holmes and Lourenco (2011) observed that emotional expressions are left-to-right spatially organized with increasing in happiness/angriness rather than positive/negative valence. A second aim of this thesis is focused on investigating the spatial coding of emotion. This was meant to understand how general are the spatial mechanisms. In a third study, the reversal paradigm (e.g. Notebaert et al. 2006) was adopted to investigate the processing mechanism underlying spatial coding of numbers and emotional valence concepts. Manipulation of the mapping between valence concepts and lateralized responses did not influence the spatial coding of numbers, suggesting a separate underlying architecture. Finally, in a fourth study, spatial coding of emotion was observed according to both valence and arousal dimensions (Casasanto 2009a; Holmes and Lourenco 2011).
Doctorat en Sciences psychologiques et de l'éducation
info:eu-repo/semantics/nonPublished

Cette thèse se situe dans un contexte de programme de recherche de Chimie Verte. Elle traite des substitutions nucléophiles aromatiques (S(N)Ar) en utilisant le couplage de deux techniques: catalyse par transfert de phase sans solvant et irradiation micro-ondes. Deux objectifs sont mis en avant: d'une part, la méthodologie pour l'amélioration de procédé (obtention des rendements les plus élevés possibles dans des conditions douces), d'autre part, la mise en évidence d'effets spécifiques des micro-ondes et la compréhension des phénomènes mis en jeu dans l'interaction rayonnement-matière. En ce qui concerne l'optimisation des rendements des S(N)Ar, l'étude se compose essentiellement de deux parties: - des éthérifications d'halogénures aromatiques ou azaaromatiques, - la fluoration de chlorodiazines. Dans le premier cas, des éthers ont pu être synthétisés avec des rendements excellents sur des substrats aromatiques activés ou non, grâce à une activation micro-ondes raisonnable et des temps de réaction d'au plus une heure. Dans le deuxième cas, l'échange fluor - chlore a été optimisé jusqu'à l'obtention de très bons rendements, de meilleures sélectivités, dans des conditions bien plus douces que la littérature. Ce mémoire propose également une discussion sur les différences non thermiques entre micro-ondes et chauffage classique (effets spécifiques). La discussion s'articule autour de la sensibilité du milieu avec le champ électrique, et de l'évolution de la polarité des espèces au cours du mécanisme réactionnel, à l'appui de mesures de caractéristiques diélectriques (e' et e") et de calculs de chimie quantique. Ces effets dépendent de la polarité et de la position relative des réactifs et de l'état de transition sur les coordonnées réactionnelles
This thesis takes place in a research program of Green Chemistry. It deals with nucleophilic aromatic substitutions (S(N)Ar) using the mixing of two techniques: solvent-free phase transfer catalysis and microwave irradiation. It consists in two objectives: - a methodology approach aiming to improvements in procedure (highest yields under mild reaction conditions), - a study of interactions between the electric field and the medium concerning specific microwave effects. Concerning the first point, the study is dealing with, on one band etherification of aromatic or azaaromatic halides and, on an other hand tluorination of chlorodiazines. In the first case, ethers have been synthesised with excellent yields on activated or non-activated aromatic halides thanks to microwave irradiation within one hour or legs as reaction time. In the second case, tluorine-chlorine exchange has been improved up to very good yields, better selectivity and under milder conditions than in the literature. This memory also focuses on non-purely thermal differences between microwave and conventional heating (specific effects). The experimental results concern the medium sensibility to the electric field and the evolution of species polarity according to the mechanism. They are based on dielectric characterics measurements (e' and e") and theoretical calculations. The specific effects depend on the relative polarities of ground and transition states and its position along the reaction coordinates

Thesis (Ph. D.)--Georgia State University, 2006.
David A. Washburn , committee chair; Claudio C. Cantalupo, Eric J. Vanman, Duane M. Rumbaugh, committee members. Electronic text (102 p. : col. ill.)) : digital, PDF file. Description based on contents viewed July 13, 2007. Includes bibliographical references (p. 79-96).

Neurons depend upon neurotransmitter release through regulated exocytosis to accomplish the immense processing performed within the central nervous system. The SNARE hypothesis points to a family of proteins that are thought to enable the membrane fusion that leads to exocytosis. The secondary structure of SNAP-25 is unique among SNARE proteins in that it has two alpha helical SNARE motifs and a cysteine rich (C85, C88, C90, C92) membrane interacting region but notransmembrane domain. The cysteines may be modified by palmitoylation or oxidation but the role of these modifications in vivo is not well understood. Our goal is to elucidate possible regulatory roles of SNAP-25 that relate to its unique structure and these reversible modifications. However, the study of SNAP-25 in reconstituted systems is hampered by a lack of readily available palmitoylated SNAP-25. A method for in vitro palmitoylation of SNAP-25 by HIP14, a neuronal acyltransferase, is described along with the application of a biotinylation streptavidin assay to verify palmitoylation. Palmitoylation increases the extent to which SNAP-25 interacts with lipids as observed with an environment sensitive trpytophan fluorescence assay. Palmitoylation also alters the phase transition of DPPC lipids differently than unpalmitoylated SNAP-25.This effect on the membrane may influence fusion events. Oxidation of the cysteine residues may be responsible for the sensitivity of SNAP-25 to reactive oxygen species. Our data suggests that, when oxidized, SNAP-25 does not interact with membranes to the same extent as palmitoylated SNAP-25. This may provide a mechanism for reducing exocytosis during oxidative stress. Also, oxidized SNAP-25 is not susceptible to Botulinum Neurotoxin E. The effects of oxidation and palmitoylation on the protein interactions of SNAP-25 may shed light on its role in the SNARE complex and membrane fusion.

La cognition numérique rend possible une approche expérimentale de l'intuition mathématique, pouvant être mise en parallèle des conceptions de philosophes et de mathématiciens, voire apporter des réponses à des questions épistémologiques. Deux aspects de l’intuition mathématique sont révélés par ces travaux. Le premier est l'existence de contraintes de la structure de notre système cognitif sur nos intuitions des nombres. Le second est la présence d'une composante spatiale de ces intuitions. Ces aspects sont repris dans deux études comportementales. La première indique une compression de l'échelle de représentation des nombres, la seconde précise les cadres de référence spatiaux impliqués dans les interactions spatio-numériques. Ces données vont dans le sens d'une intuition mathématique non figée, constituée à partir d'une pluralité d'expériences. Nous proposons que cette dynamique de l’intuition soit à l'origine d’intuitions complexes intervenant dans la pratique des mathématiques
Numerical cognition allow an experimental approach to mathematical intuition, which can be conceived as paralleling some conceptions developed by philosophers and mathematicians, and even as answering some epistemological issues. Two aspects of mathematical intuition are revealed by these studies. The first is the existence of constraints on the structure of our cognitive system on our intuitions of numbers. The second is the presence of a strong spatial component in these intuitions. These two aspects are considered in two behavioral studies we conducted. The first study shows a compressed representational scale of numbers, the second study specifies the spatial reference frames implicated in the spatio-numerical interactions. These data also support the idea of a non-static intuition, constituted from a plurality of experiences. We propose that this dynamic of intuition is at the origin of more complex intuitions, which play a crucial role in the practice of mathematics

Jack London’s maritime writing often interrogates the difference between the savage space of the “outside” sea and the relative domesticity of land’s civilized interior, as well as the ways in which this spatial distinction supports the sovereignty of space, society, and the self. But instead of maintaining these spatial differences, London’s work is all about exposing their increasing indistinction in the early twentieth century and the effects such a spatial destabilization had on sovereignty itself. This interrogation of the new world order and its effects on previous forms of sovereignty, the chapter argues, is what makes London’s contribution to American maritime writing (especially The Sea-Wolf and The Cruise of the Snark) so important. London’s sea stories not only acknowledge the world’s new “nomos” but the effects this order has on political and personal forms of autonomy and coherence.

In this work we seek to understand and to quantify the reactivity of benzofurazan derivatives toward secondary cyclic amines, like pyrrolidine, piperidine and morpholine, acting as nucleophile groups in SNAr reactions. For this aim, physico-chemical and structural descriptors were determined experimentally and theoretically using the DFT/B3LYP/6-31+ g (d,p) methodology. Thus, different 4-X-7-nitrobenzofurazans (X = OCH3, OC6H5 and Cl) and products corresponding to the electrophilic aromatic substitution by pyrrolidine, piperidine and morpholine, were investigated. Particularly, the HOMO and LUMO energy levels of the studied compounds, determined by Cyclic Voltammetry (CV) and DFT calculations, were used to evaluate the electrophilicity index (ω). The latter was exploited, according to Parr’s approach, to develop a relationship which rationalizes the kinetic data previously reported for the reactions of the 4-X-7-nitrobenzofurazans with nucleophiles cited above. Moreover, the Parr’s electrophilicity index (ω) of these benzofurazans determined in this work were combined with their electrophilicity parameters (E), reported in preceding papers, was found to predict the unknown electrophilicity parameters E of 4-piperidino, 4-morpholino and 4-pyrrolidino-7-nitrobenzofurazan. In addition, the relationship between the Parr’s electrophilicity index (ω) and Hammett constants σ, has been used as a good model to predict the electronic effect of the nucleophile groups. Finally, we will subsequently compare the electrophilicity index (ω) and the electrophilicity parameters (E) of these series of 7-X-4-nitrobenzofurazans with the calculated dipole moment (μ) in order to elucidate general relationships between E, ω and μ.

Background: A growing but contrasting evidence relates air pollution to cognitive decline. The role of cerebrovascular diseases in amplifying this risk is unclear. Objectives: 1) Investigate the association between long-term exposure to air pollution and cognitive decline; 2) Test whether cerebrovascular diseases amplify this association. Methods: We examined 2,253 participants of the Swedish National study on Aging and Care in Kungsholmen (SNAC-K). One major air pollutant (particulate matter ≤2.5 μm, PM2.5) was assessed yearly from 1990, using dispersion models for outdoor levels at residential addresses. The speed of cognitive decline (Mini-Mental State Examination, MMSE) was estimated as the rate of MMSE decline (linear mixed models) and further dichotomized into the upper (25% fastest cognitive decline), versus the three lower quartiles. The cognitive scores were used to calculate the odds of fast cognitive decline per levels of PM2.5 using regression models and considering linear and restricted cubic splines of 10 years exposure before the baseline. The potential modifier effect of cerebrovascular diseases was tested by adding an interaction term in the model. Results: We observed an inverted U-shape relationship between PM2.5 and cognitive decline. The multi-adjusted piecewise regression model showed an increased OR of fast cognitive decline of 81%(95%CI = 1.2–3.2) per interquartile range difference up to mean PM2.5 level (8.6 μg/m3) for individuals older than 80. Above such level we observed no further risk increase (OR = 0.89;95%CI = 0.74–1.06). The presence of cerebrovascular diseases further increased such risk by 6%. Conclusion: Low to mean PM2.5 levels were associated with higher risk of accelerated cognitive decline. Cerebrovascular diseases further amplified such risk.

This paper explores the ability to measure the impedance of a system consisting of the biological system of the patient combined with the mechanical system of the hot snare and, given a specified impedance threshold value, turn off the firing of an electrosurgical device before serious injury occurs. In electrosurgery, the tissue damage is caused by the thermal energy generated from the resistance in the cells. An impedance feedback control system is designed and tested to minimize the effects of too much thermal damage. This design is based on measuring the impedance of the system and implementing a microcontroller to coordinate the activity and to interrupt the electrosurgical device preventing further firing. The feedback control system was proven to automatically stop the electrosurgical device for three given impedance values of 500Ω, 750Ω, and 1000Ω with an accuracy of ±5Ω. The auto-stop system is able to measure and fire at 5.4 times a second with a duty cycle of 41%. This successfully minimizes the thermal injury sustained from electrosurgery.

Abstract A drain cover for swimming pools, spas and hot tubs has been designed which addresses eight hazards associated with conventional drain systems. This new drain cover, illustrated in Figure 1, eliminates hair entanglement, child evisceration and finger entrapment as well as minimizing body entrapment. Furthermore, its design and construction provide effective countermeasures against vandalism, broken drain covers, missing drain covers and structural deterioration due to environmental antagonists. Additional features unrelated to safety include a universal fastening system which adapts the cover to all circular main drains available in the United States. Also, the drain cover is an order of magnitude stronger than its competitors and has a safe flow rate that is 37% greater than its nearest competitor’s. The product has been manufactured using a PVC material that is the most resistant formulation currently known for counteracting the effects of ultraviolet radiation and chlorine and other chemicals typically found in pools. This paper presents an anatomy of the product’s development.