3,375 research outputs found

    Serial Position and von Restorff Effect on Memory Recall

    Get PDF
    In lieu of an abstract, below is the first paragraph of the paper. This study tested the von Restorff and Serial Position Effect on memory recall with 28 introductory psychology students at St. John Fisher College. Subjects were tested to see if they would remember the first five words and the last five words of a twenty word PowerPoint presentation. The control group saw all the words in the presentation in a black font; while the experimental group saw the same, they saw the eleventh word in a red type, testing the von Restorff effect. The control group showed results consistent with past research: that the first few words and last few words were remembered more than any of the other words; however, their results were not statistically significant. The experimental group furthered the primacy and recency effect and also furthered the von Restorff effect because the entire experimental group remembered the isolated word, p=.01

    An efficient mixed variational reduced order model formulation for non-linear analyses of elastic shells

    Get PDF
    The Koiter-Newton method had recently demonstrated a superior performance for non-linear analyses of structures, compared to traditional path-following strategies. The method follows a predictor-corrector scheme to trace the entire equilibrium path. During a predictor step a reduced order model is constructed based on Koiter's asymptotic post-buckling theory which is followed by a Newton iteration in the corrector phase to regain the equilibrium of forces. In this manuscript, we introduce a robust mixed solid-shell formulation to further enhance the efficiency of stability analyses in various aspects. We show that a Hellinger-Reissner variational formulation facilitates the reduced order model construction omitting an expensive evaluation of the inherent fourth order derivatives of the strain energy. We demonstrate that extremely large step sizes with a reasonable out-of-balance residual can be obtained with substantial impact on the total number of steps needed to trace the complete equilibrium path. More importantly, the numerical effort of the corrector phase involving a Newton iteration of the full order model is drastically reduced thus revealing the true strength of the proposed formulation. We study a number of problems from engineering and compare the results to the conventional approach in order to highlight the gain in numerical efficiency for stability problems

    An efficient numerical method for shakedown analysis

    Get PDF
    The algorithm proposed in [9] for incremental elastoplasticity is extended and applied to shakedown analysis. Using the three field mixed finite element proposed in [22] a series of mathematical programming problems or steps, obtained from the application of the proximal point algorithm to the static shakedown theorem, are obtained. Each step is solved by an Equality Constrained Sequential Quadratic Programming (EC-SQP) tech- nique that allows a consistent linearization of the equations improving the computational efficiency

    Prospective memory in patients with relapsing remitting Multiple Sclerosis

    Get PDF
    Prospective Memory (PM) is a set of cognitive abilities that allow us to remember to perform planned actions or delayed intentions. It requires the recall of the content of the planned task in the form of an intention to be able to execute it at the 4 appropriate moment. Previous studies have yielded conflicting results as some show that MS patients have difficulty in remembering the content of intentions and others in the process of self-initiation of delayed intentions. Moreover, the relationship between PM and clinical variables also remains unclear. The aim of this study is to investigate PM in Relapsing-Remitting Multiple Sclerosis (RRMS) with two experimental tests that evaluate different aspects of the MP. Another aim of the current study was to analyse the relationship between PM and demographic variables and clinical variables. Methods: 36 outpatients with a diagnosis of RRMS attending to two centers specialized in multiple sclerosis clinics, were recruited. Thirty five healthy volunteers formed the contrast group (CG), matched for age, gender and education with the MS patients. A neuropsychological test battery that included two techniques for measuring PM was administered. The Cóndor test consists of reading a text whilst simultaneously executing many actions. In the Multitask Prospective Memory (MTPM), the participant must remember to initiate a complex intention, which was previously planned. The test yields formation scores of the intention, initiation, plan retention capacity and finally two execution scores. A depression scale (Beck Depression Inventory, BDI-II) was administered and physical disability was revealed using the Expanded Disability Status Scale. Results: In the RRMS group, the majority of patients (80.6%) had none or minimal signs of depression according to BDI-II classification criteria. Seventy five % of patients were in full- or half-time employment, 13.9% were unemployed or in occasional employment and 11.1% were house wives or retired on grounds of age. With respect to cognitive performance 47.2% of MS patients presented cognitive impairment. RRMS patients and the CG did not differ significantly on age and years of formal education. Groups showed no significant differences in distribution of Gender. Patients scored significantly lower than the CG on the Cóndor?s total score, p = 5 .007, d = 0.7. On the MTPM, the CG obtained significantly more points for intention formation than patients, p = .027, d = 0.5. Sixty-three percent of patients versus 88.5% of the CG self-initiated the intention, p = .014. Patients who obtained a higher score on Formation, self-initiated more often, p = .012. Education, disease progression and depression measure with the Beck Depression Inventory, significantly and mildly correlate with the Cóndor and the MTPM. Physical disability was only associated with the intention planning phase of MTPM. Conclusion: PM appears to be impaired in patients with RRMS. A deficit was found in planning and self-initiation of planned actions. Self-initiation was influenced by planning quality. Education, disease progression and depression were shown to influence recall and execution of future intentions. Physical disability was only associated with the intention planning phase. Some previous studies have not found a significant relationship between physical disability and cognitive measures. This study suggests that PM can be affected in patients with a low level of physical impairment. Results highlight the need for objective assessment of PM in RRMS patients to be able to detect any disorder in the initial stages of the disease and start appropriate rehabilitation. Amongst the limitations of this study, the observational, non-blind design must be acknowledged, as well as the small sample size. Also, the instruments used to assess PM are relatively new and studies of their psychometric properties are lacking. Nevertheless, the use of an instrument like El Cóndor is notable, given that it was developed for local population.Fil: Cores, Evangelina Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vanotti, Sandra Ines. Universidad de Buenos Aires. Facultad de Psicología; Argentina. Instituto de Neurociencias Buenos Aires S. A.; ArgentinaFil: Orlando, Garcea. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Ramos Mejía"; ArgentinaFil: Osorio, Mabel. Provincia de Buenos Aires. Ministerio de Salud. Hospital Interzonal de Agudos "Eva Perón"; ArgentinaFil: Politis, Daniel Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Provincia de Buenos Aires. Ministerio de Salud. Hospital Interzonal de Agudos "Eva Perón"; Argentin

    A quasi-static nonlinear analysis for assessing the fire resistance of 3d frames exploiting time-dependent yield surface

    Get PDF
    In this work an automatic procedure for evaluating the axial force-biaxial bending yield surface of reinforced concrete sections in fire is proposed. It provides an accurate time-dependent expression of the yield condition by a section analysis carried out once and for all, accounting for the strength reduction of the materials, which is a function of the fire duration. The equilibrium state of 3D frames with such yield conditions, once discretized using beam finite elements, is formulated as a nonlinear vectorial equation defining a curve in the hyperspace of the discrete variables and the fire duration. A generalized path-following strategy is proposed for tracing this curve and evaluating, if it exists, the limit fire duration, that is the time of exposure which leads to structural collapse. Compared to the previous proposals on the topic, which are limited to local sectional checks, this work is the first to present a global analysis for assessing the fire resistance of 3D frames, providing a time history of the fire event and taking account of the stress redistribution. Numerical examples are given to illustrate and validate the proposal

    Lmit and shakedown analysis based on solid shell models

    Get PDF
    The paper treats the formulation of the shakedown problem and, as special case, of the limit analysis problem, using solid shell models and ES-FEM discratization technology. In this proposal the Discrete shear gap method is applied to alleviate the shear locking phenomenon

    In-Situ Observations of Longitudinal Compression Damage in Carbon-Epoxy Cross Ply Laminates Using Fast Synchrotron Radiation Computed Tomography

    Get PDF
    The role of longitudinal compressive failure mechanisms in notched cross-ply laminates is studied experimentally with in-situ synchrotron radiation based computed tomography. Carbon/epoxy specimens loaded monotonically in uniaxial compression exhibited a quasi-stable failure process, which was captured with computed tomography scans recorded continuously with a temporal resolutions of 2.4 seconds and a spatial resolution of 1.1 microns per voxel. A detailed chronology of the initiation and propagation of longitudinal matrix splitting cracks, in-plane and out-of-plane kink bands, shear-driven fiber failure, delamination, and transverse matrix cracks is provided with a focus on kink bands as the dominant failure mechanism. An automatic segmentation procedure is developed to identify the boundary surfaces of a kink band. The segmentation procedure enables 3-dimensional visualization of the kink band and conveys the orientation, inclination, and spatial variation of the kink band. The kink band inclination and length are examined using the segmented data revealing tunneling and spatial variations not apparent from studying the 2-dimensional section data

    Humans and Water in Desert “Refugium” Areas: Palynological Evidence of Climate Oscillations and Cultural Developments in Early and Mid-Holocene Saharan Edges

    Get PDF
    Saharan anthropic deposits from archaeological sites, located along wadis or close to lakes, and sedimentary sequences from permanent and dried basins demonstrate that water has always been an attractive environmental feature, especially during periods of drought. This paper reports on two very different examples of Holocene sites where “humans and water” coexisted during dry periods, as observed by stratigraphic, archaeological and palynological evidence. Independent research was carried out on the Jefara Plain (Libya, 32°N) and the Gobero area (Niger, 17°N), at the extreme northern and southern limits of the Sahara, respectively. The histories of the Jefara and Gobero areas, as revealed by the archaeological and palaeoenvironmental reconstructions, suggest that these areas were likely to have been visited and exploited for a long time, acting as anthropic refugia, and therefore they have been profoundly transformed. Human presence and actions have conditioned the local growing of plants and selected a more or less synanthropic flora. Today, modern conservation strategies should take into consideration that water reservoirs, which are crucial for the long-term conservation of biodiversity, have provided refugia in the past just as they presently do under global warming conditions

    Dal latino iam agli esiti nelle lingue romanze: verso una configurazione pragmatica complessiva*

    Get PDF
    The aim of this paper is to analyse a pragmatic marker from a pragmatic perspective, which is based both on the ‘global configuration’ of the relevant features and a prototype model. We will follow the diachronic development from Latin iam to its derivative forms in Romance languages, where the original values subsist, are reduced or augmented. The values shown in the fields of temporality (along the axes of past, present and future), aspectuality (particularly with regard to phasal features which characterise both iam and its Romance derivatives forms) and modality (with regard to different degrees of ‘expectation/sharing/presuppositionality and ‘emphasis/strengthening’ coming from the speaker’s commitment) are already present in Latin; only Rumanian testifies to the temporal value; Sardinian, Spanish, Portuguese display many modal features; Italian and French lie in an intermediate situation (even though not identical), where temporal and aspectual features are represented with a reduced presence of modal ones.Seguendo un modello a prototipo e una prospettiva pragmatica attenta alla configurazione complessiva dei tratti pertinenti, si analizza un pragmatic marker nel suo sviluppo diacronico dal latino iam ai diversi esiti nelle lingue romanze, ove i valori originari sono mantenuti, ridotti o accresciuti. I valori esplicati nell’ambito della temporalità (lungo i tre assi passato, presente, futuro), dell’aspettualità (in particolare in relazione ai tratti fasali che caratterizzano sia iam che i suoi esiti nelle lingue romanze) e della modalità (relativamente sia a gradi diversi di aspettativa/condivisione/presupposizionalità, sia ad aspetti di enfasi/rafforzamento derivanti dal commitment del parlante) sono già presenti in latino; il romeno si limita agli usi strettamente temporali; sardo, spagnolo, portoghese sfruttano vari tratti modali; italiano e francese invece sembrano porsi in una situazione intermedia (per altro non coincidente), di parziale presenza di tratti non solo temporali e aspettuali, ma anche - sebbene in misura ridotta - modali
    corecore