1,338 research outputs found

    An Exact Renormalization Group analysis of 3-d Well Developed turbulence

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    We take advantage of peculiar properties of three dimensional incompressible turbulence to introduce a nonstandard Exact Renormalization Group method. A Galilean invariance preserving regularizing procedure is utilized and a field truncation is adopted to test the method. Results are encouraging: the energy spectrum E(k) in the inertial range scales with exponent -1.666+/- 0.001 and the Kolmogorov constant C_K, computed for several (realistic) shapes of the stirring force correlator, agrees with experimental data.Comment: 12 pg, 2figures, LaTex, To be published on Physics Letters

    Notes for a Political Philosophy of Dreams: Subjectivity and Freedom of the Oniric Experience

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    Este artículo toma como disparador la lectura de El Tercer Reich de los sueños de Charlotte Beradt, a partir de la cual postularemos una doble hipótesis de trabajo. Por un lado, que los sueños pueden operar como “sismógrafo” captando los movimientos tectónicos de un contexto sociopolítico excepcional; por el otro, que tales sueños tienen la potencia de funcionar como una superficie en la cual se ponen en juego las posibilidades de acción del sujeto consigo mismo en relación con las prácticas de producción de subje-tividad para pensar y ejercer la libertad. Para ello, propondremos una analítica del poder en términos de un diagrama que se despliega punto por punto, aunque desigualmente, en una red de relaciones. Desde esta perspectiva, consideraremos a los sueños como hypomnemata, i.e. relatos verdaderos que contribuyen a la producción de subjetividad para pensar y ejercer la libertad. Nos ocuparemos de revisar cómo funciona esta propuesta tanto en el archivo beradtiano como en los sueños lazarianos (de prisión, concentracionarios y post-concentracionarios) que recupera Jean Cayrol en su archivo. Veremos que esta apuesta interpretativa nos permitirá pensar políticamente a los sueños incluso en los contextos más opresivos, así como también en la actual situación pandémica.This paper is triggered by the reading of Charlotte Beradt’s The Third Reich of Dreams, from which we will postulate two hypothesis. On the one hand, that dreams can operate as a “seismograph” capturing the tectonic movements of an exceptional socio-political context; on the other hand, that such dreams can function as a surface that put into play the subject’s possibilities of action to think and exercise freedom in relation to the practices of subjectivity production. To this end, we will propose an analytic of power in terms of a diagram that unfolds point by point, albeit unevenly, in a network of relations. From this perspective, we will consider dreams as hypomnemata, i.e. true narratives that contribute to the subjectivity production for thinking and exercising freedom. We will review how this proposal works both in the Beradtian archive and in the Lazarian dreams (prison, concentrationary and post-concentrationary dreams) recovered by Jean Cayrol in his archive. We will see that this interpretative approach will allow us to think dreams in political terms, even in the most oppressive contexts, as well as in the current pandemic situation.Fil: Mc Donnell, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de General Sarmiento; Argentina. Universidad Nacional de Rosario; ArgentinaFil: Sibio, David Antonio Paolo. Universidad Nacional de General Sarmiento; Argentina. Universidad de Buenos Aires; Argentin

    Is Sedentary Behavior or Physical Activity Associated With Loneliness in Older Adults? Results of the European-Wide SITLESS Study

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    Research has found that social relationships are central to the health and well-being of an aging population. Evidence exploring the association between physical activity (PA) and sedentary behavior (SB) with social isolation and loneliness is limited. This study uses objectively measured PA and SB (ActiGraph®) and self-reported measures of loneliness (the De Jong Gierveld Loneliness Scale) and social engagement (the Lubben Social Network Scale) from the SITLESS study, a European-wide study of community-dwelling older adults. Social isolation was associated with SB where higher levels of SB were associated with an increase in the level of social isolation, controlling for age, sex, living arrangements, employment status, body mass index, educational background, marital status, and self-reported general health. In contrast, PA was not associated with social isolation, and neither SB nor PA was a statistically significant predictor of loneliness. SB may be linked to social isolation in older adults, but PA and SB are not necessarily linked to loneliness in older community-dwelling adults

    Yielding and irreversible deformation below the microscale: Surface effects and non-mean-field plastic avalanches

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    Nanoindentation techniques recently developed to measure the mechanical response of crystals under external loading conditions reveal new phenomena upon decreasing sample size below the microscale. At small length scales, material resistance to irreversible deformation depends on sample morphology. Here we study the mechanisms of yield and plastic flow in inherently small crystals under uniaxial compression. Discrete structural rearrangements emerge as series of abrupt discontinuities in stress-strain curves. We obtain the theoretical dependence of the yield stress on system size and geometry and elucidate the statistical properties of plastic deformation at such scales. Our results show that the absence of dislocation storage leads to crucial effects on the statistics of plastic events, ultimately affecting the universal scaling behavior observed at larger scales.Comment: Supporting Videos available at http://dx.plos.org/10.1371/journal.pone.002041

    Altered hippocampal morphology in unmedicated patients with major depressive illness

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    Despite converging evidence that major depressive illness is associated with both memory impairment and hippocampal pathology, findings vary widely across studies and it is not known whether these changes are regionally specific. In the present study we acquired brain MRIs (magnetic resonance images) from 31 unmedicated patients with MDD (major depressive disorder; mean age 39.2±11.9 years; 77% female) and 31 demographically comparable controls. Three-dimensional parametric mesh models were created to examine localized alterations of hippocampal morphology. Although global volumes did not differ between groups, statistical mapping results revealed that in MDD patients, more severe depressive symptoms were associated with greater left hippocampal atrophy, particularly in CA1 (cornu ammonis 1) subfields and the subiculum. However, previous treatment with atypical antipsychotics was associated with a trend towards larger left hippocampal volume. Our findings suggest effects of illness severity on hippocampal size, as well as a possible effect of past history of atypical antipsychotic treatment, which may reflect prolonged neuroprotective effects. This possibility awaits confirmation in longitudinal studies

    The Association of Physical Activity Fragmentation with Physical Function in Older Adults: Analysis from the SITLESS Study

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    The distribution of physical activity bouts through the day may provide useful information for assessing the impacts of interventions on aspects such as physical function. This study aimed to investigate the associations between physical activity fragmentation, tested using different minimum physical activity bout lengths, with physical function in older adults. The SITLESS project recruited 1360 community-dwelling participants from four European countries (≥65 years old). Physical activity fragmentation was represented as the active-to-sedentary transition probability (ASTP), the reciprocal of the average physical activity bout duration measured using ActiGraph wGT3X+ accelerometers. Four minimum bout lengths were utilised to calculate the ASTP: ≥10-s, ≥60-s, ≥120-s and ≥300-s. Physical function was assessed using the 2-min walk test (2MWT) and the composite score from the Short Physical Performance Battery (SPPB) test. Linear regression analyses, after adjusting for relevant covariates, were used to assess cross-sectional associations. After adjustment for relevant covariates, lower ASTP using ≥10-s bouts were associated with longer 2MWT distances and higher SPPB scores. Lower ASTP using ≥120-s bouts and ≥300-s bouts were associated with longer 2MWT distances but not the SPPB. Less fragmented physical activity patterns appeared to be associated with better physical function in community-dwelling older adult

    Associations of sedentary behavior bouts with community-dwelling older adults' physical function

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    The study aim was to explore associations between sedentary behavior (SB) bouts and physical function in 1360 community-dwelling older adults (≥65 years old). SB was measured using an ActiGraph wGT3X + accelerometer for seven consecutive days at the dominant hip and processed accordingly. Various SB bout lengths were assessed including: 1- to 9-minutes; 10- to 29-minutes; 30- to 59-minutes; and ≥60-minutes, as well as maximum time spent in a SB bout. Total SB time was adjusted for within the SB bout variables used (percentage SB time in the SB bout length and number of SB bouts per total SB hour). Physical function was assessed using the 2-minute walk test (2MWT), 5-times sit-to-stand (chair stand) test, and unipedal stance test (UST). Hierarchical linear regression models were utilized. Covariates such as moderate-vigorous physical activity (MVPA), demographic and health characteristics were controlled for. Lower percentage time spent in ≥60-minute SB bouts was significantly (P <.05) associated with longer 2MWT distance while lower numbers of ≥60-minute SB bouts were associated with longer 2MWT distance, shorter chair stand time and longer UST time. There were mixed associations with physical function for 10- to 29-minute SB bouts. In a large cohort of European older adults, prolonged SB bouts lasting ≥60-minutes appear to be associated with reduced physical function after controlling for MVPA and numerous other important covariates. Besides reducing SB levels, these findings suggest there is a need to regularly interrupt prolonged SB to improve physical function in older adults
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