An empirical interaction potential has been developed primarily to simulate displacement cascades in a UO 2 matrix. After a bibliographical survey revealed that the potentials discussed in the literature are not entirely suitable for describing point defects and their migration, we decided to adapt the most representative of the existing potentials. Our objective was specifically to reproduce transport phenomena, which are fundamental to a satisfactory description of atomic displacement cascades. The modified potential more correctly describes the experimental energies of formation (...) and migration of point defects as well as the oxygen diffusion coefficients in the superionic phase. Thermal expansion, heat capacity and enthalpy are also better modelled over a wide temperature range. The new potential is much more transferable than earlier potentials fitted mainly to the properties of perfect crystals. The initial simulated atomic displacement cascades showed that this potential is well suited to the description of structural effects created by decelerating recoil nuclei in a UO 2 matrix. (shrink)

The extremely preterm infant, born before 28 weeks of gestational age, has been the focus of much ethical discussion. These infants have a significant risk of mortality and morbidity, and it is not...

Two variables are usually recognised as determinants of human causal learning: the contingency between a candidate cause and effect, and the temporal and/or spatial contiguity between them. A common finding is that reductions in temporal contiguity produce concomitant decrements in causal judgement. This finding had previously (Shanks & Dickinson, 1987) been interpreted as evidence that causal induction is based on associative learning processes. Buehner and May (2002, 2003, 2004) have challenged this notion by demonstrating that the impact of temporal delay (...) depends on expectations about the timeframe between cause and effect. A corollary of this knowledge-mediation account is that in certain situations longer delays could facilitate, while shorter delays should impair, causal learning. Here we present two experiments involving a physical apparatus that demonstrate a detrimental effect of contiguity under certain conditions. In contrast to all previous studies, delays universally promoted causal learning. This evidence is clearly at variance with the notion of a bottom-up contiguity bias in causal induction. A new, more general timeframe bias is discussed. (shrink)

ABSTRACTIn our everyday life, we frequently switch between different tasks, a faculty that changes with age. However, it is still not understood how emotion impacts on age-related changes in task s...

In order to improve our understanding of the components that reflect functionally important processes during reward anticipation and consumption, we used principle components analyses (PCA) to separate and quantify averaged ERP data obtained from each stage of a modified monetary incentive delay (MID) task. Although a small number of recent ERP studies have reported that reward and loss cues potentiate ERPs during anticipation, action preparation, and consummatory stages of reward processing, these findings are inconsistent due to temporal and spatial overlap (...) between the relevant electrophysiological components. Our results show three components following cue presentation are sensitive to incentive cues (N1, P3a, P3b). In contrast to previous research, reward‐related enhancement occurred only in the P3b, with earlier components more sensitive to break‐even and loss cues. During feedback anticipation, we observed a lateralized centroparietal negativity that was sensitive to response hand but not cue type. We also show that use of PCA on ERPs reflecting reward consumption successfully separates the reward positivity from the independently modulated feedback‐P3. Last, we observe for the first time a new reward consumption component: a late negativity distributed over the left frontal pole. This component appears to be sensitive to response hand, especially in the context of monetary gain. These results illustrate that the time course and sensitivities of electrophysiological activity that follows incentive cues do not follow a simple heuristic in which reward incentive cues produce enhanced activity at all stages and substages. (shrink)

We consider the time delay of massive, non-relativistic, one-dimensional particles due to a tunneling potential. In this setting the well-known Hartman effect asserts that often the sub-ensemble of particles going through the tunnel seems to cross the tunnel region instantaneously. An obstacle to the utilization of this effect for getting faster signals is the exponential damping by the tunnel, so there seems to be a trade-off between speedup and intensity. In this paper we prove that this trade-off is never in (...) favor of faster signals: the probability for a signal to reach its destination before some deadline is always reduced by the tunnel, for arbitrary incoming states, arbitrary positive and compactly supported tunnel potentials, and arbitrary detectors. More specifically, we show this for several different ways to define “the same incoming state” and “the same detector” when comparing the settings with and without tunnel potential. The arrival time measurements are expressed in the time-covariant approach, but we also allow the detection to be a localization measurement at a later time. (shrink)

Correction of sensory transmission delays is an intractable problem, since there is no absolute reference for calibration. Phase-alignment is a practical alternative solution and can be realized by adaptive filters that operate locally with simple error signals.

Every infant has a right to bodily integrity. Removing healthy tissue from an infant is only permissible if there is an immediate medical indication. In the case of infant male circumcision there is no evidence of an immediate need to perform the procedure. As a German court recently held, any benefit to circumcision can be obtained by delaying the procedure until the male is old enough to give his own fully informed consent. With the option of delaying circumcision providing all (...) of the purported benefits, circumcising an infant is an unnecessary violation of his bodily integrity as well as an ethically invalid form of medical violence. Parental proxy ‘consent’ for newborn circumcision is invalid. Male circumcision also violates four core human rights documents—the Universal Declaration of Human Rights, the Convention on the Rights of the Child, the International Covenant on Civil and Political Rights, and the Convention Against Torture. Social norm theory predicts that once the circumcision rate falls below a critical value, the social norms that currently distort our perception of the practice will dissolve and rates will quickly fall. (shrink)

There is some complementarity of models for the origin of the electroencephalogram (EEG) and neural network models for information storage in brainlike systems. From the EEG models of Freeman, of Nunez, and of the authors' group we argue that the wavelike processes revealed in the EEG exhibit linear and near-equilibrium dynamics at macroscopic scale, despite extremely nonlinear – probably chaotic – dynamics at microscopic scale. Simulations of cortical neuronal interactions at global and microscopic scales are then presented. The simulations depend (...) on anatomical and physiological estimates of synaptic densities, coupling symmetries, synaptic gain, dendritic time constants, and axonal delays. It is shown that the frequency content, wave velocities, frequency/wavenumber spectra and response to cortical activation of the electrocorticogram (ECoG) can be reproduced by a “lumped” simulation treating small cortical areas as single-function units. The corresponding cellular neural network simulation has properties that include those of attractor neural networks proposed by Amit and by Parisi. Within the simulations at both scales, sharp transitions occur between low and high cell firing rates. These transitions may form a basis for neural interactions across scale. To maintain overall cortical dynamics in the normal low firing-rate range, interactions between the cortex and the subcortical systems are required to prevent runaway global excitation. Thus, the interaction of cortex and subcortex via corticostriatal and related pathways may partly regulate global dynamics by a principle analogous to adiabatic control of artificial neural networks. (shrink)

We need to rethink our attitudes to the bodies of the dead in order to increase our willingness to donate organs and tissuesMy father died aged 87 on January 20, 1998. It was the day of his 42nd wedding anniversary. He been admitted to a major teaching hospital with jaundice of unknown origin. He died after a medical procedure and a delay in diagnosis and management of bleeding after the procedure. I believed it was important to understand why he had (...) died and what the underlying cause of his jaundice had been. I requested an autopsy.My father was not only the best father a person could have had, but my closest friend. The circumstances of his death were especially sad for me. I was on a plane while he was allowed to die of blood loss in intensive care over a period of hours, becoming progressively more delirious and experiencing the slow motion throes of death. I was told he had died while I was still in the air. My first thought was that I would never again see him or hear his deep chuckle. I would never again feel the gentle touch of his large hands. He would never see my daughter grow up as he had wanted to, playing, and laughing on the beach.I have witnessed many autopsies. As medical students, we had to attend autopsy each morning at 8.30 am as a part of pathology in fourth year medicine. Before this, we had two years of anatomy dissection, probing every crevice of the formalin fixed human body. I learnt an immense amount from these activities. But I also knew how gruesome the autopsy is. I knew that an autopsy would mean that my father would be dismembered. But I had no hesitation in requesting …. (shrink)

L'interprétation de l'eschatologie paulinienne est dominée par la question de son rapport avec l'apocalyptique juive. Les points communs, soulignés par J.C. Beker à la suite de E. Käsemann, ne sont pas contestables, mais ne doivent pas occulter des différences notables, qui tiennent à la prééminence du Christ dans la vision paulinienne des événements de la fin. Ni l'attente ni le retard de la parousie ne semblent avoir eu, quoi qu'on en dise, d'influence décisive sur la pensée de l'Apôtre, mais bien (...) plutôt la réconciliation avec Dieu par la Croix et l'inauguration d'une humanité nouvelle dans la résurrection du Christ.Les lettres deutéropauliniennes ne rnodifient pas fondamentalement cette eschatologie, si ce n'est qu'elles accentuent encore l'emprise de la christologie sur la vision de la fin : à ceux qui attendent les ascensions célestes promises par la littérature apocalyptique, Paul répond qu'ils possèdent déjà leur être ressuscité avec le Christ, qui trône bien au-dessus de tous les être célestes. Ses idées sur le jugement dernier et la rétribution finale sont parfois dépendantes de celles du judaïsme, souvent imprécises et limitées, mais c'est toujours sa connaissance du Ressuscité, second Adam, qui conduit sa réflexion et l'aide à déchiffrer le destin final de l'humanité dans le Christ. The interpretation of pauline eschatology is dominated by the question of its rapport with Jewish apocalypse. The common points, underlined by J.C. Beker following E. Käsemann, cannot be contested, but should not hide the notable differences, which are based on the pre-eminence of Christ in the Pauline vision of the final events. Neither the expectation nor the delay of the Parousia does not seem to have had, despite what is said, a decisive influence on the Apostle’s thinking. He was concerned more about reconciliation with God through the cross and the inauguration of a new humanity by the resurrection of Christ.The deuteropauline letters do not fundamentally modify this eschatology, except in so far as they accentuate the dominance of Christology on the vision of the end. For those who await the celestial ascensions promised by apocalyptic literature, Paul answers that they already possess their resurrected being with Christ, who sits well above are celestial beings. These ideas on the Last Judgement and the final retribution are sometimes dependent on those of Judaism, often imprecise and limited, but it is always Paul's knowledge of the Resurrected, the second Adam, which directs his reflection and helps to decipher the final destiny of humanity in Christ. (shrink)