Loved Ones Near and Far: Feinberg's Personal Significance Theory

This paper examines Todd Feinberg's theory of the misidentification syndromes

Thermal damping of quantum interference patterns of surface-state electrons

The temperature-dependent damping of quantum-mechanical interference patterns from surface-state electrons scattering off steps on Ag(111) and Cu(111) has been studied using scanning tunneling microscopy (STM) and spectroscopy in the temperature range 3,5-178 K. The thermal damping of the electron standing waves is described quantitatively within a simple plane-wave model accounting for thermal broadening due to the broadening of the Fermi-Dirac distributions of sample and tip, for beating effects between electrons with different kll vectors, and for inelastic collisions of the electrons, e.g., with phonons. Our measurements reveal that Fermi-Dirac broadening fully explains the observed damping for Ag and Cu. From the analysis of our data, lower limits of the phase-relaxation lengths at the Fermi energy EF Of the two-dimensional electron gas of L-phi(E-F)greater than or similar to 600 Angstrom at 3.5 K and greater than or similar to 250 Angstrom at 77 K for Ag(111), and of L-phi(E-F)greater than or similar to 660 Angstrom at 77 K and greater than or similar to 160 Angstrom at 178 K for Cu(111) are deduced. In contrast to integral measurements such as photoemission we measure L-phi close to EF and also locally. The latter eliminates residual line widths due to surface defect scattering found in the integrating techniques. Our STM results, therefore, currently provide a very good absolute estimate of L-phi and the inelastic lifetime tau=L-phi/v(F), respectively. Our values can be combined with photoemission results on dL(phi)/dT to derive the inelastic lifetime of surface state electrons at any T

Confinement of surface state electrons in Fabry-Perot resonators

Ag(111) surface state electrons have been confined in symmetric and asymmetric Fabry-Perot resonators formed by two atomically parallel step edges. The local density of states in the resonators has been measured by means of low-temperature scanning tunneling spectroscopy and can perfectly be explained with a simple Fabry-Perot-like model. The energy dependent reflection amplitudes and scattering phase shifts of the different kinds of Ag(111) step edges have been determined with high accuracy. The model character of the resonators opens up quantitative electron scattering experiments at test structures brought into the resonator

Capgras Syndrome: A Novel Probe for Understanding the Neural Representation of the Identity and Familiarity of Persons

Patients with Capgras syndrome regard people whom they know well such as their parents or siblings as imposters. Here we describe a case (DS) of this syndrome who presents several novel features. DS was unusual in that his delusion was modality-specific: he claimed that his parents were imposters when he was looking at them but not when speaking to them on the telephone. Unlike normals, DS's skin conductance responses to photographs of familiar people, including his parents, were not larger in magnitude than his responses to photographs of unfamiliar people. We suggest that in this patient connections from face-processing areas in the temporal lobe to the limbic system have been damaged, a loss which may explain why he calls his parents imposters. In addition, DS was very poor at judging gaze direction. Finally, when presented with a sequence of photographs of the same model's face looking in different directions, DS asserted that they were "different women who looked just like each other'. In the absence of limbic activation, DS creates separate memory "files' of the same person, apparently because he is unable to extract and link the common denominator of successive episodic memories. Thus, far from being a medical curiosity. Capgras syndrome may help us to explore the formation of new memories caught in flagrante delicto

Long-range adsorbate interactions mediated by a two-dimensional electron gas

We report on long-range interactions between adsorbates on metal surfaces with a surface state. A comparison of three adsorbate/substrate systems [Cu/Cu(111), Co/Cu(111), and Co/Ag(111)] suggests the general existence of such interactions and shows up common characteristics. In all cases, the interaction energy E(r) manifests itself up to a distance of 60 Angstrom, decays as 1/r(2), and oscillates with a period of lambda(F)/2. Our data are in excellent agreement with theory and establish the link between the spatial variation of the interaction energy and the adsorbate scattering properties. We demonstrate that the long-range interactions stabilize an ordered two-dimensional (2D) gas of adsorbates and thus create states of dilute 2D matter

Autism as a disorder of neural information processing: directions for research and targets for therapy

The broad variation in phenotypes and severities within autism spectrum disorders suggests the involvement of multiple predisposing factors, interacting in complex ways with normal developmental courses and gradients. Identification of these factors, and the common developmental path into which theyfeed, is hampered bythe large degrees of convergence from causal factors to altered brain development, and divergence from abnormal brain development into altered cognition and behaviour. Genetic, neurochemical, neuroimaging and behavioural findings on autism, as well as studies of normal development and of genetic syndromes that share symptoms with autism, offer hypotheses as to the nature of causal factors and their possible effects on the structure and dynamics of neural systems. Such alterations in neural properties may in turn perturb activity-dependent development, giving rise to a complex behavioural syndrome many steps removed from the root causes. Animal models based on genetic, neurochemical, neurophysiological, and behavioural manipulations offer the possibility of exploring these developmental processes in detail, as do human studies addressing endophenotypes beyond the diagnosis itself

Associations between language development and skin conductance responses to faces and eye gaze in children with autism spectrum disorder

Attention to social stimuli is associated with language development, and arousal is associated with the increased viewing of stimuli. We investigated whether skin conductance responses (SCRs) are associated with language development in ASD: a population that shows abnormalities in both attention to others and language development. A sample of 32 children with ASD (7 y – 15 y; M =9 y) was divided into two groups, based on language onset histories. A typically developing comparison group consisted of 18 age and IQ matched children. SCRs were taken as the participants viewed faces. SCRs differentiated the ASD group based on language onset and were associated with abnormal attention to gaze in infancy and subsequent language development