Nanoscopic Tunneling Contacts on Mesoscopic Multiprobe Conductors

We derive Bardeen-like expressions for the transmission probabilities between two multi-probe mesoscopic conductors coupled by a weak tunneling contact. We emphasize especially the dual role of a weak coupling contact as a current source and sink and analyze the magnetic field symmetry. In the limit of a point-like tunneling contact the transmission probability becomes a product of local, partial density of states of the two mesoscopic conductors. We present expressions for the partial density of states in terms of functional derivatives of the scattering matrix with respect to the local potential and in terms of wave functions. We discuss voltage measurements and resistance measurements in the transport state of conductors. We illustrate the theory for the simple case of a scatterer in an otherwise perfect wire. In particular, we investigate the development of the Hall-resistance as measured with weak coupling probes.Comment: 10 pages, 5 figures, revte

The influence of observer presence on gestural behaviors by chimpanzees (Pan troglodytes)

Previous reports of the influence of observer presence on the display of gestures by chimpanzees and other apes have been hampered by relatively small samples or confounded presentation of food and an experimenter. The present study presented each of 35 chimpanzees with four conditions in constant order: (a) both food and experimenter present, (b) food absent, experimenter present, (c) food present, experimenter absent, and (d) both food and experimenter present. Seventeen subjects exhibited 23 gesture during the course of the experiment. The gestures were not randomly distributed in time [Cochran's Q (3, N = 17) = 13.78, p < .05]: gestures were concentrated in the two conditions with the experimenter present. Seventeen of the 23 gestures exhibited were in the presence of the experimenter, and the remaining three gestures were exhibited within 2 seconds prior to the arrival of the experimenter (i.e., upon the experimenter's approach). Nearly twice as many subjects gestured when both food and the experimenter were present than when only the experimenter was present. When no food was present, gestures tended to be directed toward the experimenter, whereas when both food and an observer were present, gestures were evenly split between being directed at the food and being directed at the experimenter. Thus, referential communication is exhibited by captive chimpanzees without explicit training

The cognitive implications of intentional communication: a multifaceted mirror

There is a central concern in contemporary cognitive science with the validity of the use of epistemic and intentional terms to interpret the communication patterns of non-human animals. Here I argue (a) that the human developmental transition to intentional communication is a well-described phenomenon, from an empirical standpoint; (b) that the behavioural patterns that characterise intentional communication in our own species are also well-described in the communication of our nearest living relatives, the great apes; (c) that the presence of the behavioural markers for intentional communication in non-human primates does not unambiguously implicate any particular one of a large number of often mutually contradictory hypothetical psychological process models; and (d) that intentional communication by young humans is also consistent with hypothetical process models that are, themselves, mutually contradictory. Intentional communication is a class of behaviour that is open to public, objective measurement. In contrast, the hypothetical cognitive processes supporting intentional communication in both human and non-human animals are not specified by the fact that intentional communication has occurred—they could not be, except when there is an unambiguous behavioural index of invisible psychological processes, which is a contradiction in terms. In this chapter, I will examine a number of contemporary scientific practices that purportedly reveal aspects of psychological processes underlying intentional communication and demonstrate the deficiencies of these protocols. In general, these methodological infelicities support a systematic, discipline-wide double standard of interpretation of the communication of animals and humans. I will conclude that there is no convincing evidence extant of different psychological processes in the intentional communication of apes and preverbal humans

The credibility of digital identity information on the social web: a user study

A theory of the dynamical conductance of mesoscopic conductors is presented. It is applied to mesoscopic capacitors, resonant double barriers, ballistic wires, metallic diffusive wires, and to the Corbino disk and the Hall bar in quantizing magnetic fields. Central to this approach is a discussion of the charge and potential distribution in mesoscopic conductors. It is necessary to take into account the implications of the long-range Coulomb interaction in order to obtain a charge and current conserving theory. We emphasize the low-frequency response. This has the advantage that the approach is of considerable generality. The theory can be used to discuss the self-consistency of the dc-conductance formula. The theory can also be applied to discuss the rectifying (nonlinear) behavior of mesoscopic conductors.Comment: 29 pages, figures not included (preprints with figures can be obtained by conventional mail on request from T.Christen [email protected]

PI3K-C2γ is a Rab5 effector selectively controlling endosomal Akt2 activation downstream of insulin signalling

In the liver, insulin-mediated activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway is at the core of metabolic control. Multiple PI3K and Akt isoenzymes are found in hepatocytes and whether isoform-selective interplays exist is currently unclear. Here we report that insulin signalling triggers the association of the liver-specific class II PI3K isoform γ (PI3K-C2γ) with Rab5-GTP, and its recruitment to Rab5-positive early endosomes. In these vesicles, PI3K-C2γ produces a phosphatidylinositol-3,4-bisphosphate pool specifically required for delayed and sustained endosomal Akt2 stimulation. Accordingly, loss of PI3K-C2γ does not affect insulin-dependent Akt1 activation as well as S6K and FoxO1-3 phosphorylation, but selectively reduces Akt2 activation, which specifically inhibits glycogen synthase activity. As a consequence, PI3K-C2γ-deficient mice display severely reduced liver accumulation of glycogen and develop hyperlipidemia, adiposity as well as insulin resistance with age or after consumption of a high-fat diet. Our data indicate PI3K-C2γ supports an isoenzyme-specific forking of insulin-mediated signal transduction to an endosomal pool of Akt2, required for glucose homeostasis