Collective dynamics of strain-coupled nanomechanical pillar resonators

Semiconductur nano- and micropillars represent a promising platform for hybrid nanodevices. Their ability to couple to a broad variety of nanomechanical, acoustic, charge, spin, excitonic, polaritonic, or electromagnetic excitations is utilized in fields as diverse as force sensing or optoelectronics. In order to fully exploit the potential of these versatile systems e.g. for metamaterials, synchronization or topologically protected devices an intrinsic coupling mechanism between individual pillars needs to be established. This can be accomplished by taking advantage of the strain field induced by the flexural modes of the pillars. Here, we demonstrate strain-induced, strong coupling between two adjacent nanomechanical pillar resonators. Both mode hybridization and the formation of an avoided level crossing in the response of the nanopillar pair are experimentally observed. The described coupling mechanism is readily scalable, enabling hybrid nanomechanical resonator networks for the investigation of a broad range of collective dynamical phenomena.

Ordination and cognitive complexity as related to clinical depression

Personal construct psychology has contributed substantially to our understanding of psychopathology. The few studies of personal construct psychology in depression have focused on the content of self-constructs and cognitive complexity. The purpose of this study was to examine the construct system in depressed patients by investigating the relation of depressive symptoms to the content of constructs about others, cognitive complexity, and ordination. Participants were divided into three groups of 25. The depressed group had either a major depressive episode or dysthymic disorder; psychiatric controls had nonaffective psychological disorders; normal controls were hospital employees who had not exhibited psychological distress. Results indicated no differences among the three groups in cognitive complexity. However, normal controls exhibited a higher degree of ordination than either patient group. Furthermore, depressed and psychiatric controls utilized ambiguous constructs more than normal subjects. Finally, symptom severity within the depressed group related to the use of ambiguous and undesirable constructs. On the basis of these and others' results, a "two-level" personal construct explanation of depression is offered. On a comprehensive level, ordination and the use of ambiguous constructs could be viewed as relating to general psychological adaptation, whereas negative self-construing (and perhaps ambiguous construing) may relate more directly to depression. Therapeutic implications and directions for future research are discussed.