Development of early expressive and communicative action: Reinterpreting the evidence from a dynamic systems perspective.

A systems approach is introduced and applied to the development of expressive and communicative action of infants in the first year of life. In this approach, expressive and communicative actions are organized, as part of cooperative systems with other elements of the infants' physiology, cognition, behavior, and social environment. A systems approach presumes that order arises dynamically as a result of the interaction between the cooperating elements that are changing asynchronously, rather than as the result of centrally coordinated developmental change that is synchronous across domains. The systems approach further assumes that the control parameter responsible for eliciting developmental change may be different depending on age, context, and task. It offers a means to understand previously unexplained developmental phenomena: the appearance of mature forms of expression before mature functon has been achieved, the asynchronous rates of development of communicative-action components, discontinuous developmental shifts arising from continuous processes, and the process by which adults influence communicative development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Confidentiality in psychotherapy: History, issues, and research.

Discusses ethical guidelines of the American Psychological Association regarding confidentiality in psychotherapy. Possible inconsistencies between these guidelines and privileged communication are explored. It is asserted that additional research is needed to determine the implications for psychotherapy of the ethical limitations to confidentiality and the legal restrictions on privileged communication. The relevance of moral philosophy to issues of confidentiality is considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A monolithically integrated optical differential amplifier forapplications in smart pixel arrays

A cascadable, optical differential amplifier with an active output is realized in AlGaAs-GaAs by the monolithic integration of three devices: A photodiode (PD), a light-emitting diode (LED) and a combination of a photodiode and a junction field-effect transistor (PINFET). A minimum optical switching power of 15 pW, an optical gain of more than 10⁶, a contrast ratio greater than 1000 and an optical output power of 17 μW are obtained. For a contrast ratio of 10, a switching energy of 2 pJ is required, resulting in a unity gain bandwidth of 4.2 MHz     

Phantom study of optimization of spiral-CT and 3D reconstruction of the tracheobronchial system

PURPOSE: To optimise three-dimensional spiral CT of the tracheobronchial tree using adequate acquisition and reconstruction parameters for spiral CT of the chest. MATERIAL AND METHODS: Qualitative and quantitative assessment of different 3 D reconstructions of two test objects of the tracheobronchial tree depending on section thickness, reconstruction interval, pitch, and reconstruction algorithm used in spiral CT (Siemens, Somatom plus S) of the chest. The frequency of volume and stairstep artifacts was evaluated. The 3 D reconstructions were generated using a seeded VOI-technique (Allegro, ISG). RESULTS: Reduction of artifacts was achieved by decreasing section thickness. Increasing overlap of source images, lowering the pitch factor, and application of the reconstruction algorithm "slim". Section thickness was the single most important factor which was mainly responsible for the occurrence of volume artifacts. Stairstep artifacts were primarily influenced by the reconstruction interval. CONCLUSION: Spiral CT with a section thickness > 4 mm is not adequate for 3 D reconstructions of the tracheobronchial tree. Overlapping source images with a pitch of 1 and the reconstruction algorithm "slim" can be recommended to reduce artifacts.     

Focusing experiments in plasma coaxial railguns

The "projectile" being accelerated in a plasma coaxial railgun is a complex mixture: besides plasma, it contains solid particles of fuse, liquid and vapor metal. Materials accelerated are not limited to the fuse metal, the rail material through ablation also contributes to them. For such a situation "plasma focusing" is a simplified term, borrowed from electron beams in vacuum technology (and electron lenses) where the Busch's theorem describes the tendency of electrons to approach the axis (or to focus) in the presence of radial and axial components of magnetic fields and under the assumption that on the time scale of interest, the ions remain essentially motionless. The present work is the first in a series of papers trying to classify and to explain a larger spectrum of problems affecting a mixture of metals in different states (solid, liquid, and vapor) in which magnetic fields, transient diffusion, and other phenomena may be used to contain or focus a flowing stream under thermal expansion. The main variable used in experiments to affect the focusing was the topology of magnetic fields, temporal and spatial. Emphasis was given to the effects of penetration of magnetic field in the bulk of the "projectile" being accelerated. Experiments were conducted on a 0.5-m coaxial railgun with inner and outer coaxial radii of 0.25 and 0.31 in., respectively. The rails were constructed from stock sizes of copper pipe with a CVD tungsten coating on the inner rail surface to minimize arc damage during the shots. External magnetic fields were applied to a 3-mg metallic vapor arc accelerated with a 250 kA capacitive discharge. Plasma characteristics were measured with magnetic pick-up coils and langmuir probes. Confinement and focusing of the arc was examined with break screens and metal deposition analysis.     

Final design of an air core, compulsator driven, 60 caliber railgunsystem

The manufacturing phase of a laboratory-based small-caliber electromagnetic (EM) launcher and compulsator power supply is discussed. The objective of the 29-month program is to develop a compact, lightweight test bed capable of accelerating 32 g masses to 2 km/s at a rate of 10 Hz. Both the power supply and launcher feature significant component design advances which will allow the system to operate at considerably higher energy and power densities than previously demonstrated. The 750 kg compulsator will generate 2.2 kV and the silicon-controlled rectifier (SCR) switch will commutate 386 kA pulses into the 1.6-m long, 0.60 caliber augmented solid armature railgun. The final design and predicted operating characteristics of the compulsator system are described. Overall system performance parameters are reported, including results from the optimization code used to aid in the design of the compulsator system. A system design overview is presented, with emphasis on new materials and state-of-the-art machine components to be used for the first time in a compulsator     

A retina with parallel input and pulsed output, extractinghigh-resolution information

Animal eyes resolve images 10-100 times better than either the acceptance angle of a single photoreceptor or the center-to-center distance between neighboring photoreceptors. A new model of the fly's visual system emulates this improved performance, offering a different approach to subpixel resolution. That an animal without a cortex is capable of this performance suggests that high level computation is not involved. The model takes advantage of a photoreceptor cell's internal structure for capturing and transducing light. This organelle is a waveguide. Neurocircuitry exploits the waveguide's optical nonlinearities, namely the shoulder region of its gaussian, angular-sensitivity profile, to extract high resolution information from the visual scene. The receptive fields of optically disparate inputs overlap in space. Photoreceptor input is continuous rather than discretely sampled. The output of the integrating module is a signal proportional to the position of the target within the detector array. Input imbalance at the level of the photodiode modules is detected by circuitry connecting neighboring visual elements. A pulsed network of these connections forms a parallel array that segments edges of an object and continuously reports its position to the underlying layer of feature extractors, offering a new approach to real time processing with high resolution and reduced computational load.