Artificial Antigen-Presenting Interfaces in the Service of Immunology

While the beneficial impact of modifying and/or targeting T lymphocytes is becoming increasingly accepted in the treatment of different diseases, the road towards cell-based immunotherapy is still long and winding. Major challenges that remain include, amongst others, the guidance and exquisite regulation of immune processes ex vivo. In part, this is due to the difficulties of simulating ex vivo the intimate cellular interactions that occur between T cells and antigen-presenting cells (APCs). The fate of T cells is not solely regulated by the presence of certain molecules on the surface of APCs but also by their density and spatial distribution on the micro- and nanometric scale. Moreover, mechanical properties of APCs and force-dependent conformational changes during the formation of an immunological synapse (IS; a highly organized supramolecular complex at the T cell APC interface), play a crucial role in T cell fate regulation. Various different technical means have been developed to create APC substitutes that are able to simulate ex vivo signals originating from naturally occurring APCs. Here, we review the performance of APC surrogates and discuss their contribution to understanding mechanisms underlying the ability of T cells to perform the “intelligent” mission of acquiring, processing and responding to environmental information.     

Explicit cost sensitivity analysis for linear systems with quadratic criteria

For linear systems subject to large variations in a single parameter, it is shown that the quadratic cost can be expressed exactly as the ratio of two polynomials in that parameter.     

Review of observational methods in attention deficit hyperactivity disorder (ADHD): Implications for diagnosis.

Reviewed 39 empirical studies in which direct observational methods were used to assess children in whom ADHD had been diagnosed. Classroom studies distinguished ADHD children from comparison groups better than laboratory studies. Behaviors that most consistently distinguished ADHD children from comparison groups included measures of attention, activity, and vocalization. Ways are suggested to improve the efficiency and reliability of observational research. Recommendations are made regarding the importance of classroom observations in the evaluation of ADHD children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comments on "Optimal and suboptimal stationary controls for Markov chains"

It is pointed out that the application of the theory of aggregation to the reduction method of Chen and Shieh is in error.     

A linear-quadratic-Gaussian control problem with innovations-feedthrough solution

The structure of the separation-theorem solution to the standard linear-quadratic-Gaussian (LQG) control problem does not involve direct output feedback as a consequence of the form of the performance index. It is shown here that the performance index may be generalized in a natural fashion so that the optimal control law involves output feedback [or equivalently, innovations feedthrough (IF)]. Applications where this formulation may be advantageous are indicated through an examination of properties of the IF control law.     

The 2-D Wigner solid transition in a magnetic field: A perspective

A 2-D electron system in the presence of a perpendicular magnetic field of arbitrary strength is expected to form a Wigner solid in certain regimes of density and filling factor. Some estimates of the phase diagram in these two parameters are presented and a few recent experimental results are reviewed.