13 research outputs found
Characterization of optical properties and surface roughness profiles: The Casimir force between real materials
The Lifshitz theory provides a method to calculate the Casimir force between
two flat plates if the frequency dependent dielectric function of the plates is
known. In reality any plate is rough and its optical properties are known only
to some degree. For high precision experiments the plates must be carefully
characterized otherwise the experimental result cannot be compared with the
theory or with other experiments. In this chapter we explain why optical
properties of interacting materials are important for the Casimir force, how
they can be measured, and how one can calculate the force using these
properties. The surface roughness can be characterized, for example, with the
atomic force microscope images. We introduce the main characteristics of a
rough surface that can be extracted from these images, and explain how one can
use them to calculate the roughness correction to the force. At small
separations this correction becomes large as our experiments show. Finally we
discuss the distance upon contact separating two rough surfaces, and explain
the importance of this parameter for determination of the absolute separation
between bodies.}Comment: 33 pages, 14 figures, to appear in Springer Lecture Notes in Physics,
Volume on Casimir Physics, edited by Diego Dalvit, Peter Milonni, David
Roberts, and Felipe da Ros
Electrophysiological footprint of slMFB-DBS in depression: Study design and preliminary results
Element cycling during the transition from alkaline to acidic environment in an active porphyry copper tailings impoundment, Chuquicamata, Chile
Cultivation of Medicinal Plants as a Tool for Biodiversity Conservation and Poverty Alleviation in the Amatola Region, South Africa
Perspectives on the implementation of closed-loop deep brain stimulation: from neurological to psychiatric disorders
Background: Deep brain stimulation (DBS) is a highly efficient, evidence-based therapy to alleviate symptoms and improve quality of life in movement disorders such as Parkinson’s disease, essential tremor, and dystonia, which is also being applied in several psychiatric disorders, such as obsessive-compulsive disorder and depression, when they are otherwise resistant to therapy. Summary: At present, DBS is clinically applied in the so-called open-loop approach, with fixed stimulation parameters, irrespective of the patients’ clinical state(s). This approach ignores the brain states or feedback from the central nervous system or peripheral recordings, thus potentially limiting its efficacy and inducing side effects by stimulation of the targeted networks below or above the therapeutic level. Key Messages: The currently emerging closed-loop (CL) approaches are designed to adapt stimulation parameters to the electrophysiological surrogates of disease symptoms and states. CL-DBS paves the way for adaptive personalized DBS protocols. This review elaborates on the perspectives of the CL technology and discusses its opportunities as well as its potential pitfalls for both clinical and research use in neuropsychiatric disorders. Neurological Motor Disorder