Tracing of Neuronal Connections in the Human Brain by Magnetic Resonance Imaging in vivo

Axon degeneration after disruption of fibre tracts in the mammalian nervous system is accompanied by myelin breakdown which leads to changes in its magnetic resonance properties. In two patients with pure motor strokes due to small ischaemic lesions restricted to the internal capsule, magnetic resonance imaging disclosed a narrow band of pathological signal increase descending band-like into the brain stem and ascending to the precentral gyrus, which corresponded to the well-known path of the pyramidal tract. The findings suggest that in man anterograde and possibly retrograde fibre degeneration can be traced in vivo by conventional magnetic resonance imaging techniques. Critical conditions are the presence of small, strategically located lesions, appropriate choice of imaging plane, and the interval between time of lesion and of imaging. This demonstration may open a new era for functional neuroanatomy of man

Projections of Virasoro Singular Vectors

We use recently derived explicit formulae for the Virasoro algebra's singular vectors to give constructive proofs of three results due to Feigin and Fuchs. The main result, which is needed for a rigorous treatment of fusion, describes the action of the singular vectors on conformal fields.Comment: 11 p

Singular Vectors of the Virasoro Algebra

We give expressions for the singular vectors in the highest weight representations of the Virasoro algebra. We verify that the expressions --- which take the form of a product of operators applied to the highest weight vector --- do indeed define singular vectors. These results explain the patterns of embeddings amongst Virasoro algebra highest weight representations.Comment: 15 p

Matrix Product State applications for the ALPS project

The density-matrix renormalization group method has become a standard computational approach to the low-energy physics as well as dynamics of low-dimensional quantum systems. In this paper, we present a new set of applications, available as part of the ALPS package, that provide an efficient and flexible implementation of these methods based on a matrix-product state (MPS) representation. Our applications implement, within the same framework, algorithms to variationally find the ground state and low-lying excited states as well as simulate the time evolution of arbitrary one-dimensional and two-dimensional models. Implementing the conservation of quantum numbers for generic Abelian symmetries, we achieve performance competitive with the best codes in the community. Example results are provided for (i) a model of itinerant fermions in one dimension and (ii) a model of quantum magnetism.Comment: 11+5 pages, 8 figures, 2 example

EXTERNAL QUALITY FACTOR OF ANTENNAS AND THEIR USE IN FILTENNA DESIGN

Filtering antennas, or filtennas, have become a growing topic of interest in the pursuit of the minimization of the RF front end. Combining the filter and antenna, which are integral to RF front ends, allow for a decrease in the size, weight, and power consumption. In addition, a fully integrated filtenna can improve the overall performance of the RF system due to decreases in losses without sacrificing filtering capabilities. This improvement in performance is demonstrated through a noise analysis comparing a traditional RF front end utilizing a wideband antenna and an RF front end utilizing a tunable filtenna. The design of filtennas has been mostly outlined already in the existing literature and is achieved through similar methods to filter design. However, the existing filtenna literature has very little discussion on the external quality factor of the antenna, a parameter that is important to obtaining the correct desired bandwidth and correct desired response of the structure. The discussion of this topic is expanded upon in this work, and in doing so another method for finding this parameter is presented. Other methods for finding the external quality factor of antennas can also be applied from the antenna literature once the relationship between the external quality factor in filter design and the external quality factor of an antenna is understood as is presented in this work. An example second-order tunable filtenna covering all of S-band is simulated and fabricated to validate the ideas presented

The Cost of Monitoring Alone

We compare the succinctness of two monitoring systems for properties of infinite traces, namely parallel and regular monitors. Although a parallel monitor can be turned into an equivalent regular monitor, the cost of this transformation is a double-exponential blowup in the syntactic size of the monitors, and a triple-exponential blowup when the goal is a deterministic monitor. We show that these bounds are tight and that they also hold for translations between corresponding fragments of Hennessy-Milner logic with recursion over infinite traces.Comment: 22 page

Advanced methods for safe visualization on automotive displays

Camera Monitor Systems (CMSs), for example, for backup cameras or mirror replacements, become increasingly important and already cover safety aspects such as guaranteed latency and no frame freeze. Today\u27s approaches deal only with supervision of the digital interface, LCD backlight, and power supply. This paper introduces methods for advanced safety monitoring of panel electronics and optical display output that aim to enable future CMS based automotive use cases. Our methods are based on correlation of physical measurements with predicted values derived from a corresponding display model. This model was made via calibration measurements and many test patterns. Correlation of the monitoring results with predicted values corresponds to the probability that the RGB data are shown as intended. This implies that an overlying system, an Automotive Safety Integrity Level (ASIL) Prepared Video Safety System (APVSS), ensures that only safety verified RGB data are provided to the panel electronics. In case of failures, our methods enable a safe system state, for example, by deactivating the panel. An additional challenge is to allow graceful degradations, a safe but slightly degraded image may provide a better customer experience compared with no information. We successfully verified our approach by a fully functional prototype and extensive evaluation towards “light-to-light” (camera to display output) supervision