Migrating monarch butterflies (Danaus plexippus) use a time-compensated sun compass to navigate from eastern North America to their overwintering grounds in central Mexico. Here we describe the neuronal layout of those aspects of the butterfly's central complex likely to establish part of the internal sun compass and find them highly homologous to those of the desert locust. Intracellular recor...

How do birds orient over familiar terrain? In the best studied avian species, the homing pigeon (Columba livia), two apparently independent primary mechanisms are currently debated: either memorized visual landmarks provide homeward guidance directly, or birds rely on a compass to home from familiar locations. Using miniature Global Positioning System tracking technology and clock-shift procedu...

The radical pair model has been successful in explaining behavioral characteristics of the geomagnetic compass believed to underlie the navigation capability of certain avian species. In this study, the spin dynamics of the radical pair model and decoherence therein are interpreted from a microscopic state transition point of view. This helps to elucidate the interplay between the hyperfine and...

Background Several water-based sports (swimming, surfing and stand up paddle boarding) require adequate thoracic mobility (specifically rotation) in order to perform the appropriate activity requirements. The measurement of thoracic spine rotation is problematic for clinicians due to a lack of convenient and reliable measurement techniques. More recently, smartphones have been used to quantify ...

Constraint networks over relation algebras are deened. Compass algebras are introduced for reasoning about space. They are related to the interval algebras, which are used for reasoning about time. The problem of determining whether a network has a closed zeroless reduction is shown to NP-complete for almost all compass and interval algebras. This implies constraint satisfaction for these algeb...

This paper presents a study of the effects of compass bias on navigational accuracy of autonomous underwater vehicles. Low cost vehicle systems utilize a magnetometer, and Doppler sonar for dead reckoning, and a DGPS fix when surfaced. By learning the compass bias from a few DGPS fixes, the navigational errors can be bounded with only a small number of fixes. The study is conducted using the Fl...

The aim of COMPASS (short for COMmon Positioning Architecture for Several Sensors) is to realize a location infrastructure which can make use of a multitude of different sensors and combine their output in a meaningful way to produce a so called Probability Distribution Function (PDF) that describes the location of a user or device as coordinates and corresponding location probabilities. Furthe...

Geometric Algebra is a very general mathematical system providing simultaneously a geometrification of algebra, and also an algebrification of geometry. As an example, we present a specific Geometric Algebra, that we call Compass Ruler Algebra, which is very well suited to compute similar to working with compass and ruler. Geometric objects such as circles and lines as well as geometric operati...

We describe a hadron physics program attainable with a partially instrumented CERN COMPASS spectrometer, involving tracking detectors and moderate-size ECAL2/HCAL2 calorimeters. COMPASS can realize a state-of-the-art hadron beam physics program based on hadron polarizability, hybrid mesons, chiral anomaly, and meson radiative transition studies. We review here the physics motivation for this ha...

The Eleventh Annual Conference on Computer Assurance (COMPASS ’96) was hosted by the Computer Systems Laboratory of the National Institute of Standards and Technology on June 17-21, 1996. COMPASS is an organization whose mission is to advance the theory and practice of building assurance into critical computer systems. Each year, COMPASS brings together researchers, developers, and evaluators o...