A model-theoretic interpretation of environmentally-induced superselection

Environmentally-induced superselection or "einselection" has been proposed as an observer-independent mechanism by which apparently classical systems "emerge" from physical interactions between degrees of freedom described completely quantum-mechanically. It is shown that einselection can only generate classical systems if the "environment" is assumed \textit{a priori} to be classical; einselection therefore does not provide an observer-independent mechanism by which classicality can emerge from quantum dynamics. Einselection is then reformulated in terms of positive operator-valued measures (POVMs) acting on a global quantum state. It is shown that this re-formulation enables a natural interpretation of apparently-classical systems as virtual machines that requires no assumptions beyond those of classical computer science.Comment: 15 pages, 1 figure; minor correction

α-Synuclein-specific T cell reactivity is associated with preclinical and early Parkinson’s disease

A diagnosis of motor Parkinson’s disease (PD) is preceded by a prolonged premotor phase with accumulating neuronal damage. Here we examined the temporal relation between α-synuclein (α-syn) T cell reactivity and PD. A longitudinal case study revealed that elevated α-syn-specific T cell responses were detected prior to the diagnosis of motor PD, and declined after. The relationship between T cell reactivity and early PD in two independent cohorts showed that α-syn-specific T cell responses were highest shortly after diagnosis of motor PD and then decreased. Additional analysis revealed significant association of α-syn-specific T cell responses with age and lower levodopa equivalent dose. These results confirm the presence of α-syn-reactive T cells in PD and show that they are most abundant immediately after diagnosis of motor PD. These cells may be present years before the diagnosis of motor PD, suggesting avenues of investigation into PD pathogenesis and potential early diagnosis

The Earth: Plasma Sources, Losses, and Transport Processes

This paper reviews the state of knowledge concerning the source of magnetospheric plasma at Earth. Source of plasma, its acceleration and transport throughout the system, its consequences on system dynamics, and its loss are all discussed. Both observational and modeling advances since the last time this subject was covered in detail (Hultqvist et al., Magnetospheric Plasma Sources and Losses, 1999) are addressed

Orthogonal Versus Zero-Forced Beamforming in Multibeam Antenna Systems: Review and Challenges for Future Wireless Networks

Orthogonality in multibeam antennas is revisited. The difference between orthogonal beamforming and zero-forced beamforming is highlighted. The intriguing relation between orthogonality, reciprocity and losses is recapitulated. Different approaches on the design of orthogonal beamforming networks and implementation of zero-forced beamforming strategies are shown with various examples from the antenna-research-oriented literature. The use of orthogonal and zero-forced beamforming is discussed from the communication system perspective with relevant studies from diverse disciplines. Some of the future research challenges and potential benefits are outlined for the next generation satellite and cellular communication applications.Microwave Sensing, Signals & System

Active phase coupling in electric fish: Behavioral control with microsecond precision

Pairs of very high frequency electric fish from South America (Sternarchorhynchus sp. and Sternarchorhamphus sp.) synchronize their discharge and finally engage in phase coupling which is maintained over minutes (Fig. 2). This manoeuvre, called Active Phase Coupling (APC), may be as precise as a few microseconds phase jitter over half a min (Fig. 5). Phase coupling is also accomplished to other fish and to stimuli the frequency of which is several hundred Hz away (Fig. 3). In this case the EOD of the responding fish and the stimulus finally are higher harmonics of a common fundamental and phase coupling is to every nth wave of the stimulus. The APC is more complex a behavior than the known Jamming Avoidance Response. Its social significance is yet to be determined. It involves a neuronal control loop with at least 4 synapses some of which are probably electrotonic. © 1978 Springer-Verlag