The bodily-self, our experience of being a body, arises from the interaction of several processes. For example, embodied Sense of Agency (SoA), the feeling of controlling our body’s actions, is a fundamental facet of the bodily-self. SoA is disturbed in psychosis, with stress promoting its inception. However, there is little knowledge regarding the relationship between SoA, stress, and other facets of the bodily-self. In four experiments manipulating embodied SoA using a virtual hand (VH), we examined (1) How is embodied SoA related to other facets of the bodily-self?; and (2) How is SoA impacted by stress? We found that increased alteration of the VH significantly decreased subjective ratings of SoA and body ownership (Exp. 1), supporting the close relation between SoA and body ownership. Interoceptive accuracy and SoA were positively correlated (Exp. 3), connecting awareness to one’s actions and cardiac signals. Contrary to our expectations, SoA was not related to trait anxiety (Exp. 3), nor did induced stress impair SoA (Exp. 4). Finally, we found a negative correlation between self-reported prodromal symptoms and SoA. These results strongly support the connection between SoA and the bodily-self. Whereas, SoA was not impaired by stress, and weakly related to psychotic symptoms.

Stimulated Brillouin scattering (SBS) in optical fibers has long been used in frequency-selective optical signal processing, including in the realization of microwave-photonic (MWP) filters. In this work, we report a significant enhancement in the selectivity of SBS-based MWP filters. Filters having a single passband of 250 MHz-1 GHz bandwidth are demonstrated, with selectivity of up to 44 dB. The selectivity of the filters is better than that of the corresponding previous arrangements by about 15 dB. The shape factor of the filters, defined as the ratio between their −20 dB bandwidth and their −3 dB bandwidth, is between 1.35 and 1.5. The central transmission frequency, bandwidth, and spectral shape of the passband are all independently adjusted. Performance enhancement is based on two advances, compared with previous demonstrations of tunable SBS-based MWP filters: (a) the polarization attributes of SBS in standard, weakly birefringent fibers are used to discriminate between in-band and out-of-band components and (b) a sharp and uniform power spectral density of the SBS pump waves is synthesized through external modulation of an optical carrier by broadband, frequency-swept waveforms. The signal-to-noise ratio of filtered radio-frequency waveforms and the linear dynamic range of the filters are estimated analytically and quantified experimentally. Lastly, a figure of merit for the performance of the filters is proposed and discussed. The filters are applicable to radio-over-fiber transmission systems.

Thermal drifts in long fiber-optic delay lines are compensated based on chromatic dispersion. An arbitrary input radio-frequency (RF) waveform and a control RF sine wave modulate two different tunable laser sources and are coupled into the fiber delay line. The RF phase of the control tone at the output of the delay line is monitored and used to adjust the wavelengths of both sources, so that the effects of thermal drifts and dispersion cancel out. The input and control waveforms are separated in the optical domain, and no restrictions are imposed on their RF spectra. A figure of merit is proposed, in terms of the fiber delay, range of temperature changes that may be compensated for, and residual delay variations. An upper bound on performance is established in terms of the specifications of the tunable lasers. The principle is used in the stable distribution of sine waves and of broadband linear frequency-modulated (LFM) waveforms, which are commonly employed in radar systems. Lastly, the method is incorporated in stable interrogation of a localized hot-spot within a high-resolution, distributed Brillouin fiber sensing setup. The results demonstrate the applicability of the proposed protocol in the processing of arbitrary waveforms, as part of larger, more complex systems.

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