Stealth and secured optical coherent transmission using a gain switched frequency comb and multi-homodyne coherent detection.

A novel all-optical stealth and secured transmission is proposed and demonstrated. Spectral replicas of the covert signal are carried by multiple tones of a gain switched optical frequency comb, optically coded with spectral phase mask, and concealed below EDFA's noise. The secured signal's spectrum is spread far beyond the bandwidth of a coherent receiver, thus forcing real time all-optical processing. An unauthorized user, who does not possess knowledge on the phase mask, can only obtain a noisy and distorted signal, that cannot be improved by post-processing. On the other hand, the authorized user decodes the signal using an inverse spectral phase mask and achieves a substantial optical processing gain via multi-homodyne coherent detection. A transmission of 20 Gbps under negative -7.5 dB OSNR is demonstrated here, yielding error-free detection by the eligible user.

50 Gb/s short-reach interconnects with DSP-free direct-detection enabled by CAPS codes.

We experimentally demonstrate 50 Gb/s transmission below an uncorrected bit error rate (BER) of 10-3 in the C band over a transmission reach that extends from 0 to 20 km using combined amplitude and phase shift (CAPS) codes. The CAPS signal, which is not required to be specifically dispersion compensated for each reach within the 20 km operating range, is amenable for simple direct detection using a single photodetector without any subsequent digital signal processing (DSP). Hence, the presented solution constitutes a potentially attractive low cost solution for mobile Xhaul applications employing single mode fiber interconnects with reaches extending to 20 km. Furthermore, the CAPS signaling is compared to other modulation schemes all delivering 50 Gb/s and is found to outperform on-off-keying (OOK), 4-level pulse amplitude modulation (PAM4) and dispersion precompensated OOK in terms of dispersion tolerance. At a lower reach of 10 km, the maximum bit rate that can be achieved using CAPS coding at a BER below 10-3 is found to increase to 67 Gb/s. In addition, using the same testbed, we experimentally tested the IQ duobinary modulation format, which is an alternative format that approximates the CAPS transmitted waveforms in order to omit the need for a power consuming digital-to-analog converter (DAC) to generate the transmitted waveforms at the expense of slightly worse dispersion tolerance. Though the IQ duobinary format can be in principle generated using a simple DAC-less analog transmitter, our proof-of-concept experiment used a DAC to emulate the analog transmitter by generating the corresponding transmitted waveforms due to unavailability of all required analog parts. The IQ duobinary format was found experimentally to enable 50 Gb/s over a reach of ~17 km; that is slightly less than a CAPS signal at the same bit rate. Finally, we verified the excellent performance of the CAPS signaling in an ASE-limited regime where the CAPS signal achieved very low OSNR penalty after 10 km relative to OOK in back-to-back.

Theory of Mind intervention for outpatients with schizophrenia.

Social disability is one of the critical areas known to be a predictor of daily functioning in schizophrenia. Recent studies showed that impairments in Theory of Mind (ToM) contribute to real-world social functioning and are more strongly associated with community outcomes than other neuropsychological domains of cognition. Several experiments revealed an improving potential of social cognition targeted training, particularly through introduction of verbalisation and explicit manipulation of information about others' mental states. Based on these data, we evaluated longitudinally, with a controlled trial, the feasibility and efficacy of ToM training and the possible influences of daily functioning and IQ on the enhancement of ToM abilities. Thirty outpatients with schizophrenia were recruited and randomly allocated to two groups: ToM Intervention (ToMI), based on verbalisation of selected comic strips representing ToM scenarios, or active control group (ACG). Results showed a significant improvement of ToM abilities among subjects allocated to ToMI compared to ACG, confirming the hypothesis of the enhancing potential of training methods targeting ToM functions. Moreover, we observed no influences of neuropsychological and functional variables on ToM improvement. Development of future studies should take into account possible effects of ToM training on functional outcome, according to the strong associations between ToM abilities and real-world social functioning.

Versatile offset-free 16-QAM single dual-drive IQ modulator driven by binary signals.

A customized IQ modulator driven by equal-amplitude binary signals for generating offset-free 16-quadrature amplitude modulation (QAM) is proposed and validated through simulations. The incorporation of tunable splitters demonstrates the feasibility of the transmitter and enables more efficient constellations such as hexagonal 16-QAM.

Patterns of evidence integration in schizophrenia and delusion.

Previous studies documented a bias against disconfirmatory evidence (BADE) in patients affected by schizophrenia spectrum disorders, with some discrepant findings on its relationship with delusions. In order to further investigate the patterns of evidence integration in schizophrenia and delusion, we recruited 40 deluded and non-deluded patients with schizophrenia and 40 healthy control subjects. Participants were administered the BADE test, which consisted of 30 delusion-neutral scenarios, each one progressively described by three subsequent disambiguating statements and providing four types of interpretation to rate for plausibility; at every additional evidence presentation, participants were asked to adjust their ratings. In contrast to previous works, patients displayed both a BADE and a bias against confirmatory evidence (BACE) relative to healthy subjects, as they reduced plausibility ratings on incorrect interpretations and increased plausibility ratings on correct interpretation significantly less over trial progress. Moreover, BACE and BADE measures showed to discriminate differentially control from schizophrenia participants and delusional from non-delusional patients.

Theory of mind and emotion processing training for patients with schizophrenia: preliminary findings.

Impairments in social cognition are critical predictors of social functioning in patients with schizophrenia. Emotion processing (EP) and theory of mind (ToM) are hypothesized to influence real-world behavior more directly than basic cognition and represent important targets of intervention. The use of video scenes depicting human interactions could constitute an appropriate tool to enhance understanding of the characters' behavior and stimulate inferences on mental states. The aim of our pilot study was to evaluate longitudinally, with a controlled trial, the feasibility and the efficacy of a single-paradigm emotion recognition and ToM training designed for outpatients affected by schizophrenia, with the goal to create an ecological treatment, overcoming artificial laboratory biases, by the use of specific videotaped material. Fifty-two outpatients were randomly assigned to an EP and ToM video-based training (n=27) or to a standard social cognitive rehabilitation treatment (n=24). They were assessed before and after 12 weeks of intervention and compared to a time-matched control group (n=24). Our results show a statistically significant improvement in ToM abilities, confirming the hypothesis of the enhancing potential of social cognitive interventions, but no changes with respect to EP; despite the need for a deeper examination, these data support further development of this treatment approach.

Programmable fiber-based picosecond optical pulse shaper using time-domain binary phase-only linear filtering.

We demonstrate a fiber-based programmable arbitrary picosecond optical pulse shaper using binary phase-only linear filtering. The reconfigurable filtering operation is implemented in the time domain using an electro-optical phase modulator driven by a high-speed bit pattern generator. The required binary phase code is designed using a genetic algorithm. Precise matching between the predispersive and postdispersive media in the system is achieved by use of a single linearly chirped fiber Bragg grating subsequently operated from its two input ends. As a proof of concept, different pulse waveforms of practical interest are generated using this new pulse shaper.

Behavioural sensitization to repeated sleep deprivation in a mice model of mania.

Sensitization to the effect of stress has been hypothesized as a mechanism to explain episode recurrence and cycle acceleration in bipolar disorder. Naturalistic observations and experimental work in human patients suggested that sleep deprivation can trigger manic episodes of illness. In rats sleep deprivation (SD) with the platform method caused mania-like behaviours thus providing an animal model of mania with face, construct, and predictive validity. In the present study we administered SD or control stress to male CD1 mice following a dose-response protocol based on time of exposure to the experimental conditions (6, 12 or 24 h) and repetition of treatment (three times). SD, but not stress-control conditions, increased motor activity and aggressive behaviours. The behavioural activation followed a dose-response curve based on length of treatment, with non-significant trends after 6h, significant effects after 12 h, and maximal effects after 24 h. Moreover, the behavioural activation followed a time-response curve, with progressive sensitization to the effects of SD, but not of control stress, upon its repetition. This is the first animal model of behavioural sensitization to the effects of a specific stress (sleep deprivation) known to trigger mania in bipolar patients. We expect it to be useful to test the efficacy of antimanic and mood-stabilizer drugs, and to study the neurobiological correlates of manic reactions in order to gain new insight into the pathophysiology of bipolar illness and to identify new targets for treatment.

Continuously spacing-tunable multiwavelength semiconductor-optical-amplifier-based fiber ring laser incorporating a superimposed chirped fiber Bragg grating.

We investigate a flexibly tunable multiwavelength semiconductor-optical-amplifier-based fiber ring laser with continuous wavelength spacing controllability incorporating a superimposed chirped fiber Bragg grating (CFBG). The wavelength spacing of a superimposed CFBG can be continuously controlled by symmetrically modifying the chirp bandwidth of the grating with the specially designed apparatus. We achieve a wide and continuous tuning range of the wavelength spacing from 0.35 to 0.78 nm. The continuous tunability of the wavelength spacing is measured to be ~ +/-0.033 nm/mm. By controlling the reflection bandwidth of the tunable CFBG, we can independently adjust the number of lasing channels from 2 to 23 at the wavelength spacing of 0.51 nm.