Visible femtosecond fiber laser.

Femtosecond fiber lasers have revolutionized the industry of laser technology by providing ultrashort pulses of high brightness through compact, affordable, and reliable setups. In this work, we extend the scope of application of such sources by reporting, to our knowledge, the first femtosecond fiber laser operating in the visible spectrum. The passively mode-locked ring cavity is based on nonlinear polarization evolution in a single-mode Pr3+-doped fluoride fiber and runs in an all-normal dispersion regime. Compressed pulses at 635 nm have a duration of 168 fs, a peak power of 0.73 kW, and a repetition rate of 137 MHz.

Monolithic silica fiber laser operating at 585 nm.

We report, to the best of our knowledge, the first monolithic silica fiber laser operating in the visible. The laser cavity is based on a dysprosium-doped aluminosilicate fiber bounded by a pair of fiber Bragg gratings operating at 585 nm. The yellow laser signal reaches a record output power of 147 mW. Although the pump irradiation causes photodarkening, significant reduction of the photoinduced absorption losses is demonstrated via a photobleaching process with visible light.

2.3 W monolithic fiber laser operating in the visible.

We report, to the best of our knowledge, the first monolithic visible fiber laser pumped by a pigtailed diode. The robust cavity design proposed is based on a highly reflective fiber Bragg grating spliced to a double-clad praseodymium-doped fiber. The laser signal generated at 635.5 nm is single-mode, has a FWHM bandwidth of 0.16 nm, and reaches a maximum cw output power of 2.3 W. This demonstration breaks ground for the development of reliable high-power visible fiber lasers.

Effect Sizes of Deletions and Duplications on Autism Risk Across the Genome.

OBJECTIVE: Deleterious copy number variants (CNVs) are identified in up to 20% of individuals with autism. However, levels of autism risk conferred by most rare CNVs remain unknown. The authors recently developed statistical models to estimate the effect size on IQ of all CNVs, including undocumented ones. In this study, the authors extended this model to autism susceptibility. METHODS: The authors identified CNVs in two autism populations (Simons Simplex Collection and MSSNG) and two unselected populations (IMAGEN and Saguenay Youth Study). Statistical models were used to test nine quantitative variables associated with genes encompassed in CNVs to explain their effects on IQ, autism susceptibility, and behavioral domains. RESULTS: The "probability of being loss-of-function intolerant" (pLI) best explains the effect of CNVs on IQ and autism risk. Deleting 1 point of pLI decreases IQ by 2.6 points in autism and unselected populations. The effect of duplications on IQ is threefold smaller. Autism susceptibility increases when deleting or duplicating any point of pLI. This is true for individuals with high or low IQ and after removing de novo and known recurrent neuropsychiatric CNVs. When CNV effects on IQ are accounted for, autism susceptibility remains mostly unchanged for duplications but decreases for deletions. Model estimates for autism risk overlap with previously published observations. Deletions and duplications differentially affect social communication, behavior, and phonological memory, whereas both equally affect motor skills. CONCLUSIONS: Autism risk conferred by duplications is less influenced by IQ compared with deletions. The model applied in this study, trained on CNVs encompassing >4,500 genes, suggests highly polygenic properties of gene dosage with respect to autism risk and IQ loss. These models will help to interpret CNVs identified in the clinic.

Erbium-doped aluminophosphosilicate all-fiber laser operating at 1584 nm.

We report on an ytterbium-free erbium-doped aluminophosphosilicate all-fiber laser, producing an output power of 25 W at a wavelength of 1584 nm with a slope efficiency of 30% with respect to the 976 nm absorbed pump power. The simple cavity design proposed takes advantage of fiber Bragg gratings written directly in the gain fiber. The single-mode erbium-doped aluminophosphosilicate fiber was fabricated in-house and was doped with 0.06 mol.% of Er2O3, 1.77 mol.% of Al2O3 and 1.04 mol.% of P2O5. The incorporation of aluminium and phosphorus into the fiber core allowed for an increased concentration of erbium without inducing significant clustering, while keeping the numerical aperture low to ensure a single-mode laser operation.

Autistic children at risk of being underestimated: school-based pilot study of a strength-informed assessment.

BACKGROUND: An important minority of school-aged autistic children, often characterized as 'nonverbal' or 'minimally verbal,' displays little or no spoken language. These children are at risk of being judged 'low-functioning' or 'untestable' via conventional cognitive testing practices. One neglected avenue for assessing autistic children so situated is to engage current knowledge of autistic cognitive strengths. Our aim was thus to pilot a strength-informed assessment of autistic children whose poor performance on conventional instruments suggests their cognitive potential is very limited. METHODS: Thirty autistic children (6 to 12 years) with little or no spoken language, attending specialized schools for autistic children with the highest levels of impairment, were assessed using Wechsler Intelligence Scale for Children (WISC-IV), Raven's Colored Progressive Matrices board form (RCPM), Children's Embedded Figures Test (CEFT), and a visual search task. An age-matched control group of 27 typical children was also assessed. RESULTS: None of the autistic children could complete WISC-IV; only six completed any subtest. In contrast, 26 autistic children could complete RCPM, with 17 scoring between the 5th and 90th percentile. Twenty-seven autistic children completed the visual search task, while 26 completed CEFT, on which autistic children were faster than RCPM-matched typical children. Autistic performance on RCPM, CEFT, and visual search were correlated. CONCLUSION: These results indicate that 'minimally verbal' or 'nonverbal' school-aged autistic children may be at risk of being underestimated: they may be wrongly regarded as having little cognitive potential. Our findings support the usefulness of strength-informed approaches to autism and have important implications for the assessment and education of autistic children.

Increased topographical variability of task-related activation in perceptive and motor associative regions in adult autistics.

BACKGROUND: An enhanced plasticity is suspected to play a role in various microstructural alterations, as well as in regional cortical reallocations observed in autism. Combined with multiple indications of enhanced perceptual functioning in autism, and indications of atypical motor functioning, enhanced plasticity predicts a superior variability in functional cortical allocation, predominant in perceptual and motor regions. METHOD: To test this prediction, we scanned 23 autistics and 22 typical participants matched on age, FSIQ, Raven percentile scores and handedness during a visuo-motor imitation task. For each participant, the coordinates of the strongest task-related activation peak were extracted in the primary (Brodmann area 4) and supplementary (BA 6) motor cortex, the visuomotor superior parietal cortex (BA 7), and the primary (BA 17) and associative (BAs 18 + 19) visual areas. Mean signal changes for each ROI in both hemispheres, and the number of voxels composing the strongest activation cluster were individually extracted to compare intensity and size of the signal between groups. For each ROI, in each hemisphere, and for every participant, the distance from their respective group average was used as a variable of interest to determine group differences in localization variability using repeated measures ANOVAs. Between-group comparison of whole-brain activation was also performed. RESULTS: Both groups displayed a higher mean variability in the localization of activations in the associative areas compared to the primary visual or motor areas. However, despite this shared increased variability in associative cortices, a direct between-group comparison of the individual variability in localization of the activation revealed a significantly greater variability in the autistic group than in the typical group in the left visuo-motor superior parietal cortex (BA 7) and in the left associative visual areas (BAs 18 + 19). CONCLUSION: Different and possibly unique strategies are used by each autistic individual. That enhanced variability in localization of activations in the autistic group is found in regions typically more variable in non-autistics raises the possibility that autism involves an enhancement and/or an alteration of typical plasticity mechanisms. The current study also highlights the necessity to verify, in fMRI studies involving autistic people, that hypoactivation at the group level does not result from each individual successfully completing a task using a unique brain allocation, even by comparison to his own group.