The Peculiar Periodic YSO WL 4 in ρ Ophiuchus

We present the discovery of 130.87 day periodic near-infrared flux variability for the Class II T Tauri star WL 4 (= 2MASS J16271848-2429059, ISO-Oph 128). Our data are from the 2MASS Calibration Point Source Working Database, and constitute 1580 observations in J, H and K_s of a field in ρ Ophiuchus used to calibrate the 2MASS All-Sky Survey. We identify a light curve for WL 4 with eclipse amplitudes of ~0.4 mag lasting more than one-quarter the period, and color variations in J-H and H-K_s, of ~0.1 mag. The long period cannot be explained by stellar rotation. We propose that WL 4 is a triple YSO system, with an inner binary orbital period of 130.87 days. We posulate that we are observing each component of the inner binary alternately being eclipsed by a circum-binary disk with respect to our line of sight. This system will be useful in investigating terrestrial zone YSO disk properties and dynamics at ~1 Myr

Multivariate Time Series Support Vector Machine for Multispectral Remote Sensing Image Classifications

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Noise transfer functions of mode-locked semiconductor laser

The noise behavior of mode-locked semiconductor ring laser, including timing jitter, and pulse energy fluctuation are investigated using the notion of a noise transfer function. Numerical simulation predicts that semiconductor mode-locked lasers have very complex structure in the transfer function which is confirmed experimentally by corresponding noise measurements

High Speed Pulse Slicer/Demultiplexer With Gain For Use In Solid State Regenerative Amplifier Systems

A mode-locked solid state laser is disclosed for generating ultrashort optical pulses from a semiconductor type laser. A semiconductor pulse slicer/demultiplexer/modulator with gain amplification is used to modulate and amplify a generated optical beam whether or not the beam is pulsed, continuous wave, q-switched, or modelocked. Alternatively, the semiconductor pulse slicer/demultiplexer/modulator with gain amplification is used to gate a generated optical beam whether or not the beam is pulsed, continuous wave, q-switched, or modelocked. Alternatively, the semiconductor pulse slicer/demultiplexer/modulator with gain amplification is used to demultiplex a generated optical beam whether or not the beam is pulsed, continuous wave, q-switched, or modelocked. The invention uses only semiconductor type materials such as Titanium Saphire, Gallium Arsenide, Aluminum Gallium Arsenide (GaAs/AlGaAs) as both the pulse slicer/demultiplexer/modulator with gain amplification, and the mode-locked l

Ultralow Noise Mode-locked Laser and RF Sinewave Source. DIV

Systems, devices and methods of generating both a precision electrical timing signal as well as a precision optical timing signal. A novel, modified opto-electronic loop oscillator is used to drive a harmonic mode-locked laser. A novel opto-electronic loop has a larger Q factor by increasing the electrical loop oscillating frequency w0 by using a beat note created by the selection of two optical longitudinal modes from the modelocked laser. The beat note is detected and divided down to drive a modulator that modelocks the laser. The frequency division stage also reduces the noise

Optical Frequency Self Sabilization in a Couple of Optoelectronic Oscillator

Methods and devices for a coupled optoelectronic oscillator having optical frequency stabilization. The coupled optoelectronic oscillator includes a harmonically mode-locked laser cavity having a Mach-Zehnder modulator for mode-locking and an intracavity Fabry-Perot etalon to allow only one single supermode to lase, a stabilization loop coupled with the Fabry-Perot etalon to detect changes in the laser cavity optical frequency and generate an error signal to compensate for the frequency change to stabilize the mode-locking of the laser frequency stabilization, and an electrical loop between the laser cavity and the stabilization loop for driving the Mach-Zehnder modulator with the coupled optoelectronic oscillator signal

High Precision Measurement of the Free Spectral Range of an Etalon

Methods, systems, apparatus and devices for using a modified PDH technique to measure the FSR of an etalon with one part per l0^4 precision. This method is especially useful for etalons with small FSR (less than 10 GHz) because this method does not require a high resolution OSA or tuneable laser. As the ITU grid for DWDM becomes denser, this method will have a larger impact on the FSR measurement of etalons

Review: Delivering mental health support within schools and colleges – a thematic synthesis of barriers and facilitators to implementation of indicated psychological interventions for adolescents

Background: Increasing the role of schools and colleges in the provision of mental health services for young people has the potential to improve early intervention and access to treatment. We aimed to understand what factors influence the successful implementation of indicated psychological interventions within schools and colleges to help guide increased provision of mental health support within education settings. Methods: Systematic search for studies that have reported barriers or facilitators to the implementation of indicated interventions for adolescent emotional disorders delivered within schools and further education/sixth form colleges (CRD42018102830). Databases searched were EMBASE, MEDLINE, PsycINFO, CINAHL, British Nursing Index, ASSIA, ERIC and British Education Index. A thematic synthesis of factors reported to impact implementation was conducted. Results: Two thousand five hundred and sixty-nine records and 177 full texts were screened. Fifty studies were identified for inclusion, all of which were of school-based interventions. Eleven analytic themes were developed encompassing intervention characteristics, organisational capacity, training and technical assistance, provider characteristics and community-level factors. Findings indicate the need to select appropriate interventions, consider logistical challenges of the school context and provide training and supervision to enable staff to deliver interventions with fidelity. However, structural and environmental support is required for these facilitators to have the greatest impact on successful implementation. Conclusions: Implementing indicated school-based mental health interventions is challenging. Those involved in planning school-based mental health initiatives must be alert to the impact of factors on multiple interacting levels. There is a lack of research on implementing mental health support within further education and sixth form colleges

Two-mode beat phase noise of actively modelocked lasers

An analytic expression for the phase noise spectrum is estimated when two arbitrary longitudinal modes are selected for beating from the output of an actively modelocked laser. A separate experiment confirmed the theory qualitatively. It was found that two- mode beating posseses more phase noise than the beating involving the entire mode spectrum, especially at low offset frequency, even though two mode beating noise is decoupled from the RF oscillator noise to the first order