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One challenge of using nonlinear optical phenomena for practical applications is the need to perform phase-matching. Recently, epsilon-near-zero materials have been shown to demonstrate strong optical nonlinearities, in addition to their other unique properties. As suggested by their name, the permittivity of the material is close to zero for a certain wavelength range. We demonstrate that this small permittivity allows for efficient three-wave mixing interactions to take place in indium-tin-oxide thin films without the need for phase matching the pump and signal beams. The efficiency of the second-order nonlinear interactions is characterized, and cascaded three-wave mixing is demonstrated.

Numerical simulations have become a cornerstone technology in the development of nanophotonic devices. Specifically, 3D finite difference time domain (FDTD) simulations are a widely used due to their flexibility and powerful design capabilities. More recently, FDTD simulations in conjunction with a design methodology called inverse design has become a popular way to optimize device topology, reducing a device's footprint and increasing performance. We implement a commercial inverse design tool to generate complex grating couplers and explore a variety of grating coupler design methodologies. We compare the conventionally designed grating couplers to those generated by the inverse design tool. Finally, we discuss the limitations of the inverse design tool and how different design strategies for grating couplers affect inverse design performance, both in terms of computational cost and performance of the resulting device.

Numerical simulations have become an essential design tool in the field of photonics, especially for nanophotonics. In particular, 3D finite-difference-time-domain (FDTD) simulations are popular for their powerful design capabilities. Increasingly, researchers are developing or using inverse design tools to improve device footprints and performance. These tools often make use of 3D FDTD simulations and the adjoint optimization method. In this work, we implement a commercial inverse design tool with these features for several plasmonic devices that push the boundaries of the tool. We design a logic gate with complex design requirements, as well as a y-splitter and waveguide crossing. With minimal code changes, we implement a design that incorporates phase encoded inputs in a dielectric-loaded surface plasmon polariton waveguide. The complexity of the requirements in conjunction with limitations in the inverse design tool force us to make concessions regarding the density of encoding and to use on-off keying to encode the outputs. We compare the performance of the inverse-designed devices to conventionally-designed devices with the same operational behavior. Finally, we discuss the limitations of the inverse design tools for realizing complex device designs and comment on what is possible at present and where improvements can be made.

Although the first lasers invented operated in the visible, the first on-chip devices were optimized for near-infrared (IR) performance driven by demand in telecommunications. However, as the applications of integrated photonics has broadened, the wavelength demand has as well, and we are now returning to the visible (Vis) and pushing into the ultraviolet (UV). This shift has required innovations in device design and in materials as well as leveraging nonlinear behavior to reach these wavelengths. This review discusses the key nonlinear phenomena that can be used as well as presents several emerging material systems and devices that have reached the UV-Vis wavelength range., Comment: 58 pages, 10 figures

The RadiaBeam/SLAC dechirper, a structure consisting of pairs of flat, metallic, corrugated plates, %a corrugated structure in flat geometry, has been installed just upstream of the undulators in the Linac Coherent Light Source (LCLS). As a dechirper, with the beam passing between the plates on axis, longitudinal wakefields are induced that can remove unwanted energy chirp in the beam. However, with the beam passing off axis, strong transverse wakes are also induced. This mode of operation has already been used for the production of intense, multi-color photon beams using the Fresh-Slice technique, and is being used to develop a diagnostic for attosecond bunch length measurements. Here we measure, as function of offset, the strength of the transverse wakefields that are excited between the two plates, and also for the case of the beam passing near to a single plate. We compare with analytical formulas from the literature, and find good agreement. This report presents the first systematic measurements of the transverse wake strength in a dechirper, one that has been excited by a bunch with the short pulse duration and high energy found in an X-ray free electron laser., Comment: 8 pages, double column, 6 figures

Promoting Alternative Thinking Strategies (PATHS) is a school-based social and emotional learning (SEL) curriculum that aims to help children in primary school manage their behaviour, understand their emotions, and work well with others. PATHS consists of a series of lessons that cover topics such as identifying and labelling feelings, controlling impulses, reducing stress, and understanding other people's perspectives. It is delivered twice weekly in 30-40 minute lessons by teachers to all children in a given class, typically in the slots allocated for Personal, Social and Health Education. This curriculum is supplemented by activities that support the application of new skills during the school day and activities that are sent home to parents that cover the topics taught in class. In this trial, 45 participating schools from Greater Manchester were randomly allocated to implement PATHS for two years (school years 2012-2013 and 2013-2014) or continue their usual practice during the same period. This evaluation focuses on the academic outcomes of the intervention for children in Years 5 and 6 in English/reading and maths. The outcomes of this study include: social and emotional competence, quality of life, and attendance. Key conclusions are as follows: (1) Overall, PATHS did not have a positive impact upon children's academic attainment; (2) The evidence does not indicate that PATHS produced differential gains for children eligible for free school meals (FSM); (3) Higher levels of PATHS implementation quality and reach were associated with better academic outcomes; (4) Teachers reported a lack of time to implement PATHS at the recommended frequency. On average, only half of the lessons were delivered; and (5) While PATHS does not appear to be a cost-effective way of improving students' attainment, it may have an impact on other, non-cognitive outcomes. A full report on the NIHR trial looking at these outcomes will be published at a later date. Overall, the findings of this study can be considered to be robust and secure. Additionally, it is worthy of note that the study also complied with the EEF's various quality markers.

Historical data concerning the federal Guaranteed Student Loan Program/Stafford Student Loan Program/Family Education Loan Program are presented, tracing default rates since 1980 and the population distributions for borrowers by institution type (overall, collegiate, noncollegiate, public or private, two- or four-year, proprietary). Individual characteristics associated with default are also discussed. (MSE)

This proposed toilet facility has a straightforward design. It has few moving parts and is easily maintained. Air and water flow provide sanitary movement of the waste. The toilet's chambers are coated with Teflon which, along with the water flow, makes it self-cleaning. An added disinfectant called Betadiene kills any bacteria that may form on the chamber walls. The chair is contoured to take into account the neutral body position and the necessary strain position for defecation. Restraints at the ankles, knees, and midsection hold the body in the chair. The waste is stored in discs of Gortex material which are inside a replaceable storage chamber. This chamber can be removed, capped and stored until eventual return to earth.