Toward high laser power beam manipulation with nanophotonic materials: evaluating thin film damage performance.

Nanophotonic materials enable unprecedented control of light-matter interactions, including the ability to dynamically steer or shape wavefronts. Consequently, nanophotonic systems such as metasurfaces have been touted as promising candidates for free-space optical communications, directed energy and additive manufacturing, which currently rely on slow mechanical scanners or electro-optical components for beam steering and shaping. However, such applications necessitate the ability to support high laser irradiances (> kW/cm2) and systematic studies on the high-power laser damage performance of nanophotonic materials and designs are sparse. Here, we experimentally investigate the pulsed laser-induced damage performance (at λ ∼ 1 µm) of model nanophotonic thin films including gold, indium tin oxide, and refractory materials such as titanium nitride and titanium oxynitride. We also model the spatio-thermal dissipation dynamics upon single-pulse illumination by anchoring experimental laser damage thresholds. Our findings show that gold exhibits the best laser damage resistance, but we argue that alternative materials such as transparent conducting oxides could be optimized to balance the tradeoff between damage resistance and optical tunability, which is critical for the design of thermally robust nanophotonic systems. We also discuss damage mitigation and ruggedization strategies for future device-scale studies and applications requiring high power beam manipulation.

Filament damage formation in fused silica glass as a result of 1-50 ps near-infrared laser pulses.

We measure filament damage due to self-focusing in fused silica glass using short laser pulses of 1-50 ps of 1053 nm wavelength. We examine the dependence of the effect on the excitation fluence and pulse length. A beam propagation model adjusted to picosecond pulse lengths shows a good fit to the measurements. Whereas for longer pulses a filament appears within the bulk, for the shorter pulses surface damage appears due to the high nonlinearity of the system.

Adaptive step-size algorithm for Fourier beam-propagation method with absorbing boundary layer of auto-determined width.

Two algorithms that enhance the utility of the absorbing boundary layer are presented, mainly in the framework of the Fourier beam-propagation method. One is an automated boundary layer width selector that chooses a near-optimal boundary size based on the initial beam shape. The second algorithm adjusts the propagation step sizes based on the beam shape at the beginning of each step in order to reduce aliasing artifacts.

Short vs long hospitalization: a prospective controlled study. VI Two-year follow-up results for schizophrenics.

A controlled, prospective study examined the relative effectiveness of short-term versus long-term psychiatric hospitalization. The results of a two-year follow-up of a sample of 141 schizophrenic patients are reported here. The differences favoring long-term subjects that were apparent at one year postadmission had decreased by two years postadmission. However, there appears to be an interaction between prehospital functioning and length of hospital stay, with subjects who had good prehospital functioning doing better at two years when assigned to long-term hospitalization. Subjects with poor prehospital functioning did about equally well, regardless of length of stay, and may even have showed some tendency to do better with a shorter hospital stay. This reversal of effect was more prominent for women, although this sex difference was not statistically significant.

Colored solitons interactions: particle-like and beyond.

The interaction of two colored solitons was analyzed in the framework of a particle-like model, derived from a soliton perturbation theory. From "energy" considerations, a soliton capture threshold and the re-coloring of the escaping solitons were derived. The results were compared to the spectral boundaries of a second order soliton as well as to previous reports. The capture of colored solitons was shown to be impractical without additional means. This particle-like model was further generalized to apply also for non-equal intensity colored solitons. Detailed calculations-beyond the particle-like approximation, exhibited additional mechanisms, namely dissipation and friction-like forces, which served as sources for the relaxation of the solitons oscillations within the captured state, thus enhancing the capture phenomenon.

Cochlear implant devices for the profoundly hearing impaired.

The cochlear implant is a neural prosthetic device that provides a perception of hearing and facilitates communication for persons who are profoundly deaf. Speech and sound information is transformed into electrical signals that create a perception of sound upon their application to fibers of the auditory nerve within the cochlea. The device is intended for persons with profound sensorineural deafness. This condition exists when the sensory hair cells of the organ of Corti are disabled while fibers of the auditory nerve and their connection in the central nervous system remain functionally intact. The electrical stimuli that are applied within the cochlea are then appropriately conveyed and interpreted as audible information. Cochlear prostheses are designed to stimulate the auditory nerve in a manner that exploits the ability of the cochlea and central nervous system to discriminate the frequency, tempo aditensity. of ambient sound in ways that assist the wearer to recognize ItS source and information content. Selection of candidates for implantation involves confirmation of profound bilateral sensorineural deafness that cannot be mitigated by the use of a modern powerful hearing aid capable of providing benefits equal to those obtainable from an implant. In addition, the cognitive ability to make use of auditory clues, and the willingness to conscientiously pursue an extended program of aural/visual rehabilitation, must be present. Patients who have become deaf after developing normal language skills are most amenable to implantation since sound recognition is aided by established associations and memory.

A communications seminar series for general practice residents.

This article describes a seminar series for general practice residents dealing with communication, interpersonal relations, self-image, and patient-dentist interactions. Objectives, content, and methods of evaluation are presented.

Toward the library of the future.

Over the past decade libraries have become increasingly aware of the revolutionary impact of developments in information technology on their key function. The new developments challenge the library's traditional role as electronic information products and services open up a previously unimaginable array of options. The author contemplates a vision of the future in which the unpredictability of the human mind interacts with an expanding array of new technologies and libraries strive to develop an information infrastructure to serve teaching and research in universities.

Computer-assisted decision making in medicine.

This article reviews the strengths and limitations of five major paradigms of medical computer-assisted decision making (CADM): (1) clinical algorithms, (2) statistical analysis of collections of patient data, (3) mathematical models of physical processes, (4) decision analysis, and (5) symbolic reasoning or artificial intelligence (AI). No one technique is best for all applications, and there is recent promising work which combines two or more established techniques. We emphasize both the inherent power of symbolic reasoning and the promise of artificial intelligence and the other techniques to complement each other.