Compact fiber-optic curvature sensor based on super-mode interference in a seven-core fiber.

A compact, low loss, and highly sensitive optical fiber curvature sensor is presented. The device consists of a few-millimeter-long piece of seven-core fiber spliced between two single-mode fibers. When the optical fiber device is kept straight, a pronounced interference pattern appears in the transmission spectrum. However, when the device is bent, a spectral shift of the interference pattern is produced, and the visibility of the interference notches changes. This allows for using either visibility or spectral shift for sensor interrogation. The dynamic range of the device can be tailored through the proper selection of the length of the seven-core fiber. The effects of temperature and refractive index of the external medium on the response of the curvature sensor are also discussed. Linear sensitivity of about 3000 nm/mm(-1) for bending was observed experimentally.

Ultralow emittance, multi-MeV proton beams from a laser virtual-cathode plasma accelerator.

The laminarity of high-current multi-MeV proton beams produced by irradiating thin metallic foils with ultraintense lasers has been measured. For proton energies >10 MeV, the transverse and longitudinal emittance are, respectively, <0.004 mm mrad and <10(-4) eV s, i.e., at least 100-fold and may be as much as 10(4)-fold better than conventional accelerator beams. The fast acceleration being electrostatic from an initially cold surface, only collisions with the accelerating fast electrons appear to limit the beam laminarity. The ion beam source size is measured to be <15 microm (FWHM) for proton energies >10 MeV.

The role of the neonatal intensive care nurse in the delivery room.

The experienced Neonatal Intensive Care Unit (NICU) nurse is a crucial member of the delivery room resuscitation team. In a survey of tertiary centers, the neonatal nurse was the most consistent member of the team in attendance at high risk deliveries. This nursing role, including rationale, preparation for, and future potential, is explored in this article.

Comment on the interpretation of dynamic derivative thermogravimetric curves.

A comparison is made of dynamic thermograms and their derivative curves, and the significance of the various features of these curves is discussed. The designation of peak temperatures on derivative curves as decomposition temperatures is shown to be wrong. An illustration is given of the value of a derivative thermogram in disclosing the existence of successive overlapping reactions that might escape detection on an integral thermogram.