Second-harmonic generation in optically trapped nonlinear particles with pulsed lasers

Pulsed lasers are used for simultaneous single-beam three-dimensional optical trapping of and second-harmonic generation in 50--100-nm nonlinear particles. The emission power of the frequency-doubled light, the trapping stability, and the particle degradation are investigated for KTP and LiNbO3 particles trapped by 25-kHz-repetition-rate Q-switched Nd:YAG and 76-MHz mode-locked Ti:sapphire l a s e r s . Typically 1 pW-10 nW of frequency-doubled light is detected from stably trapped particles. The particles may be used as probes for nonintrusively scanned near-field optical microscopy

Droplet-target laser-plasma source for proximity x-ray lithography

A compact, high-brightness and practically debris-free laser-plasma soft x-ray source for proximity x-ray lithography is described. The target of the source is small liquid fluorocarbon droplets injected into vacuum with a piezoelectrically vibrated nozzle. Emission from helium- and hydrogenlike fluorine in the 1.2-1.7 nm wavelength range was determined to similar to 2X10(12) photons/(sr-pulse). which corresponds to a conversion efficiency of similar to 5% of the 70 mJ laser pulse. Exposure of a copolymer of PMMA-MAA confirms the measured photon flux. Debris production was approximately 70 pg/sr pulse. The applicability of the source for dedicated lithography systems is discussed. (C) 1996 American Institute of Physics

Liquid-jet target for laser-plasma soft x-ray generation

We describe a new liquid-target system for low-debris laser-plasma soft x-ray sources. The system is based on a microscopic liquid jet and is experimentally evaluated for 0.7-1 keV proximity lithography and water-window x-ray microscopy applications. Compared to an existing liquid-droplet target, this target system has the same low debris emission, high x-ray photon flux, and narrow spectral bandwidth. The advantages of the liquid-jet target include improved x-ray flux stability, increased range of suitable target liquids, and elimination of the need for temporal synchronization, thereby allowing less complex laser systems to be used. (C) 1996 American Institute of Physics

Clustering patients on the basis of their individual course of low back pain over a six month period

<p>Abstract</p> <p>Background</p> <p>Several researchers have searched for subgroups in the heterogeneous population of patients with non-specific low back pain (LBP). To date, subgroups have been identified based on psychological profiles and the variation of pain.</p> <p>Methods</p> <p>This multicentre prospective observational study explored the 6- month clinical course with measurements of bothersomeness that were collected from weekly text messages that were sent by 176 patients with LBP. A hierarchical cluster analysis, Ward's method, was used to cluster patients according to the development of their pain.</p> <p>Results</p> <p>Four clusters with distinctly different clinical courses were described and further validated against clinical baseline variables and outcomes. Cluster 1, a "stable" cluster, where the course was relatively unchanged over time, contained young patients with good self- rated health. Cluster 2, a group of "fast improvers" who were very bothered initially but rapidly improved, consisted of patients who rated their health as relatively poor but experienced the fewest number of days with bothersome pain of all the clusters. Cluster 3 was the "typical patient" group, with medium bothersomeness at baseline and an average improvement over the first 4-5 weeks. Finally, cluster 4 contained the "slow improvers", a group of patients who improved over 12 weeks. This group contained older individuals who had more LBP the previous year and who also experienced most days with bothersome pain of all the clusters.</p> <p>Conclusions</p> <p>It is possible to define clinically meaningful clusters of patients based on their individual course of LBP over time. Future research should aim to reproduce these clusters in different populations, add further clinical variables to distinguish the clusters and test different treatment strategies for them.</p

Studier av kärnladdning och masstal för atomkärnor i den primära kosmiska strålningen

[abstract missing

Trapped-particle Optical Microscopy

A scanned probe optical microscope allowing nondestructive studies of a wide range of objects and surfaces is described. The microscope utilizes a noninvasive optical trap to position a microscopic probe light source in immediate proximity to the studied object. We demonstrate the method experimentally and show theoretically its potential for optical imaging with subdiffraction limited resolution of, e.g., biological objects