X-ray ptychography using randomized zone plates.

We have developed a randomized grating condenser zone plate (GCZP) that provides a µm-scale probe for use in x-ray ptychography. This delivers a significantly better x-ray throughput than probes defined by pinhole apertures, while providing a clearly-defined level of phase diversity to the illumination on the sample, and helping to reduce the dynamic range of the detected signal by spreading the zero-order light over an extended area of the detector. The first use of this novel x-ray optical element has been demonstrated successfully for both amplitude and phase contrast imaging using soft x-rays on the TwinMic beamline at the Elettra synchrotron.

Pain and discomfort associated with common hospital procedures and experiences.

To determine whether reliable and valid rankings of pain and discomfort resulting from hospital procedures encountered by advanced dementia patients could be developed from interviews with cognitively intact adults, rankings of pain and discomfort resulting from 16 common procedures were obtained from two samples of hospitalized, nondemented adults using ten- (N = 100) and five- (N = 35) point numeric rating scales (NRS). Reliability was assessed by having 30 additional subjects complete ten-point NRS representing the ten most frequent procedures in a re-arranged order. By repeated measure analysis of variance, the scales discriminated between procedures (F = 35.1, P < 0.001). Subjects could discriminate between pain and discomfort (F = 21.6, P < 0.001). The five-point NRS exhibited better subject discrimination between experiences. Reliability was also acceptable. A five-point NRS produced reliable and valid pain and discomfort rankings for 16 common hospital procedures and experiences. These rankings should prove useful in reducing suffering and can serve as surrogates for quantifying pain and discomfort in dementia patients.

Soft X-ray spectromicroscopy using ptychography with randomly phased illumination.

Ptychography is a form of scanning diffractive imaging that can successfully retrieve the modulus and phase of both the sample transmission function and the illuminating probe. An experimental difficulty commonly encountered in diffractive imaging is the large dynamic range of the diffraction data. Here we report a novel ptychographic experiment using a randomly phased X-ray probe to considerably reduce the dynamic range of the recorded diffraction patterns. Images can be reconstructed reliably and robustly from this setup, even when scatter from the specimen is weak. A series of ptychographic reconstructions at X-ray energies around the L absorption edge of iron demonstrates the advantages of this method for soft X-ray spectromicroscopy, which can readily provide chemical sensitivity without the need for optical refocusing. In particular, the phase signal is in perfect registration with the modulus signal and provides complementary information that can be more sensitive to changes in the local chemical environment.

On estimating processing variance: commentary and reanalysis of Kail's "Developmental functions for speeds of cognitive processes".

A recent paper by Kail (1988) in this journal appears to contain a significant error in the data analysis. The "goodness-of-fit" coefficients reported which suggest that overall about 94% of the variance can be accounted for by the model seem to be a substantial overestimation as a result of inappropriate procedures for statistical modeling. Using the data made available to us by Kail, we have reanalyzed these results. The corrected values range from 0.9 to 92.1% for the individual tasks with an overall average between 40 and 60%. We suggest that the support for the original conclusions is considerably weaker than reported.