Nanoscale electronic order in iron pnictides

The charge distribution in RFeAsO1-xFx (R=La,Sm) iron pnictides is probed using As nuclear quadrupole resonance. Whereas undoped and optimally doped or overdoped compounds feature a single charge environment, two charge environments are detected in the underdoped region. Spin-lattice relaxation measurements show their coexistence at the nanoscale. Together with the quantitative variations of the spectra with doping, they point to a local electronic order in the iron layers, where low- and high-doping-like regions would coexist. Implications for the interplay of static magnetism and superconductivity are discussed.

Comparison of performance of computer display monitors for radiological diagnosis; "diagnostic" high brightness monochrome LCD, 3MP vs "clinical review" colour LCD, 2MP

A study to compare performance of the following display monitors for application as PACS CR diagnostic workstations is described. 1. Diagnostic quality, 3 Mega Pixel, 21 inch monochrome LCD monitors--Planar C3i. 2. Clinical review quality, 2 Mega Pixel, 21 inch colour LCD monitors--Planar PX212. Two sets of seventy radiological studies were presented to four senior radiologists on two occasions, using different displays on each occasion. The clinical condition used for this investigation was to query for the presence of a solitary pulmonary nodule. Receiver Operating Characteristic (ROC) curves were constructed for diagnostic performance for each presentation. Areas under the ROC curves (AUC) for diagnosis using different monitors were compared and the following results obtained: Monochrome AUC = 0.813 +/- 0.02, Colour AUC = 0.801 +/- 0.021. These results indicate that there is no statistically significant difference in the performance of these monitor types at a 95% confidence level.

Comparison of computer display monitors for computed radiography diagnostic application in a radiology PACS

A study to compare the performance of the following display monitors for application as PACS CR diagnostic workstations is described. 1. Diagnostic quality, 3 megapixel, 21 inch monochrome LCD monitors. 2. Commercial grade, 2 megapixel, 20 inch colour LCD monitors. Two sets of fifty radiological studies each were presented separately to five radiologists on two occasions, using different displays on each occasion. The two sets of radiological studies were CR of the chest, querying the presence of pneumothorax, and CR of the wrist, querying the presence of a scaphoid fracture. Receiver Operating Characteristic (ROC) curves were constructed for diagnostic performance for each presentation. Areas under the ROC curves (AUC) for diagnosis using different monitors were compared for each image set and the following results obtained: Set 1: Monochrome AUC = 0.873 +/- 0.026; Colour AUC = 0.831 +/- 0.032; Set 2: Monochrome AUC = 0.945 +/- 0.014; Colour AUC = 0.931 +/- 0.019; Differences in AUC were attributed to the different monitors. While not significant at a 95% confidence level, the results have supported a cautious approach to consideration of the use of commercial grade LCD colour monitors for diagnostic application.

Can CT pulmonary angiography replace ventilation-perfusion scans as a first line investigation for pulmonary emboli?

A prospective study was performed to determine efficacy of diagnosis of pulmonary emboli by computed tomographic pulmonary angiography (CTPA) in patients who underwent both CTPA and ventilation-perfusion (V/Q) scanning. The results were compared with the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study in which conventional pulmonary angiography had been performed instead of CTPA. Forty-two of 161 (26%) patients had a positive CTPA compared with a 27% prevalence in the PIOPED population. Fourteen of 16 patients (87.5%) with high-probability V/Q scans also had a positive CTPA compared with 87% in PIOPED. Twelve of 40 patients (30%) with intermediate probability V/Q scans also had a positive CTPA compared with 34.7% in PIOPED, while 12 of 80 patients (15%) who had low-probability V/Q scans had positive CTPA compared with 14.5% in PIOPED. Four of 25 patients (16%) with normal V/Q scans had positive CTPA compared with 0% in PIOPED. While the present study size was relatively small, the results compared favourably with PIOPED, suggesting that equivalent prevalence of clot was being detected using CTPA. This result, together with the cost considerations, has led us to replace V/Q scanning with CTPA for investigation of the majority of cases of suspected, acute pulmonary emboli.