Hidden Charge Order in an Iron Oxide Square-Lattice Compound.

Since the discovery of charge disproportionation in the FeO_{2} square-lattice compound Sr_{3}Fe_{2}O_{7} by Mössbauer spectroscopy more than fifty years ago, the spatial ordering pattern of the disproportionated charges has remained "hidden" to conventional diffraction probes, despite numerous x-ray and neutron scattering studies. We have used neutron Larmor diffraction and Fe K-edge resonant x-ray scattering to demonstrate checkerboard charge order in the FeO_{2} planes that vanishes at a sharp second-order phase transition upon heating above 332 K. Stacking disorder of the checkerboard pattern due to frustrated interlayer interactions broadens the corresponding superstructure reflections and greatly reduces their amplitude, thus explaining the difficulty of detecting them by conventional probes. We discuss the implications of these findings for research on "hidden order" in other materials.

Role of coronary angiography in patients with a non-diagnostic electrocardiogram following out of hospital cardiac arrest: Rationale and design of the multicentre randomized controlled COUPE trial.

BACKGROUND: Coronary artery disease (CAD) is a major cause of out-of-hospital cardiac arrest (OHCA). The role of emergency coronary angiography (CAG) and percutaneous coronary intervention (PCI) following cardiac arrest in patients without ST-segment elevation myocardial infarction (STEMI) remains unclear. AIMS: We aim to assess whether emergency CAG and PCI, when indicated, will improve survival with good neurological outcome in post-OHCA patients without STEMI who remain comatose. METHODS: COUPE is a prospective, multicentre and randomized controlled clinical trial. A total of 166 survivors of OHCA without STEMI will be included. Potentially non-cardiac aetiology of the cardiac arrest will be ruled out prior to randomization. Randomization will be 1:1 for emergency (within 2 h) or deferred (performed before discharge) CAG. Both groups will receive routine care in the intensive cardiac care unit, including therapeutic hypothermia. The primary efficacy endpoint is a composite of in-hospital survival free of severe dependence, which will be evaluated using the Cerebral Performance Category Scale. The safety endpoint will be a composite of major adverse cardiac events including death, reinfarction, bleeding and ventricular arrhythmias. CONCLUSIONS: This study will assess the efficacy of an emergency CAG versus a deferred one in OHCA patients without STEMI in terms of survival and neurological impairment.

A multicentre randomized pilot trial on the effectiveness of different levels of cooling in comatose survivors of out-of-hospital cardiac arrest: the FROST-I trial.

PURPOSE: To obtain initial data on the effect of different levels of targeted temperature management (TTM) in out-of-hospital cardiac arrest (OHCA). METHODS: We designed a multicentre pilot trial with 1:1:1 randomization to either 32 °C (n = 52), 33 °C (n = 49) or 34 °C (n = 49), via endovascular cooling devices during a 24-h period in comatose survivors of witnessed OHCA and initial shockable rhythm. The primary endpoint was the percentage of subjects surviving with good neurologic outcome defined by a modified Rankin Scale (mRS) score of ≤ 3, blindly assessed at 90 days. RESULTS: At baseline, different proportions of patients who had received defibrillation administered by a bystander were assigned to groups of 32 °C (13.5%), 33 °C (34.7%) and 34 °C (28.6%; p = 0.03). The percentage of patients with an mRS ≤ 3 at 90 days (primary endpoint) was 65.3, 65.9 and 65.9% in patients assigned to 32, 33 and 34 °C, respectively, non-significant (NS). The multivariate Cox proportional hazards model identified two variables significantly related to the primary outcome: male gender and defibrillation by a bystander. Among the 43 patients who died before 90 days, 28 died following withdrawal of life-sustaining therapy, as follows: 7/16 (43.8%), 10/13 (76.9%) and 11/14 (78.6%) of patients assigned to 32, 33 and 34 °C, respectively (trend test p = 0.04). All levels of cooling were well tolerated. CONCLUSIONS: There were no statistically significant differences in neurological outcomes among the different levels of TTM. However, future research should explore the efficacy of TTM at 32 °C. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov unique identifier: NCT02035839 ( http://clinicaltrials.gov ).

Repeatability of measurements obtained with a ray tracing aberrometer.

PURPOSE: To evaluate the repeatability of ocular aberrometry at distance and near vision conditions provided by the latest version of a ray tracing aberrometer. METHODS: A total of 22 healthy eyes of 22 patients with ages ranging from 21 to 65 years were included in this study. All eyes achieved a best spectacle corrected visual acuity of 20/20, and had not undergone previous ocular surgeries. Three consecutive aberrometric measurements were obtained with the iTrace system (Tracey Technologies) by an experienced examiner at distance (5 m) and near (40 cm). RESULTS: Low values of within-subject standard deviation (Sw) were found for sphere and cylinder at distance and near and for the power vector components of refraction. However, a more pronounced variability was observed for the coefficients associated with higher order aberrations, with the poorest repeatability for the vertical coma at near, Sw of 0.011 µm for a mean value of 0.018 µm. Additionally, Sw for vertical coma was significantly larger at near (p = 0.01). No significant differences between the distance and near values of Sw for the power vector components of refraction were found (p ≥ 0.08). The Sw values for the distance and near modulation transfer function parameters were low when compared with their corresponding mean values. CONCLUSIONS: The iTrace system provides repeatable measurements of the spherocylindrical refraction at near and distance, but consistency of aberrometric and optical quality measurements seems to be limited.