Mobile orbitons in Ca2_2CuO3_3: crucial role of the Hund's exchange

We investigate the Cu $L_3$ edge resonant inelastic x-ray scattering (RIXS) spectra of a quasi-1D antiferromagnet Ca$_2$CuO$_3$. In addition to the magnetic excitations, which are well-described by the two-spinon continuum, we observe two dispersive orbital excitations, the $3d_{xy}$ and the $3d_{yz}$ orbitons. We carry out a quantitative comparison of the RIXS spectra, obtained with two distinct incident polarizations, with a theoretical model. We show that any realistic spin-orbital model needs to include a finite, but realistic, Hund's exchange $J_H \approx 0.5$ eV. Its main effect is an increase in orbiton velocities, so that their theoretically calculated values match those observed experimentally. Even though Hund's exchange also mediates some interaction between spinon and orbiton, the picture of spin-orbit separation remains intact and describes orbiton motion in this compound.Comment: 13 pages, 10 figure

The role of a surveillance programme for introducing peripherally inserted central catheters: a 2-year observational study in an academic hospital.

AIMS OF THE STUDY In our hospital, a previous attempt to introduce peripherally inserted central catheters (PICC) was aborted after a nonsystematic approach, seemingly accompanied by high rates of complications. The goal of this new interdisciplinary project was to introduce PICCs in an academic hospital, with an embedded interdisciplinary surveillance programme for both infectious and noninfectious outcomes. METHODS We prospectively collected data for this surveillance study from all patients who underwent PICC insertion from 1 January 2014 and had the catheter removed by 31 December 2015 in our 950-bed academic hospital (Bern University Hospital, Switzerland). Infectious complications were defined according to Centers for Disease Control and Prevention / National Healthcare Safety Network criteria. PICCs were restricted to cancer and infectious disease patients, and were followed up irrespective of the management setting (inpatient, outpatient or intermittently hospitalised after insertion). An interdisciplinary team reviewed the outcomes on a routine basis and discussed changes to the process to improve outcomes, if necessary. RESULTS One hundred and thirty-five PICCs were inserted in 124 patients, the majority of whom were patients from the medical oncology department (n = 107, 86.3%). Indications for PICC insertion included: chemotherapy (n = 97, 71.9%), antibiotic therapy (n = 24, 17.8%), total parenteral nutrition (n = 8, 5.9%), blood product transfusion (n = 4, 3.0%) and palliative care (n = 2, 1.5%). During a total of 10 402 catheter-days (median dwell time 62 days), there were five central line-associated bloodstream infections, including one mucosal barrier injury laboratory-confirmed bloodstream infection and two exit-site infections, yielding incidence rates of 0.48 and 0.19 infections per 1000 catheter-days, respectively. Incidence rates were 0.67 per 1000 catheter-days (n = 7) for radiologically documented deep venous thrombosis, 0.96 (n = 10) for tip dislocation and 0.67 (n = 7) for catheter occlusion. The overall rate of complications was 4.5 per 1000 catheter-days. Seventeen catheters (12.6%) were removed because of any complication. CONCLUSION We successfully introduced PICCs in an academic hospital by implementing a systematic surveillance programme for complications. Both infectious and noninfectious complications were rare. Infection prevention specialists should be actively involved during the introduction of new intravascular devices in order to provide quality indicators and assure patient safety

Automated Billing Code Retrieval from MRI Scanner Log Data.

Although the level of digitalization and automation steadily increases in radiology, billing coding for magnetic resonance imaging (MRI) exams in the radiology department is still based on manual input from the technologist. After the exam completion, the technologist enters the corresponding exam codes that are associated with billing codes in the radiology information system. Moreover, additional billing codes are added or removed, depending on the performed procedure. This workflow is time-consuming and we showed that billing codes reported by the technologists contain errors. The coding workflow can benefit from an automated system, and thus a prediction model for automated assignment of billing codes for MRI exams based on MRI log data is developed in this work. To the best of our knowledge, it is the first attempt to focus on the prediction of billing codes from modality log data. MRI log data provide a variety of information, including the set of executed MR sequences, MR scanner table movements, and given a contrast medium. MR sequence names are standardized using a heuristic approach and incorporated into the features for the prediction. The prediction model is trained on 9754 MRI exams and tested on 1 month of log data (423 MRI exams) from two MRI scanners of the radiology site for the Swiss medical tariffication system Tarmed. The developed model, an ensemble of classifier chains with multilayer perceptron as a base classifier, predicts medical billing codes for MRI exams with a micro-averaged F1-score of 97.8% (recall 98.1%, precision 97.5%). Manual coding reaches a micro-averaged F1-score of 98.1% (recall 97.4%, precision 98.8%). Thus, the performance of automated coding is close to human performance. Integrated into the clinical environment, this work has the potential to free the technologist from a non-value adding an administrative task, therefore enhance the MRI workflow, and prevent coding errors