Weyl-mediated helical magnetism in NdAlSi.

Emergent relativistic quasiparticles in Weyl semimetals are the source of exotic electronic properties such as surface Fermi arcs, the anomalous Hall effect and negative magnetoresistance, all observed in real materials. Whereas these phenomena highlight the effect of Weyl fermions on the electronic transport properties, less is known about what collective phenomena they may support. Here, we report a Weyl semimetal, NdAlSi, that offers an example. Using neutron diffraction, we found a long-wavelength helical magnetic order in NdAlSi, the periodicity of which is linked to the nesting vector between two topologically non-trivial Fermi pockets, which we characterize using density functional theory and quantum oscillation measurements. We further show the chiral transverse component of the spin structure is promoted by bond-oriented Dzyaloshinskii-Moriya interactions associated with Weyl exchange processes. Our work provides a rare example of Weyl fermions driving collective magnetism.

Antiferromagnetic Order and Spin-Canting Transition in the Corrugated Square Net Compound Cu3(TeO4)(SO4)·H2O.

Strongly correlated electrons in layered perovskite structures have been the birthplace of high-temperature superconductivity, spin liquids, and quantum criticality. Specifically, the cuprate materials with layered structures made of corner-sharing square-planar CuO4 units have been intensely studied due to their Mott insulating ground state, which leads to high-temperature superconductivity upon doping. Identifying new compounds with similar lattice and electronic structures has become a challenge in solid-state chemistry. Here, we report the hydrothermal crystal growth of a new copper tellurite sulfate, Cu3(TeO4)(SO4)·H2O, a promising alternative to layered perovskites. The orthorhombic phase (space group Pnma) is made of corrugated layers of corner-sharing CuO4 square-planar units that are edge-shared with TeO4 units. The layers are linked by slabs of corner-sharing CuO4 and SO4. Using both the bond valence sum analysis and magnetization data, we find purely Cu2+ ions within the layers but a mixed valence of Cu2+/Cu+ between the layers. Cu3(TeO4)(SO4)·H2O undergoes an antiferromagnetic transition at TN = 67 K marked by a peak in the magnetic susceptibility. Upon further cooling, a spin-canting transition occurs at T* = 12 K, evidenced by a kink in the heat capacity. The spin-canting transition is explained on the basis of a J1-J2 model of magnetic interactions, which is consistent with the slightly different in-plane superexchange paths. We present Cu3(TeO4)(SO4)·H2O as a promising platform for the future doping and strain experiments that could tune the Mott insulating ground state into superconducting or spin liquid states.

Focused Critical Care Echocardiography: Development and Evaluation of an Image Acquisition Assessment Tool.

OBJECTIVES: Little attention has been placed on assessment tools to evaluate image acquisition quality for focused critical care echocardiography. We designed a novel assessment tool to objectively evaluate the image acquisition skills of critical care trainees learning focused critical care echocardiography and examined the tool for evidence of validity. DESIGN: Prospective observational study. SETTING: Medical-surgical ICUs at a tertiary care teaching hospital. SUBJECTS: Trainees in our critical care medicine fellowship program. INTERVENTIONS: Six trainees completed a focused critical care echocardiography training curriculum followed by performing 20 transthoracic echocardiograms on patients receiving invasive mechanical ventilation. At three assessment intervals (the 1st and 2nd examinations, 10th and 11th examinations, and 19th and 20th examinations), echocardiograms performed by trainees were compared with those of critical care physicians certified in echocardiography and scored according to the focused critical care echocardiography assessment tool. The primary outcome was an efficiency score (overall assessment tool score divided by examination time). Differences in mean efficiency scores between echocardiographers of differing skill levels and changes in trainees' mean efficiency scores with increasing focused critical care echocardiography experience were compared by using t tests. MEASUREMENTS AND MAIN RESULTS: On the initial assessment, mean efficiency scores (SD) for trainees and experienced physicians were 1.55 (0.95) versus 2.78 (1.38), respectively (p = 0.02), and for the second and third assessments, the corresponding efficiency ratings for trainees and experienced physicians were 2.48 (0.97) versus 4.55 (1.32) (p < 0.01) and 2.61 (1.37) versus 4.17 (2.12) (p = 0.04), respectively. CONCLUSIONS: Trainees' efficiency in focused critical care echocardiography image acquisition improved quickly in the first 10 studies, yet, it could not match with the performance of experienced physicians after 20 focused critical care echocardiography studies. The focused critical care echocardiography assessment tool demonstrated evidence of validity and could discern changes in trainees' image acquisition performance with increasing experience.

Accuracy of peripheral thermometers for estimating temperature: a systematic review and meta-analysis.

BACKGROUND: Body temperature is commonly used to screen patients for infectious diseases, establish diagnoses, monitor therapy, and guide management decisions. PURPOSE: To determine the accuracy of peripheral thermometers for estimating core body temperature in adults and children. DATA SOURCES: MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and CINAHL Plus from inception to July 2015. STUDY SELECTION: Prospective studies comparing the accuracy of peripheral (tympanic membrane, temporal artery, axillary, or oral) thermometers with central (pulmonary artery catheter, urinary bladder, esophageal, or rectal) thermometers. DATA EXTRACTION: 2 reviewers extracted data on study characteristics, methods, and outcomes and assessed the quality of individual studies. DATA SYNTHESIS: 75 studies (8682 patients) were included. Most studies were at high or unclear risk of patient selection bias (74%) or index test bias (67%). Compared with central thermometers, peripheral thermometers had pooled 95% limits of agreement (random-effects meta-analysis) outside the predefined clinically acceptable range (± 0.5 °C), especially among patients with fever (-1.44 °C to 1.46 °C for adults; -1.49 °C to 0.43 °C for children) and hypothermia (-2.07 °C to 1.90 °C for adults; no data for children). For detection of fever (bivariate random-effects meta-analysis), sensitivity was low (64% [95% CI, 55% to 72%]; I2 = 95.7%; P < 0.001) but specificity was high (96% [CI, 93% to 97%]; I2 = 96.3%; P < 0.001). Only 1 study reported sensitivity and specificity for the detection of hypothermia. LIMITATIONS: High-quality data for some temperature measurement techniques are limited. Pooled data are associated with interstudy heterogeneity that is not fully explained by stratified and metaregression analyses. CONCLUSION: Peripheral thermometers do not have clinically acceptable accuracy and should not be used when accurate measurement of body temperature will influence clinical decisions. PRIMARY FUNDING SOURCE: None.

Cu substitution effects on the local magnetic properties of Ba(Fe(1-x)Cu(x))(2)As(2): a site-selective (75)As and (63)Cu NMR study.

We take advantage of the site-selective nature of the ^{75}As and ^{63}Cu NMR techniques to probe the Cu substitution effects on the local magnetic properties of the FeAs planes in Ba(Fe_{1-x}Cu_{x})_{2}As_{2}. We show that the suppression of antiferromagnetic Fe spin fluctuations induced by Cu substitution is weaker than a naive expectation based on a simple rigid band picture, in which each Cu atom would donate three electrons to the FeAs planes. Comparison between ^{63}Cu and ^{75}As NMR data indicates that spin fluctuations are suppressed at the Cu and their neighboring Fe sites in the tetragonal phase, suggesting the strongly local nature of the Cu substitution effects. We attribute the absence of a large superconducting dome in the phase diagram of Ba(Fe_{1-x}Cu_{x})_{2}As_{2} to the emergence of a nearly magnetically ordered FeAs plane under the presence of orthorhombic distortion.

Methods for determination of optimal positive end-expiratory pressure: a protocol for a scoping review.

INTRODUCTION: Titrated application of positive end-expiratory pressure (PEEP) is an important part of any mechanical ventilation strategy. However, the method by which the optimal PEEP is determined and titrated varies widely. Methods for determining optimal PEEP have been assessed using a variety of different study designs and patient populations. We will conduct a scoping review to systematically identify all methods for determining optimal PEEP, and to identify the patient populations, outcomes measured and study designs used for each method. The goal will be to identify gaps in the optimal PEEP literature and identify areas where there may be an opportunity to further systematically synthesise and meta-analyse existing literature. METHODS AND ANALYSIS: Using scoping review methodology, we will generate a comprehensive search strategy based on inclusion and exclusion criteria generated using the population, concept, context framework. Five different databases will be searched (MEDLINE, EMBASE, CENTRAL, Web of Science and Scopus). Three investigators will independently screen titles and abstracts, and two investigators will independently complete full-text review and data extraction. Included citations will be categorised in terms of PEEP method, study design, patient population and outcomes measured. The methods for PEEP titration will be described in detail, including strengths and limitations. ETHICS AND DISSEMINATION: Given this is a synthesis of existing literature, ethics approval is not required. The results will be disseminated to stakeholders via presentation at local, regional and national levels, as well as publication in a high-impact critical care journal. There is also the potential to impact local clinical care protocols and inform broader clinical practice guidelines undertaken by societies.

Adapting Feedback to Individual Residents: An Examination of Preceptor Challenges and Approaches.

Background: Feedback conversations between preceptors and residents usually occur in closed settings. Little is known about how preceptors address the challenges posed by residents with different skill sets, performance levels, and personal contexts. Objective: This study explored the challenges that preceptors experienced and approaches taken in adapting feedback conversations to individual residents. Methods: In 2015, 18 preceptors participated in feedback simulations portraying residents with variations in skill, insight, confidence, and distress, followed by debriefing of the feedback conversation with a facilitator. These interactions were recorded, transcribed, and analyzed using thematic and framework analysis. Results: The preceptors encountered common challenges with feedback conversations, including uncertainty in how to individualize feedback to residents and how to navigate tensions between resident- and preceptor-identified goals. Preceptors questioned their ability to enhance skills for highly performing residents, whether they could be directive when residents had insight gaps, how they could reframe the perceptions of the overly confident resident, and whether they should offer support to emotionally distressed residents or provide feedback about performance. Preceptors adapted their approach to feedback, drawing on techniques of coaching for highly performing residents, directing for residents with insight gaps, mediation with overly confident residents, and mentoring with emotionally distressed residents. Conclusions: Examining the feedback challenges preceptors encounter and the approaches taken to adapt feedback to individual residents can provide insight into how preceptors meet the challenges of competency-based medical education, in which frequent, focused feedback is essential for residents to achieve educational milestones and entrustable professional activity expectations.

Exploring Faculty Approaches to Feedback in the Simulated Setting: Are They Evidence Informed?

INTRODUCTION: Feedback in clinical education and after simulated experiences facilitates learning. Although evidence-based guidelines for feedback exist, faculty experience challenges in applying the guidelines. We set out to explore how faculty approach feedback and how these approaches align with current recommendations. METHODS: There is strong evidence for the following four components of feedback: feedback as a social interaction, tailoring content, providing specific descriptions of performance, and identifying actionable items. Faculty preceptors participated in feedback simulations followed by debriefing. The simulations were video recorded, transcribed, and analyzed qualitatively using template analysis to examine faculty approaches to feedback relative to evidence-informed recommendations. RESULTS: Recorded encounters involving 18 faculty and 11 facilitators yielded 111 videos. There was variability in the extent to which feedback approaches aligned with recommended practices. Faculty behaviors aligned with recommendations included a conversational approach, flexibly adapting feedback techniques to resident context, offering rich descriptions of observations with specific examples and concrete suggestions, achieving a shared understanding of strengths and gaps early on to allow sufficient time for problem-solving, and establishing a plan for ongoing development. Behaviors misaligned with guidelines included prioritizing the task of feedback over the relationship, lack of flexibility in techniques applied, using generic questions that did not explore residents' experiences, and ending with a vague plan for improvement. CONCLUSIONS: Faculty demonstrate variability in feedback skills in relation to recommended practices. Simulated feedback experiences may offer a safe environment for faculty to further develop the skills needed to help residents progress within competency-based medical education.

Canadian Association of Emergency Physicians sepsis treatment checklist: optimizing sepsis care in Canadian emergency departments.

OBJECTIVE: The Canadian Association of Emergency Physicians (CAEP) sepsis guidelines created by the CAEP Critical Care Practice Committee (C4) and published in the Canadian Journal of Emergency Medicine (CJEM) form the most definitive publication on Canadian emergency department (ED) sepsis care to date. Our intention was to identify which of the care items in this document are specifically necessary in the ED and then to provide these items in a tiered checklist that can be used by any Canadian ED practitioner. METHODS: Practice points from the CJEM sepsis publication were identified to create a practice point list. Members of C4 then used a Delphi technique consensus process over May to October 2009 via e-mail to create a tiered checklist of sepsis care items that can or could be completed in a Canadian ED when caring for the septic shock patient. This checklist was then assessed for use by a survey of ED practitioners from varying backgrounds (rural ED, community ED, tertiary ED) from July to October 2010. RESULTS: Twenty sepsis care items were identified in the CAEP sepsis guidelines. Fifteen items were felt to be necessary for ED care. Two levels of checklists were then created that can be used in a Canadian ED. Most ED physicians in community and tertiary care centres could complete all parts of the level I sepsis checklist. Rural centres often struggle with the ability to obtain lactate values and central venous access. Many items of the level II sepsis checklist could not be completed outside the tertiary care centre ED. CONCLUSION: Sepsis care continues to be an integral and major part of the ED domain. Practice points for sepsis care that require specialized monitoring and invasive techniques are often limited to larger tertiary care EDs and, although heavily emphasized by many medical bodies, cannot be reasonably expected in all centres. When the resources of a centre limit patient care, transfer may be required.