Gate-Tunable Anomalous Hall Effect in a 3D Topological Insulator/2D Magnet van der Waals Heterostructure.

We demonstrate advantages of samples made by mechanical stacking of exfoliated van der Waals materials for controlling the topological surface state of a three-dimensional topological insulator (TI) via interaction with an adjacent magnet layer. We assemble bilayers with pristine interfaces using exfoliated flakes of the TI BiSbTeSe2 and the magnet Cr2Ge2Te6, thereby avoiding problems caused by interdiffusion that can affect interfaces made by top-down deposition methods. The samples exhibit an anomalous Hall effect (AHE) with abrupt hysteretic switching. For the first time in samples composed of a TI and a separate ferromagnetic layer, we demonstrate that the amplitude of the AHE can be tuned via gate voltage with a strong peak near the Dirac point. This is the signature expected for the AHE due to Berry curvature associated with an exchange gap induced by interaction between the topological surface state and an out-of-plane-oriented magnet.

Impact of Hospital-Based Rehabilitation Services on Discharge to the Community by Value-Based Payment Programs After Joint Replacement Surgery.

OBJECTIVE: The purpose of this study was to examine the impact of hospital-based rehabilitation services on community discharge rates after hip and knee replacement surgery according to hospital participation in value-based care models: bundled payments for care improvement (BPCI) and comprehensive care for joint replacement (CJR). The secondary objective was to determine whether community discharge rates after hip and knee replacement surgery differed by participation in these models. METHODS: A secondary analysis of Medicare fee-for-service claims was conducted for beneficiaries 65 years of age or older who underwent hip and knee replacement surgery from 2016 to 2017. Independent variables were hospital participation in value-based programs categorized as: (1) BPCI, (2) CJR, and (3) non-BPCI/CJR; and total minutes per day of hospital-based rehabilitation services categorized into tertiles. The primary outcome variable was discharged to the community versus discharged to institutional post-acute care settings. The association between rehabilitation amount and community discharge among BPCI, CJR, and non-BPCI/CJR hospitals was adjusted for patient-level clinical and hospital characteristics. RESULTS: Participation in BPCI or CJR was not associated with community discharge. This analysis found a dose-response relationship between the amount of rehabilitation services and odds of community discharge. Among those who received a hip replacement, this relationship was most pronounced in the BPCI group; compared with the low rehabilitation category, the medium category had odds ratio (OR) = 1.28 (95% CI = 1.17 to 1.41), and the high category had OR = 1.90 (95% CI = 1.71 to 2.11). For those who received a knee replacement, there was a dose-response relationship in the CJR group only; compared with the low rehabilitation category, the medium category had OR = 1.21 (95% CI = 1.15 to 1.28), and the high category had OR = 1.56 (95% CI = 1.46 to 1.66). CONCLUSION: Regardless of hospital participation in BPCI or CJR models, higher amounts of rehabilitation services delivered during acute hospitalization is associated with a higher likelihood of discharge to community following hip and knee replacement surgery. IMPACT: In the era of value-based care, frontloading of rehabilitation care is vital for improving patient-centered health outcomes in acute phases of lower extremity joint replacement.

Anomalous negative longitudinal magnetoresistance and violation of Ohm's law deep in the topological insulating regime in Bi[Formula: see text]Sb[Formula: see text].

Bi[Formula: see text]Sb[Formula: see text] is a topological insulator (TI) for [Formula: see text]-0.20. Close to the Topological phase transition at [Formula: see text], a magnetic field induced Weyl semi-metal (WSM) state is stabilized due to the splitting of the Dirac cone into two Weyl cones of opposite chirality. A signature of the Weyl state is the observation of a Chiral anomaly [negative longitudinal magnetoresistance (LMR)] and a violation of the Ohm's law (non-linear [Formula: see text]). We report the unexpected discovery of Chiral anomaly-like features in the whole range ([Formula: see text]) of the TI state. This points to a field induced WSM state in an extended x range and not just near the topological transition at [Formula: see text]. Surprisingly, the strongest Weyl phase is found at [Formula: see text] with a non-saturating negative LMR much larger than observed for [Formula: see text]. The negative LMR vanishes rapidly with increasing angle between B and I. Additionally, non-linear I-V is found for [Formula: see text] indicating a violation of Ohm's law. This unexpected observation of a strong Weyl state in the whole TI regime in Bi[Formula: see text]Sb[Formula: see text] points to a gap in our understanding of the detailed crystal and electronic structure evolution in this alloy system.

Mixed type I and type II superconductivity due to intrinsic electronic inhomogeneities in the type II Dirac semimetal PdTe2.

The type II Dirac semimetal PdTe[Formula: see text] is unique in the family of topological parent materials because it displays a superconducting ground state below 1.7 K. Despite wide speculation on the possibility of an unconventional topological superconducting phase, tunneling and heat capacity measurements revealed that the superconducting phase of PdTe[Formula: see text] follows predictions of the microscopic theory of Bardeen, Cooper and Schrieffer for conventional superconductors. The superconducting phase in PdTe[Formula: see text] is further interesting because it also displays properties that are characteristic of type-I superconductors and are generally unexpected for binary compounds. Here, from scanning tunneling spectroscopic measurements we show that the surface of PdTe[Formula: see text] displays intrinsic electronic inhomogeneities in the normal state which leads to a mixed type I and type II superconducting behaviour along with a spatial distribution of critical fields in the superconducting state. Understanding of the origin of such inhomogeneities may be important for understanding the topological properties of PdTe[Formula: see text] in the normal state.

Current Risk Adjustment and Comorbidity Index Underperformance in Predicting Post-Acute Utilization and Hospital Readmissions After Joint Replacements: Implications for Comprehensive Care for Joint Replacement Model.

OBJECTIVE: To compare the performances of 3 comorbidity indices, the Charlson Comorbidity Index, the Elixhauser Comorbidity Index, and the Centers for Medicare & Medicaid Services (CMS) risk adjustment model, Hierarchical Condition Category (HCC), in predicting post-acute discharge settings and hospital readmission for patients after joint replacement. METHODS: A retrospective study of Medicare beneficiaries with total knee replacement (TKR) or total hip replacement (THR) discharged from hospitals in 2009-2011 (n = 607,349) was performed. Study outcomes were post-acute discharge setting and unplanned 30-, 60-, and 90-day hospital readmissions. Logistic regression models were built to compare the performance of the 3 comorbidity indices using C statistics. The base model included patient demographics and hospital use. Subsequent models included 1 of the 3 comorbidity indices. Additional multivariable logistic regression models were built to identify individual comorbid conditions associated with high risk of hospital readmissions. RESULTS: The 30-, 60-, and 90-day unplanned hospital readmission rates were 5.3%, 7.2%, and 8.5%, respectively. Patients were most frequently discharged to home health (46.3%), followed by skilled nursing facility (40.9%) and inpatient rehabilitation facility (12.7%). The C statistics for the base model in predicting post-acute discharge setting and 30-, 60-, and 90-day readmission in TKR and THR were between 0.63 and 0.67. Adding the Charlson Comorbidity Index, the Elixhauser Comorbidity Index, or HCC increased the C statistic minimally from the base model for predicting both discharge settings and hospital readmission. The health conditions most frequently associated with hospital readmission were diabetes mellitus, pulmonary disease, arrhythmias, and heart disease. CONCLUSION: The comorbidity indices and CMS-HCC demonstrated weak discriminatory ability to predict post-acute discharge settings and hospital readmission following joint replacement.