Imaging orbital ferromagnetism in a moiré Chern insulator

Electrons in moiré flat band systems can spontaneously break time-reversal symmetry, giving rise to a quantized anomalous Hall effect. In this study, we use a superconducting quantum interference device to image stray magnetic fields in twisted bilayer graphene aligned to hexagonal boron nitride. We find a magnetization of several Bohr magnetons per charge carrier, demonstrating that the magnetism is primarily orbital in nature. Our measurements reveal a large change in the magnetization as the chemical potential is swept across the quantum anomalous Hall gap, consistent with the expected contribution of chiral edge states to the magnetization of an orbital Chern insulator. Mapping the spatial evolution of field-driven magnetic reversal, we find a series of reproducible micrometer-scale domains pinned to structural disorder.

Intrinsic quantized anomalous Hall effect in a moiré heterostructure

The quantum anomalous Hall (QAH) effect combines topology and magnetism to produce precisely quantized Hall resistance at zero magnetic field. We report the observation of a QAH effect in twisted bilayer graphene aligned to hexagonal boron nitride. The effect is driven by intrinsic strong interactions, which polarize the electrons into a single spin- and valley-resolved moiré miniband with Chern number C = 1. In contrast to magnetically doped systems, the measured transport energy gap is larger than the Curie temperature for magnetic ordering, and quantization to within 0.1% of the von Klitzing constant persists to temperatures of several kelvin at zero magnetic field. Electrical currents as small as 1 nanoampere controllably switch the magnetic order between states of opposite polarization, forming an electrically rewritable magnetic memory.

The feasibility of a telecommunications service in support of outpatient congestive heart failure care in a diverse patient population

A home telemonitoring system for patients with congestive heart failure was studied for feasibility and efficacy in a diverse patient population. Fifty patients used the service, in which they weighed themselves and answered yes/no questions about symptoms. Changes in patient weights or symptoms prompted a nurse to call the patient and/or the physician. Patients were given educational and quality of life surveys at enrollment, at 30 days, and at 6 months. The average daily usage rate was 94%. Patients were contacted 57 times--prompting 57 physician notifications, eight medication changes, and 11 nonroutine clinic visits. Patient response to lifestyle surveys showed an improvement in quality of life and improved understanding of prevention measures. Eighty-four percent of patients and 65% of physicians reported satisfaction with the system. This pilot study suggests that home telemonitoring is feasible and has clinical utility in diverse patient groups, and may improve patients' satisfaction and knowledge of self-care. (c)2000 by CHF, Inc.

Possible role of the V3 domain of gp120 in resistance to an amphotericin B derivative (MS8209) blocking human immunodeficiency virus entry

MS8209, an amphotericin B derivative blocking human immunodeficiency virus type 1 (HIV-1) entry after CD4 binding, neutralized the HIV-2 strains EHO and ROD10 but not ROD(CEM). In the V3 domain of gp120, ROD(CEM) differed from ROD10 at two positions (a threonine instead of an isoleucine at position 312 and an arginine instead of a glutamine at position 329), and drug resistance was conferred to HIV-1 by substitution of the ROD(CEM) V3 but not the ROD10 V3. V3 mutations may prevent the interaction of gp120 with MS8209 or modify the mechanism of virus entry, rendering it less accessible to neutralization.

Inter-relationship among individual vitamin K-dependent clotting factors at different levels of anticoagulation

1. The effect of subtherapeutic doses of warfarin on the activities of the four vitamin K-dependent clotting factors was studied at steady state in five patients each of whom had completed a therapeutic course of anticoagulation. 2. The four clotting factor activities were shown to be depressed to a similar extent for a given dose of warfarin. 3. The prothrombin complex activity was significantly lower than that of any of the clotting factors.