Microscopic Manipulation of Ferroelectric Domains in SnSe Monolayers at Room Temperature.

Two-dimensional (2D) van der Waals ferroelectrics provide an unprecedented architectural freedom for the creation of artificial multiferroics and nonvolatile electronic devices based on vertical and coplanar heterojunctions of 2D ferroic materials. Nevertheless, controlled microscopic manipulation of ferroelectric domains is still rare in monolayer-thick 2D ferroelectrics with in-plane polarization. Here we report the discovery of robust ferroelectricity with a critical temperature close to 400 K in SnSe monolayer plates grown on graphene and the demonstration of controlled room-temperature ferroelectric domain manipulation by applying appropriate bias voltage pulses to the tip of a scanning tunneling microscope (STM).

Standing Waves Induced by Valley-Mismatched Domains in Ferroelectric SnTe Monolayers.

Two-dimensional (2D) quasiparticle standing waves originate from the interference of coherent quantum states and are usually created by the scattering off edges, atomic steps, or adatoms that induce large potential barriers. We report standing waves close to the valence band maximum (E_{V}), confined by electrically neutral domain walls of newly discovered ferroelectric SnTe monolayers, as revealed by spatially resolved scanning tunneling spectroscopy. Ab initio calculations show that this novel confinement arises from the polarization lifted hole valley degeneracy and a ∼90° rotation of the Brillouin zones that render holes' momentum mismatched across neighboring domains.

Hospitalizations for pelvic inflammatory disease in Texas. A population-based analysis.

Objective: To calculate pelvic inflammatory disease (PID) hospitalization rates for Texas and identify risk factors for prolonged length of stay (PLOS) among women hospitalized for PID throughout Texas and discharged during a 2-year period.

Study Design: A cross-sectional study of 6,421 women discharged from Texas hospitals in 2004 and 2005 with a diagnosis of PID was conducted. Data for 2004 and 2005 were obtained from the Texas Department of State Health Services.