Many-Body Theory Calculations of Positron Scattering and Annihilation in H_{2}, N_{2}, and CH_{4}.

The recently developed ab initio many-body theory of positron molecule binding [22J. Hofierka et al., Many-body theory of positron binding to polyatomic molecules, Nature (London) 606, 688 (2022)NATUAS0028-083610.1038/s41586-022-04703-3] is combined with the shifted pseudostates method [A. R. Swann and G. F. Gribakin, Model-potential calculations of positron binding, scattering, and annihilation for atoms and small molecules using a Gaussian basis, Phys. Rev. A 101, 022702 (2020)PLRAAN2469-992610.1103/PhysRevA.101.022702] to calculate positron scattering and annihilation rates on small molecules, namely H_{2}, N_{2}, and CH_{4}. The important effects of positron-molecule correlations are delineated. The method provides uniformly good results for annihilation rates on all the targets, from the simplest (H_{2}, for which only a sole previous calculation agrees with experiment), to larger targets, where high-quality calculations have not been available.

TDDFT versus GW/BSE Methods for Prediction of Light Absorption and Emission in a TADF Emitter.

Design concepts for organic light emitting diode (OLED) emitters, which exhibit thermally activated delayed fluorescence (TADF) and thereby achieve quantum yields exceeding 25%, depend on singlet-triplet splitting energies of order kT to allow reverse intersystem crossing at ambient temperatures. Simulation methods for these systems must be able to treat relatively large organic molecules, as well as predict their excited state energies, transition energies, singlet-triplet splittings, and absorption and emission cross sections with reasonable accuracy, in order to prove useful in the design process. Here we compare predictions of TDDFT with M06-2X and ωB97X-D exchange-correlation functionals and a GoWo@HF/BSE method for these quantities in the well-studied DPTZ-DBTO2 TADF emitter molecule. Geometry optimization is performed for ground state (GS) and lowest donor-acceptor charge transfer (CT) state for each functional. Optical absorption and emission cross sections and energies are calculated at these geometries. Relaxation energies are on the order of 0.5 eV, and the importance of obtaining excited state equilibrium geometries in predicting delayed fluorescence is demonstrated. There are clear trends in predictions of GoWo@HF/BSE, and TDDFT/ωB97X-D and M06-2X methods in which the former method favors local exciton (LE) states while the latter favors DA CT states and ωB97X-D makes intermediate predictions. GoWo@HF/BSE suffers from triplet instability for LE states but not CT states relevant for TADF. Shifts in HOMO and LUMO levels on adding a conductor-like polarizable continuum model dielectric background are used to estimate changes in excitation energies on going from the gas phase to a solvated molecule.

Density fitting in periodic systems: Application to TDHF in diamond and oxides.

A robust density fitting method for calculating Coulomb matrix elements over Bloch functions based on the calculation of two- and three-center matrix elements of the Ewald potential is described and implemented in a Gaussian orbital basis in the Exciton code. The method is tested by comparing Coulomb and exchange energies from density fitting to corresponding energies from SCF Hartree-Fock (HF) calculations for diamond, magnesium oxide, and bulk Ne. Density fitting coefficients from the robust method are compared to coefficients from a variational method applied to wave function orbital products in bulk Ne. Four center Coulomb matrix elements from density fitting are applied to time dependent (TDHF) calculations in diamond, magnesium oxide, and anatase and rutile polytypes of titanium dioxide. Shifting virtual states downwards uniformly relative to occupied states and scaling the electron-hole attraction term in the TDHF Hamiltonian by 0.4 yields good agreement with either experiment or Bethe-Salpeter equation calculations. This approach mirrors similar "scissors" adjustments of occupied and virtual states and introduction of a scaled electron-hole attraction term in some time dependent DFT calculations.

High resolution electron energy loss spectroscopy of clean and hydrogen covered Si(001) surfaces: first principles calculations.

Surface phonons, conductivities, and loss functions are calculated for reconstructed (2×1), p(2×2) and c(4×2) clean Si(001) surfaces, and (2×1) H and D covered Si(001) surfaces. Surface conductivities perpendicular to the surface are significantly smaller than conductivities parallel to the surface. The surface loss function is compared to high resolution electron energy loss measurements. There is good agreement between calculated loss functions and experiment for H and D covered surfaces. However, agreement between experimental data from different groups and between theory and experiment is poor for clean Si(001) surfaces. Formalisms for calculating electron energy loss spectra are reviewed and the mechanism of electron energy losses to surface vibrations is discussed.

Atomic and electronic structures of Si(1 1 1)-(√3 x √3)R30°-Au and (6 × 6)-Au surfaces.

Si(1 1 1)-Au surfaces with around one monolayer of Au exhibit many ordered structures and structures containing disordered domain walls. Hybrid density functional theory (DFT) calculations presented here reveal the origin of these complex structures and tendency to form domain walls. The conjugate honeycomb chain trimer (CHCT) structure of the [Formula: see text]-Au phase contains Si atoms with non-bonding surface states which can bind Au atoms in pairs in interstices of the CHCT structure and make this surface metallic. Si adatoms adsorbed on the [Formula: see text]-Au surface induce a gapped surface through interaction with the non-bonding states. Adsorption of extra Au atoms in interstitial sites of the [Formula: see text]-Au surface is stabilized by interaction with the non-bonding orbitals and leads to higher coverage ordered structures including the [Formula: see text]-Au phase. Extra Au atoms bound in interstitial sites of the [Formula: see text]-Au surface result in top layer Si atoms with an SiAu4 butterfly wing configuration. The structure of a [Formula: see text]-Au phase, whose in-plane top atomic layer positions were previously determined by an electron holography technique (Grozea et al 1998 Surf. Sci. 418 32), is calculated using total energy minimization. The Patterson function for this structure is calculated and is in good agreement with data from an in-plane x-ray diffraction study (Dornisch et al 1991 Phys. Rev. B 44 11221). Filled and empty state scanning tunneling microscopy (STM) images are calculated for domain walls and the [Formula: see text]-Au structure. The [Formula: see text]-Au phase is 2D chiral and this is evident in computed and actual STM images. [Formula: see text]-Au and domain wall structures contain the SiAu4 motif with a butterfly wing shape. Chemical bonding within the Si-Au top layers of the [Formula: see text]-Au and [Formula: see text]-Au surfaces is analyzed and an explanation for the SiAu4 motif structure is given.

Joint Commission on Accreditation of Healthcare Organizations.

The Joint Commission on Accreditation of Healthcare Organizations was founded in 1951 as a private, not-for-profit organization that evaluates and accredits hospitals and other healthcare organizations. In 1987, the JCAHO launched its Agenda for Change to create a more modern and sophisticated accreditation process to place primary emphasis on actual performance. Coincident with this new emphasis, a number of task forces were established, including two for infection control standards.

Perceptions and misconceptions regarding the Joint Commission's view of quality monitoring.

The Joint Commission recently has revised its hospital standards for infection control to reflect more accurately current state-of-the-art practices. In addition, the Joint Commission's Agenda for Change initiatives include the development of clinical indicators; one of the topics that will be included in those clinical indicator sets will be infection control. How the hospital chooses to organize itself to conduct the historically required monitoring and evaluation of clinical patient care currently required by the standards of the Joint Commission is at the option of the hospital. How the hospital will organize and collect data specific to infection control indicators yet to be developed by the Joint Commission has not been determined and will not be defined until specific research and development projects are completed. The hospital is expected to have in place infection prevention, surveillance, and control programs; it also is expected to have in place a quality assurance program that focuses not only on solving identified problems but also on the improvement of patient care quality. How the hospitals organize and/or integrate these activities is also at its option. It is expected that qualified professionals will direct and enforce infection prevention, surveillance, and control practices; indicators for infection control can provide data that will help assess the relative success of those practices and activities. The Joint Commission is not developing the capability to judge, on its own part, the actual quality of care provided by an organization seeking accreditation. Rather, the Joint Commission is committed to developing more accurate means to evaluate the structures, processes, and outcomes of diagnosis and treatment activities, as well as their interrelationships. Clinical excellence is supported by quality in the organizational environment and the managerial and leadership contexts within which patient care is delivered. Both clinical and organizational excellence are essential components of quality, and the Joint Commission is convinced that it is appropriate and timely to undertake more direct assessments of both.

Explosives detection in soil using a field-portable continuous flow immunosensor.

A field method for quantitative analysis of explosives in contaminated soil samples is described. The method is based on a displacement immunoassay performed in a commercial instrument, the FAST 2000, engineered by Research International Inc. The method can be used on-site to measure 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) within 5min. For this study, replicate analyses were performed on soil extracts prepared from each field sample as well as appropriate controls, blanks, and laboratory standards. Statistical analyses were done to assess accuracy, bias, and predictability of the method. The results demonstrated that the immunosensor could be used effectively to screen environmental samples for the presence or absence of explosives. In most samples, the method also provided quantitative values that were in good agreement with standard laboratory analyses using HPLC. A limited number of sample matrices interfered with the immunoassay and produced results that varied significantly from the laboratory data. In each case, the compounds causing the problem have been identified and efforts are being made to minimize these matrix interferences in future field evaluations.

Standards of patient care: the Joint Commission focus on nursing quality assurance.

A process is described for qualified nurse administrators to set their own standards of care (as opposed to standards of practice set by professional organizations) in order to enhance and simplify the Joint Commission monitoring and evaluation activities required to measure both the quality and the appropriateness of clinical nursing care that patients receive.

Questions & answers from the JCAHO. What new standards are in store for 2000?

Preparing for 2000? So is the Joint Commission. Learn about changed standards that will impact nurse leaders in the Comprehensive Accreditation Manuals for Ambulatory Care, Behavioral Health Care, Health Care Networks, Home Care, Hospitals, and Long-term Care.

How does the JCAHO define new restraint standards?

The Joint Commission's restraint standards draw differences between restraint and behavior management and outline special circumstances for hospital-based long-term care.

Engineering controls vs. infection control.

Two new JCAHO requirements focus on engineering controls with infection control crossover.

Partners keep hospitals safe.

The Joint Commission targets patient, staff, and visitor safety through leadership, environment, and infection control initiatives. The JCAHO/OSHA Education Partnership has streamlined and accelerated plans for safer hospitals.

New standards support nursing's licensed independent practitioners.

New standards give nurses who work as licensed independent practitioners recourse when an organization limits or revokes privileges.

Quality assurance, control, and monitoring. The future role of information technology from the Joint Commission's perspective.

In summary, the Joint Commission's current perspective on "quality assurance" in the 1990s includes three different, but complementary, activities: 1) structure and process triennial reviews (Joint Commission surveys); 2) Case-based reviews conducted by professional review organizations and/or other third parties; and 3) a combination of internal and external data-driven improvement systems. All these systems will work best supported by computers and software programs that foster the manipulation and management of data related to quality of care monitoring systems in addition to those in use today to monitor the hospital's profit and loss position. The Joint Commission's accreditation decision process will continue to be based on surveys of compliance with standards and their key characteristics. Problems related to the organization's performance against the external monitoring systems will not directly impact accreditation status. The Joint Commission will be more interested in how the organization responds to aberrant indicator data and how it conducts problem solving activities. New Joint Commission standards (yet to be developed) will relate to such activity and only then, after standards are written, field tested, and published, could the information generated by the Joint Commission's external indicator monitoring system impact on accreditation status. During a speaking engagement in Florida, a physician on the panel with me from the state's physician monitoring organization shared the following diagnostic label: "Mural Graphic Dyslexia." He defined it as the inability to read the handwriting on the wall. I believe that the handwriting is very clear and can be read very well. Data-driven quality improvement processes are the survival tools of the future.(ABSTRACT TRUNCATED AT 250 WORDS)