Patching the Exchange-Correlation Potential in Density Functional Theory.
Huang, Chen
2016-05-10
A method for directly patching exchange-correlation (XC) potentials in materials is derived. The electron density of a system is partitioned into subsystem densities by dividing its Kohn-Sham (KS) potential among the subsystems. Inside each subsystem, its projected KS potential is required to become the total system's KS potential. This requirement, together with the nearsightedness principle of electronic matters, ensures that the electronic structures inside subsystems can be good approximations to the total system's electronic structure. The nearsightedness principle also ensures that subsystem densities could be well localized in their regions, making it possible to use high-level methods to invert the XC potentials for subsystem densities. Two XC patching methods are developed. In the local XC patching method, the total system's XC potential is improved in the cluster region. We show that the coupling between a cluster and its environment is important for achieving a fast convergence of the electronic structure in the cluster region. In the global XC patching method, we discuss how to patch the subsystem XC potentials to construct the XC potential in the total system, aiming to scale up high-level quantum mechanics simulations of materials. Proof-of-principle examples are given.
DEFF Research Database (Denmark)
Wellendorff, Jess; Lundgård, Keld Troen; Møgelhøj, Andreas
2012-01-01
A methodology for semiempirical density functional optimization, using regularization and cross-validation methods from machine learning, is developed. We demonstrate that such methods enable well-behaved exchange-correlation approximations in very flexible model spaces, thus avoiding the overfit...
Vyboishchikov, Sergei F
2016-12-05
We report correlation energies, electron densities, and exchange-correlation potentials obtained from configuration interaction and density functional calculations on spherically confined He, Be, Be(2+) , and Ne atoms. The variation of the correlation energy with the confinement radius Rc is relatively small for the He, Be(2+) , and Ne systems. Curiously, the Lee-Yang-Parr (LYP) functional works well for weak confinements but fails completely for small Rc . However, in the neutral beryllium atom the CI correlation energy increases markedly with decreasing Rc . This effect is less pronounced at the density-functional theory level. The LYP functional performs very well for the unconfined Be atom, but fails badly for small Rc . The standard exchange-correlation potentials exhibit significant deviation from the "exact" potential obtained by inversion of Kohn-Sham equation. The LYP correlation potential behaves erratically at strong confinements. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.
Laplacian-level density functionals for the kinetic energy density and exchange-correlation energy
Perdew, John P.; Constantin, Lucian A.
2007-04-01
We construct a Laplacian-level meta-generalized-gradient-approximation (meta-GGA) for the noninteracting (Kohn-Sham orbital) positive kinetic energy density τ of an electronic ground state of density n . This meta-GGA is designed to recover the fourth-order gradient expansion τGE4 in the appropriate slowly varying limit and the von Weizsäcker expression τW=∣∇n∣2/(8n) in the rapidly varying limit. It is constrained to satisfy the rigorous lower bound τW(r)⩽τ(r) . Our meta-GGA is typically a strong improvement over the gradient expansion of τ for atoms, spherical jellium clusters, jellium surfaces, the Airy gas, Hooke’s atom, one-electron Gaussian density, quasi-two-dimensional electron gas, and nonuniformly scaled hydrogen atom. We also construct a Laplacian-level meta-GGA for exchange and correlation by employing our approximate τ in the Tao-Perdew-Staroverov-Scuseria (TPSS) meta-GGA density functional. The Laplacian-level TPSS gives almost the same exchange-correlation enhancement factors and energies as the full TPSS, suggesting that τ and ∇2n carry about the same information beyond that carried by n and ∇n . Our kinetic energy density integrates to an orbital-free kinetic energy functional that is about as accurate as the fourth-order gradient expansion for many real densities (with noticeable improvement in molecular atomization energies), but considerably more accurate for rapidly varying ones.
Molecular Kohn-Sham exchange-correlation potential from the correlated ab initio electron density
Gritsenko, Oleg V.; van Leeuwen, Robert; Baerends, Evert Jan
1995-09-01
The molecular Kohn-Sham (KS) exchange-correlation potential vxc has been constructed for LiH from the correlated ab initio density ρ by means of the simple iterative procedure developed by van Leeuwen and Baerends [Phys. Rev. A 49, 2421 (1994)]. The corresponding KS energy characteristics, such as the kinetic energy of noninteracting particles Ts, kinetic part of the exchange-correlation energy Tc, and energy of the highest occupied molecular orbital ɛN, have been obtained with reasonable accuracy. A relation between the form of vxc and the electronic structure of LiH has been discussed. Test calculations for the two-electron H2 molecule have shown the efficiency of the procedure.
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Ahuja, B.L., E-mail: blahuja@yahoo.ik [Department of Physics, M.L. Sukhadia University, Udaipur 313001, Rajasthan (India); Raykar, Veera; Joshi, Ritu [Department of Physics, M.L. Sukhadia University, Udaipur 313001, Rajasthan (India); Tiwari, Shailja [Department of Physics, Govt. Women Engineering College, Ajmer 305001, Rajasthan (India); Talreja, Sonal [Department of Computer Science, M.L. Sukhadia University, Udaipur 313001 (India); Choudhary, Gopal [Department of Physics, Techno India NJR Institute of Technology, Udaipur 313001, Rajasthan (India)
2015-05-15
We report Compton profiles of SnS and SnTe at a momentum resolution of 0.34 a.u. using a 20 Ci {sup 137}Cs Compton spectrometer. To compare our experimental data, we have also computed the theoretical Compton profiles using density functional theory within linear combination of atomic orbitals (LCAO) method. To interpret the relative nature of bonding in these compounds, we have scaled the experimental and theoretical Compton profiles on equal-valence-electron-density (EVED). On the basis of EVED profiles, it is seen that SnTe shows more covalent character than SnS. To rectify the substantial disagreement between experimental and theoretical band gaps, we have also presented the energy bands and density of states of both the compounds using full-potential linearized augmented plane wave method (FP-LAPW) including spin–orbit interaction within the PBEsol exchange-correlation potential.
Mattsson, Ann E.; Wills, John M.
2013-03-01
The inability to computationally describe the physics governing the properties of actinides and their alloys is the poster child of failure of existing Density Functional Theory exchange-correlation functionals. The intricate competition between localization and delocalization of the electrons, present in these materials, exposes the limitations of functionals only designed to properly describe one or the other situation. We will discuss the manifestation of this competition in real materials and propositions on how to construct a functional able to accurately describe properties of these materials. I addition we will discuss both the importance of using the Dirac equation to describe the relativistic effects in these materials, and the connection to the physics of transition metal oxides. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
Exchange-Correlation Effects for Noncovalent Interactions in Density Functional Theory.
Otero-de-la-Roza, A; DiLabio, Gino A; Johnson, Erin R
2016-07-12
In this article, we develop an understanding of how errors from exchange-correlation functionals affect the modeling of noncovalent interactions in dispersion-corrected density-functional theory. Computed CCSD(T) reference binding energies for a collection of small-molecule clusters are decomposed via a molecular many-body expansion and are used to benchmark density-functional approximations, including the effect of semilocal approximation, exact-exchange admixture, and range separation. Three sources of error are identified. Repulsion error arises from the choice of semilocal functional approximation. This error affects intermolecular repulsions and is present in all n-body exchange-repulsion energies with a sign that alternates with the order n of the interaction. Delocalization error is independent of the choice of semilocal functional but does depend on the exact exchange fraction. Delocalization error misrepresents the induction energies, leading to overbinding in all induction n-body terms, and underestimates the electrostatic contribution to the 2-body energies. Deformation error affects only monomer relaxation (deformation) energies and behaves similarly to bond-dissociation energy errors. Delocalization and deformation errors affect systems with significant intermolecular orbital interactions (e.g., hydrogen- and halogen-bonded systems), whereas repulsion error is ubiquitous. Many-body errors from the underlying exchange-correlation functional greatly exceed in general the magnitude of the many-body dispersion energy term. A functional built to accurately model noncovalent interactions must contain a dispersion correction, semilocal exchange, and correlation components that minimize the repulsion error independently and must also incorporate exact exchange in such a way that delocalization error is absent.
Borgoo, Alex; Teale, Andrew M; Tozer, David J
2012-01-21
Correlated electron densities, experimental ionisation potentials, and experimental electron affinities are used to investigate the homogeneity of the exchange-correlation and non-interacting kinetic energy functionals of Kohn-Sham density functional theory under density scaling. Results are presented for atoms and small molecules, paying attention to the influence of the integer discontinuity and the choice of the electron affinity. For the exchange-correlation functional, effective homogeneities are highly system-dependent on either side of the integer discontinuity. By contrast, the average homogeneity-associated with the potential that averages over the discontinuity-is generally close to 4/3 when the discontinuity is computed using positive affinities for systems that do bind an excess electron and negative affinities for those that do not. The proximity to 4/3 becomes increasingly pronounced with increasing atomic number. Evaluating the discontinuity using a zero affinity in systems that do not bind an excess electron instead leads to effective homogeneities on the electron abundant side that are close to 4/3. For the non-interacting kinetic energy functional, the effective homogeneities are less system-dependent and the effect of the integer discontinuity is less pronounced. Average values are uniformly below 5/3. The study provides information that may aid the development of improved exchange-correlation and non-interacting kinetic energy functionals. © 2012 American Institute of Physics
Aldegunde, Manuel; Kermode, James R.; Zabaras, Nicholas
2016-04-01
This paper presents the development of a new exchange-correlation functional from the point of view of machine learning. Using atomization energies of solids and small molecules, we train a linear model for the exchange enhancement factor using a Bayesian approach which allows for the quantification of uncertainties in the predictions. A relevance vector machine is used to automatically select the most relevant terms of the model. We then test this model on atomization energies and also on bulk properties. The average model provides a mean absolute error of only 0.116 eV for the test points of the G2/97 set but a larger 0.314 eV for the test solids. In terms of bulk properties, the prediction for transition metals and monovalent semiconductors has a very low test error. However, as expected, predictions for types of materials not represented in the training set such as ionic solids show much larger errors.
Holas, A; March, N H; Rubio, Angel
2005-11-15
Holas and March [Phys. Rev. A. 51, 2040 (1995)] gave a formally exact theory for the exchange-correlation (xc) force F(xc)(r)= -inverted Deltaupsilon(xc)(r) associated with the xc potential upsilon(xc)(r) of the density-functional theory in terms of low-order density matrices. This is shown in the present study to lead, rather directly, to the determination of a sum rule nF(xc)=0 relating the xc force with the ground-state density n(r). Some connection is also made with an earlier result relating to the external potential by Levy and Perdew [Phys. Rev. A. 32, 2010 (1985)] and with the quite recent study of Joubert [J. Chem. Phys. 119, 1916 (2003)] relating to the separation of the exchange and correlation contributions.
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Torres, M.B. [Dpto. de Matematicas y Computacion, Universidad de Burgos, Burgos (Spain); Balbas, L.C. [Dpto. de Fisica Teorica, Universidad de Valladolid, Valladolid (Spain)
2002-06-17
The atomic exchange-correlation (xc) potential with the correct -1/r asymptotic behaviour constructed by Parr and Ghosh (Parr R G and Ghosh S K 1995 Phys. Rev. A 51 3564) is adapted here to study, within time density functional theory, the linear response to external fields of (i) neutral and charged sodium clusters, and (ii) doped clusters of the type Na{sub n}Pb (n=4, 6, 16). The resulting photoabsorption cross sections are compared to experimental results, when available, and to results from previous calculations using local and non-local xc functionals. The calculated static polarizabilities and plasmon frequencies are closer to the experimental values than previous results. (author)
Borgoo, Alex; Tozer, David J
2012-06-07
The influence of the asymptotic exchange-correlation potential and density-scaling homogeneity on negative electron affinities determined using the approach of Tozer and De Proft [J. Phys. Chem. A2005, 109, 8923] is investigated. Application of an asymptotic correction to the potential improves the accuracy for several of the systems with the most negative affinities, reflecting their diffuse lowest unoccupied orbitals. For systems with modest affinities, it reduces the accuracy marginally. Enforcing a near-exact effective homogeneity through a simple shift in the potential leads to improved correlation with experimental values but significantly overestimated affinities. Optimal effective homogeneities are therefore determined, and a simple scheme is proposed for enforcing an average optimal value. Application of the scheme to a series of organic molecules maintains the excellent correlation with the experimental values while significantly reducing the absolute errors.
Current Density Functional Theory Using Meta-Generalized Gradient Exchange-Correlation Functionals.
Furness, James W; Verbeke, Joachim; Tellgren, Erik I; Stopkowicz, Stella; Ekström, Ulf; Helgaker, Trygve; Teale, Andrew M
2015-09-08
We present the self-consistent implementation of current-dependent (hybrid) meta-generalized gradient approximation (mGGA) density functionals using London atomic orbitals. A previously proposed generalized kinetic energy density is utilized to implement mGGAs in the framework of Kohn-Sham current density functional theory (KS-CDFT). A unique feature of the nonperturbative implementation of these functionals is the ability to seamlessly explore a wide range of magnetic fields up to 1 au (∼235 kT) in strength. CDFT functionals based on the TPSS and B98 forms are investigated, and their performance is assessed by comparison with accurate coupled-cluster singles, doubles, and perturbative triples (CCSD(T)) data. In the weak field regime, magnetic properties such as magnetizabilities and nuclear magnetic resonance shielding constants show modest but systematic improvements over generalized gradient approximations (GGA). However, in the strong field regime, the mGGA-based forms lead to a significantly improved description of the recently proposed perpendicular paramagnetic bonding mechanism, comparing well with CCSD(T) data. In contrast to functionals based on the vorticity, these forms are found to be numerically stable, and their accuracy at high field suggests that the extension of mGGAs to CDFT via the generalized kinetic energy density should provide a useful starting point for further development of CDFT approximations.
Current Density-Functional Theory using meta-Generalized Gradient Exchange--Correlation Functionals
Furness, James W; Tellgren, Erik I; Stopkowicz, Stella; Ekström, Ulf; Helgaker, Trygve; Teale, Andrew M
2015-01-01
We present the self-consistent implementation of current-dependent (hybrid) meta generalized gradient approximation (mGGA) density functionals using London atomic orbitals. A previously proposed generalized kinetic energy density is utilized to implement mGGAs in the framework of Kohn--Sham current density-functional theory (KS-CDFT). A unique feature of the non-perturbative implementation of these functionals is the ability to seamlessly explore a wide range of magnetic fields up to 1 a.u. ($\\sim 235000$T) in strength. CDFT functionals based on the TPSS and B98 forms are investigated and their performance is assessed by comparison with accurate CCSD(T) data. In the weak field regime magnetic properties such as magnetizabilities and NMR shielding constants show modest but systematic improvements over GGA functionals. However, in strong field regime the mGGA based forms lead to a significantly improved description of the recently proposed perpendicular paramagnetic bonding mechanism, comparing well with CCSD(T...
Choi, Jinwoo; Chang, Eonho; Anstine, Dylan M.; Chakraborty, Himadri
2016-05-01
We study the ground state properties of C60 and C240 molecules in a spherical frame of local density approximation (LDA). Within this mean-field theory, two different approximations to the exchange-correlation (xc) functional are used: (i) The Gunnerson-Lundqvist parametrization augmented by a treatment to correct for the electron self-interaction and (ii) the van Leeuwen and Baerends (LB94) model potential that inclusively restores electron's asymptotic properties. Results show differences in the ground-state potential, level energies and electron densities between the two xc choices. We then use the ground structure to find the excited and ionized states of the systems and calculate dipole single-photoionization cross sections in a time-dependent LDA method that incorporates linear-response dynamical correlations. Comparative effects of the choices of xc on collective plasmon and single-excitation Auger resonances as well as on geometry driven cavity oscillations are found significant. The work is supported by the NSF, USA.
Choi, Jinwoo; Chang, EonHo; Anstine, Dylan M.; Madjet, Mohamed El-Amine; Chakraborty, Himadri S.
2017-02-01
We study the photoionization properties of the C60 versus C240 molecule in a spherical jellium frame of the density-functional method. Two prototypical approximations of the exchange-correlation (xc) functional are used: (i) the Gunnarsson-Lundqvist parametrization [Gunnarsson and Lundqvist, Phys. Rev. B 13, 4274 (1976), 10.1103/PhysRevB.13.4274] with a correction for the electron self-interaction (SIC) introduced artificially from the outset and (ii) a gradient-dependent augmentation of approximation (i) using the van Leeuwen and Baerends model potential [van Leeuwen and Baerends, Phys. Rev. A 49, 2421 (1994), 10.1103/PhysRevA.49.2421], in lieu of SIC, that restores electrons' asymptotic properties intrinsically within the formalism. Ground-state results from the two schemes for both molecules show differences in the shapes of mean-field potentials and bound-level properties. The choice of an xc scheme also significantly alters the dipole single-photoionization cross sections obtained by an ab initio method that incorporates linear-response dynamical correlations. Differences in the structures and ionization responses between C60 and C240 uncover the effect of molecular size on the underlying physics. Analysis indicates that the collective plasmon resonances with the gradient-based xc option produce results noticeably closer to the experimental data available for C60.
Choi, Jinwoo; Anstine, Dylan M; Madjet, Mohamed El-Amine; Chakraborty, Himadri S
2016-01-01
We study the photoionization properties of the C_60 versus C_240 molecule in a spherical jellium frame of density functional method. Two different approximations to the exchange-correlation (xc) functional are used: (i) The Gunnerson-Lundqvist parametrization [Phys. Rev. B 13, 4274 (1976)] with an explicit correction for the electron self-interaction (SIC) and (ii) a gradient-dependent augmentation of (i) by using the van Leeuwen and Baerends model potential [Phys. Rev. A 49, 2421 (1994)], in lieu of SIC, to implicitly restore electrons' asymptotic properties. Ground state results from the two schemes for both molecules show differences in the shapes of mean-field potentials and bound-level properties. The choice of a xc scheme also significantly alters the dipole single-photoionization cross sections obtained by an abinitio method that incorporates linear-response dynamical correlations. Differences in the structures and ionization responses between C_60 and C_240 uncover the effect of molecular size on the ...
Holland, Jason P; Green, Jennifer C
2010-04-15
The electronic absorption spectra of a range of copper and zinc complexes have been simulated by using time-dependent density functional theory (TD-DFT) calculations implemented in Gaussian03. In total, 41 exchange-correlation (XC) functionals including first-, second-, and third-generation (meta-generalized gradient approximation) DFT methods were compared in their ability to predict the experimental electronic absorption spectra. Both pure and hybrid DFT methods were tested and differences between restricted and unrestricted calculations were also investigated by comparison of analogous neutral zinc(II) and copper(II) complexes. TD-DFT calculated spectra were optimized with respect to the experimental electronic absorption spectra by use of a Matlab script. Direct comparison of the performance of each XC functional was achieved both qualitatively and quantitatively by comparison of optimized half-band widths, root-mean-squared errors (RMSE), energy scaling factors (epsilon(SF)), and overall quality-of-fit (Q(F)) parameters. Hybrid DFT methods were found to outperform all pure DFT functionals with B1LYP, B97-2, B97-1, X3LYP, and B98 functionals providing the highest quantitative and qualitative accuracy in both restricted and unrestricted systems. Of the functionals tested, B1LYP gave the most accurate results with both average RMSE and overall Q(F) unity (>0.990) for the copper complexes. The XC functional performance in spin-restricted TD-DFT calculations on the zinc complexes was found to be slightly worse. PBE1PBE, mPW1PW91 and B1LYP gave the most accurate results with typical RMSE and Q(F) values between 5.3 and 7.3%, and epsilon(SF) around 0.930. These studies illustrate the power of modern TD-DFT calculations for exploring excited state transitions of metal complexes.
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Betzinger, Markus
2011-12-14
In this thesis, we extended the applicability of the full-potential linearized augmented-plane-wave (FLAPW) method, one of the most precise, versatile and generally applicable electronic structure methods for solids working within the framework of density-functional theory (DFT), to orbital-dependent functionals for the exchange-correlation (xc) energy. Two different schemes that deal with orbital-dependent functionals, the Kohn-Sham (KS) and the generalized Kohn-Sham (gKS) formalism, have been realized. Hybrid functionals, combining some amount of the orbital-dependent exact exchange energy with local or semi-local functionals of the density, are implemented within the gKS scheme. We work in particular with the PBE0 hybrid of Perdew, Burke, and Ernzerhof. Our implementation relies on a representation of the non-local exact exchange potential - its calculation constitutes the most time consuming step in a practical calculation - by an auxiliary mixed product basis (MPB). In this way, the matrix elements of the Hamiltonian corresponding to the non-local potential become a Brillouin-zone (BZ) sum over vector-matrix-vector products. Several techniques are developed and explored to further accelerate our numerical scheme. We show PBE0 results for a variety of semiconductors and insulators. In comparison with experiment, the PBE0 functional leads to improved band gaps and an improved description of localized states. Even for the ferromagnetic semiconductor EuO with localized 4f electrons, the electronic and magnetic properties are correctly described by the PBE0 functional. Subsequently, we discuss the construction of the local, multiplicative exact exchange (EXX) potential from the non-local, orbital-dependent exact exchange energy. For this purpose we employ the optimized effective potential (OEP) method. Central ingredients of the OEP equation are the KS wave-function response and the single-particle density response function. We show that a balance between the LAPW
Smith, J. C.; Pribram-Jones, A.; Burke, K.
2016-06-01
Thermal density functional theory calculations often use the Mermin-Kohn-Sham scheme, but employ ground-state approximations to the exchange-correlation (XC) free energy. In the simplest solvable nontrivial model, an asymmetric Hubbard dimer, we calculate the exact many-body energies and the exact Mermin-Kohn-Sham functionals for this system and extract the exact XC free energy. For moderate temperatures and weak correlation, we find this approximation to be excellent. We extract various exact free-energy correlation components and the exact adiabatic connection formula.
Yu, Haoyu S; He, Xiao; Truhlar, Donald G
2016-03-08
Kohn-Sham density functional theory is widely used for applications of electronic structure theory in chemistry, materials science, and condensed-matter physics, but the accuracy depends on the quality of the exchange-correlation functional. Here, we present a new local exchange-correlation functional called MN15-L that predicts accurate results for a broad range of molecular and solid-state properties including main-group bond energies, transition metal bond energies, reaction barrier heights, noncovalent interactions, atomic excitation energies, ionization potentials, electron affinities, total atomic energies, hydrocarbon thermochemistry, and lattice constants of solids. The MN15-L functional has the same mathematical form as a previous meta-nonseparable gradient approximation exchange-correlation functional, MN12-L, but it is improved because we optimized it against a larger database, designated 2015A, and included smoothness restraints; the optimization has a much better representation of transition metals. The mean unsigned error on 422 chemical energies is 2.32 kcal/mol, which is the best among all tested functionals, with or without nonlocal exchange. The MN15-L functional also provides good results for test sets that are outside the training set. A key issue is that the functional is local (no nonlocal exchange or nonlocal correlation), which makes it relatively economical for treating large and complex systems and solids. Another key advantage is that medium-range correlation energy is built in so that one does not need to add damped dispersion by molecular mechanics in order to predict accurate noncovalent binding energies. We believe that the MN15-L functional should be useful for a wide variety of applications in chemistry, physics, materials science, and molecular biology.
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Lee, Sang Uck [Univ. of Ulsan, Ulsan (Korea, Republic of)
2013-08-15
The accurate prediction of vertical excitation energies is very important for the development of new materials in the dye and pigment industry. A time-dependent density functional theory (TD-DFT) approach coupled with 22 different exchange-correlation functionals was used for the prediction of vertical excitation energies in the halogenated copper phthalocyanine molecules in order to find the most appropriate functional and to determine the accuracy of the prediction of the absorption wavelength and observed spectral shifts. Among the tested functional, B3LYP functional provides much more accurate vertical excitation energies and UV-vis spectra. Our results clearly provide a benchmark calibration of the TD-DFT method for phthalocyanine based dyes and pigments used in industry.
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Lembarki, A.
1994-12-01
In this work, we have developed some gradient-corrected exchange-correlation functionals. This study is in keeping with the density functional theory (DFT) formalism. In the first part of this memory, a description of Hartree-Fock (HF), post-HF and density functional theories is given. The second part is devoted the study the different approximations of DFT exchange-correlation functionals which have been proposed in the last years. In particular, we have underlined the approximations used for the construction of these functionals. The third part of this memory consists in the development of new gradient-corrected functionals. In this study, we have established a new relation between exchange energy, correlation energy and kinetic energy. We have deduced two new possible forms of exchange or correlation functionals, respectively. In the fourth part, we have studied the exchange potential, for which the actual formulation does not satisfy some theoretical conditions, such as the asymptotic behavior -1/r. Our contribution lies in the development of an exchange potential with a correct asymptotic -1/r behavior for large values of r. In this chapter, we have proposed a model which permits the obtention of the exchange energy from the exchange potential, using the virial theorem. The fifth part of this memory is devoted the application of these different functionals to simple systems (H{sub 2}O, CO, N{sub 2}O, H{sub 3}{sup +} and H{sub 5}{sup +}) in order to characterize the performance of DFT calculations in regards to those obtained with post-HF methods. (author). 215 refs., 8 figs., 28 tabs.
Kraisler, Eli; Kelson, Itzhak
2010-01-01
The total energies and the spin states for atoms and their first ions with Z = 1-86 are calculated within the the local spin-density approximation (LSDA) and the generalized-gradient approximation (GGA) to the exchange-correlation (xc) energy in density-functional theory. Atoms and ions for which the ground-state density is not pure-state v-representable, are treated as ensemble v- representable with fractional occupations of the Kohn-Sham system. A newly developed algorithm which searches over ensemble v-representable densities [E. Kraisler et al., Phys. Rev. A 80, 032115 (2009)] is employed in calculations. It is found that for many atoms the ionization energies obtained with the GGA are only modestly improved with respect to experimental data, as compared to the LSDA. However, even in those groups of atoms where the improvement is systematic, there remains a non-negligible difference with respect to the experiment. The ab-initio electronic configuration in the Kohn-Sham reference system does not always equ...
Santra, Biswajit; Klimeš, Jiří; Tkatchenko, Alexandre; Alfè, Dario; Slater, Ben; Michaelides, Angelos; Car, Roberto; Scheffler, Matthias
2013-10-01
Density-functional theory (DFT) has been widely used to study water and ice for at least 20 years. However, the reliability of different DFT exchange-correlation (xc) functionals for water remains a matter of considerable debate. This is particularly true in light of the recent development of DFT based methods that account for van der Waals (vdW) dispersion forces. Here, we report a detailed study with several xc functionals (semi-local, hybrid, and vdW inclusive approaches) on ice Ih and six proton ordered phases of ice. Consistent with our previous study [B. Santra, J. Klimeš, D. Alfè, A. Tkatchenko, B. Slater, A. Michaelides, R. Car, and M. Scheffler, Phys. Rev. Lett. 107, 185701 (2011)] which showed that vdW forces become increasingly important at high pressures, we find here that all vdW inclusive methods considered improve the relative energies and transition pressures of the high-pressure ice phases compared to those obtained with semi-local or hybrid xc functionals. However, we also find that significant discrepancies between experiment and the vdW inclusive approaches remain in the cohesive properties of the various phases, causing certain phases to be absent from the phase diagram. Therefore, room for improvement in the description of water at ambient and high pressures remains and we suggest that because of the stern test the high pressure ice phases pose they should be used in future benchmark studies of simulation methods for water.
Gritsenko, Oleg; Baerends, Evert Jan
2004-07-08
Time-dependent density functional theory (TDDFT) calculations of charge-transfer excitation energies omegaCT are significantly in error when the adiabatic local density approximation (ALDA) is employed for the exchange-correlation kernel fxc. We relate the error to the physical meaning of the orbital energy of the Kohn-Sham lowest unoccupied molecular orbital (LUMO). The LUMO orbital energy in Kohn-Sham DFT--in contrast to the Hartree-Fock model--approximates an excited electron, which is correct for excitations in compact molecules. In CT transitions the energy of the LUMO of the acceptor molecule should instead describe an added electron, i.e., approximate the electron affinity. To obtain a contribution that compensates for the difference, a specific divergence of fxc is required in rigorous TDDFT, and a suitable asymptotically correct form of the kernel fxc(asymp) is proposed. The importance of the asymptotic correction of fxc is demonstrated with the calculation of omegaCT(R) for the prototype diatomic system HeBe at various separations R(He-Be). The TDDFT-ALDA curve omegaCT(R) roughly resembles the benchmark ab initio curve omegaCT CISD(R) of a configuration interaction calculation with single and double excitations in the region R=1-1.5 A, where a sizable He-Be interaction exists, but exhibits the wrong behavior omegaCT(R)
Casida, Mark E.; Salahub, Dennis R.
2000-11-01
The time-dependent density functional theory (TD-DFT) calculation of excitation spectra places certain demands on the DFT exchange-correlation potential, vxc, that are not met by the functionals normally used in molecular calculations. In particular, for high-lying excitations, it is crucial that the asymptotic behavior of vxc be correct. In a previous paper, we introduced a novel asymptotic-correction approach which we used with the local density approximation (LDA) to yield an asymptotically corrected LDA (AC-LDA) potential [Casida, Casida, and Salahub, Int. J. Quantum Chem. 70, 933 (1998)]. The present paper details the theory underlying this asymptotic correction approach, which involves a constant shift to incorporate the effect of the derivative discontinuity (DD) in the bulk region of finite systems, and a spliced asymptotic correction in the large r region. This is done without introducing any adjustable parameters. We emphasize that correcting the asymptotic behavior of vxc is not by itself sufficient to improve the overall form of the potential unless the effect of the derivative discontinuity is taken into account. The approach could be used to correct vxc from any of the commonly used gradient-corrected functionals. It is here applied to the LDA, using the asymptotically correct potential of van Leeuwen and Baerends (LB94) in the large r region. The performance of our AC-LDA vxc is assessed for the calculation of TD-DFT excitation energies for a large number of excitations, including both valence and Rydberg states, for each of four small molecules: N2, CO, CH2O, and C2H4. The results show a significant improvement over those from either the LB94 or the LDA functionals. This confirms that the DD is indeed an important element in the design of functionals. The quality of TDLDA/LB94 and TDLDA/AC-LDA oscillator strengths were also assessed in what we believe to be the first rigorous assessment of TD-DFT molecular oscillator strengths in comparison with
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Benam, M.R., E-mail: m_benam@pnu.ac.ir [Department of Physics, Payame Noor University, P.O. BOX 19395-3697 (Iran, Islamic Republic of); Abdoshahi, N.; Majidiyan Sarmazdeh, M. [Department of Physics, Payame Noor University, P.O. BOX 19395-3697 (Iran, Islamic Republic of)
2014-08-01
In this paper the effect of pressure on the structural and electronic properties of cubic-LaAlO{sub 3} including the equilibrium lattice constant, bulk modulus, derivative of bulk modulus and band structure have been calculated by density functional theory (DFT) using GGA, LDA, and PBEsol exchange correlation potentials. It is found that the change of the lattice constant with pressure has an exponential behavior: with increasing pressure, the lattice constant decreases first sharply at low pressures, and then more slowly at high pressures. Furthermore, the lattice constant calculated by the PBEsol method and the bulk modulus calculated by LDA and PBEsol methods are closer to the available experimental values than those obtained using other exchange correlation potentials. Regarding the electronic properties, it is shown that an increase in pressure increases the band gap, the change being 0.26 eV at 34.00 GPa. The total density of state (t-DOS) calculations demonstrate that increasing pressure has a significant effect on the core and conduction band, but little effect on the valence band. The band structure calculations indicate that, in this material, the band gap changes from indirect to direct at a pressure of about 25 GPa. Also, increasing pressure produces a clear curvature in the band structure near the bottom of the conduction band, a behavior consistent with the strong pressure dependence of the transport properties.
Benam, M. R.; Abdoshahi, N.; Majidiyan Sarmazdeh, M.
2014-08-01
In this paper the effect of pressure on the structural and electronic properties of cubic-LaAlO3 including the equilibrium lattice constant, bulk modulus, derivative of bulk modulus and band structure have been calculated by density functional theory (DFT) using GGA, LDA, and PBEsol exchange correlation potentials. It is found that the change of the lattice constant with pressure has an exponential behavior: with increasing pressure, the lattice constant decreases first sharply at low pressures, and then more slowly at high pressures. Furthermore, the lattice constant calculated by the PBEsol method and the bulk modulus calculated by LDA and PBEsol methods are closer to the available experimental values than those obtained using other exchange correlation potentials. Regarding the electronic properties, it is shown that an increase in pressure increases the band gap, the change being 0.26 eV at 34.00 GPa. The total density of state (t-DOS) calculations demonstrate that increasing pressure has a significant effect on the core and conduction band, but little effect on the valence band. The band structure calculations indicate that, in this material, the band gap changes from indirect to direct at a pressure of about 25 GPa. Also, increasing pressure produces a clear curvature in the band structure near the bottom of the conduction band, a behavior consistent with the strong pressure dependence of the transport properties.
Roper, Ian P E; Besley, Nicholas A
2016-03-21
The simulation of X-ray emission spectra of transition metal complexes with time-dependent density functional theory (TDDFT) is investigated. X-ray emission spectra can be computed within TDDFT in conjunction with the Tamm-Dancoff approximation by using a reference determinant with a vacancy in the relevant core orbital, and these calculations can be performed using the frozen orbital approximation or with the relaxation of the orbitals of the intermediate core-ionised state included. Both standard exchange-correlation functionals and functionals specifically designed for X-ray emission spectroscopy are studied, and it is shown that the computed spectral band profiles are sensitive to the exchange-correlation functional used. The computed intensities of the spectral bands can be rationalised by considering the metal p orbital character of the valence molecular orbitals. To compute X-ray emission spectra with the correct energy scale allowing a direct comparison with experiment requires the relaxation of the core-ionised state to be included and the use of specifically designed functionals with increased amounts of Hartree-Fock exchange in conjunction with high quality basis sets. A range-corrected functional with increased Hartree-Fock exchange in the short range provides transition energies close to experiment and spectral band profiles that have a similar accuracy to those from standard functionals.
Exact Exchange-Correlation Functional for the Infinitely Stretched Hydrogen Molecule
Matito, Eduard; Lopez, Xabier; Ugalde, Jesus M
2016-01-01
The exchange-correlation hole density of the infinitely stretched (dissociated) hydrogen molecule can be cast into a closed analytical form by using its exact wave function. This permits to obtain an explicit exchange-correlation energy functional of the electron density which allows for its functional derivation to yield the corresponding Kohh-Sham effective exchange-correlation potential. We have shown that this exchange-correlation functional is exact for the dissociated hydrogen molecule, yields its dissociation energy correctly, and its corresponding exchange-correlation potential has the correct $-1/r$ asymptotic behavior.
Labat, Frédéric; Baranek, Philippe; Domain, Christophe; Minot, Christian; Adamo, Carlo
2007-04-21
The two polymorphs of TiO2, rutile and anatase, have been investigated at the ab initio level using different Hamiltonians with all-electron Gaussian and projector augmented plane wave basis sets. Their equilibrium lattice parameters, relative stabilities, binding energies, and band structures have been evaluated. The calculations have been performed at the Hartree-Fock, density functional theory (DFT), and hybrid (B3LYP and PBE0) levels. As regards DFT, the local density and generalized gradient (PBE) approximations have been used. Our results show an excellent agreement with the experimental band structures and binding energies for the B3LYP and PBE0 functionals, while the best structural descriptions are obtained at the PBE0 level. However, no matter which Hamiltonian and method are used, anatase is found more stable than rutile, in contrast with recent experimental reports, although the relative stabilities of the two phases are very close to each other. Nevertheless, based on the overall results, the hybrid PBE0 functional appears as a good compromise to obtain an accurate description of both structural and electronic properties of solids.
Energy Technology Data Exchange (ETDEWEB)
Arantes, J. T.; Lima, M. P.; Fazzio, A.; Xiang, H.; Wei, S. H.; Dalpian, G. M.
2009-04-01
The structural and electronic properties of perylene diimide liquid crystal PPEEB are studied using ab initio methods based on the density functional theory (DFT). Using available experimental crystallographic data as a guide, we propose a detailed structural model for the packing of solid PPEEB. We find that due to the localized nature of the band edge wave function, theoretical approaches beyond the standard method, such as hybrid functional (PBE0), are required to correctly characterize the band structure of this material. Moreover, unlike previous assumptions, we observe the formation of hydrogen bonds between the side chains of different molecules, which leads to a dispersion of the energy levels. This result indicates that the side chains of the molecular crystal not only are responsible for its structural conformation but also can be used for tuning the electronic and optical properties of these materials.
March, N H; Nagy, A
2008-11-21
Following some studies of integral(n)(r)inverted DeltaV(r)dr by earlier workers for the density functional theory (DFT) one-body potential V(r) generating the exact ground-state density, we consider here the special case of spherical atoms. The starting point is the differential virial theorem, which is used, as well as the Hiller-Sucher-Feinberg [Phys. Rev. A 18, 2399 (1978)] identity to show that the scalar quantity paralleling the above vector integral, namely, integral(n)(r) partial differential(V)(r)/partial differential(r)dr, is determined solely by the electron density n(0) at the nucleus for the s-like atoms He and Be. The force - partial differential(V)/ partial differential(r) is then related to the derivative of the exchange-correlation potential V(xc)(r) by terms involving only the external potential in addition to n(r). The resulting integral constraint should allow some test of the quality of currently used forms of V(xc)(r). The article concludes with results from the differential virial theorem and the Hiller-Sucher-Feinberg identity for the exact many-electron theory of spherical atoms, as well as for the DFT for atoms such as Ne with a closed p shell.
Gritsenko, Oleg V; Baerends, Evert Jan
2009-06-14
Time-dependent density functional (response) theory (TDDF(R)T) is applied almost exclusively in its adiabatic approximation (ATDDFT), which is restricted to predominantly single electronic excitations and neglects additional roots of the TDDFT eigenvalue problem stemming from the interaction between single and double excitations. We incorporate the effect of the latter interaction into a non-adiabatic frequency-dependent and spatially non-local Hartree-exchange-correlation (Hxc) kernel fCEDAHxc (r1, r2, omega), the explicit analytical expression of which is derived for interacting single and double excitations well separated from the other excitations, within the common energy denominator approximation (CEDA) for the Kohn-Sham (KS) and interacting density response functions, chis and chi, respectively. The kernel fCEDAHxc (r1, r2, omega) obtained from the direct analytical inverse of chiCEDAs and chiCEDA is a sum of the delta-function and non-local orbital-dependent spatial terms with frequency-dependent factors, with which fCEDAHxc acquires a modulated quadratic dependence on omega. The effective incorporation in fCEDAHxc of the complete manifold of excited states (through the delta function term) represents an extension of the kernel reported by Maitra, Zhang, Cave, and Burke [J. Chem. Phys., 2004, 120, 5932]. In the TDDFT eigenvalue equations considered in the diagonal approximation, fCEDAHxc generates two excitation energies omegaq and omegaq+1, which both correspond to the same single KS excitation omegasq, thus producing the effect of the single-double excitation interaction.
Quantum dust magnetosonic waves with spin and exchange correlation effects
Energy Technology Data Exchange (ETDEWEB)
Maroof, R.; Qamar, A. [Department of Physics, University of Peshawar, Peshawar 25000 (Pakistan); Mushtaq, A. [Department of Physics, Abdul Wali Khan University, Mardan 23200 (Pakistan); National Center for Physics, Shahdra Valley Road, Islamabad 44000 (Pakistan)
2016-01-15
Dust magnetosonic waves are studied in degenerate dusty plasmas with spin and exchange correlation effects. Using the fluid equations of magnetoplasma with quantum corrections due to the Bohm potential, temperature degeneracy, spin magnetization energy, and exchange correlation, a generalized dispersion relation is derived. Spin effects are incorporated via spin force and macroscopic spin magnetization current. The exchange-correlation potentials are used, based on the adiabatic local-density approximation, and can be described as a function of the electron density. For three different values of angle, the dispersion relation is reduced to three different modes under the low frequency magnetohydrodynamic assumptions. It is found that the effects of quantum corrections in the presence of dust concentration significantly modify the dispersive properties of these modes. The results are useful for understanding numerous collective phenomena in quantum plasmas, such as those in compact astrophysical objects (e.g., the cores of white dwarf stars and giant planets) and in plasma-assisted nanotechnology (e.g., quantum diodes, quantum free-electron lasers, etc.)
Role of nonlocal exchange correlation in activated adsorption
DEFF Research Database (Denmark)
Hammer, Bjørk; Jacobsen, Karsten Wedel; Nørskov, Jens Kehlet
1993-01-01
The barrier for dissociative adsorption of H-2 on Al(110) has been calculated within the generalized gradient approximation. A pronounced increase of the barrier height is found compared with what is calculated in the local density approximation (LDA). The apparent LDA underestimation...... of the barrier height is shown to be intimately linked with the LDA underbinding of core electrons and we suggest it to be a general phenomenon not limited to the particular nonlocal exchange-correlation approximation used or the particular system studied....
Asymptotic Correction Schemes for Semilocal Exchange-Correlation Functionals
Pan, Chi-Ruei; Chai, Jeng-Da
2013-01-01
Aiming to remedy the incorrect asymptotic behavior of conventional semilocal exchange-correlation (XC) density functionals for finite systems, we propose an asymptotic correction scheme, wherein an exchange density functional whose functional derivative has the correct (-1/r) asymptote can be directly added to any semilocal density functional. In contrast to semilocal approximations, our resulting exchange kernel in reciprocal space exhibits the desirable singularity of the type O(-1/q^2) as q -> 0, which is a necessary feature for describing the excitonic effects in non-metallic solids. By applying this scheme to a popular semilocal density functional, PBE [J. P. Perdew, K. Burke, and M. Ernzerhof, Phys. Rev. Lett. 77, 3865 (1996)], the predictions of the properties that are sensitive to the asymptote are significantly improved, while the predictions of the properties that are insensitive to the asymptote remain essentially the same as PBE. Relative to the popular model XC potential scheme, our scheme is sig...
Development and testing of new exchange correlation functionals
DEFF Research Database (Denmark)
Lundgård, Keld Troen
, selectivity or similar of current chemical processes, or to make new technologies economical feasible. Kohn-Sham density functional theory (KS-DFT) has proven to be a powerful theory to find trends in current catalytic materials, which can empower a more informed search for better alternatives. KS-DFT relies...... generally applicable models; a robust MM-estimator loss function, for ensuring resistance to outliers in data; and a hierarchical bootstrap resampling estimating prediction error validation method, for selecting the model complexity that provide best transferability outside the training data. Three new semi...... on accurate and efficient approximations to the exchange correlation functional, yet these functional approximations have lacked a systematic way to estimate the underlying uncertainties. A Bayesian error estimation approach provides a mechanism for calculating approximative uncertainties, and so accurate...
Assessing Accuracy of Exchange-Correlation Functionals for the Description of Atomic Excited States
Makowski, Marcin; Hanas, Martyna
2016-09-01
The performance of exchange-correlation functionals for the description of atomic excitations is investigated. A benchmark set of excited states is constructed and experimental data is compared to Time-Dependent Density Functional Theory (TDDFT) calculations. The benchmark results show that for the selected group of functionals good accuracy may be achieved and the quality of predictions provided is competitive to computationally more demanding coupled-cluster approaches. Apart from testing the standard TDDFT approaches, also the role of self-interaction error plaguing DFT calculations and the adiabatic approximation to the exchange-correlation kernels is given some insight.
Energy Technology Data Exchange (ETDEWEB)
Zhou, Yongxi; Ernzerhof, Matthias, E-mail: Matthias.Ernzerhof@UMontreal.ca [Département de Chimie, Université de Montréal, C.P. 6128, Succursale A, Montréal, Québec H3C 3J7 (Canada); Bahmann, Hilke [Department of Chemistry, Technische Universität Berlin, Strasse des 17 Juni, Berlin (Germany)
2015-09-28
Drawing on the adiabatic connection of density functional theory, exchange-correlation functionals of Kohn-Sham density functional theory are constructed which interpolate between the extreme limits of the electron-electron interaction strength. The first limit is the non-interacting one, where there is only exchange. The second limit is the strong correlated one, characterized as the minimum of the electron-electron repulsion energy. The exchange-correlation energy in the strong-correlation limit is approximated through a model for the exchange-correlation hole that is referred to as nonlocal-radius model [L. O. Wagner and P. Gori-Giorgi, Phys. Rev. A 90, 052512 (2014)]. Using the non-interacting and strong-correlated extremes, various interpolation schemes are presented that yield new approximations to the adiabatic connection and thus to the exchange-correlation energy. Some of them rely on empiricism while others do not. Several of the proposed approximations yield the exact exchange-correlation energy for one-electron systems where local and semi-local approximations often fail badly. Other proposed approximations generalize existing global hybrids by using a fraction of the exchange-correlation energy in the strong-correlation limit to replace an equal fraction of the semi-local approximation to the exchange-correlation energy in the strong-correlation limit. The performance of the proposed approximations is evaluated for molecular atomization energies, total atomic energies, and ionization potentials.
Improved Lieb-Oxford exchange-correlation inequality with gradient correction
Mathieu, Lewin
2014-01-01
We prove a Lieb-Oxford-type inequality on the exchange-correlation energy of a general many-particle quantum state, with a lower constant than the original statement but involving an additional gradient correction. The result is similar to a recent inequality of Benguria, Bley and Loss, except that the correction term is purely local, as is appropriate for density functional theory.
Exchange-correlation functionals via local interpolation along the adiabatic connection
Vuckovic, Stefan; Savin, Andreas; Teale, Andrew M; Gori-Giorgi, Paola
2016-01-01
The construction of density-functional approximations is explored by modeling the adiabatic connection em locally, using energy densities defined in terms of the electrostatic potential of the exchange-correlation hole. These local models are more amenable to the construction of size-consistent approximations than their global counterparts. In this work we use accurate input local ingredients to assess the accuracy of range of local interpolation models against accurate exchange-correlation energy densities. The importance of the strictly-correlated electrons (SCE) functional describing the strong coupling limit is emphasized, enabling the corresponding interpolated functionals to treat strong correlation effects. In addition to exploring the performance of such models numerically for the helium and beryllium isoelectronic series and the dissociation of the hydrogen molecule, an approximate analytic model is presented for the initial slope of the local adiabatic connection. Comparisons are made with approache...
Design of exchange-correlation functionals through the correlation factor approach
Energy Technology Data Exchange (ETDEWEB)
Pavlíková Přecechtělová, Jana, E-mail: j.precechtelova@gmail.com, E-mail: Matthias.Ernzerhof@UMontreal.ca [Département de Chimie, Université de Montréal, C.P. 6128 Succursale A, Montréal, Québec H3C 3J7 (Canada); Institut für Chemie, Theoretische Chemie / Quantenchemie, Sekr. C7, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany); Bahmann, Hilke; Kaupp, Martin [Institut für Chemie, Theoretische Chemie / Quantenchemie, Sekr. C7, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany); Ernzerhof, Matthias, E-mail: j.precechtelova@gmail.com, E-mail: Matthias.Ernzerhof@UMontreal.ca [Département de Chimie, Université de Montréal, C.P. 6128 Succursale A, Montréal, Québec H3C 3J7 (Canada)
2015-10-14
The correlation factor model is developed in which the spherically averaged exchange-correlation hole of Kohn-Sham theory is factorized into an exchange hole model and a correlation factor. The exchange hole model reproduces the exact exchange energy per particle. The correlation factor is constructed in such a manner that the exchange-correlation energy correctly reduces to exact exchange in the high density and rapidly varying limits. Four different correlation factor models are presented which satisfy varying sets of physical constraints. Three models are free from empirical adjustments to experimental data, while one correlation factor model draws on one empirical parameter. The correlation factor models are derived in detail and the resulting exchange-correlation holes are analyzed. Furthermore, the exchange-correlation energies obtained from the correlation factor models are employed to calculate total energies, atomization energies, and barrier heights. It is shown that accurate, non-empirical functionals can be constructed building on exact exchange. Avenues for further improvements are outlined as well.
Rodríguez, Juan I; Thompson, David C; Ayers, Paul W; Köster, Andreas M
2008-06-14
A new numerical integration procedure for exchange-correlation energies and potentials is proposed and "proof of principle" results are presented. The numerical integration grids are built from sparse-tensor product grids (constructed according to Smolyak's prescription [Dokl. Akad. Nauk. 4, 240 (1963)] ) on the unit cube. The grid on the unit cube is then transformed to a grid over real space with respect to a weight function, which we choose to be the promolecular density. This produces a "whole molecule" grid, in contrast to conventional integration methods in density-functional theory, which use atom-in-molecule grids. The integration scheme was implemented in a modified version of the DEMON2K density-functional theory program, where it is used to evaluate integrals of the exchange-correlation energy density and the exchange-correlation potential. Ground-state energies and molecular geometries are accurately computed. The biggest advantages of the grid are its flexibility (it is easy to change the number and distribution of grid points) and its whole molecule nature. The latter feature is potentially helpful for basis-set-free computational algorithms.
Convexity and the translational-invariance constraint on the exchange-correlation functional
Joubert, Daniel; Levy, Mel
1996-07-01
Knowledge of the properties of the exchange-correlation functional in the form 1/λvxc([ρλ],r/λ), where ρλ(r)= λ3ρ(λr), is important when expressing the exchange-correlation energy as a line integral Exc[ρ]=∫10dλ∫dr1/λvxc([ρλ],r/λ) [3ρ(r)+r.∇ρ(r)] [R. van Leeuwen and E. J. Baerends, Phys. Rev. A 51, 170 (1995)]. With this in mind, it is shown that in the low-density limit limλ-->0∫ρ(r)∇21/λvxc([ρλ],r/λ)d3 r<=4π∫ρ(r)2d3r. This inequality is violated in the local-density approximation.
Accurate exchange-correlation energies for the warm dense electron gas
Malone, FD; Blunt, NS; Brown, EW; Lee, DKK; Spencer, JS; Foulkes, WMC; Shepherd, JJ
2016-01-01
Density matrix quantum Monte Carlo (DMQMC) is used to sample exact-on-average $N$-body density matrices for uniform electron gas systems of up to 10$^{124}$ matrix elements via a stochastic solution of the Bloch equation. The results of these calculations resolve a current debate over the accuracy of the data used to parametrize finite-temperature density functionals. Exchange-correlation energies calculated using the real-space restricted path-integral formalism and the $k$-space configurati...
Exchange-correlation energy of a hole gas including valence band coupling
Bobbert, P. A.; Wieldraaijer, H.; van der Weide, R.; Kemerink, M.; Koenraad, P. M.; Wolter, J. H.
1997-08-01
We have calculated an accurate exchange-correlation energy of a hole gas, including the complexities related to the valence band coupling as occurring in semiconductors like GaAs, but excluding the band warping. A parametrization for the dependence on the density and the ratio between light- and heavy-hole masses is given. We apply our results to a hole gas in an AlxGa1-xAs/GaAs/AlxGa1-xAs quantum well and calculate the two-dimensional band structure and the band-gap renormalization. The inclusion of the valence band coupling in the calculation of the exchange-correlation potentials for holes and electrons leads to a much better agreement between theoretical and experimental data than when it is omitted.
Yu, Haoyu S; Zhang, Wenjing; Verma, Pragya; He, Xiao; Truhlar, Donald G
2015-05-14
The goal of this work is to develop a gradient approximation to the exchange-correlation functional of Kohn-Sham density functional theory for treating molecular problems with a special emphasis on the prediction of quantities important for homogeneous catalysis and other molecular energetics. Our training and validation of exchange-correlation functionals is organized in terms of databases and subdatabases. The key properties required for homogeneous catalysis are main group bond energies (database MGBE137), transition metal bond energies (database TMBE32), reaction barrier heights (database BH76), and molecular structures (database MS10). We also consider 26 other databases, most of which are subdatabases of a newly extended broad database called Database 2015, which is presented in the present article and in its ESI. Based on the mathematical form of a nonseparable gradient approximation (NGA), as first employed in the N12 functional, we design a new functional by using Database 2015 and by adding smoothness constraints to the optimization of the functional. The resulting functional is called the gradient approximation for molecules, or GAM. The GAM functional gives better results for MGBE137, TMBE32, and BH76 than any available generalized gradient approximation (GGA) or than N12. The GAM functional also gives reasonable results for MS10 with an MUE of 0.018 Å. The GAM functional provides good results both within the training sets and outside the training sets. The convergence tests and the smooth curves of exchange-correlation enhancement factor as a function of the reduced density gradient show that the GAM functional is a smooth functional that should not lead to extra expense or instability in optimizations. NGAs, like GGAs, have the advantage over meta-GGAs and hybrid GGAs of respectively smaller grid-size requirements for integrations and lower costs for extended systems. These computational advantages combined with the relatively high accuracy for all
A generalized exchange-correlation functional: the Neural-Networks approach
Zheng, X; Wang, X J; Chen, G H; Zheng, Xiao; Hu, LiHong; Wang, XiuJun; Chen, GuanHua
2003-01-01
A Neural-Networks-based approach is proposed to construct a new type of exchange-correlation functional for density functional theory. It is applied to improve B3LYP functional by taking into account of high-order contributions to the exchange-correlation functional. The improved B3LYP functional is based on a neural network whose structure and synaptic weights are determined from 116 known experimental atomization energies, ionization potentials, proton affinities or total atomic energies which were used by Becke in his pioneer work on the hybrid functionals [J. Chem. Phys. ${\\bf 98}$, 5648 (1993)]. It leads to better agreement between the first-principles calculation results and these 116 experimental data. The new B3LYP functional is further tested by applying it to calculate the ionization potentials of 24 molecules of the G2 test set. The 6-311+G(3{\\it df},2{\\it p}) basis set is employed in the calculation, and the resulting root-mean-square error is reduced to 2.2 kcal$\\cdot$mol$^{-1}$ in comparison to ...
D., I. Bilc; R., Orlando; R., Shaltaf; G., M. Rignanese; J., Íñiguez; Ph., Ghosez
2008-01-01
Using a linear combination of atomic orbitals approach, we report a systematic comparison of various Density Functional Theory (DFT) and hybrid exchange-correlation functionals for the prediction of the electronic and structural properties of prototypical ferroelectric oxides. It is found that none of the available functionals is able to provide, at the same time, accurate electronic and structural properties of the cubic and tetragonal phases of BaTiO$_3$ and PbTiO$_3$. Some, although not al...
Quantum Monte Carlo Benchmark of Exchange-Correlation Functionals for Bulk Water.
Morales, Miguel A; Gergely, John R; McMinis, Jeremy; McMahon, Jeffrey M; Kim, Jeongnim; Ceperley, David M
2014-06-10
The accurate description of the thermodynamic and dynamical properties of liquid water from first-principles is a very important challenge to the theoretical community. This represents not only a critical test of the predictive capabilities of first-principles methods, but it will also shed light into the microscopic properties of such an important substance. Density Functional Theory, the main workhorse in the field of first-principles methods, has been so far unable to properly describe water and its unusual properties in the liquid state. With the recent introduction of exact exchange and an improved description of dispersion interaction, the possibility of an accurate description of the liquid is finally within reach. Unfortunately, there is still no way to systematically improve exchange-correlation functionals, and the number of available functionals is very large. In this article we use highly accurate quantum Monte Carlo calculations to benchmark a selection of exchange-correlation functionals typically used in Density Functional Theory simulations of bulk water. This allows us to test the predictive capabilities of these functionals in water, giving us a way to choose optimal functionals for first-principles simulations. We compare and contrast the importance of different features of functionals, including the hybrid component, the vdW component, and their importance within different aspects of the PES. In addition, in order to correct the inaccuracies in the description of short-range interactions in the liquid, we test a recently introduced scheme that combines Density Functional Theory with Coupled Cluster calculations through a Many-Body expansion of the energy.
Accurate Exchange-Correlation Energies for the Warm Dense Electron Gas.
Malone, Fionn D; Blunt, N S; Brown, Ethan W; Lee, D K K; Spencer, J S; Foulkes, W M C; Shepherd, James J
2016-09-09
The density matrix quantum Monte Carlo (DMQMC) method is used to sample exact-on-average N-body density matrices for uniform electron gas systems of up to 10^{124} matrix elements via a stochastic solution of the Bloch equation. The results of these calculations resolve a current debate over the accuracy of the data used to parametrize finite-temperature density functionals. Exchange-correlation energies calculated using the real-space restricted path-integral formalism and the k-space configuration path-integral formalism disagree by up to ∼10% at certain reduced temperatures T/T_{F}≤0.5 and densities r_{s}≤1. Our calculations confirm the accuracy of the configuration path-integral Monte Carlo results available at high density and bridge the gap to lower densities, providing trustworthy data in the regime typical of planetary interiors and solids subject to laser irradiation. We demonstrate that the DMQMC method can calculate free energies directly and present exact free energies for T/T_{F}≥1 and r_{s}≤2.
Clay, Raymond; Morales, Miguel; Bonev, Stanimir
Lithium at ambient conditions is the simplest alkali metal and exhibits textbook nearly-free electron character. However, increased core/valence electron overlap under compression leads to surprisingly complex behavior. Dense lithium is known to posses a maximum in the melting line, a metal to semiconductor phase transition around 80GPa, reemergent metallicity around 120GPa, and low coordination solid and liquid phases. In addition to its complex electronic structure at high pressure, the atomic mass of lithium is low enough that nuclear quantum effects could have a nontrivial impact on its phase diagram. Through a combination of density functional theory based path-integral and classical molecular dynamics simulations, we have investigated the impact of both nuclear quantum effects and anharmonicity on the melting line and solid phase boundaries. Additionally, we have determined the robustness of previously predicted tetrahedral clustering in the dense liquid to the inclusion of nuclear quantum effects and approximate treatment of electronic exchange-correlation effects.
Constantin, L A; Della Sala, F
2013-01-01
Using a reverse-engineering method we construct a meta-generalized gradient approximation (meta-GGA) angle-averaged exchange-correlation hole model which has a general applicability. It satisfies known exact hole constraints and can exactly recover the exchange-correlation energy density of any reasonable meta-GGA exchange-correlation energy functional satisfying a minimal set of exact properties. The hole model is applied to several non-empirical meta-GGA functionals: the Tao-Perdew-Staroverov-Scuseria (TPSS), the revised TPSS (revTPSS) and the recently Balanced LOCalization (BLOC) meta-GGA of L.A. Constantin, E. Fabiano, and F. Della Sala, (J. Chem. Theory Comput. 9, 2256 (2013)). The empirical M06-L meta-GGA functional is also considered. Real-space analyses of atoms and ions as well as wave-vector analyses of jellium surface energies, show that the meta-GGA hole models, in particular the BLOC one, are very realistic and can reproduce many features of benchmark XC holes. In addition, the BLOC hole model ca...
Importance of finite-temperature exchange correlation for warm dense matter calculations
Karasiev, Valentin V.; Calderín, Lázaro; Trickey, S. B.
2016-06-01
The effects of an explicit temperature dependence in the exchange correlation (XC) free-energy functional upon calculated properties of matter in the warm dense regime are investigated. The comparison is between the Karasiev-Sjostrom-Dufty-Trickey (KSDT) finite-temperature local-density approximation (TLDA) XC functional [Karasiev et al., Phys. Rev. Lett. 112, 076403 (2014), 10.1103/PhysRevLett.112.076403] parametrized from restricted path-integral Monte Carlo data on the homogeneous electron gas (HEG) and the conventional Monte Carlo parametrization ground-state LDA XC [Perdew-Zunger (PZ)] functional evaluated with T -dependent densities. Both Kohn-Sham (KS) and orbital-free density-functional theories are used, depending upon computational resource demands. Compared to the PZ functional, the KSDT functional generally lowers the dc electrical conductivity of low-density Al, yielding improved agreement with experiment. The greatest lowering is about 15% for T =15 kK. Correspondingly, the KS band structure of low-density fcc Al from the KSDT functional exhibits a clear increase in interband separation above the Fermi level compared to the PZ bands. In some density-temperature regimes, the deuterium equations of state obtained from the two XC functionals exhibit pressure differences as large as 4% and a 6% range of differences. However, the hydrogen principal Hugoniot is insensitive to the explicit XC T dependence because of cancellation between the energy and pressure-volume work difference terms in the Rankine-Hugoniot equation. Finally, the temperature at which the HEG becomes unstable is T ≥7200 K for the T -dependent XC, a result that the ground-state XC underestimates by about 1000 K.
Construction of Exchange-Correlation Potentials for Strongly Interacting One-Dimensional Systems
Silva, J. Wildon O.; Vieira, Daniel
2017-08-01
One-dimensional (1D) systems are useful laboratories aiming further improvement of electronic structure calculations. In order to simulate electron-electron interactions, two types of expressions are commonly considered: soft-Coulomb and exponential. For both cases, in the context of density-functional theory (DFT), 1D systems can be employed to gain insight into the ingredients accurate exchange-correlation (XC) density functionals must incorporate. A question of major interest is the treatment of strongly interacting situations, one of the main modern challenges for DFT. In this manuscript, we propose a generalization of preexisting XC potentials which can be applied to investigate the transition from weak to strong interactions. Specifically, we employ the intriguing behavior of electrons confined in one dimension: the spin-charge separation, for which spin and charge are decoupled to form two independent quasiparticles, spinons, and chargons. By means of Friedel oscillations, our results indicate it is possible to reproduce the weak-strong interaction transition by using a simple strategy we name, from previous works, spin-charge separation correction (SCSC). In addition, SCSC also yields good results in reproducing the constancy of the highest occupied Kohn-Sham eigenvalues upon fractional electron charges.
Away from generalized gradient approximation: orbital-dependent exchange-correlation functionals.
Baerends, E J; Gritsenko, O V
2005-08-08
The local-density approximation of density functional theory (DFT) is remarkably accurate, for instance, for geometries and frequencies, and the generalized gradient approximations have also made bond energies quite reliable. Sometimes, however, one meets with failure in individual cases. One of the possible routes towards better functionals would be the incorporation of orbital dependence (which is an implicit density dependency) in the functionals. We discuss this approach both for energies and for response properties. One possibility is the use of the Hartree-Fock-type exchange energy expression as orbital-dependent functional. We will argue that in spite of the increasing popularity of this approach, it does not offer any advantage over Hartree-Fock for energies. We will advocate not to apply the separation of exchange and correlation, which is so ingrained in quantum chemistry, but to model both simultaneously. For response properties the energies and shapes of the virtual orbitals are crucial. We will discuss the benefits that Kohn-Sham potentials can offer which are derived from either an orbital-dependent energy functional, including the exact-exchange functional, or which can be obtained directly as orbital-dependent functional. We highlight the similarity of the Hartree-Fock and Kohn-Sham occupied orbitals and orbital energies, and the essentially different meanings the virtual orbitals and orbital energies have in these two models. We will show that these differences are beneficial for DFT in the case of localized excitations (in a small molecule or in a fragment), but are detrimental for charge-transfer excitations. Again, orbital dependency, in this case in the exchange-correlation kernel, offers a solution.
Hoover, Eric; Millman, Sierra
2007-01-01
Marilee Jones's career had been a remarkable success. She joined Massachusetts Institute of Technology's (MIT's) admissions office in 1979, landing a job in Cambridge at a time when boys ruled the sandbox of the admissions profession. Her job was to help MIT recruit more women, who then made up less than one-fifth of the institute's students. She…
Schipper, P. R. T.; Gritsenko, O. V.; van Gisbergen, S. J. A.; Baerends, E. J.
2000-01-01
An approximate Kohn-Sham exchange-correlation potential νxcSAOP is developed with the method of statistical averaging of (model) orbital potentials (SAOP) and is applied to the calculation of excitation energies as well as of static and frequency-dependent multipole polarizabilities and hyperpolarizabilities within time-dependent density functional theory (TDDFT). νxcSAOP provides high quality results for all calculated response properties and a substantial improvement upon the local density approximation (LDA) and the van Leeuwen-Baerends (LB) potentials for the prototype molecules CO, N2, CH2O, and C2H4. For the first three molecules and the lower excitations of the C2H4 the average error of the vertical excitation energies calculated with νxcSAOP approaches the benchmark accuracy of 0.1 eV for the electronic spectra.
Admissions Testing & Institutional Admissions Processes
Hossler, Don; Kalsbeek, David
2009-01-01
The array of admissions models and the underlying, and sometimes conflicting goals people have for college admissions, create the dynamics and the tensions that define the contemporary context for enrollment management. The senior enrollment officer must ask, for example, how does an institution try to assure transparency, equality of access,…
The effect of the exchange-correlation functional on H2 dissociation on Ru(0001)
Wijzenbroek, M.; Kroes, G. J.
2014-02-01
The specific reaction parameter (SRP) approach to density functional theory (DFT) has enabled a chemically accurate description of reactive scattering experiments for activated H2-metal systems (H2 + Cu(111) and Cu(100)), but its application has not yet resulted in a similarly accurate description of non-activated or weakly activated H2-metal systems. In this study, the effect of the choice of the exchange-correlation functional in DFT on the potential energy surface and dynamics of H2 dissociation on Ru(0001), a weakly activated system, is investigated. In total, full potential energy surfaces were calculated for over 20 different functionals. The functionals investigated include functionals incorporating an approximate description of the van der Waals dispersion in the correlation functional (vdW-DF and vdW-DF2 functionals), as well as the revTPSS meta-GGA. With two of the functionals investigated here, which include vdW-DF and vdW-DF2 correlation, it has been possible to accurately reproduce molecular beam experiments on sticking of H2 and D2, as these functionals yield a reaction probability curve with an appropriate energy width. Diffraction probabilities computed with these two functionals are however too high compared to experimental diffraction probabilities, which are extrapolated from surface temperatures (Ts) ⩾ 500 K to 0 K using a Debye-Waller model. Further research is needed to establish whether this constitutes a failure of the two candidate SRP functionals or a failure of the Debye-Waller model, the use of which can perhaps in future be avoided by performing calculations that include the effect of surface atom displacement or motion, and thereby of the experimental Ts.
Energy Technology Data Exchange (ETDEWEB)
Segala, Maximiliano [Universidade Estadual do Rio Grande do Sul, Rua Oscar Matzembacher 475, 96760-000, Tapes, RS (Brazil); Chong, Delano P. [Department of Chemistry, 2036 Main Mall, University of British Columbia, Vancouver, B.C., V6T 1Z1 (Canada)], E-mail: chong@chem.ubc.ca
2009-04-15
In this paper, ionization energies of gas-phase atoms and molecules are calculated by energy-difference method and by approximate transition-state models with density functional theory (DFT). To determine the best functionals for ionization energies, we first study the H to Ar atoms. An approximation is used in which the electron density is first obtained from Kohn-Sham computations with an exchange-correlation potential V{sub xc} known as statistical average of orbital potentials (SAOP), after which the energy is computed from that density with 59 different exchange-correlation energy functionals E{sub xc}. For the 18 atoms, the best E{sub xc} functional providing an average absolute deviation (AAD) of only 0.110 eV is one known as the Krieger-Chen-Iafrate-Savin functional modified by Krieger, Chen, Iafrate, and Kurth, if one uses the spin-polarized spherical atom description. On the other hand, if one imposes the condition of integer-electrons, the best functional is the Becke 1997 functional modified by Wilson, Bradley, and Tozer, with an AAD of 0.107 eV, while several other functionals perform almost as well. For molecules, we can achieve an accuracy of AAD = 0.21 eV for valence VIPs of nonperhalo molecules with {delta}E(V{sub xc} = SAOP;PBE0) using integer-electron description. For perhalo molecules our best approach is {delta}E(V{sub xc} from either E{sub xc} or SAOP;mPW1PW) with full symmetry to obtain an AAD = 0.24 eV.
Directory of Open Access Journals (Sweden)
Yu-Jiao Sun
2013-04-01
Full Text Available This study assessed the relationship between low-density lipoprotein cholesterol (LDL-C levels on admission and the incidence of major adverse cardiovascular events (MACE in patients with acute ST-segment-elevation myocardial infarction (ASTEMI. Patients with ASTEMI who had a lipid profile tested within 24 hours of symptom onset were enrolled. They were stratified into high and low LDL-C groups according to whether their LDL-C was above (n = 501 or below (n = 575 the median level, respectively. The incidence of MACE, cardiovascular death, non-fatal MI, revascularization, and stroke was compared between the groups at 1 month, 6 months, and 1 year. Survival analysis and Cox proportional hazard analysis were performed. In-hospital use of beta blockers was better in the high than in the low LDL-C group (76.6% vs. 69.7%, p = 0.01. Statin use was significantly higher in the high than in the low LDL-C group during follow-up (86.8% vs. 80.0%, p = 0.003 at1 month; 71.6% vs. 62.4%, p = 0.002 at 6 months; 67.8% vs. 61.2%, p = 0.03 at 1 year. The incidence of MACE on follow-up at 1 month was higher in the low than in the high LDL-C group (12.0% vs. 8.1%, p = 0.04. At 1 year, survival was not significantly different between the groups. Cox proportional hazards analysis indicated that the incidence of MACE was significantly associated with hypertension, current smoking, high-density lipoprotein cholesterol (HDL-C, in-hospital use of beta blockers, and statin use on follow-up (p < 0.01. LDL-C levels on admission in patients with ASTEMI had no significant effect on the 6-month and 1-year incidence of MACE, but the incidence of MACE was significantly higher in the low LDL-C group at 1 month. It would be relevant to further investigate the HDL-C level on admission, in-hospital use of beta blockers, and statin use during follow-up in relation to MACE.
Impact of exchange-correlation effects on the IV characteristics of a molecular junction
DEFF Research Database (Denmark)
Thygesen, Kristian Sommer
2008-01-01
The role of exchange-correlation effects in nonequilibrium quantum transport through molecular junctions is assessed by analyzing the IV curve of a generic two-level model using self-consistent many-body perturbation theory (second Born and GW approximations) on the Keldysh contour...
Origin of the step structure of molecular exchange-correlation potentials.
Kohut, Sviataslau V; Polgar, Alexander M; Staroverov, Viktor N
2016-08-21
The exact exchange-correlation potential of a stretched heteronuclear diatomic molecule exhibits a localized upshift in the region around the more electronegative atom; by this device the Kohn-Sham scheme ensures that the molecule dissociates into neutral atoms. Baerends and co-workers showed earlier that the upshift originates in the response part of the exchange-correlation potential. We describe a reliable numerical method for constructing the response potential of a given many-electron system and report accurate plots of this quantity. We also demonstrate that the step feature itself can be obtained directly from the interacting wavefunction of the system by computing the so-called average local electron energy. These findings illustrate in previously unavailable detail the mechanism of the formation of the upshift and the role played by static correlation in this process.
Lee, Ji-Hwan; Park, Jong-Hun; Soon, Aloysius
2016-07-01
Current materials-related calculations employ density-functional theory (DFT), commonly using the (semi-)local-density approximations for the exchange-correlation (xc) functional. The difficulties in arriving at a reasonable description of van der Waals (vdW) interactions by DFT-based models is to date a big challenge. In this work, we use various flavors of vdW-corrected DFT xc functionals—ranging from the quasiempirical force-field add-on vdW corrections to self-consistent nonlocal correlation functionals—to study the bulk lattice and mechanical properties (including the elastic constants and anisotropic indices) of the coinage metals (copper, silver, and gold). We critically assess the reliability of the different vdW-corrected DFT methods in describing their anisotropic mechanical properties which have been less reported in the literature. In the context of this work, we regard that our results reiterate the fact that advocating a so-called perfect vdW-inclusive xc functional for describing the general physics and chemistry of these coinage metals could be a little premature. These challenges to modern-day functionals for anisotropically strained coinage metals (e.g., at the faceted surfaces of nanostructures) may well be relevant to other strained material systems.
Yao, Yi; Kanai, Yosuke
2017-06-01
We present the implementation and performance of the strongly constrained and appropriately normed, SCAN, meta-GGA exchange-correlation (XC) approximation in the planewave-pseudopotential (PW-PP) formalism using the Troullier-Martins pseudopotential scheme. We studied its performance by applying the PW-PP implementation to several practical applications of interest in condensed matter sciences: (a) crystalline silicon and germanium, (b) martensitic phase transition energetics of phosphorene, and (c) a single water molecule physisorption on a graphene sheet. Given the much-improved accuracy over the GGA functionals and its relatively low computational cost compared to hybrid XC functionals, the SCAN functional is highly promising for various practical applications of density functional theory calculations for condensed matter systems. At same time, the SCAN meta-GGA functional appears to require more careful attention to numerical details. The meta-GGA functional shows more significant dependence on the fast Fourier transform grid, which is used for evaluating the XC potential in real space in the PW-PP formalism, than other more conventional GGA functionals do. Additionally, using pseudopotentials that are generated at a different/lower level of XC approximation could introduce noticeable errors in calculating some properties such as phase transition energetics.
Anua, N. Najwa
2013-08-20
Exchange correlation (XC) energy functionals play a vital role in the efficiency of density functional theory (DFT) calculations, more soundly in the calculation of fundamental electronic energy bandgap. In the present DFT study of III-arsenides, we investigate the implications of XC-energy functional and corresponding potential on the structural, electronic and optical properties of XAs (X = B, Al, Ga, In). Firstly we report and discuss the optimized structural lattice parameters and the band gap calculations performed within different non-local XC functionals as implemented in the DFT-packages: WIEN2k, CASTEP and SIESTA. These packages are representative of the available code in ab initio studies. We employed the LDA, GGA-PBE, GGA-WC and mBJ-LDA using WIEN2k. In CASTEP, we employed the hybrid functional, sX-LDA. Furthermore LDA, GGA-PBE and meta-GGA were employed using SIESTA code. Our results point to GGA-WC as a more appropriate approximation for the calculations of structural parameters. However our electronic bandstructure calculations at the level of mBJ-LDA potential show considerable improvements over the other XC functionals, even the sX-LDA hybrid functional. We report also the optical properties within mBJ potential, which show a nice agreement with the experimental measurements in addition to other theoretical results. © 2013 IOP Publishing Ltd.
Charles, Nenian; Rondinelli, James M.
2016-11-01
Motivated by the resurgence of electronic and optical property design in ordered fluoride and oxyfluoride compounds, we present a density functional theory (DFT) study of 19 materials with structures, ranging from simple to complex, and variable oxygen-to-fluorine ratios. We focus on understanding the accuracy of the exchange-correlation potentials (Vx c) to DFT for the prediction of structural, electronic, and lattice dynamical properties at four different levels of theory, i.e., the local density approximation (LDA), generalized gradient approximation (GGA), metaGGA, and hybrid functional level which includes fractions of exact exchange. We investigate in detail the metaGGA functionals MS2 [Sun et al., Phys. Rev. Lett. 111, 106401 (2013), 10.1103/PhysRevLett.111.106401] and SCAN [Sun et al., Phys. Rev. Lett. 115, 036402 (2015), 10.1103/PhysRevLett.115.036402], and show that although the metaGGAs show improvements over the LDA and GGA functionals in describing the electronic structure and phonon frequencies, the static structural properties of fluorides and oxyfluorides are often more accurately predicted by the GGA-level Perdew-Burke-Ernzerhof functional for solids, PBEsol. Results from LDA calculations are unsatisfactory for any compound, regardless of oxygen concentration. The PBEsol and Heyd-Scuseria-Ernzerhof (HSE06) functionals give good performance in all-oxide or all-fluoride compounds. For the oxyfluorides, PBEsol is consistently more accurate for structural properties across all oxygen concentrations; however, we stress the need for detailed property assessment with various functionals for oxyfluorides with variable composition. The "best" functional is anticipated to be more strongly dependent on the property of interest. Our study provides useful insights in selecting an Vx c that achieves optimal performance compromises, enabling more accurate predictive design of functional fluoride-based materials with density functional theory.
libvdwxc: a library for exchange-correlation functionals in the vdW-DF family
Hjorth Larsen, Ask; Kuisma, Mikael; Löfgren, Joakim; Pouillon, Yann; Erhart, Paul; Hyldgaard, Per
2017-09-01
We present libvdwxc, a general library for evaluating the energy and potential for the family of vdW-DF exchange-correlation functionals. libvdwxc is written in C and provides an efficient implementation of the vdW-DF method and can be interfaced with various general-purpose DFT codes. Currently, the Gpaw and Octopus codes implement interfaces to libvdwxc. The present implementation emphasizes scalability and parallel performance, and thereby enables ab initio calculations of nanometer-scale complexes. The numerical accuracy is benchmarked on the S22 test set whereas parallel performance is benchmarked on ligand-protected gold nanoparticles ({{Au}}144{({{SC}}11{{NH}}25)}60) up to 9696 atoms.
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Density functional theory in quantum chemistry
Tsuneda, Takao
2014-01-01
This book examines density functional theory based on the foundation of quantum chemistry. Unconventional in approach, it reviews basic concepts, then describes the physical meanings of state-of-the-art exchange-correlation functionals and their corrections.
Swart, M; Snijders, JG
The geometries of a set of small molecules were optimized using eight different exchange-correlation (xc) potentials in a few different basis sets of Slater-type orbitals, ranging from a minimal basis (I) to a triple-zeta valence basis plus double polarization functions (VII). This enables a
Linear-response thermal time-dependent density functional theory
Pribram-Jones, Aurora; Burke, Kieron
2015-01-01
The van Leeuwen proof of linear-response time-dependent density functional theory (TDDFT) is generalized to thermal ensembles. This allows generalization to finite temperatures of the Gross-Kohn relation, the exchange-correlation kernel of TDDFT, and fluctuation dissipation theorem for DFT. This produces a natural method for generating new thermal exchange-correlation (XC) approximations.
Gould, Tim
2013-01-01
By considering the physics of non-interacting ensembles we better generalise the notion of `exact exchange' (EXX) to systems with fractional occupations in the frontier orbitals (called LEXX), in part by exploiting ambiguities in the definitions of `correlation', `exchange' and `Hartree' physics in ensemble systems. The LEXX is employed in an optimised effective potential (OEP) approach (OLEXX) to approximate groundstate energies, where it is bounded by the `ensemble EXX' (EEXX) energy and standard fractional OEXX energy via $E^{\\EEXX}\\leq E^{\\OLEXX} \\leq E^{\\OEXX}$. Analysis of the OLEXX explains the success of standard OEP methods for diatoms at large spacing, and why they can fail when both spins are allowed to be non-integer. The OLEXX is demonstrated on H, Li and Na with fractional electron number with improvements over OEXX for all cases.
Gould, Tim; Dobson, John F.
2013-01-01
By exploiting freedoms in the definitions of "correlation," "exchange," and "Hartree" physics in ensemble systems, we better generalise the notion of "exact exchange" (EXX) to systems with fractional occupations of the frontier orbitals, arising in the dissociation limit of some molecules. We introduce the linear EXX ("LEXX") theory whose pair distribution and energy are explicitly piecewise linear in the occupations f^{σ }i. We provide explicit expressions for these functions for frontier s and p shells. Used in an optimised effective potential (OEP) approach the LEXX yields energies bounded by the piecewise linear "ensemble EXX" (EEXX) energy and standard fractional optimised EXX energy: EEEXX ⩽ ELEXX ⩽ EEXX. Analysis of the LEXX explains the success of standard OEP methods for diatoms at large spacing, and why they can fail when both spins are allowed to be non-integer so that "ghost" Hartree interactions appear between opposite spin electrons in the usual formula. The energy ELEXX contains a cancellation term for the spin ghost case. It is evaluated for H, Li, and Na fractional ions with clear derivative discontinuities for all cases. The p-shell form reproduces accurate correlation-free energies of B-F and Al-Cl. We further test LEXX plus correlation energy calculations on fractional ions of C and F and again we find both derivative discontinuities and good agreement with exact results.
Gould, Tim; Dobson, John F
2013-01-07
By exploiting freedoms in the definitions of "correlation," "exchange," and "Hartree" physics in ensemble systems, we better generalise the notion of "exact exchange" (EXX) to systems with fractional occupations of the frontier orbitals, arising in the dissociation limit of some molecules. We introduce the linear EXX ("LEXX") theory whose pair distribution and energy are explicitly piecewise linear in the occupations f(i)(σ). We provide explicit expressions for these functions for frontier s and p shells. Used in an optimised effective potential (OEP) approach the LEXX yields energies bounded by the piecewise linear "ensemble EXX" (EEXX) energy and standard fractional optimised EXX energy: E(EEXX) ≤ E(LEXX) ≤ E(EXX). Analysis of the LEXX explains the success of standard OEP methods for diatoms at large spacing, and why they can fail when both spins are allowed to be non-integer so that "ghost" Hartree interactions appear between opposite spin electrons in the usual formula. The energy E(LEXX) contains a cancellation term for the spin ghost case. It is evaluated for H, Li, and Na fractional ions with clear derivative discontinuities for all cases. The p-shell form reproduces accurate correlation-free energies of B-F and Al-Cl. We further test LEXX plus correlation energy calculations on fractional ions of C and F and again we find both derivative discontinuities and good agreement with exact results.
Grüning, M.; Gritsenko, O. V.; van Gisbergen, S. J. A.; Baerends, E. J.
2001-01-01
Shape corrections to the standard approximate Kohn-Sham exchange-correlation (xc) potentials are considered with the aim to improve the excitation energies (especially for higher excitations) calculated with time-dependent density functional perturbation theory. A scheme of gradient-regulated connection (GRAC) of inner to outer parts of a model potential is developed. Asymptotic corrections based either on the potential of Fermi and Amaldi or van Leeuwen and Baerends (LB) are seamlessly connected to the (shifted) xc potential of Becke and Perdew (BP) with the GRAC procedure, and are employed to calculate the vertical excitation energies of the prototype molecules N2, CO, CH2O, C2H4, C5NH5, C6H6, Li2, Na2, K2. The results are compared with those of the alternative interpolation scheme of Tozer and Handy as well as with the results of the potential obtained with the statistical averaging of (model) orbital potentials. Various asymptotically corrected potentials produce high quality excitation energies, which in quite a few cases approach the benchmark accuracy of 0.1 eV for the electronic spectra. Based on these results, the potential BP-GRAC-LB is proposed for molecular response calculations, which is a smooth potential and a genuine "local" density functional with an analytical representation.
Morris, John S.
1983-01-01
Discusses the changing role of admissions officers which corresponds to the declining student enrollment rate. Looks at changes in higher education over the past 15 years, and considers such issues as marketing, consumerism, and integrity as they relate to college admissions. (WAS)
van Aggelen, Helen; Yang, Yang; Yang, Weitao
2014-05-14
Despite their unmatched success for many applications, commonly used local, semi-local, and hybrid density functionals still face challenges when it comes to describing long-range interactions, static correlation, and electron delocalization. Density functionals of both the occupied and virtual orbitals are able to address these problems. The particle-hole (ph-) Random Phase Approximation (RPA), a functional of occupied and virtual orbitals, has recently known a revival within the density functional theory community. Following up on an idea introduced in our recent communication [H. van Aggelen, Y. Yang, and W. Yang, Phys. Rev. A 88, 030501 (2013)], we formulate more general adiabatic connections for the correlation energy in terms of pairing matrix fluctuations described by the particle-particle (pp-) propagator. With numerical examples of the pp-RPA, the lowest-order approximation to the pp-propagator, we illustrate the potential of density functional approximations based on pairing matrix fluctuations. The pp-RPA is size-extensive, self-interaction free, fully anti-symmetric, describes the strong static correlation limit in H2, and eliminates delocalization errors in H2(+) and other single-bond systems. It gives surprisingly good non-bonded interaction energies--competitive with the ph-RPA--with the correct R(-6) asymptotic decay as a function of the separation R, which we argue is mainly attributable to its correct second-order energy term. While the pp-RPA tends to underestimate absolute correlation energies, it gives good relative energies: much better atomization energies than the ph-RPA, as it has no tendency to underbind, and reaction energies of similar quality. The adiabatic connection in terms of pairing matrix fluctuation paves the way for promising new density functional approximations.
Sun, Hsiao-Ling; Chai, Jeng-Da
2015-01-01
We examine the performance of our recently developed LFAs-PBE exchange-correlation (XC) potential [C.-R. Pan, P.-T. Fang, and J.-D. Chai, Phys. Rev. A, 2013, 87, 052510] for the high-order harmonic generation (HHG) spectra and related properties of H2+ molecules aligned parallel and perpendicular to the polarization of an intense linearly polarized laser pulse, employing the real-time formulation of time-dependent density functional theory (RT-TDDFT). The results are compared with the exact solutions of the time-dependent Schr\\"odinger equation as well as those obtained with other XC potentials in RT-TDDFT. Owing to its correct $(-1/r)$ asymptote, the LFAs-PBE potential significantly outperforms conventional XC potentials for the HHG spectra and the properties that are sensitive to the XC potential asymptote. Accordingly, the LFAs-PBE potential, which has a computational cost similar to that of the popular Perdew-Burke-Ernzerhof (PBE) potential, can be very promising for the study of the ground-state, excited...
Al-Hamdani, Yasmine S; von Lilienfeld, O Anatole; Michaelides, Angelos
2016-01-01
Density functional theory (DFT) studies of weakly interacting complexes have recently focused on the importance of van der Waals dispersion forces whereas, the role of exchange has received far less attention. Here, by exploiting the subtle binding between water and a boron and nitrogen doped benzene derivative (1,2-azaborine) we show how exact exchange can alter the binding conformation within a complex. Benchmark values have been calculated for three orientations of the water monomer on 1,2-azaborine from explicitly correlated quantum chemical methods, and we have also used diffusion quantum Monte Carlo. For a host of popular DFT exchange-correlation functionals we show that the lack of exact exchange leads to the wrong lowest energy orientation of water on 1,2-azaborine. As such, we suggest that a high proportion of exact exchange and the associated improvement in the electronic structure could be needed for the accurate prediction of physisorption sites on doped surfaces and in complex organic molecules. ...
Morrison, Robert C
2015-01-07
Accurate densities were determined from configuration interaction wave functions for atoms and ions of Li, Be, and B with up to four electrons. Exchange-correlation potentials, Vxc(r), and functional derivatives of the noninteracting kinetic energy, δK[ρ]/δρ(r), obtained from these densities were used to examine their discontinuities as the number of electrons N increases across integer boundaries for N = 1, N = 2, and N = 3. These numerical results are consistent with conclusions that the discontinuities are characterized by a jump in the chemical potential while the shape of Vxc(r) varies continuously as an integer boundary is crossed. The discontinuity of the Vxc(r) is positive, depends on the ionization potential, electron affinity, and orbital energy differences, and the discontinuity in δK[ρ]/δρ(r) depends on the difference between the energies of the highest occupied and lowest unoccupied orbitals. The noninteracting kinetic energy and the exchange correlation energy have been computed for integer and noninteger values of N between 1 and 4.
Energy Technology Data Exchange (ETDEWEB)
Clay, Raymond C. [Univ. of Illinois, Urbana, IL (United States); Mcminis, Jeremy [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); McMahon, Jeffrey M. [Univ. of Illinois, Urbana, IL (United States); Pierleoni, Carlo [Istituto Nazionale di Fisica Nucleare (INFN), L' aquila (Italy). Lab. Nazionali del Gran Sasso (INFN-LNGS); Ceperley, David M. [Univ. of Illinois, Urbana, IL (United States); Morales, Miguel A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2014-05-01
The ab initio phase diagram of dense hydrogen is very sensitive to errors in the treatment of electronic correlation. Recently, it has been shown that the choice of the density functional has a large effect on the predicted location of both the liquid-liquid phase transition and the solid insulator-to-metal transition in dense hydrogen. To identify the most accurate functional for dense hydrogen applications, we systematically benchmark some of the most commonly used functionals using quantum Monte Carlo. By considering several measures of functional accuracy, we conclude that the van der Waals and hybrid functionals significantly outperform local density approximation and Perdew-Burke-Ernzerhof. We support these conclusions by analyzing the impact of functional choice on structural optimization in the molecular solid, and on the location of the liquid-liquid phase transition.
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Nonimmigrant Admission: Fiscal Year 2007
Department of Homeland Security — Nonimmigrants are foreign nationals granted temporary admission into the United States. The major purposes for which nonimmigrant admission may be authorized include...
Nonimmigrant Admissions - Fiscal Year 2013
Department of Homeland Security — Nonimmigrants are foreign nationals granted temporary admission into the United States. The major purposes for which nonimmigrant admission may be authorized include...
Nonimmigrant Admissions: Fiscal Year 2010
Department of Homeland Security — Nonimmigrants are foreign nationals granted temporary admission into the United States. The major purposes for which nonimmigrant admission may be authorized include...
Admissible and Restrained Revision
Booth, R; 10.1613/jair.1874
2011-01-01
As partial justification of their framework for iterated belief revision Darwiche and Pearl convincingly argued against Boutiliers natural revision and provided a prototypical revision operator that fits into their scheme. We show that the Darwiche-Pearl arguments lead naturally to the acceptance of a smaller class of operators which we refer to as admissible. Admissible revision ensures that the penultimate input is not ignored completely, thereby eliminating natural revision, but includes the Darwiche-Pearl operator, Nayaks lexicographic revision operator, and a newly introduced operator called restrained revision. We demonstrate that restrained revision is the most conservative of admissible revision operators, effecting as few changes as possible, while lexicographic revision is the least conservative, and point out that restrained revision can also be viewed as a composite operator, consisting of natural revision preceded by an application of a "backwards revision" operator previously studied by Papini. ...
Involuntary admission and treatment
Directory of Open Access Journals (Sweden)
Anirudh Kala
2015-01-01
Full Text Available Provisions for involuntary admission proposed in the Mental Health Care Bill, which is currently before the parliament, are discussed. Concerns about feasibility and cost-effectiveness of the postadmission judicial review, which is a novel feature in the Indian context, are put forward.
The Admissions Equity Struggle
Freedman, Eric
2012-01-01
It has been a long, litigious road from Heman Sweatt, an African-American mail carrier who wanted to attend the prestigious, all-White law school at the University of Texas at Austin in 1946, to Abigail Fisher, a White high school student who failed to win undergraduate admission to the same university a half-century later. Depending on what the…
Pressure Correction in Density Functional Theory Calculations
Lee, S H
2008-01-01
First-principles calculations based on density functional theory have been widely used in studies of the structural, thermoelastic, rheological, and electronic properties of earth-forming materials. The exchange-correlation term, however, is implemented based on various approximations, and this is believed to be the main reason for discrepancies between experiments and theoretical predictions. In this work, by using periclase MgO as a prototype system we examine the discrepancies in pressure and Kohn-Sham energy that are due to the choice of the exchange-correlation functional. For instance, we choose local density approximation and generalized gradient approximation. We perform extensive first-principles calculations at various temperatures and volumes and find that the exchange-correlation-based discrepancies in Kohn-Sham energy and pressure should be independent of temperature. This implies that the physical quantities, such as the equation of states, heat capacity, and the Gr\\"{u}neisen parameter, estimat...
The role of exchange and correlation in time-dependent density-functional theory for photoionization
Stener, M.; Decleva, P.; Görling, A.
2001-05-01
Atomic photoionization cross sections are calculated by time-dependent density-functional (TDDF) methods using different exchange-correlation potentials including the exact one. The exchange-correlation kernel is treated in the adiabatic local density approximation (ALDA). Results for the exact full and the exact exchange-only Kohn-Sham (KS) potential are very similar, the calculated photo cross section agree very well with experimental data. Thus the exact correlation potential seems to have no influence on photoionization and the ALDA for the exchange-correlation kernel seems to be sufficient for most features of the cross sections. The TDDF method employing the exact exchange-only KS potential in combination with the ALDA exchange-correlation kernel therefore is a promising approach to describe photoionization. Deviations from experiment are observed for the widths and shape of the autoionization resonances and have to be attributed to deficiencies of the ALDA exchange-correlation kernel. The calculation of widths and shapes of autoionization resonances therefore may serve as a severe test for new approximate exchange-correlation density-functionals. The asymptotically exact exchange-correlation potential of van Leeuwen and Baerends also leads to quite good photo cross section, which, however, shows deficiencies close to the ionization threshold and in the energetic position of the autoionization resonances. Supplementation of the exact exchange potential with the LDA correlation potential leads to a worsening of the photo cross section because the LDA correlation potential is too attractive.
Mathematics Admission Test Remarks
Directory of Open Access Journals (Sweden)
Ideon Erge
2016-12-01
Full Text Available Since 2014, there have been admission tests in mathematics for applicants to the Estonian University of Life Sciences for Geodesy, Land Management and Real Estate Planning; Civil Engineering; Hydraulic Engineering and Water Pollution Control; Engineering and Technetronics curricula. According to admission criteria, the test must be taken by students who have not passed the specific mathematics course state exam or when the score was less than 20 points. The admission test may also be taken by those who wish to improve their state exam score. In 2016, there were 126 such applicants of whom 63 took the test. In 2015, the numbers were 129 and 89 and in 2014 150 and 47 accordingly. The test was scored on scale of 100. The arithmetic average of the score was 30.6 points in 2016, 29.03 in 2015 and 18.84 in 2014. The test was considered to be passed with 1 point in 2014 and 20 points in 2015 and 2016. We analyzed test results and gave examples of problems which were solved exceptionally well or not at all.
Multicomponent density functional theory embedding formulation.
Culpitt, Tanner; Brorsen, Kurt R; Pak, Michael V; Hammes-Schiffer, Sharon
2016-07-28
Multicomponent density functional theory (DFT) methods have been developed to treat two types of particles, such as electrons and nuclei, quantum mechanically at the same level. In the nuclear-electronic orbital (NEO) approach, all electrons and select nuclei, typically key protons, are treated quantum mechanically. For multicomponent DFT methods developed within the NEO framework, electron-proton correlation functionals based on explicitly correlated wavefunctions have been designed and used in conjunction with well-established electronic exchange-correlation functionals. Herein a general theory for multicomponent embedded DFT is developed to enable the accurate treatment of larger systems. In the general theory, the total electronic density is separated into two subsystem densities, denoted as regular and special, and different electron-proton correlation functionals are used for these two electronic densities. In the specific implementation, the special electron density is defined in terms of spatially localized Kohn-Sham electronic orbitals, and electron-proton correlation is included only for the special electron density. The electron-proton correlation functional depends on only the special electron density and the proton density, whereas the electronic exchange-correlation functional depends on the total electronic density. This scheme includes the essential electron-proton correlation, which is a relatively local effect, as well as the electronic exchange-correlation for the entire system. This multicomponent DFT-in-DFT embedding theory is applied to the HCN and FHF(-) molecules in conjunction with two different electron-proton correlation functionals and three different electronic exchange-correlation functionals. The results illustrate that this approach provides qualitatively accurate nuclear densities in a computationally tractable manner. The general theory is also easily extended to other types of partitioning schemes for multicomponent systems.
Multicomponent density functional theory embedding formulation
Culpitt, Tanner; Brorsen, Kurt R.; Pak, Michael V.; Hammes-Schiffer, Sharon
2016-07-01
Multicomponent density functional theory (DFT) methods have been developed to treat two types of particles, such as electrons and nuclei, quantum mechanically at the same level. In the nuclear-electronic orbital (NEO) approach, all electrons and select nuclei, typically key protons, are treated quantum mechanically. For multicomponent DFT methods developed within the NEO framework, electron-proton correlation functionals based on explicitly correlated wavefunctions have been designed and used in conjunction with well-established electronic exchange-correlation functionals. Herein a general theory for multicomponent embedded DFT is developed to enable the accurate treatment of larger systems. In the general theory, the total electronic density is separated into two subsystem densities, denoted as regular and special, and different electron-proton correlation functionals are used for these two electronic densities. In the specific implementation, the special electron density is defined in terms of spatially localized Kohn-Sham electronic orbitals, and electron-proton correlation is included only for the special electron density. The electron-proton correlation functional depends on only the special electron density and the proton density, whereas the electronic exchange-correlation functional depends on the total electronic density. This scheme includes the essential electron-proton correlation, which is a relatively local effect, as well as the electronic exchange-correlation for the entire system. This multicomponent DFT-in-DFT embedding theory is applied to the HCN and FHF- molecules in conjunction with two different electron-proton correlation functionals and three different electronic exchange-correlation functionals. The results illustrate that this approach provides qualitatively accurate nuclear densities in a computationally tractable manner. The general theory is also easily extended to other types of partitioning schemes for multicomponent systems.
Communication: Testing and using the Lewin-Lieb bounds in density functional theory
Feinblum, David V.; Kenison, John; Burke, Kieron
2014-12-01
Lewin and Lieb have recently proven several new bounds on the exchange-correlation energy that complement the Lieb-Oxford bound. We test these bounds for atoms, for slowly-varying gases, and for Hooke's atom, finding them usually less strict than the Lieb-Oxford bound. However, we also show that, if a generalized gradient approximation is to guarantee satisfaction of the new bounds for all densities, new restrictions on the exchange-correlation enhancement factor are implied.
Communication: Testing and using the Lewin-Lieb bounds in density functional theory
Energy Technology Data Exchange (ETDEWEB)
Feinblum, David V. [Department of Chemistry, University of California, Irvine, California 92697 (United States); Kenison, John [Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States); Burke, Kieron [Department of Chemistry, University of California, Irvine, California 92697 (United States); Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)
2014-12-28
Lewin and Lieb have recently proven several new bounds on the exchange-correlation energy that complement the Lieb-Oxford bound. We test these bounds for atoms, for slowly-varying gases, and for Hooke’s atom, finding them usually less strict than the Lieb-Oxford bound. However, we also show that, if a generalized gradient approximation is to guarantee satisfaction of the new bounds for all densities, new restrictions on the exchange-correlation enhancement factor are implied.
Testing and Using the Lewin-Lieb Bound in Density Functional Theory
Feinblum, David V; Burke, Kieron
2014-01-01
Lewin and Lieb have recently proven several new bounds on the exchange-correlation energy that complement the Lieb-Oxford bound. We test these bounds for atoms, for slowly-varying gases, and for Hooke's atom, finding them usually (but not always) less strict than the Lieb-Oxford bound. However, we also show that, if a GGA is to guarantee satisfaction of the new bounds for all densities, new restrictions on the the exchange-correlation enhancement factor are implied.
Optimal admission to higher education
DEFF Research Database (Denmark)
Albæk, Karsten
2016-01-01
that documents the relevance of theory and illustrates how to apply optimal admission procedures. Indirect gains from optimal admission procedures include the potential for increasing entire cohorts of students' probability of graduating with a higher education degree, thereby increasing the skill level...
Optimal admission to higher education
DEFF Research Database (Denmark)
Albæk, Karsten
2016-01-01
that documents the relevance of theory and illustrates how to apply optimal admission procedures. Indirect gains from optimal admission procedures include the potential for increasing entire cohorts of students' probability of graduating with a higher education degree, thereby increasing the skill level...
Optimal Admission to Higher Education
Albaek, Karsten
2017-01-01
This paper analyses admission decisions when students from different high school tracks apply for admission to university programmes. I derive a criterion that is optimal in the sense that it maximizes the graduation rates of the university programmes. The paper contains an empirical analysis that documents the relevance of theory and illustrates…
Development of New Density Functional Approximations
Su, Neil Qiang; Xu, Xin
2017-05-01
Kohn-Sham density functional theory has become the leading electronic structure method for atoms, molecules, and extended systems. It is in principle exact, but any practical application must rely on density functional approximations (DFAs) for the exchange-correlation energy. Here we emphasize four aspects of the subject: (a) philosophies and strategies for developing DFAs; (b) classification of DFAs; (c) major sources of error in existing DFAs; and (d) some recent developments and future directions.
Santra, Biswajit; Michaelides, Angelos; Fuchs, Martin; Tkatchenko, Alexandre; Filippi, Claudia; Scheffler, Matthias
2008-01-01
Second order Møller–Plesset perturbation theory at the complete basis set limit and diffusion quantum Monte Carlo are used to examine several low energy isomers of the water hexamer. Both approaches predict the so-called prism to be the lowest energy isomer, followed by cage, book, and cyclic isomer
Energy Technology Data Exchange (ETDEWEB)
Gritsenko, O.V.; Schipper, P.R.T.; Baerends, E.J.
2000-01-20
The long-range asymptotic behavior of the exchange-correlation Kohn-Sham (KS) potential {nu}{sub xc} and its relation to the exchange-correlation energy E{sub xc} are considered using various approaches. The line integral of {nu}{sub xc}([{rho}];r) yielding the exchange-correlation part {Delta}E{sub xc} of a relative energy {Delta}E of a finite system, shows that a uniform constant shift of {nu}{sub xc} never shows up in any physically meaningful energy difference {Delta}E. {nu}{sub xv} may thus be freely chosen to tend asymptotically to zero or to some nonzero constant. Possible choices of the asymptotics of the potential are discussed with reference to the theory of open systems with a fractional number of electrons. The authors adhere to the conventional choice {nu}{sub xc}({infinity}) = 0 for the asymptotics of the potential leading to {epsilon}{sub N} = {minus}I{sub p} for the energy {epsilon}{sub N} of the highest occupied orbital. A statistical average of orbital dependent model potentials is proposed as a way to model {nu}{sub xc}. An approximate potential {nu}{sub xco}{sup SAOP} with exact {minus}1/r asymptotics is developed using the statistical average of, on the one hand, a model potential {nu}{sub xc{sigma}}{sup Ei} for the highest occupied KS orbital {psi}{sub N{sigma}} and, on the other hand, a model potential {nu}{sub xc}{sup GLB} for other occupied orbitals. It is demonstrated for the well-studied case of the Ne atom, that calculations with the new model potential can, in principle, reproduce perfectly all energy characteristics.
Admissibility of logical inference rules
Rybakov, VV
1997-01-01
The aim of this book is to present the fundamental theoretical results concerning inference rules in deductive formal systems. Primary attention is focused on: admissible or permissible inference rules the derivability of the admissible inference rules the structural completeness of logics the bases for admissible and valid inference rules. There is particular emphasis on propositional non-standard logics (primary, superintuitionistic and modal logics) but general logical consequence relations and classical first-order theories are also considered. The book is basically self-contained and
General Practitioners and Involuntary Admission
DEFF Research Database (Denmark)
Jepsen, Britta; Lomborg, Kirsten; Engberg, Marianne
2010-01-01
in involuntary admissions. Setting: General practice, Aarhus, Denmark. Method: One focus group interview and six individual interviews were conducted with 13 Danish GPs, who had recently sectioned one of their own patients. Results: GPs experienced stress and found the admission procedure time consuming....... They felt that sectioning patients was unpleasant, and felt nervous, but experienced relief and professional satisfaction if things went well. The GPs experienced the doctor-patient relationship to be at risk, but also reported that it could be improved. GPs felt that they were not taken seriously...... by the psychiatric system. Conclusion: The unpleasant experiences and induced feelings resulting from involuntary admissions reflect an undesirable and stressful working environment....
Integer Discontinuity of Density Functional Theory
Mosquera, Martin A
2014-01-01
Density functional approximations to the exchange-correlation energy of Kohn-Sham theory, such as the local density approximation and generalized gradient approximations, lack the well-known integer discontinuity, a feature that is critical to describe molecular dissociation correctly. Moreover, standard approximations to the exchange-correlation energy also fail to yield the correct linear dependence of the ground-state energy on the number of electrons when this is a non-integer number obtained from the grand canonical ensemble statistics. We present a formal framework to restore the integer discontinuity of any density functional approximation. Our formalism derives from a formula for the exact energy functional and a new constrained search functional that recovers the linear dependence of the energy on the number of electrons.
Asymptotic admissibility of priors and elliptic differential equations
Hartigan, J A
2010-01-01
We evaluate priors by the second order asymptotic behavior of the corresponding estimators.Under certain regularity conditions, the risk differences between efficient estimators of parameters taking values in a domain D, an open connected subset of R^d, are asymptotically expressed as elliptic differential forms depending on the asymptotic covariance matrix V. Each efficient estimator has the same asymptotic risk as a 'local Bayes' estimate corresponding to a prior density p. The asymptotic decision theory of the estimators identifies the smooth prior densities as admissible or inadmissible, according to the existence of solutions to certain elliptic differential equations. The prior p is admissible if the quantity pV is sufficiently small near the boundary of D. We exhibit the unique admissible invariant prior for V=I,D=R^d-{0). A detailed example is given for a normal mixture model.
Non-uniqueness of Admissible Weak Solutions to Compressible Euler Systems with Source Terms
Luo, Tianwen; Xie, Chunjing; Xin, Zhouping
2015-01-01
We consider admissible weak solutions to the compressible Euler system with source terms, which include rotating shallow water system and the Euler system with damping as special examples. In the case of anti-symmetric sources such as rotations, for general piecewise Lipschitz initial densities and some suitably constructed initial momentum, we obtain infinitely many global admissible weak solutions. Furthermore, we construct a class of finite-states admissible weak solutions to the Euler sys...
The admission index in the dental school admissions process.
Staat, R H; Yancey, J M
1982-08-01
Preprofessional students' grade point averages (GPAs) and aptitude test scores have been moderately successful in predicting student performance in dental school. The authors attempted to improve the predictability of the school's admission process by combining several preprofessional academic averages and selected nongraded personal attributes into a single Admission Index (AI) score. A Pearson r of 0.67 was found for the relationship between the AI and first-year dental school GPA for University of Louisville dental students accepted into the class of 1984. The correlation coefficient generated from the AI and first-year dental school GPA was markedly superior to those generated by any single predictor. The authors propose that the AI is of value not only for its use in the admission process, but also in the development of an interceptive student monitoring program for the less-qualified student.
Orbital-Free Density Functional Theory for Molecular Structure Calculations
Institute of Scientific and Technical Information of China (English)
Huajie Chen; Aihui Zhou
2008-01-01
We give here an overview of the orbital-free density functional theory that is used for modeling atoms and molecules. We review typical approximations to the kinetic energy, exchange-correlation corrections to the kinetic and Hartree energies, and constructions of the pseudopotentials. We discuss numerical discretizations for the orbital-free methods and include several numerical results for illustrations.
Exact ensemble density-functional theory for excited states
Yang, Zeng-hui; Pribram-Jones, Aurora; Burke, Kieron; Needs, Richard J; Ullrich, Carsten A
2014-01-01
We construct exact Kohn-Sham potentials for the ensemble density-functional theory (EDFT) of excited states from the ground and excited states of helium. The exchange-correlation potential is compared with current approximations, which miss prominent features. The ensemble derivative discontinuity is tested, and the virial theorem is proven and illustrated.
Probabilistic Anonymity and Admissible Schedulers
Garcia, Flavio D; Sokolova, Ana
2007-01-01
When studying safety properties of (formal) protocol models, it is customary to view the scheduler as an adversary: an entity trying to falsify the safety property. We show that in the context of security protocols, and in particular of anonymizing protocols, this gives the adversary too much power; for instance, the contents of encrypted messages and internal computations by the parties should be considered invisible to the adversary. We restrict the class of schedulers to a class of admissible schedulers which better model adversarial behaviour. These admissible schedulers base their decision solely on the past behaviour of the system that is visible to the adversary. Using this, we propose a definition of anonymity: for all admissible schedulers the identity of the users and the observations of the adversary are independent stochastic variables. We also develop a proof technique for typical cases that can be used to proof anonymity: a system is anonymous if it is possible to `exchange' the behaviour of two...
Optimal Admission to Higher Education
DEFF Research Database (Denmark)
Albæk, Karsten
This paper constructs higher education admission rules that maximise graduation rates and thus increase the skill level of the work force. An application shows that students with a low level in mathematics in secondary school ought to find it easier to be admitted to an economics programme than...... to law or psychology programmes, even though economics is the most difficult programme from which to graduate without a strong background in mathematics. Indirect gains from optimal admission include the potential of making whole cohorts of students more able to graduate with a higher education degree....
Degenerate Density Perturbation Theory
Palenik, Mark C
2016-01-01
Fractional occupation numbers can be used in density functional theory to create a symmetric Kohn-Sham potential, resulting in orbitals with degenerate eigenvalues. We develop the corresponding perturbation theory and apply it to a system of $N_d$ degenerate electrons in a harmonic oscillator potential. The order-by-order expansions of both the fractional occupation numbers and unitary transformations within the degenerate subspace are determined by the requirement that a differentiable map exists connecting the initial and perturbed states. Using the X$\\alpha$ exchange-correlation (XC) functional, we find an analytic solution for the first-order density and first through third-order energies as a function of $\\alpha$, with and without a self-interaction correction. The fact that the XC Hessian is not positive definite plays an important role in the behavior of the occupation numbers.
Degenerate density perturbation theory
Palenik, Mark C.; Dunlap, Brett I.
2016-09-01
Fractional occupation numbers can be used in density functional theory to create a symmetric Kohn-Sham potential, resulting in orbitals with degenerate eigenvalues. We develop the corresponding perturbation theory and apply it to a system of Nd degenerate electrons in a harmonic oscillator potential. The order-by-order expansions of both the fractional occupation numbers and unitary transformations within the degenerate subspace are determined by the requirement that a differentiable map exists connecting the initial and perturbed states. Using the X α exchange-correlation (XC) functional, we find an analytic solution for the first-order density and first- through third-order energies as a function of α , with and without a self-interaction correction. The fact that the XC Hessian is not positive definite plays an important role in the behavior of the occupation numbers.
Kumar, Sant; Yadav, Umesh K.; Maitra, T.; Singh, Ishwar
2016-02-01
Ground state magnetic properties of the spin-dependent Falicov-Kimball model (FKM) are studied by incorporating the intrasite exchange correlation J (between itinerant d- and localized f-electrons) and intersite (superexchange) correlation Jse (between localized f-electrons) on a triangular lattice for two different fillings. Numerical diagonalization and Monte-Carlo techniques are used to determine the ground state magnetic properties. Transitions from antiferromagnetic to ferromagnetic and again to re-entrant antiferromagnetic phase is observed in a wide range of parameter space. The magnetic moments of d- and f-electrons are observed to depend strongly on the value of J, Jse and also on the total number of d-electrons (Nd).
Xu, Shengxian; Wang, Jinglan; Xia, Hongying; Zhao, Feng; Wang, Yibo
2015-02-01
The accurate prediction for the emission energies of the phosphorescent Ir (III) complexes is very useful for the realizing of full-color displays and large-area solid-state lighting in OLED fields. Quantum chemistry calculations based on TDDFT methods are most widely used to directly compute the triplet vertical excitation energies, yet sometimes the universality of these calculations can be limited because of the lack of experimental data for the relative family of structural analogues. In this letter, 16 literature emission energies at low temperature are linearly correlated with their theoretical values computed by TDDFT using exchange-correlation functionals containing various HF exchange percentage with the relation of E exp (em) = 1.2Ē calc (em). The relation is proven to be robust across a wide range of structures for Ir (III) complexes. These theoretical studies should be expected to provide some guides for the design and synthesis of efficient emitting materials.
Admissions Plan Goes beyond Numbers
Hoover, Eric
2007-01-01
Northeastern University's Torch Scholars Program is designed to seek out first-generation students who would not qualify under the university's regular admissions process. The scholarships go to motivated students who have shown determination in overcoming personal challenges. Northeastern believes the experiment will enhance the socioeconomic…
College Admissions: Beyond Conventional Testing
Sternberg, Robert J.
2012-01-01
Standardized admissions tests such as the SAT (originally stood for "Scholastic Aptitude Test") and the ACT measure only a narrow segment of the skills needed to become an active citizen and possibly a leader who makes a positive, meaningful, and enduring difference to the world. The problem with these tests is that they promised, under…
Optimal Admission to Higher Education
DEFF Research Database (Denmark)
Albæk, Karsten
to law or psychology programmes, even though economics is the most difficult programme from which to graduate without a strong background in mathematics. Indirect gains from optimal admission include the potential of making whole cohorts of students more able to graduate with a higher education degree....
Local density approximations from finite systems
Entwistle, Mike; Wetherell, Jack; Longstaff, Bradley; Ramsden, James; Godby, Rex
2016-01-01
The local density approximation (LDA) constructed through quantum Monte Carlo calculations of the homogeneous electron gas (HEG) is the most common approximation to the exchange-correlation functional in density functional theory. We introduce an alternative set of LDAs constructed from slab-like systems of one, two and three electrons that resemble the HEG within a finite region, and illustrate the concept in one dimension. Comparing with the exact densities and Kohn-Sham potentials for various test systems, we find that the LDAs give a good account of the self-interaction correction, but are less reliable when correlation is stronger or currents flow.
Tran, Fabien; Blaha, Peter
2017-05-04
Recently, exchange-correlation potentials in density functional theory were developed with the goal of providing improved band gaps in solids. Among them, the semilocal potentials are particularly interesting for large systems since they lead to calculations that are much faster than with hybrid functionals or methods like GW. We present an exhaustive comparison of semilocal exchange-correlation potentials for band gap calculations on a large test set of solids, and particular attention is paid to the potential HLE16 proposed by Verma and Truhlar. It is shown that the most accurate potential is the modified Becke-Johnson potential, which, most noticeably, is much more accurate than all other semilocal potentials for strongly correlated systems. This can be attributed to its additional dependence on the kinetic energy density. It is also shown that the modified Becke-Johnson potential is at least as accurate as the hybrid functionals and more reliable for solids with large band gaps.
Vikas, Hash(0x125f4490)
2011-02-01
Evolution of the helium atom in a strong time-dependent (TD) magnetic field ( B) of strength up to 1011 G is investigated through a quantum fluid dynamics (QFD) based current-density functional theory (CDFT). The TD-QFD-CDFT computations are performed through numerical solution of a single generalized nonlinear Schrödinger equation employing vector exchange-correlation potentials and scalar exchange-correlation density functionals that depend both on the electronic charge-density and the current-density. The results are compared with that obtained from a B-TD-QFD-DFT approach (based on conventional TD-DFT) under similar numerical constraints but employing only scalar exchange-correlation potential dependent on electronic charge-density only. The B-TD-QFD-DFT approach, at a particular TD magnetic field-strength, yields electronic charge- and current-densities as well as exchange-correlation potential resembling with that obtained from the time-independent studies involving static (time-independent) magnetic fields. However, TD-QFD-CDFT electronic charge- and current-densities along with the exchange-correlation potential and energy differ significantly from that obtained using B-TD-QFD-DFT approach, particularly at field-strengths >109 G, representing dynamical effects of a TD field. The work concludes that when a helium atom is subjected to a strong TD magnetic field of order >109 G, the conventional TD-DFT based approach differs "dynamically" from the CDFT based approach under similar computational constraints.
Toward a Sociology of Law School Admissions.
Erlanger, Howard S.
1984-01-01
The law school admission process plays a major role in determining the social class origins and ethnic composition of the bar, and perhaps also the nonlegal skills lawyers will have. Research is incomplete; consideration of admission criteria, the composition and processes of admissions committees, and applicant self-selection is advisable. (MSE)
Why Do Students Repeat Admissions Tests?
Jones, Martha S.
Attitudes and beliefs about the admissions process, especially the role of standardized testing in admissions, were examined for students who took a standardized admissions test more than once. Their attitudes were compared with those of students who did not repeat the test. About 200 preveterinary students who had taken the Veterinary Aptitude…
Seasonal variations in hospital admissions for mania
DEFF Research Database (Denmark)
Medici, Clara Reece; Vestergaard, Claus Høstrup; Hadzi-Pavlovic, Dusan;
2016-01-01
Central Research Register. The Danish Meteorological Institute provided the meteorological variables. The association between weather and admissions was tested using linear regression. RESULTS: Our database comprised 24,313 admissions with mania. There was a seasonal pattern with admission rates peaking...
Admissibility of Linear Systems in Banach Spaces
Institute of Scientific and Technical Information of China (English)
GUO Fa-ming
2005-01-01
In this paper, infinite-time p-admissibility of unbounded operators is introduced and the Co-semigroup characterization of the infinite-time p-admissibility of unbounded observation operators is given. Moreover, the analogous result for the infinite-time p-admissibility of unbounded control operators is presented.
The benchmark of gutzwiller density functional theory in hydrogen systems
Energy Technology Data Exchange (ETDEWEB)
Yao, Y.; Wang, Cai-Zhuang; Ho, Kai-Ming
2012-02-23
We propose an approximate form of the exchange-correlation energy functional for the Gutzwiller density functional theory. It satisfies certain physical constraints in both weak and strong electron correlation limits. We benchmark the Gutzwiller density functional approximation in the hydrogen systems, where the static correlation error is shown to be negligible. The good transferability is demonstrated by applications to the hydrogen molecule and some crystal structures.
The Benchmark of Gutzwiller Density Functional Theory in Hydrogen Systems
Energy Technology Data Exchange (ETDEWEB)
Yao, Yongxin; Wang, Cai-Zhuang; Ho, Kai-Ming
2011-01-13
We propose an approximate form of the exchange-correlation energy functional for the Gutzwiller density functional theory. It satisfies certain physical constraints in both weak and strong electron correlation limits. We benchmark the Gutzwiller density functional approximation in the hydrogen systems, where the static correlation error is shown to be negligible. The good transferability is demonstrated by applications to the hydrogen molecule and some crystal structures. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012
Gedanken Densities and Exact Constraints in Density Functional Theory
Perdew, John P; Sun, Jianwei; Burke, Kieron
2014-01-01
Approximations to the exact density functional for the exchange-correlation energy of a many-electron ground state can be constructed by satisfying constraints that are universal, i.e., valid for all electron densities. Gedanken densities are designed for the purpose of this construction, but need not be realistic. The uniform electron gas is an old gedanken density. Here, we propose a spherical two-electron gedanken density in which the dimensionless density gradient can be an arbitrary positive constant wherever the density is non-zero. The Lieb-Oxford lower bound on the exchange energy can be satisfied within a generalized gradient approximation (GGA) by bounding its enhancement factor or simplest GGA exchange-energy density. This enhancement-factor bound is well known to be sufficient, but our gedanken density shows that it is also necessary. The conventional exact exchange-energy density satisfies no such local bound, but energy densities are not unique, and the simplest GGA exchange-energy density is no...
Raman signatures of strong Kitaev exchange correlations in (Na1-xLix)2IrO3: Experiments and theory
Nath Gupta, Satyendra; Sriluckshmy, P. V.; Mehlawat, Kavita; Balodhi, Ashiwini; Mishra, Dileep K.; Hassan, S. R.; Ramakrishnan, T. V.; Muthu, D. V. S.; Singh, Yogesh; Sood, A. K.
2016-05-01
Inelastic light scattering studies on single crystals of (Na1-x Li x )2IrO3 (x = 0, 0.05 and 0.15) show a polarization-independent broad band at ˜ 2750 cm-1 with a large band-width ˜ 1800 \\text{cm}-1 . For Na2IrO3 the broad band is seen for temperatures ≤ 200 \\text{K} and persists inside the magnetically ordered state. For Li samples, the intensity of this mode increases, shifts to lower wave numbers, and persists to higher temperatures. Such a mode has recently been predicted (by Knolle et al.) as a signature of the Kitaev spin liquid. We assign the observation of the broad band to be a signature of strong Kitaev exchange correlations. The fact that the broad band persists even inside the magnetically ordered state suggests that dynamically fluctuating moments survive even below T N . This is further supported by our mean-field calculations. The Raman response calculated in mean-field theory shows that the broad band predicted for the SL state survives in the magnetically ordered state near the zigzag-spin liquid phase boundary. A comparison with the theoretical model gives an estimate of the Kitaev exchange interaction parameter to be J_K≈ 57 \\text{meV} .
Beck, Andrew F; Moncrief, Terri; Huang, Bin; Simmons, Jeffrey M; Sauers, Hadley; Chen, Chen; Kahn, Robert S
2013-08-01
To characterize variation and inequalities in neighborhood child asthma admission rates and to identify associated community factors within one US county. This population-based prospective, observational cohort study consisted of 862 sequential child asthma admissions among 167 653 eligible children ages 1-16 years in Hamilton County, Ohio. Admissions occurred at a tertiary-care pediatric hospital and accounted for nearly 95% of in-county asthma admissions. Neighborhood admission rates were assessed by geocoding addresses to city- and county-defined neighborhoods. The 2010 US Census provided denominator data. Neighborhood admission distribution inequality was assessed by the use of Gini and Robin Hood indices. Associations between neighborhood rates and socioeconomic and environmental factors were assessed using ANOVA and linear regression. The county admission rate was 5.1 per 1000 children. Neighborhood rates varied significantly by quintile: 17.6, 7.7, 4.9, 2.2, and 0.2 admissions per 1000 children (P Robin Hood index of 0.38 indicated significant inequality. Neighborhood-level educational attainment, car access, and population density best explained variation in neighborhood admission rates (R(2) = 0.55). In a single year, asthma admission rates varied 88-fold across neighborhood quintiles in one county; a reduction of the county-wide admission rate to that of the bottom quintile would decrease annual admissions from 862 to 34. A rate of zero was present in 15 neighborhoods, which is evidence of what may be attainable. Copyright © 2013 Mosby, Inc. All rights reserved.
Patient Admission Preferences and Perceptions
Wu, Clayton; Melnikow, Joy; Dinh, Tu; Holmes, James F.; Gaona, Samuel D.; Bottyan, Thomas; Paterniti, Debora; Nishijima, Daniel K.
2015-01-01
Introduction Understanding patient perceptions and preferences of hospital care is important to improve patients’ hospitalization experiences and satisfaction. The objective of this study was to investigate patient preferences and perceptions of hospital care, specifically differences between intensive care unit (ICU) and hospital floor admissions. Methods This was a cross-sectional survey of emergency department (ED) patients who were presented with a hypothetical scenario of a patient with mild traumatic brain injury (TBI). We surveyed their preferences and perceptions of hospital care related to this scenario. A closed-ended questionnaire provided quantitative data on patient preferences and perceptions of hospital care and an open-ended questionnaire evaluated factors that may not have been captured with the closed-ended questionnaire. Results Out of 302 study patients, the ability for family and friends to visit (83%), nurse availability (80%), and physician availability (79%) were the factors most commonly rated “very important,” while the cost of hospitalization (62%) and length of hospitalization (59%) were the factors least commonly rated “very important.” When asked to choose between the ICU and the floor if they were the patient in the scenario, 33 patients (10.9%) choose the ICU, 133 chose the floor (44.0%), and 136 (45.0%) had no preference. Conclusion Based on a hypothetical scenario of mild TBI, the majority of patients preferred admission to the floor or had no preference compared to admission to the ICU. Humanistic factors such as the availability of doctors and nurses and the ability to interact with family appear to have a greater priority than systematic factors of hospitalization, such as length and cost of hospitalization or length of time in the ED waiting for an in-patient bed. PMID:26587095
Admission Criteria for MBA Programs
Directory of Open Access Journals (Sweden)
Silvana Dakduk
2016-11-01
Full Text Available This paper reports a review of studies on admission criteria for MBA programs. The method consisted in a literary review based on a systematic search in international databases (Emerald, ABI/INFORM Global, ProQuest Education Journals, ProQuest European Business, ProQuest Science Journal, ProQuest Research Library, ProQuest Psychology Journals, ProQuest Social Science Journals and Business Source Complete of studies published from January 1990 to December 2013, which explore the academic performance of students or graduates of MBA programs. A quantitative review was performed. Results show that most researchers studied relations between GMAT (Graduate Management Admission Test and UGPA (Undergraduate Grade Point Average as predictors of GGPA (Graduate Grade Point Average. On the other hand, work experience and personal traits (such as personality, motivation, learning strategies, self-efficacy beliefs and achievement expectations and their relation with GGPA had been less studied, and results are not consistent enough to consider them valid predictors of student performance at this time.
Density functional calculations of nanoscale conductance
Energy Technology Data Exchange (ETDEWEB)
Koentopp, Max; Chang, Connie [Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854 (United States); Burke, Kieron [Department of Chemistry, UC Irvine, 1102 Natural Sciences 2, Irvine, CA 92697 (United States); Car, Roberto [Department of Chemistry and Princeton Institute for the Science and Technology of Materials (PRISM), Princeton University, Princeton, NJ 08544 (United States)
2008-02-27
Density functional calculations for the electronic conductance of single molecules are now common. We examine the methodology from a rigorous point of view, discussing where it can be expected to work, and where it should fail. When molecules are weakly coupled to leads, local and gradient-corrected approximations fail, as the Kohn-Sham levels are misaligned. In the weak bias regime, exchange-correlation corrections to the current are missed by the standard methodology. For finite bias, a new methodology for performing calculations can be rigorously derived using an extension of time-dependent current density functional theory from the Schroedinger equation to a master equation. (topical review)
The Keldysh formalism applied to time-dependent current-density-functional theory
Gidopoulos, NI; Wilson, S
2003-01-01
In this work we demonstrate how to derive the Kohn-Sham equations of time-dependent current-density functional theory from a generating action functional defined on a Keldysh time contour. These Kohn-Sham equations contain an exchange-correlation contribution to the vector potential. For this
DEFF Research Database (Denmark)
Makransky, Guido; Havmose, Philip; Vang, Maria Louison;
2016-01-01
to the grade-based admissions procedure. Finally, students admitted through the MMI scored significantly higher on academic learning self-efficacy and critical thinking compared to students selected by grades. The implications for higher education admissions are discussed....
Institute of Scientific and Technical Information of China (English)
孙宇姣; 姜大明; 张波; 高远; 李玉泽; 于海杰; 齐国先
2012-01-01
目的 分析急性ST段抬高心肌梗死(ASTEMI)患者入院时高密度脂蛋白胆固醇(HDL-C)水平对随访一年主要心血管不良事件(MACCE)的影响.方法 选取2009年5月至2010年5月辽宁省20家医院1067例症状发作24h内入院并进行血脂检测的ASTEMI患者.观察基线情况、住院时症状、诊断、治疗及检查结果.随访1、6个月和1年的药物使用及MACCE(心源性死亡、非致死性心肌梗死、脑卒中及再次血运重建).采用Cox比例风险模型分析影响MACCE的独立危险因素.结果 根据患者入院时HDL-C水平均值,分为＜1.27 mmol/L组587例(低组)和≥1.27 mmol/L组489例(高组).随访1、6个月及1年时低组非致死性心肌梗死发生率显著高于高组(分别为1.4％vs.0.0％,P=0.01；2.8％vs.0.4％,P=0.003; 4.8％vs.0.9％,P＜0.001),随访6个月及1年时低组MACCE发生率显著高于高组(分别为18.3％vs.13.7％,P=0.04; 23.7％vs.18.1％,P=0.03).年龄(HR=1.02,95％CI:1.006～1.035,P=0.005)、糖尿病(HR=1.05,95％CI:1.053～2.171,P=0.03)、HDL-C水平(HR=0.56,95％CI:0.340 ～ 0.921,P=0.02)是ASTEMI患者1年后发生MACCE的独立危险因素.结论 入院时HDL-C水平高的ASTEMI患者随访1年和6个月时的MACCE(主要是非致死性心肌梗死)及1个月时的非致死性心肌梗死发生率显著低于HDL-C水平低的患者,并随时间延长其差异越明显.年龄、糖尿病及HDL-C水平是MACCE的独立危险因素.%Objective To analyze the impact of high-density lipoprotein cholesterol (HDL-C) levels at hospital admission on the incidence of major adverse cardiovascular events (MACCE) in patients with acute ST segment elevation myocardial infarction (ASTEMI).Methods 1067 patients with ASTEMI who were admitted to the 20 hospitals in Liaoning region and with lipid profile tested within the 24 hours of admission from May 2009 until May 2010,were enrolled.Data on basic demographic,clinical,status on admission and method of treatment were
Semilocal density functional theory with correct surface asymptotics
Constantin, Lucian A.; Fabiano, Eduardo; Pitarke, J. M.; Della Sala, Fabio
2016-03-01
Semilocal density functional theory is the most used computational method for electronic structure calculations in theoretical solid-state physics and quantum chemistry of large systems, providing good accuracy with a very attractive computational cost. Nevertheless, because of the nonlocality of the exchange-correlation hole outside a metal surface, it was always considered inappropriate to describe the correct surface asymptotics. Here, we derive, within the semilocal density functional theory formalism, an exact condition for the imagelike surface asymptotics of both the exchange-correlation energy per particle and potential. We show that this condition can be easily incorporated into a practical computational tool, at the simple meta-generalized-gradient approximation level of theory. Using this tool, we also show that the Airy-gas model exhibits asymptotic properties that are closely related to those at metal surfaces. This result highlights the relevance of the linear effective potential model to the metal surface asymptotics.
Unethical Admissions: Academic Integrity in Question.
Ansah, Richard Hannis; Aikhuele, Daniel O; Yao, Liu
2016-11-28
The increasing unethical practices of graduates' admissions have heightened concerns about the integrity of the academy. This article informs this important subject that affects the students, admission systems, and the entire scientific community, thus, representing an approach against scholarly black market activities including falsified documents and unethical practices by consultants and students' recruitment agencies.
The ageing society and emergency hospital admissions.
Wittenberg, Raphael; Sharpin, Luke; McCormick, Barry; Hurst, Jeremy
2017-08-01
There is strong policy interest, in England as elsewhere, in slowing the growth in emergency hospital admissions, which for older people increased by 3.3% annually between 2001/2 and 2012/3. Resource constrains have increased the importance of understanding rising emergency admissions, which in policy discourse is often explained by population aging. This study examines how far the rise in emergency admissions of people over 65 was due to population ageing, how far to the changing likelihood of entering hospital at each age, and how far to other factors which might be more amenable to policy measures. It shows that: admission rates rose with age from age 40 upward but each successive birth cohort experienced lower emergency admission rates after standardising for age and other effects. This downward cohort effect largely offset the consequences of an older and larger population aged over 65. Other factors which could explain increasing admissions, such as new technologies or rising expectations, appear more important than the changing size and age structure of the population as drivers of rising emergency admissions in old age. These findings suggest that stemming the rate of increase in emergency admissions of older people may be feasible, if challenging, despite population ageing. Copyright © 2017 Elsevier B.V. All rights reserved.
Parental Involvement in Admissions and Financial Aid.
Lange, Douglas K.; Stone, Michael E.
2001-01-01
Admissions and financial aid offices are the initial point of interaction for many parents of college students. Highlights several recent trends in higher education, including the expanding use of technology and a growing consumerism, and how these forces reshape the work of admissions and financial aid professionals. (Contains 21 references.)…
Admission to Law School: New Measures
Shultz, Marjorie M.; Zedeck, Sheldon
2012-01-01
Standardized tests have been increasingly controversial over recent years in high-stakes admission decisions. Their role in operationalizing definitions of merit and qualification is especially contested, but in law schools this challenge has become particularly intense. Law schools have relied on the Law School Admission Test (LSAT) and an INDEX…
A Logical Characterization of Iterated Admissibility
Halpern, Joseph Y
2009-01-01
Brandenburger, Friedenberg, and Keisler provide an epistemic characterization of iterated admissibility (i.e., iterated deletion of weakly dominated strategies) where uncertainty is represented using LPSs (lexicographic probability sequences). Their characterization holds in a rich structure called a complete structure, where all types are possible. Here, a logical charaacterization of iterated admisibility is given that involves only standard probability and holds in all structures, not just complete structures. A stronger notion of strong admissibility is then defined. Roughly speaking, strong admissibility is meant to capture the intuition that "all the agent knows" is that the other agents satisfy the appropriate rationality assumptions. Strong admissibility makes it possible to relate admissibility, canonical structures (as typically considered in completeness proofs in modal logic), complete structures, and the notion of ``all I know''.
Semilocal exchange hole with an application to range-separation density functional
Tao, Jianmin; Scuseria, Gustavo E
2016-01-01
Exchange-correlation hole is a central concept in density functional theory. It not only provides justification for an exchange-correlation energy functional, but also serves as a local ingredient in nonlocal range-separation density functional. However, due to the nonlocal nature, modelig the conventional exact exchange hole presents a great challenge to density functional theory. In this work, we propose a semilocal exchange hole underlying the Tao-Perdew-Staroverov-Scuseria (TPSS) meta-GGA functional. The present model is distinct from previous models at small separation between an electron and the hole around the electron. It is also different in the way it interpolates between the rapidly varying iso-orbital density and the slowly varying density, which is determined by the wave vector analysis based on the exactly solvable infinite barrier model for jellium surface. Our numerical tests show that the exchange hole generated from this model mimics the conventional exact exchange hole quite well for atoms....
Brorsen, Kurt R; Yang, Yang; Pak, Michael V; Hammes-Schiffer, Sharon
2017-05-04
The development of approximate exchange-correlation functionals is critical for modern density functional theory. A recent analysis of atomic systems suggested that some modern functionals are straying from the path toward the exact functional because electron densities are becoming less accurate while energies are becoming more accurate since the year 2000. To investigate this trend for more chemically relevant systems, the electron densities in the bonding regions and the atomization energies are analyzed for a series of diatomic molecules with 90 different functionals. For hybrid generalized gradient approximation functionals developed since the year 2000, the errors in densities and atomization energies are decoupled; the accuracy of the energies remains relatively consistent while the accuracy of the densities varies significantly. Such decoupling is not observed for generalized gradient and meta-generalized gradient approximation functionals. Analysis of electron densities in bonding regions is found to be important for the evaluation of functionals for chemical systems.
Inappropriate hospital admissions: patient participation in research.
Glasby, J; Littlechild, R
Although political interest in reducing the number of inappropriate hospital admissions is mounting, methods for researching the rate of inappropriate admissions have several major limitations. Whereas traditional studies have tended to be predominantly subjective, more recent studies using clinical review instruments also have a number of limitations. Chief among these is the failure to consider the potential input of the individual patient. To illustrate some of the possible benefits of patient participation, this article cites findings from a study in Birmingham, which sought to involve individual older people in a research study into emergency hospital admissions.
Every seventh acute medical admission is preventable
DEFF Research Database (Denmark)
Jepsen, Henrik Koldborg; Hendriksen, Carsten; Nielsen, Henrik;
2013-01-01
The majority of patients who are admitted to the departments of internal medicine are admitted acutely. The aim of this study was to evaluate the appropriateness of admissions to a community hospital in Copenhagen....
The Parent Role in College Admission.
Krugman, Mary K.
1990-01-01
Discusses techniques secondary school counselors can use to help parents understand and negotiate the college admissions process, including encouraging parental self-assessment; assisting parents to assess student; giving parents special tips; and maintaining open and ethical communication. (ABL)
Test-Based Admission to Selective Universities:
DEFF Research Database (Denmark)
Thomsen, Jens-Peter
2016-01-01
not favour first-generation students; further, the system serves as an access route for low-achieving children from the privileged professional classes. Drawing mainly on theories in the social closure tradition, I argue that children with highly educated parents will be favoured when qualitative merits......This article examines whether the existence of a secondary higher education admission system honouring more qualitative and extra-curricular merits has reduced the social class gap in access to highly sought-after university programmes in Denmark. I use administrative data to examine differences...... in the social gradient in the primary admission system, admitting students on the basis of their high school grade point average, and in the secondary admission system, admitting university students based on more qualitative assessments. I find that the secondary higher education admission system does...
Admissible Strategies in Semimartingale Portfolio Selection
Biagini, Sara
2009-01-01
The choice of admissible trading strategies in mathematical modelling of financial markets is a delicate issue, going back to Harrison and Kreps (1979). In the context of optimal portfolio selection with expected utility preferences this question has been a focus of considerable attention over the last twenty years. We propose a novel notion of admissibility that has many pleasant features -- admissibility is characterized purely under the objective measure $P$; the wealth of any admissible strategy is a supermartingale under all pricing measures; local boundedness of the price process is not required; neither strict monotonicity, strict concavity nor differentiability of the utility function are necessary; the definition encompasses both the classical mean-variance preferences and the monotone expected utility. For utility functions finite on the real line, our class represents a minimal set containing simple strategies which also contains the optimizer, under conditions that are substantially milder than th...
Call Admission Control in Mobile Cellular Networks
Ghosh, Sanchita
2013-01-01
Call Admission Control (CAC) and Dynamic Channel Assignments (DCA) are important decision-making problems in mobile cellular communication systems. Current research in mobile communication considers them as two independent problems, although the former greatly depends on the resulting free channels obtained as the outcome of the latter. This book provides a solution to the CAC problem, considering DCA as an integral part of decision-making for call admission. Further, current technical resources ignore movement issues of mobile stations and fluctuation in network load (incoming calls) in the control strategy used for call admission. In addition, the present techniques on call admission offers solution globally for the entire network, instead of considering the cells independently. CAC here has been formulated by two alternative approaches. The first approach aimed at handling the uncertainty in the CAC problem by employing fuzzy comparators. The second approach is concerned with formulation of CAC ...
DEFF Research Database (Denmark)
Paidarová, Ivana; Sauer, Stephan P. A.
2012-01-01
We have compared the performance of density functional theory (DFT) using five different exchange-correlation functionals with four coupled cluster theory based wave function methods in the calculation of geometrical derivatives of the polarizability tensor of methane. The polarizability gradient...
DEFF Research Database (Denmark)
Kelkkanen, Kari André; Lundqvist, Bengt; Nørskov, Jens Kehlet
2009-01-01
A recent extensive study has investigated how various exchange-correlation (XC) functionals treat hydrogen bonds in water hexamers and has shown traditional generalized gradient approximation and hybrid functionals used in density-functional (DF) theory to give the wrong dissociation-energy trend...
Drug related hospital admissions. Results from an intervention program
DEFF Research Database (Denmark)
Hallas, J.; Harvald, B.; Worm, J.
1994-01-01
Farmakologi, drug education, hospital admission, adverse drug reactions, drug utilisation, intervention......Farmakologi, drug education, hospital admission, adverse drug reactions, drug utilisation, intervention...
Every seventh acute medical admission is preventable
DEFF Research Database (Denmark)
Jepsen, Henrik Koldborg; Hendriksen, Carsten; Nielsen, Henrik
2013-01-01
The majority of patients who are admitted to the departments of internal medicine are admitted acutely. The aim of this study was to evaluate the appropriateness of admissions to a community hospital in Copenhagen.......The majority of patients who are admitted to the departments of internal medicine are admitted acutely. The aim of this study was to evaluate the appropriateness of admissions to a community hospital in Copenhagen....
Every seventh acute medical admission is preventable
DEFF Research Database (Denmark)
Jepsen, Henrik Koldborg; Hendriksen, Carsten; Nielsen, Henrik;
2013-01-01
The majority of patients who are admitted to the departments of internal medicine are admitted acutely. The aim of this study was to evaluate the appropriateness of admissions to a community hospital in Copenhagen.......The majority of patients who are admitted to the departments of internal medicine are admitted acutely. The aim of this study was to evaluate the appropriateness of admissions to a community hospital in Copenhagen....
Time-dependent density functional theory for strong-field ionization by circularly polarized pulses
Chirilă, Ciprian C.; Lein, Manfred
2017-03-01
By applying time-dependent density functional theory to a two-dimensional multielectron atom subject to strong circularly polarized light pulses, we confirm that the ionization of p orbitals with defined angular momentum depends on the sense of rotation of the applied field. A simple ad-hoc modification of the adiabatic local-density exchange-correlation functional is proposed to remedy its unphysical behavior under orbital depletion.
Ghosh, Soumen; Sonnenberger, Andrew L; Hoyer, Chad E; Truhlar, Donald G; Gagliardi, Laura
2015-08-11
The correct description of charge transfer in ground and excited states is very important for molecular interactions, photochemistry, electrochemistry, and charge transport, but it is very challenging for Kohn-Sham (KS) density functional theory (DFT). KS-DFT exchange-correlation functionals without nonlocal exchange fail to describe both ground- and excited-state charge transfer properly. We have recently proposed a theory called multiconfiguration pair-density functional theory (MC-PDFT), which is based on a combination of multiconfiguration wave function theory with a new type of density functional called an on-top density functional. Here we have used MC-PDFT to study challenging ground- and excited-state charge-transfer processes by using on-top density functionals obtained by translating KS exchange-correlation functionals. For ground-state charge transfer, MC-PDFT performs better than either the PBE exchange-correlation functional or CASPT2 wave function theory. For excited-state charge transfer, MC-PDFT (unlike KS-DFT) shows qualitatively correct behavior at long-range with great improvement in predicted excitation energies.
45 CFR 84.42 - Admissions and recruitment.
2010-10-01
... 45 Public Welfare 1 2010-10-01 2010-10-01 false Admissions and recruitment. 84.42 Section 84.42... Education § 84.42 Admissions and recruitment. (a) General. Qualified handicapped persons may not, on the basis of handicap, be denied admission or be subjected to discrimination in admission or recruitment by...
34 CFR 104.42 - Admissions and recruitment.
2010-07-01
... 34 Education 1 2010-07-01 2010-07-01 false Admissions and recruitment. 104.42 Section 104.42... ASSISTANCE Postsecondary Education § 104.42 Admissions and recruitment. (a) General. Qualified handicapped... admission or recruitment by a recipient to which this subpart applies. (b) Admissions. In administering its...
15 CFR 8b.20 - Admission and recruitment.
2010-01-01
... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Admission and recruitment. 8b.20... Secondary Education § 8b.20 Admission and recruitment. (a) General. Qualified handicapped may not, on the basis of handicap, be denied admission or be subjected to discrimination in admission or recruitment by...
22 CFR 217.42 - Admissions and recruitment.
2010-04-01
... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Admissions and recruitment. 217.42 Section 217... Admissions and recruitment. (a) General. Qualified handicapped persons may not, on the basis of handicap, be denied admission or be subjected to discrimination in admission or recruitment by a recipient to which...
45 CFR 605.42 - Admissions and recruitment.
2010-10-01
... 45 Public Welfare 3 2010-10-01 2010-10-01 false Admissions and recruitment. 605.42 Section 605.42... Postsecondary Education § 605.42 Admissions and recruitment. (a) General. Qualified handicapped persons may not... recruitment by a recipient to which this subpart applies. (b) Admissions. In administering its admission...
The "Admissions" Side of BCCAT: An Update. Special Report
British Columbia Council on Admissions and Transfer, 2008
2008-01-01
To spearhead increased emphasis on admissions, the British Columbia Council on Admissions and Transfer (BCCAT) formed an Admissions Committee in Fall 2003. The committee recognized the importance of institutional autonomy in determining admissions policies and processes at each institution. Following initiation of the Student Transitions Project…
Hedlund, Jennifer; Wilt, Jeanne M.; Nebel, Kristina L.; Ashford, Susan J.; Sternberg, Robert J.
2006-01-01
The Graduate Management Admission Test (GMAT) is the most widely used measure of managerial potential in MBA admissions. GMAT scores, although predictive of grades in business school, leave much of the variance in graduate school performance unexplained. The GMAT also produces disparities in test scores between groups, generating the potential for…
Hedlund, Jennifer; Wilt, Jeanne M.; Nebel, Kristina L.; Ashford, Susan J.; Sternberg, Robert J.
2006-01-01
The Graduate Management Admission Test (GMAT) is the most widely used measure of managerial potential in MBA admissions. GMAT scores, although predictive of grades in business school, leave much of the variance in graduate school performance unexplained. The GMAT also produces disparities in test scores between groups, generating the potential for…
Directory of Open Access Journals (Sweden)
R. Louise Rushworth
2016-01-01
Full Text Available Objective. To examine patterns of hospitalisation for acute medical conditions in children with congenital adrenal hyperplasia (CAH. Design. A retrospective study of hospitalisation using administrative data. Setting. All hospitals in NSW, Australia. Patients. All patients admitted with CAH and a random sample of admissions in patients aged 0 to 18 years without adrenal insufficiency (AI. Main Outcome Measures. Admissions and comorbidities by age and sex. Results. Of 573 admissions for medical problems in CAH children, 286 (49.9% were in males, and 236 (41.2% had a principal diagnosis of CAH or had an adrenal crisis (AC. 37 (6.5% ACs were recorded. An infection was found in 43.5% (n=249 of the CAH patient admissions and 51.7% (n=1613 of the non-AI group, p<0.001. Children aged up to one year had the highest number of admissions (n=149 and six ACs (four in males. There were 21 ACs recorded for children aged 1–5 years. Older CAH children had fewer admissions and fewer ACs. No in-hospital deaths were recorded. Conclusions. Admission for medical problems in CAH children declines with age. An AC was recorded in 6.5% of the admissions, with the majority of ACs occurring in the 1 to 5 years age group and there were no deaths.
DEFF Research Database (Denmark)
Makransky, Guido; Havmose, Philip; Vang, Maria Louison;
2016-01-01
The aim of this study was to evaluate the predictive validity of a two-step admissions procedure that included a cognitive ability test followed by multiple mini-interviews (MMI) used to assess non-cognitive skills compared to a grade-based admissions relative to subsequent drop-out rates and aca...
Makransky, Guido; Havmose, Philip; Vang, Maria Louison; Andersen, Tonny Elmose; Nielsen, Tine
2017-01-01
The aim of this study was to evaluate the predictive validity of a two-step admissions procedure that included a cognitive ability test followed by multiple mini-interviews (MMIs) used to assess non-cognitive skills, compared to grade-based admissions relative to subsequent drop-out rates and academic achievement after one and two years of study.…
Accurate Semilocal Density Functional for Condensed-Matter Physics and Quantum Chemistry.
Tao, Jianmin; Mo, Yuxiang
2016-08-12
Most density functionals have been developed by imposing the known exact constraints on the exchange-correlation energy, or by a fit to a set of properties of selected systems, or by both. However, accurate modeling of the conventional exchange hole presents a great challenge, due to the delocalization of the hole. Making use of the property that the hole can be made localized under a general coordinate transformation, here we derive an exchange hole from the density matrix expansion, while the correlation part is obtained by imposing the low-density limit constraint. From the hole, a semilocal exchange-correlation functional is calculated. Our comprehensive test shows that this functional can achieve remarkable accuracy for diverse properties of molecules, solids, and solid surfaces, substantially improving upon the nonempirical functionals proposed in recent years. Accurate semilocal functionals based on their associated holes are physically appealing and practically useful for developing nonlocal functionals.
Accurate Semilocal Density Functional for Condensed-Matter Physics and Quantum Chemistry
Tao, Jianmin; Mo, Yuxiang
2016-08-01
Most density functionals have been developed by imposing the known exact constraints on the exchange-correlation energy, or by a fit to a set of properties of selected systems, or by both. However, accurate modeling of the conventional exchange hole presents a great challenge, due to the delocalization of the hole. Making use of the property that the hole can be made localized under a general coordinate transformation, here we derive an exchange hole from the density matrix expansion, while the correlation part is obtained by imposing the low-density limit constraint. From the hole, a semilocal exchange-correlation functional is calculated. Our comprehensive test shows that this functional can achieve remarkable accuracy for diverse properties of molecules, solids, and solid surfaces, substantially improving upon the nonempirical functionals proposed in recent years. Accurate semilocal functionals based on their associated holes are physically appealing and practically useful for developing nonlocal functionals.
Drug use before hospital admission in Zimbabwe.
Taylor, H G; Stein, C M; Jongeling, G
1988-01-01
Drug use before hospital admission was studied prospectively in 284 consecutive patients admitted to general medical wards in Zimbabwe. Drugs were used by 84% of patients. Self-medication was used by 143 (50%) patients, aspirin (54%) and chloroquine (17%) being the most commonly used drugs. Traditional medicines were used by 55 (19%) patients. Drugs dispensed from orthodox medical sources were taken by 128 (45%) patients. Analgesics (22%), antibiotics (18%), and chloroquine (13%) were the commonest drugs dispensed. Urine screening tests were performed and were positive for aspirin in 37% of cases, chloroquine (33%), and antibiotics (20%). Adverse drug reactions requiring hospital admission occurred in 14 patients (10 orthodox medicines, 4 traditional medicines). Drug use before hospital admission, which is often poorly documented, is a source of potential drug toxicity and may obscure a diagnosis of infective illness.
Affirmative action policy in medical school admissions.
Frazer, Ricardo A
2005-02-01
Legal challenges to affirmative action are growing, a trend suggesting that a proactive stance is needed to maintain a policy that still has viability, legitimacy, and utility. Medical schools admissions offices in the United States emphasize the Medical College Admissions Test (MCAT), even though many studies have found that grade point averages are better single predictors of future academic achievement, regardless of the student's socioeconomic or racial category. The current essay suggests there is an overreliance on the MCAT in medical school admissions. Medical colleges should encourage the development of additional applicant selection criteria, while continuing to use affirmative action programs, in part to address the need for increased community-oriented health care.
The therapeutic relationship after psychiatric admission.
LENUS (Irish Health Repository)
Roche, Eric
2014-03-01
The therapeutic relationship is one of the most central and important factors in the treatment of mental health disorders. A better therapeutic relationship is associated with service engagement, medication adherence, and satisfaction with services. This study aimed to compare the demographic and clinical factors associated with the therapeutic relationship in voluntarily and involuntarily admitted psychiatric service users. We found that individuals who had been admitted involuntarily, who had a diagnosis of a psychotic disorder, and who reported higher levels of perceived pressures on admission were more likely to have a poorer therapeutic relationship with their consultant psychiatrist. Greater levels of insight and treatment satisfaction, together with higher levels of procedural justice experienced on admission, were associated with a better therapeutic relationship. We found that the level of perceived coercion on admission was not related to the therapeutic relationship. Targeted interventions to improve the therapeutic relationship, particularly for involuntarily admitted service users, are discussed.
Increased admissions for diabetes mellitus after burn.
Duke, Janine M; Randall, Sean M; Fear, Mark W; Boyd, James H; O'Halloran, Emily; Rea, Suzanne; Wood, Fiona M
2016-12-01
Currently, limited long-term data on hyperglycaemia and insulin sensitivity in burn patients are available and the data that do exist are primarily related to paediatric severe burns. The aim of this study was to assess if burn is associated with increased post-burn admissions for diabetes mellitus. A population-based longitudinal study using linked hospital morbidity and death data from Western Australia was undertaken of all persons hospitalized for a first burn (n=30,997) in 1980-2012 and a frequency matched non-injury comparison cohort, randomly selected from Western Australia's birth registrations and electoral roll (n=123,399). Crude admission rates and summed length of stay for diabetes mellitus were calculated. Negative binomial and Cox proportional hazards regression modelling were used to generate incidence rate ratios (IRR) and hazard ratios (HR), respectively. After adjustment for socio-demographic factors and pre-existing health status, the burn cohort had 2.21 times (95% Confidence Interval (CI): 1.36-1.56) as many admissions and almost three times the number of days in hospital with a diabetes mellitus diagnosis (IRR, 95% CI: 2.94, 2.12-4.09) than the uninjured cohort. Admission rates were significantly elevated for those burned during childhood (diabetes mellitus in the burn cohort provide evidence that burns have longer term effects on blood glucose and insulin regulation after wound healing. The first five years after burn discharge appears to be a critical period with significantly elevated incident admissions for diabetes mellitus during this time. Results would suggest prolonged clinical management after discharge and or wound healing to minimise post-burn admissions for diabetes mellitus is required. Copyright © 2016 Elsevier Ltd and ISBI. All rights reserved.
Bernoulli measure of complex admissible kneading sequences
Bruin, Henk
2012-01-01
Iterated quadratic polynomials give rise to a rich collection of different dynamical systems that are parametrized by a simple complex parameter $c$. The different dynamical features are encoded by the \\emph{kneading sequence} which is an infinite sequence over $\\{0,\\1\\}$. Not every such sequence actually occurs in complex dynamics. The set of admissible kneading sequences was described by Milnor and Thurston for real quadratic polynomials, and by the authors in the complex case. We prove that the set of admissible kneading sequences has positive Bernoulli measure within the set of sequences over $\\{0,\\1\\}$.
Modeling admissible behavior using event signals.
Pinzon, Luz; Jafari, Mohsen A; Hanisch, Hans-Michael; Zhao, Peng
2004-06-01
We describe here how to obtain a model for the admissible behavior of a discrete event system that is represented by a safe Petri net (PN) model. The transitions of this PN model may be controllable or uncontrollable. Also given is a sequential specification which is modeled with a special state machine. Then, using the condition and event arcs of net condition/event systems, a combined model of plant and specification is obtained. We use only the structure of this combined model to develop a method which gives the admissible behavior of the system. Thus, we avoid the complexity of a complete state enumeration.
Entropy Production and Admissibility of Shocks
Institute of Scientific and Technical Information of China (English)
Tai-Ping Liu; Tommaso Ruggeri
2003-01-01
In shock wave theory there are two considerations in selecting the physically relevant shock waves.There is the admissibility criterion for the well-posedness of hyperbolic conservation laws. Another consideration concerns the entropy production across the shocks. The latter is natural from the physical point of view, but is not sufficient in its straightforward formulation, if the system is not genuinely nonlinear. In this paper we propose the principles of increasing entropy production and that of the superposition of shocks. These principles are shown to be equivalent to the admissibility criterion.
Energy Technology Data Exchange (ETDEWEB)
Vikas [Quantum Chemistry Group, Department of Chemistry and Centre of Advanced Studies in Chemistry, Panjab University, 160014 Chandigrah (India)
2011-02-15
Evolution of the helium atom in a strong time-dependent (TD) magnetic field (B) of strength up to 10{sup 11} G is investigated through a quantum fluid dynamics (QFD) based current-density functional theory (CDFT). The TD-QFD-CDFT computations are performed through numerical solution of a single generalized nonlinear Schroedinger equation employing vector exchange-correlation potentials and scalar exchange-correlation density functionals that depend both on the electronic charge-density and the current-density. The results are compared with that obtained from a B-TD-QFD-DFT approach (based on conventional TD-DFT) under similar numerical constraints but employing only scalar exchange-correlation potential dependent on electronic charge-density only. The B-TD-QFD-DFT approach, at a particular TD magnetic field-strength, yields electronic charge- and current-densities as well as exchange-correlation potential resembling with that obtained from the time-independent studies involving static (time-independent) magnetic fields. However, TD-QFD-CDFT electronic charge- and current-densities along with the exchange-correlation potential and energy differ significantly from that obtained using B-TD-QFD-DFT approach, particularly at field-strengths >10{sup 9} G, representing dynamical effects of a TD field. The work concludes that when a helium atom is subjected to a strong TD magnetic field of order >10{sup 9} G, the conventional TD-DFT based approach differs 'dynamically' from the CDFT based approach under similar computational constraints. (author)
Multiconfiguration Pair-Density Functional Theory.
Li Manni, Giovanni; Carlson, Rebecca K; Luo, Sijie; Ma, Dongxia; Olsen, Jeppe; Truhlar, Donald G; Gagliardi, Laura
2014-09-09
We present a new theoretical framework, called Multiconfiguration Pair-Density Functional Theory (MC-PDFT), which combines multiconfigurational wave functions with a generalization of density functional theory (DFT). A multiconfigurational self-consistent-field (MCSCF) wave function with correct spin and space symmetry is used to compute the total electronic density, its gradient, the on-top pair density, and the kinetic and Coulomb contributions to the total electronic energy. We then use a functional of the total density, its gradient, and the on-top pair density to calculate the remaining part of the energy, which we call the on-top-density-functional energy in contrast to the exchange-correlation energy of Kohn-Sham DFT. Because the on-top pair density is an element of the two-particle density matrix, this goes beyond the Hohenberg-Kohn theorem that refers only to the one-particle density. To illustrate the theory, we obtain first approximations to the required new type of density functionals by translating conventional density functionals of the spin densities using a simple prescription, and we perform post-SCF density functional calculations using the total density, density gradient, and on-top pair density from the MCSCF calculations. Double counting of dynamic correlation or exchange does not occur because the MCSCF energy is not used. The theory is illustrated by applications to the bond energies and potential energy curves of H2, N2, F2, CaO, Cr2, and NiCl and the electronic excitation energies of Be, C, N, N(+), O, O(+), Sc(+), Mn, Co, Mo, Ru, N2, HCHO, C4H6, c-C5H6, and pyrazine. The method presented has a computational cost and scaling similar to MCSCF, but a quantitative accuracy, even with the present first approximations to the new types of density functionals, that is comparable to much more expensive multireference perturbation theory methods.
Luzon, Javier; Castro, Miguel; Vertelman, Esther J.M.; Gengler, Régis Y.N.; van Koningsbruggen, Petra J.; Molodtsova, Olga; Knupfer, Martin; Rudolf, Petra; Loosdrecht, Paul H.M. van; Broer, Ria
2008-01-01
A periodic density functional theory method using the B3LYP hybrid exchange-correlation potential is applied to the Prussian blue analogue RbMn[Fe(CN)(6)] to evaluate the suitability of the method for studying, and predicting, the photomagnetic behavior of Prussian blue analogues and related materia
32 CFR 242.5 - Admission procedures.
2010-07-01
..., Attn: Assistant Dean for Academic Support. The School of Medicine shall not process a military person's...) MISCELLANEOUS ADMISSION POLICIES AND PROCEDURES FOR THE SCHOOL OF MEDICINE, UNIFORMED SERVICES UNIVERSITY OF THE... to the School of Medicine shall make direct application following instructions published in...
Foundation Schools and Admissions: The Local Dimension.
Wise, Christine; Anderson, Lesley; Bush, Tony
2001-01-01
In 1988, the Labour Government abolished Grant Maintained schools and introduced three new categories of school: community, voluntary, and foundation. Reports findings of a study that gathered the perceptions of heads, governors, and senior staff about admission issues in 11 foundation schools after their first full term. (26 references)…
2010-01-01
... 7 Agriculture 1 2010-01-01 2010-01-01 false Admission. 15a.16 Section 15a.16 Agriculture Office of the Secretary of Agriculture EDUCATION PROGRAMS OR ACTIVITIES RECEIVING OR BENEFITTING FROM FEDERAL... institutions, subpart C applies only to institutions of vocational education, professional education,...
Differential Prediction Generalization in College Admissions Testing
Aguinis, Herman; Culpepper, Steven A.; Pierce, Charles A.
2016-01-01
We introduce the concept of "differential prediction generalization" in the context of college admissions testing. Specifically, we assess the extent to which predicted first-year college grade point average (GPA) based on high-school grade point average (HSGPA) and SAT scores depends on a student's ethnicity and gender and whether this…
The National Center Test for University Admissions
Watanabe, Yoshinori
2013-01-01
This article describes the National Center Test for University Admissions, a unified national test in Japan, which is taken by 500,000 students every year. It states that implementation of the Center Test began in 1990, with the English component consisting only of the written section until 2005, when the listening section was first implemented…
Reporting Subscores from College Admission Tests
Lyren, Per-Erik
2009-01-01
The added value of reporting subscores on a college admission test (SweSAT) was examined in this study. Using a CTT-derived objective method for determining the value of reporting subscores, it was concluded that there is added value in reporting section scores (Verbal/Quantitative) as well as subtest scores. These results differ from a study of…
False confessions, expert testimony, and admissibility.
Watson, Clarence; Weiss, Kenneth J; Pouncey, Claire
2010-01-01
The confession of a criminal defendant serves as a prosecutor's most compelling piece of evidence during trial. Courts must preserve a defendant's constitutional right to a fair trial while upholding the judicial interests of presenting competent and reliable evidence to the jury. When a defendant seeks to challenge the validity of that confession through expert testimony, the prosecution often contests the admissibility of the expert's opinion. Depending on the content and methodology of the expert's opinion, testimony addressing the phenomenon of false confessions may or may not be admissible. This article outlines the scientific and epistemological bases of expert testimony on false confession, notes the obstacles facing its admissibility, and provides guidance to the expert in formulating opinions that will reach the judge or jury. We review the 2006 New Jersey Superior Court decision in State of New Jersey v. George King to illustrate what is involved in the admissibility of false-confession testimony and use the case as a starting point in developing a best-practice approach to working in this area.
Hospital admissions before and after shipyard closure.
Bartley, M; Fagin, L
1990-03-01
"To determine the effect of job loss on health an investigation was made of admissions to hospitals in 887 men five years before and three years after the closure of a Danish shipyard. The control group comprised 441 men from another shipyard. The information on hospital admissions was obtained from the Danish national register of patients. The relative risk of admission in the control group dropped significantly in terms of the number of men admitted from the study group from 1.29 four to five years before closure to 0.74 in the three years after closure. This was especially true of admissions due to accidents (1.33 to 0.46) and diseases of the digestive system (4.53 to 1.03). For diseases of the circulatory system, particularly cardiovascular diseases, the relative risk increased from 0.8 to 1.60, and from 1.0 to 2.6 respectively. These changes in risk of illness after redundancy are probably a consequence of a change from the effects of a high risk work environment to the effects of psychosocial stresses such as job insecurity and unemployment."
Differential Prediction Generalization in College Admissions Testing
Aguinis, Herman; Culpepper, Steven A.; Pierce, Charles A.
2016-01-01
We introduce the concept of "differential prediction generalization" in the context of college admissions testing. Specifically, we assess the extent to which predicted first-year college grade point average (GPA) based on high-school grade point average (HSGPA) and SAT scores depends on a student's ethnicity and gender and whether this…
Göltl, Florian; Sautet, Philippe
2014-04-01
The inclusion of non-local interactions is one of the large challenges in density functional theory. Very promising methods are the vdW-DF2 and BEEF-vdW functionals, which combine a semi-local approximation for exchange interactions and a non-local correlation expression. In this work we apply those functionals to model the adsorption of short alkanes in the zeolite SSZ-13. Even though results for energetics are improved with respect to other vdW-DF based methods, we still find a comparatively large error compared to high-level calculations. These errors result from approximations in the determination of the dielectric function and of the van der Waals kernel. The insights presented in this work will help to understand the performance not only of vdW-DF2 and BEEF-vdW, but all vdW-DF based functionals in various chemically or physically important systems.
Singh, Prashant; Harbola, Manoj K.; Johnson, Duane D.
2017-10-01
This work constitutes a comprehensive and improved account of electronic-structure and mechanical properties of silicon-nitride (Si3 N4 ) polymorphs via van Leeuwen and Baerends (LB) exchange-corrected local density approximation (LDA) that enforces the exact exchange potential asymptotic behavior. The calculated lattice constant, bulk modulus, and electronic band structure of Si3 N4 polymorphs are in good agreement with experimental results. We also show that, for a single electron in a hydrogen atom, spherical well, or harmonic oscillator, the LB-corrected LDA reduces the (self-interaction) error to exact total energy to ∼10%, a factor of three to four lower than standard LDA, due to a dramatically improved representation of the exchange-potential.
DEFF Research Database (Denmark)
Makransky, Guido; Havmose, Philip S.; Vang, Maria
2016-01-01
The aim of this study was to evaluate the predictive validity of a two-step admissions procedure that included a cognitive ability test followed by multiple mini-interviews (MMI) used to assess non-cognitive skills compared to a grade-based admissions relative to subsequent drop-out rates...... and academic achievement after one and two years of study. The participants consisted of the entire population of 422 psychology students who were admitted to the University of Southern Denmark between 2010 and 2013. The results showed significantly lower drop-out rates after the first year of study, and non......-significant lower drop-out rates after the second year of study for the admission procedure that included the assessment of non-cognitive skills though the MMI. Furthermore, this admission procedure resulted in a significant lower risk of failing the final exam after the first and second year of study, compared...
Density functionals for the strong-interaction limit
Seidl, Michael; Perdew, John P.; Kurth, Stefan
2000-07-01
The strong-interaction limit of density-functional (DF) theory is simple and provides information required for an accurate resummation of DF perturbation theory. Here we derive the point-charge-plus-continuum (PC) model for that limit, and its gradient expansion. The exchange-correlation (xc) energy Exc[ρ]≡∫10dαWα[ρ] follows from the xc potential energies Wα at different interaction strengths α>=0 [but at fixed density ρ(r)]. For small α~0, the integrand Wα is obtained accurately from perturbation theory, but the perturbation expansion requires resummation for moderate and large α. For that purpose, we present density functionals for the coefficients in the asymptotic expansion Wα-->W∞+W'∞α-1/2 for α-->∞ in the PC model. WPC∞ arises from strict correlation, and W'PC∞ from zero-point vibration of the electrons around their strictly correlated distributions. The PC values for W∞ and W'∞ agree with those from a self-correlation-free meta-generalized gradient approximation, both for atoms and for atomization energies of molecules. We also (i) explain the difference between the PC cell and the exchange-correlation hole, (ii) present a density-functional measure of correlation strength, (iii) describe the electron localization and spin polarization energy in a highly stretched H2 molecule, and (iv) discuss the soft-plasmon instability of the low-density uniform electron gas.
Spin in Density-Functional Theory
Jacob, Christoph R; 10.1002/qua.24309
2012-01-01
The accurate description of open-shell molecules, in particular of transition metal complexes and clusters, is still an important challenge for quantum chemistry. While density-functional theory (DFT) is widely applied in this area, the sometimes severe limitations of its currently available approximate realizations often preclude its application as a predictive theory. Here, we review the foundations of DFT applied to open-shell systems, both within the nonrelativistic and the relativistic framework. In particular, we provide an in-depth discussion of the exact theory, with a focus on the role of the spin density and possibilities for targeting specific spin states. It turns out that different options exist for setting up Kohn-Sham DFT schemes for open-shell systems, which imply different definitions of the exchange-correlation energy functional and lead to different exact conditions on this functional. Finally, we suggest some possible directions for future developments.
Hybrid density functional theory LCAO calculations on phonons in Ba (Ti,Zr,Hf) O3
Evaestov, Robert A
2010-01-01
Phonon frequencies at {\\Gamma},X,M,R-points of Brilloin zone in cubic phase of Ba(Ti,Zr,Hf)O3 were first time calculated by frozen phonon method using density functional theory (DFT) with hybrid exchange correlation functional PBE0. The calculations use linear combination of atomic orbitals (LCAO) basis functions as implemented in CRYSTAL09 computer code. The Powell algorithm was applied for basis set optimization. In agreement with the experimental observations the structural instability via...
Performance of one-body reduced density-matrix functionals for the homogeneous electron gas
Lathiotakis, N. N.; Helbig, N.; Gross, E. K. U.
2007-05-01
The subject of this study is the exchange-correlation-energy functional of reduced density-matrix functional theory. Approximations of this functional are tested by applying them to the homogeneous electron gas. We find that two approximations recently proposed by Gritsenko , [J. Chem. Phys. 122, 204102 (2005)] yield considerably better correlation energies and momentum distributions than previously known functionals. We introduce modifications to these functionals, which, by construction, reproduce the exact correlation energy of the homogeneous electron gas.
Treatment Episode Data Set: Admissions (TEDS-A-2011)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-2013)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-1994)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-2002)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-2010)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-1997)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-2001)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-1995)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-2003)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-2004)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-2005)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-2009)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-2006)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-1996)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-2012)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-1999)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-2008)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-1993)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-2000)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-1992)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-1998)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Treatment Episode Data Set: Admissions (TEDS-A-2007)
U.S. Department of Health & Human Services — The Treatment Episode Data Set -- Admissions (TEDS-A) is a national census data system of annual admissions to substance abuse treatment facilities. TEDS-A provides...
Pattern and Outcome of Gynaecological Admissions at a Nigerian ...
African Journals Online (AJOL)
Pattern and Outcome of Gynaecological Admissions at a Nigerian Tertiary Care Centre. ... Abortion accounted for 15.6% of total gynaecological admissions and was ... This was followed by infections, 43.5% with post abortal sepsis contributing ...
Effect Of Admission Hyperglycaemia On Short-Term Outcome In ...
African Journals Online (AJOL)
Effect Of Admission Hyperglycaemia On Short-Term Outcome In Adult ... AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search · USING AJOL ... Admission hyperglycaemia is a significant predictor of short-term case fatality but ...
Admission criteria and diversity in medical school
DEFF Research Database (Denmark)
O'Neill, Lotte; Vonsild, Maria; Wallstedt, Birgitta
2013-01-01
Introduction: The underrepresentation of students from lower socioeconomic backgrounds in medical education is an important social issue. There is currently little evidence about whether changes in admission strategy could increase the diversity of medical students. Denmark introduced an “attribute...... on other attributes. To explore the social mix of the two tracks, we obtained information on social indices associated with educational attainment in Denmark (ethnic origin, father’s education, mother’s education, parenthood, parents live together, parent on benefit). Result: Selection strategy (grade......-based or attribute-based) had no statistically significant effect on the social diversity of medical students admitted to USD. Discussion: It may be a myth that attribute-based admission widens access and increases social diversity. To the contrary, there is evidence that combining grade-based with attribute...
THE OBJECT OF THE ADMISSION OF GUILT
Directory of Open Access Journals (Sweden)
Constantin NEDELCU
2015-07-01
Full Text Available This paper aims at studying how elements of negotiated justice specific to common law systems entered into the Romanian criminal procedural law system. It particularly deals with the admission of guilt and about one of its most controversial aspects – the object of recognition. The research concludes that what is recognized within this simplified procedure it is the deed and not its legal classification given by the criminal prosecution bodies.
Lie Admissible Non-Associative Algebras
Institute of Scientific and Technical Information of China (English)
H.Mohammad Ahmadi; Ki-Bong Nam; Jonathan Pakinathan
2005-01-01
A non-associative ring which contains a well-known associative ring or Lie ring is interesting. In this paper, a method to construct a Lie admissible non-associative ring is given; a class of simple non-associative algebras is obtained; all the derivations of the non-associative simple N0,0,1 algebra defined in this paper are determined; and finally, a solid algebra is defined.
Characteristics of delayed admission to stroke unit.
Silvestrelli, Giorgio; Parnetti, Lucilla; Tambasco, Nicola; Corea, Francesco; Capocchi, Giuseppe
2006-01-01
Early admission to stroke unit (SU) and factors that may cause admission delay represent relevant issues to obtain an optimal management of acute stroke. This study was aimed at recording timing from clinical onset to admission to our SU and to identify the reasons for delay. We prospectively examined acute stroke patients consecutively admitted to the Perugia SU. Baseline characteristics of stroke patients, stroke type and etiology, time from symptom onset to arrival in the SU were obtained from the Hospital-Based Perugia Stroke Registry. 60.8% of 2,213 consecutive stroke patients admitted to the SU arrived within 6 hrs and 39.2% after 6 hrs. Underestimation of symptoms was the cause of delay in 48.7% of cases. Younger age, especially for females, ischemic stroke, mild and/or unspecific symptoms and the underestimation of symptoms seem to be the main reasons for delayed arrival in the SU. To increase the proportion of stroke patients arriving in the SU within 3 hr of symptom onset, it is necessary to improve public and general practitioner awareness of stroke through educational programs.
Perceived coercion in voluntary hospital admission.
LENUS (Irish Health Repository)
O'Donoghue, Brian
2014-01-30
The legal status of service users admitted to psychiatric wards is not synonymous with the level of coercion that they can perceive during the admission. This study aimed to identify and describe the proportion of individuals who were admitted voluntarily but experienced levels of perceived coercion comparable to those admitted involuntarily. Individuals admitted voluntarily and involuntarily to three psychiatric hospitals were interviewed using the MacArthur Admission Experience Interview and the Structured Clinical Interview for DSM-IV diagnoses. One hundered sixty-one individuals were interviewed and 22% of the voluntarily admitted service users had levels of perceived coercion similar to that of the majority of involuntarily admitted service users. Voluntarily admitted service users who experienced high levels of perceived coercion were more likely to have more severe psychotic symptoms, have experienced more negative pressures and less procedural justices on admission. Individuals brought to hospital under mental health legislation but who subsequently agreed to be admitted voluntarily and those treated on a secure ward also reported higher levels of perceived coercion. It needs to be ensured that if any service user, whether voluntary or involuntary, experiences treatment pressures or coercion that there is sufficient oversight of the practice, to ensure that individual\\'s rights are respected.
Energy Technology Data Exchange (ETDEWEB)
Kraisler, Eli; Kronik, Leeor [Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100 (Israel)
2014-05-14
The fundamental gap is a central quantity in the electronic structure of matter. Unfortunately, the fundamental gap is not generally equal to the Kohn-Sham gap of density functional theory (DFT), even in principle. The two gaps differ precisely by the derivative discontinuity, namely, an abrupt change in slope of the exchange-correlation energy as a function of electron number, expected across an integer-electron point. Popular approximate functionals are thought to be devoid of a derivative discontinuity, strongly compromising their performance for prediction of spectroscopic properties. Here we show that, in fact, all exchange-correlation functionals possess a derivative discontinuity, which arises naturally from the application of ensemble considerations within DFT, without any empiricism. This derivative discontinuity can be expressed in closed form using only quantities obtained in the course of a standard DFT calculation of the neutral system. For small, finite systems, addition of this derivative discontinuity indeed results in a greatly improved prediction for the fundamental gap, even when based on the most simple approximate exchange-correlation density functional – the local density approximation (LDA). For solids, the same scheme is exact in principle, but when applied to LDA it results in a vanishing derivative discontinuity correction. This failure is shown to be directly related to the failure of LDA in predicting fundamental gaps from total energy differences in extended systems.
Electronic Zero-Point Oscillations in the Strong-Interaction Limit of Density Functional Theory.
Gori-Giorgi, Paola; Vignale, Giovanni; Seidl, Michael
2009-04-14
The exchange-correlation energy in Kohn-Sham density functional theory can be expressed exactly in terms of the change in the expectation of the electron-electron repulsion operator when, in the many-electron Hamiltonian, this same operator is multiplied by a real parameter λ varying between 0 (Kohn-Sham system) and 1 (physical system). In this process, usually called adiabatic connection, the one-electron density is kept fixed by a suitable local one-body potential. The strong-interaction limit of density functional theory, defined as the limit λ→∞, turns out to be like the opposite noninteracting Kohn-Sham limit (λ→0) mathematically simpler than the physical (λ = 1) case and can be used to build an approximate interpolation formula between λ→0 and λ→∞ for the exchange-correlation energy. Here we extend the systematic treatment of the λ→∞ limit [Phys. Rev. A 2007, 75, 042511] to the next leading term, describing zero-point oscillations of strictly correlated electrons, with numerical examples for small spherical atoms. We also propose an improved approximate functional for the zero-point term and a revised interpolation formula for the exchange-correlation energy satisfying more exact constraints.
45 CFR 1170.42 - Admissions and recruitment.
2010-10-01
... 45 Public Welfare 3 2010-10-01 2010-10-01 false Admissions and recruitment. 1170.42 Section 1170... FEDERALLY ASSISTED PROGRAMS OR ACTIVITIES Postsecondary Education § 1170.42 Admissions and recruitment. (a... subjected to discrimination in admission or recruitment by a recipient to which this subpart applies. (b...
38 CFR 18.442 - Admissions and recruitment.
2010-07-01
... recruitment. 18.442 Section 18.442 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS... Postsecondary Education § 18.442 Admissions and recruitment. (a) General. Qualified handicapped persons may not... recruitment by a recipient. (b) Admission. In administering its admission policies, a recipient; (1) May not...
7 CFR 15b.30 - Admissions and recruitment.
2010-01-01
... 7 Agriculture 1 2010-01-01 2010-01-01 false Admissions and recruitment. 15b.30 Section 15b.30... ACTIVITIES RECEIVING FEDERAL FINANCIAL ASSISTANCE Postsecondary Education § 15b.30 Admissions and recruitment... be subjected to discrimination in admission or recruitment by a recipient to which this subpart...
22 CFR 142.42 - Admissions and recruitment.
2010-04-01
... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Admissions and recruitment. 142.42 Section 142... and recruitment. (a) General. Qualified handicapped persons may not, on the basis of handicap, be denied admission or be subjected to discrimination in admission or recruitment by a recipient to which...
Equity of Access. New Approaches to Minority Admissions
Bingham, Rebecca Saady
1978-01-01
One new approach to the admission of minorities to medical schools is that of the Simulated Minority Admission Exercises (SMAE). It sensitizes admission committee members to the different backgrounds of minority applicants and teaches them to evaluate them more effectively. (Author/AM)
Early Admissions at Selective Colleges. NBER Working Paper No. 14844
Avery, Christopher; Levin, Jonathan D.
2009-01-01
Early admissions is widely used by selective colleges and universities. We identify some basic facts about early admissions policies, including the admissions advantage enjoyed by early applicants and patterns in application behavior, and propose a game-theoretic model that matches these facts. The key feature of the model is that colleges want to…
Reclaiming the Educational Role of Chief Admission Officers.
McDonough, Patricia; Robertson, Larry
1995-01-01
Describes changes that have occurred in high schools, colleges, and the entrepreneurial admission sector. Relates the evolution of the admission officer's job since the early 1960s and the profession's rapid growth. Details the hybrid role of marketer and educator for chief admissions officers, and issues a call for professional standards. (RJM)
Is Density Functional Theory adequate for quantum transport?
Burke, Kieron
2007-03-01
Density functional calculations for the electronic conductance of single molecules attached to leads are now common. I'll examine the methodology from a rigorous point of view, discussing where it can be expected to work, and where it should fail. When molecules are weakly coupled to leads, local and gradient-corrected approximations fail, as the Kohn-Sham levels are misaligned. In the weak bias regime, XC corrections to the current are missed by the standard methodology. Finally, I will compare and contrast several new methodologies that go beyond the present standard approach of applying the Landauer formula to ground-state DFT. Self-interaction errors in density functional calculations of electronictransport, C. Toher, A. Filippetti, S. Sanvito, and K. Burke, Phys. Rev. Lett. 95, 146402 (2005) The Dramatic Role of the Exchange-Correlation Potential in ab initio Electron Transport Calculations, S-H. Ke, H.U. Baranger, and W. Yang, cond-mat/0609367. Zero-bias molecular electronics: Exchange-correlation corrections to Landauer's formula, M. Koentopp, K. Burke, and F. Evers, Phys. Rev. B Rapid Comm., 73, 121403 (2006). Density Functional Theory of the Electrical Conductivity of Molecular Devices, K. Burke, Roberto Car, and Ralph Gebauer, Phys. Rev. Lett. 94, 146803 (2005). Density functional calculations of nanoscale conductance, Connie Chang, Max Koentopp, Kieron Burke, and Roberto Car, in prep.
Bayesian error estimation in density-functional theory
DEFF Research Database (Denmark)
Mortensen, Jens Jørgen; Kaasbjerg, Kristen; Frederiksen, Søren Lund
2005-01-01
We present a practical scheme for performing error estimates for density-functional theory calculations. The approach, which is based on ideas from Bayesian statistics, involves creating an ensemble of exchange-correlation functionals by comparing with an experimental database of binding energies...... for molecules and solids. Fluctuations within the ensemble can then be used to estimate errors relative to experiment on calculated quantities such as binding energies, bond lengths, and vibrational frequencies. It is demonstrated that the error bars on energy differences may vary by orders of magnitude...
Non-Local Density Functional Description of Poly-Para-Phenylene Vinylene
Institute of Scientific and Technical Information of China (English)
ZHENG Guang; Clark S. J.; Brand S.; Abram R. A.
2007-01-01
A fully non-local exchange-correlation formalism within the framework of density functional theory, known as the weighted density approximation (WDA), has been applied to the conjugated polymer poly-para-phenylene vinylene (PPV) and is shown to lead to a marked improvement in the agreement of theory and experiment for the electronic band structure of the conjugated polymer. In particular, some new model WDA functions are developed, which substantially increase the electronic band gap of the polymer relative to those obtained with the local density approximation and generalized gradient approximation. The calculated band gap of PPV is quantitatively or at 1east semiquantitatively in agreement with the experimental data.
Testing and using the Lewin-Lieb bounds in density functional theory
Feinblum, David; Kenison, John; Burke, Kieron
Lewin and Lieb have recently proven several new bounds on the exchange-correlation energy that complement the Lieb-Oxford bound. We test these bounds for atoms, for slowly-varying gases, and for Hooke's atom, finding them usually less strict than the Lieb-Oxford bound. However, we also show that, if a generalized gradient approximation (GGA) is to guarantee satisfaction of the new bounds for all densities, new restrictions on the the exchange-correlation enhancement factor are implied. We thank Mathieu Lewin and Elliott Lieb for bringing their new bounds to our attention, and Eberhard Engel for developing the OPMKS atom code. This work was supported by NSF under Grant CHE-1112442.
Admission Hyperglycemia in Head Injured Patients
Directory of Open Access Journals (Sweden)
Yousefzadeh Chabok Sh
2009-04-01
Full Text Available Hyperglycemia, in trauma patient, is commonly associated with a hyper metabolic stress response. Our objective is to determine the effects of hyperglycemia on the overall outcome of head trauma patients. In this descriptive study data were collected from head trauma patients' admitted to Intensive Care Unit (ICU of Poursina University Hospital in a one-year period (Jan 2004-Jan 2005, retrospectively. All patients had stayed in the ICU for more than 48 hours post-injuries. They were divided into two groups according to their serum glucose levels at the time of admission (<200mg/dl or >200mg/dl, age, gender and Injury Severity Score (ISS. Patients with diabetes mellitus were excluded .We determined the outcome according to duration of hospitalization and ICU stay as well as mortality rates. Variables were analyzed with t-test and chi square test. Out of 115 patients, 89.6% were men. About 36 % of patients had serum glucose levels ≥ 200 mg/dl over the study period and this group had significantly greater mortality rate but without necessarily longer ICU or hospital stay. In this study we have shown that admission hyperglycemia has significant effect on patient's mortality but it is still unclear whether it can be a cause for longer ICU/hospital stay."n© 2009 Tehran University of Medical Sciences. All rights reserved.
Interpretation of van der Waal density functionals
Hyldgaard, Per; Schröder, Elsebeth
2014-01-01
The nonlocal correlation energy in the van der Waals density functional (vdW-DF) method [Phys. Rev. Lett. 92, 246401 (2004); Phys. Rev. B 76, 125112 (2007); Phys. Rev. B 89, 035412 (2014)] can be interpreted in terms of a coupling of zero-point energies of characteristic modes of semilocal exchange-correlation (xc) holes. These xc holes reflect the internal functional in the framework of the vdW-DF method [Phys. Rev. B 82, 081101(2010)]. We explore the internal xc hole components, showing that they share properties with those of the generalized-gradient approximation. We use these results to illustrate the nonlocality in the vdW-DF description and analyze the vdW-DF formulation of nonlocal correlation.
Wabwoba, Franklin; Mwakondo, Fullgence M.
2011-01-01
Every year, the Joint Admission Board (JAB) is tasked to determine those students who are expected to join various Kenyan public universities under the government sponsorship scheme. This exercise is usually extensive because of the large number of qualified students compared to the very limited number of slots at various institutions and the…
Wabwoba, Franklin; Mwakondo, Fullgence M.
2011-01-01
Every year, the Joint Admission Board (JAB) is tasked to determine those students who are expected to join various Kenyan public universities under the government sponsorship scheme. This exercise is usually extensive because of the large number of qualified students compared to the very limited number of slots at various institutions and the…
Unemployment and Causes of Hospital Admission Considering Different Analytical Approaches
DEFF Research Database (Denmark)
Berg-Beckhoff, Gabriele; Gulis, Gabriel; Kronborg Bak, Carsten
2016-01-01
The association between unemployment and hospital admission is known, but the causal relationship is still under discussion. The aim of the present analysis is to compare results of a cross-sectional and a cohort approach considering overall hospital admission and hospital admission due to cancer...... compensated unemployment and both types of disease specific hospital admission was associated statistically significant in the cross-sectional analysis. With regard to circulatory disease, the cohort approach suggests that social welfare compensated unemployment might lead to hospital admission due...... to the disease. Given the significant results in the cross-sectional analysis for hospital admission due to cancer, the unfound cohort effect might indicate a reverse causation suggesting that the disease caused joblessness and finally, social welfare compensated unemployment and not vice versa. Comparing...
Loneliness and nursing home admission among rural older adults.
Russell, D W; Cutrona, C E; de la Mora, A; Wallace, R B
1997-12-01
In this study, the authors tested the relation between loneliness and subsequent admission to a nursing home over a 4-year time period in a sample of approximately 3,000 rural older Iowans. Higher levels of loneliness were found to increase the likelihood of nursing home admission and to decrease the time until nursing home admission. The influence of extremely high loneliness on nursing home admission remained statistically significant after controlling for other variables, such as age, education, income, mental status, physical health, morale, and social contact, that were also predictive of nursing home admission. Several mechanisms are proposed to explain the link between extreme loneliness and nursing home admission. These include loneliness as a precipitant of declines in mental and physical health and nursing home placement as a strategy to gain social contact with others. Implications for preventative interventions are discussed.
Preferential Treatment in College Admissions and Student Incentives
Pastine, Tuvana; Pastine, Ivan
2011-01-01
This paper examines student incentives when faced with a college admissions policy which pursues student body diversity. The effect of a diversify-conscious admissions policy critically depends on the design of the policy. If the admissions policy fails to incentivize students from a disadvantaged socioeconomic background it may lead to a deterioration in the intergroup score gap while failing to improve student body diversity in equilibrium.
Emergency department orthopedics observation unit as an alternative to admission.
Ernst, Amy A; Jones, Jaime; Weiss, Steven J; Silva, Otono
2014-10-01
Inclusion of select orthopedic problems in the orthopedics observation unit (OOU) may reduce hospital admissions. Our system allows OOU status for 24 hours, but the effect on admissions is unknown. Our primary hypothesis was that we could predict which OOU patients required admission based on the presence of uncontrolled pain. Data were prospectively collected for all OOU patients in this prospective observational study, including data on extremity cellulitis, fractures, and spine injuries awaiting brace placement.The primary outcome variable was admission to the hospital versus discharge home. The a priori hypotheses were that patients with more persistent or worsening pain would require admission more often and that the OOU would result in fewer patients needing a costlier inpatient admission to the hospital. An a priori power analysis showed adequate power of 80% to detect a difference between admitted and discharged patients. Data were prospectively collected from August 2011 to August 2012 for 199 consecutive OOU patients, 62% of whom were men. Diagnoses included infection (cellulitis or abscess of extremity) in 76%, fracture in 15% and other in 9% of the patients. Sixty-two patients (31%) were admitted and 7 patients (4%) made return visits for the same problem within a 30-day period. No significant relations existed between any of the independent variables and admission on bivariate analysis. Multivariable logistic regression found no significant predictors of hospital admission. Logistic regression was not performed on 30-day returns because of the low event rate (4%). An OOU prevented 138 of 199 (69%) patients from being admitted to a hospital. There were no significant predictors of which patients would require admission. Pain was not a predictor of need for admission. The lack of significant predictors is important in suggesting that without the ability to predict which patients require admission, a system using an OOU can reduce admissions by more than
Student incentives and preferential treatment in college admissions
2012-01-01
We consider a framework in which the optimal admissions policy of a purely academicquality oriented college implements preferential treatment in favor of the student from the deprived socioeconomic background which maximizes the competition between candidates. We find that the exact form of the preferential treatment admissions policy matters for student incentives and hence for student-body diversity in equilibrium. Preferential treatment policy in college admissions often tak...
Vikas, Hash(0xb7f6e60)
2012-01-01
Hydrogen molecule in a strong ultrashort magnetic field is investigated through a current-density functional theory (CDFT) and quantum fluid dynamics (QFD) based approach employing current-density dependent vector exchange-correlation potential and energy density functional derived with a vorticity variable. The numerical computations through the CDFT based approach are performed for the H2 molecule, starting initially from its field-free ground state, in a parallel internuclear axis and magnetic field-axis configuration with the internuclear separation R ranging from 0.1 a.u. to 14.0 a.u., and the strength of the time-dependent (TD) magnetic field varying between 0-1011 G over a few femtoseconds. The numerical results are compared with that obtained using an approach based on the current-density independent approximation under similar computational constraints but employing only scalar exchange-correlation potential dependent on the electronic charge-density alone. The current-density based approach yields exchange- and correlation energy as well as electronic charge-density of the H2 molecule drastically different from that obtained using current-independent approach, in particular, at TD magnetic field-strengths >109 G during a typical time-period of the field when the magnetic-field had attained maximum applied field-strength and is switched to a decreasing ramp function. This nonadiabatic behavior of the TD electronic charge-density is traced to the TD vorticity-dependent vector exchange-correlation potential of the CDFT based approach. The interesting electron dynamics of the H2 molecule in strong TD magnetic field is further elucidated by treating electronic charge-density as an `electron-fluid'. The present work also reveals interesting real-time dynamics on the attosecond time-scale in the electronic charge-density distribution of the hydrogen molecule.
Namibia's exceptional admission to the ILO.
Fromont, M
1998-01-01
Namibia officially became the 136th ¿member state¿ of the International Labour Office (ILO) on October 3, 1978. At that time Namibia was politically dependent on South Africa and lived under apartheid. This stood in contradiction to international law, given that since October 1966 the UN General Assembly had terminated the Republic of South Africa's mandate over the territory. In 1967 it had entrusted its official administration to the UN Council for Namibia, which requested Namibia's admission to the ILO as a full member. Namibia met all the criteria required of a state: an established population and territory, a stable and internationally recognized legal structure, together with the capacity to enter into relations with other states. Namibia was recognized by the Conference as the de-facto authentic government through an election in which 368 voted in favor of Namibia with no oppositions and 50 abstentions.
Allocation and Admission Policies for Service Streams
Mazzucco, Michele; Fisher, Mike; McKee, Paul
2011-01-01
A service provisioning system is examined, where a number of servers are used to offer different types of services to paying customers. A customer is charged for the execution of a stream of jobs; the number of jobs in the stream and the rate of their submission is specified. On the other hand, the provider promises a certain quality of service (QoS), measured by the average waiting time of the jobs in the stream. A penalty is paid if the agreed QoS requirement is not met. The objective is to maximize the total average revenue per unit time. Dynamic policies for making server allocation and stream admission decisions are introduced and evaluated. The results of several simulations are described.
Superconformal minimal models and admissible Jack polynomials
Blondeau-Fournier, Olivier; Ridout, David; Wood, Simon
2016-01-01
We give new proofs of the rationality of the N=1 superconformal minimal model vertex operator superalgebras and of the classification of their modules in both the Neveu-Schwarz and Ramond sectors. For this, we combine the standard free field realisation with the theory of Jack symmetric functions. A key role is played by Jack symmetric polynomials with a certain negative parameter that are labelled by admissible partitions. These polynomials are shown to describe free fermion correlators, suitably dressed by a symmetrising factor. The classification proofs concentrate on explicitly identifying Zhu's algebra and its twisted analogue. Interestingly, these identifications do not use an explicit expression for the non-trivial vacuum singular vector. While the latter is known to be expressible in terms of an Uglov symmetric polynomial or a linear combination of Jack superpolynomials, it turns out that standard Jack polynomials (and functions) suffice to prove the classification.
Weight Representations of Admissible Affine Vertex Algebras
Arakawa, Tomoyuki; Futorny, Vyacheslav; Ramirez, Luis Enrique
2017-08-01
For an admissible affine vertex algebra {V_k{(\\mathfrak{g})}} of type A, we describe a new family of relaxed highest weight representations of {V_k{(\\mathfrak{g})}}. They are simple quotients of representations of the affine Kac-Moody algebra {\\widehat{\\mathfrak{g}}} induced from the following {\\mathfrak{g}}-modules: (1) generic Gelfand-Tsetlin modules in the principal nilpotent orbit, in particular all such modules induced from {\\mathfrak{sl}_2}; (2) all Gelfand-Tsetlin modules in the principal nilpotent orbit that are induced from {\\mathfrak{sl}_3}; (3) all simple Gelfand-Tsetlin modules over {\\mathfrak{sl}_3}. This in particular gives the classification of all simple positive energy weight representations of {V_k{(\\mathfrak{g})}} with finite dimensional weight spaces for {\\mathfrak{g}=\\mathfrak{sl}_3}.
[Triage in acute medical admission units.
DEFF Research Database (Denmark)
Brabrand, Mikkel; Folkestad, Lars; Hallas, Peter
2010-01-01
. At 87% of the MAUs, a doctor was contacted by the admitting physician, while the contact was the responsibility of a nurse in 13% of MAUs. None of the contacted MAUs used a validated triage tool and 95% answered that they triaged on the basis of individual clinical assessment of patients. However, 22......INTRODUCTION: Many emergency departments use validated triage tools. It is currently undocumented if such a practice is common in Danish medical admission units (MAU). The current study was conducted in order to clarify this. MATERIAL AND METHODS: Questionnaire survey with data collected from......% answered that selected groups of patients were routinely assessed by a senior physician. CONCLUSION: None of the Danish MAUs uses a validated triage tool to prioritize acutely admitted medical patients. Udgivelsesdato: 2010-May-31...
Recurrent Admissions for Diabetic Foot Complications
Directory of Open Access Journals (Sweden)
Ang CL
2013-07-01
Full Text Available Diabetic foot complications are a significant source of morbidity and mortality. Patients who undergo recurrent admissions for the same diabetic foot problems represent a difficult subgroup to treat. From July 2007 to June 2008, there were 38 such patients who were admitted recurrently. Eighteen patients (47% were re-admitted because of previous refusal of surgical treatment. Eighteen patients (47% received treatment as necessary but were still readmitted for recurrent infection at the same wound site. Assessment of patients’ compliance to outpatient treatment was found to be generally lacking. As a significant proportion were re-admitted because of previous refusal of surgery, a trained counselor may be suitable in counselling patients for debridement or amputation surgery.
Steady-State Density Functional Theory for Finite Bias Conductances.
Stefanucci, G; Kurth, S
2015-12-09
In the framework of density functional theory, a formalism to describe electronic transport in the steady state is proposed which uses the density on the junction and the steady current as basic variables. We prove that, in a finite window around zero bias, there is a one-to-one map between the basic variables and both local potential on as well as bias across the junction. The resulting Kohn-Sham system features two exchange-correlation (xc) potentials, a local xc potential, and an xc contribution to the bias. For weakly coupled junctions the xc potentials exhibit steps in the density-current plane which are shown to be crucial to describe the Coulomb blockade diamonds. At small currents these steps emerge as the equilibrium xc discontinuity bifurcates. The formalism is applied to a model benzene junction, finding perfect agreement with the orthodox theory of Coulomb blockade.
Analytical gradients for excitation energies from frozen-density embedding.
Kovyrshin, Arseny; Neugebauer, Johannes
2016-08-21
The formulation of analytical excitation-energy gradients from time-dependent density functional theory within the frozen-density embedding framework is presented. In addition to a comprehensive mathematical derivation, we discuss details of the numerical implementation in the Slater-function based Amsterdam Density Functional (ADF) program. Particular emphasis is put on the consistency in the use of approximations for the evaluation of second- and third-order non-additive kinetic-energy and exchange-correlation functional derivatives appearing in the final expression for the excitation-energy gradient. We test the implementation for different chemical systems in which molecular excited-state potential-energy curves are affected by another subsystem. It is demonstrated that the analytical implementation for the evaluation of excitation-energy gradients yields results in close agreement with data from numerical differentiation. In addition, we show that our analytical results are numerically more stable and thus preferable over the numerical ones.
Density Functional Theory and Materials Modeling at Atomistic Length Scales
Directory of Open Access Journals (Sweden)
Swapan K. Ghosh
2002-04-01
Full Text Available Abstract: We discuss the basic concepts of density functional theory (DFT as applied to materials modeling in the microscopic, mesoscopic and macroscopic length scales. The picture that emerges is that of a single unified framework for the study of both quantum and classical systems. While for quantum DFT, the central equation is a one-particle Schrodinger-like Kohn-Sham equation, the classical DFT consists of Boltzmann type distributions, both corresponding to a system of noninteracting particles in the field of a density-dependent effective potential, the exact functional form of which is unknown. One therefore approximates the exchange-correlation potential for quantum systems and the excess free energy density functional or the direct correlation functions for classical systems. Illustrative applications of quantum DFT to microscopic modeling of molecular interaction and that of classical DFT to a mesoscopic modeling of soft condensed matter systems are highlighted.
Double-hybrid density-functional theory made rigorous
Sharkas, Kamal; Savin, Andreas
2010-01-01
We provide a rigorous derivation of a class of double-hybrid approximations, combining Hartree-Fock exchange and second-order Moller-Plesset correlation with a semilocal exchange-correlation density functional. These double-hybrid approximations contain only one empirical parameter and use a density-scaled correlation energy functional. Neglecting density scaling leads to an one-parameter version of the standard double-hybrid approximations. We assess the performance of these double-hybrid schemes on representative test sets of atomization energies and reaction barrier heights, and we compare to other hybrid approximations, including range-separated hybrids. Our best one-parameter double-hybrid approximation, called 1DH-BLYP, roughly reproduces the two parameters of the standard B2-PLYP or B2GP-PLYP double-hybrid approximations, which shows that these methods are not only empirically close to an optimum for general chemical applications but are also theoretically supported.
Assisted admissions? A national survey of general practitioner experience of involuntary admissions.
LENUS (Irish Health Repository)
Kelly, M
2011-10-01
The 2001 Mental Health Act introduced in 2006, changed how a patient is admitted involuntarily to a psychiatric unit. This paper reports on a national survey of general practitioners\\' experience implementing the Act. Five hundred and sixty eight (568) GPs completed the survey. Twenty five percent (25%) of respondants had not used it. When used, twenty four percent (24%) report that it takes seven hours or more to complete an admission. Fifty percent (50%) of respondents are confident to complete the necessary paperwork. Overall GPs are dissatisfied with arrangements for transport of patients (mean Likert score 3.5), primarily due to the time delay. GPs believe this places risk on the patient, family and GP. Only thirty-three percent (33%) of respondents feel that the Mental Health Act has improved the patient, GP and family experience of involuntary admission.
Numerical Methods for a Kohn-Sham Density Functional Model Based on Optimal Transport.
Chen, Huajie; Friesecke, Gero; Mendl, Christian B
2014-10-14
In this paper, we study numerical discretizations to solve density functional models in the "strictly correlated electrons" (SCE) framework. Unlike previous studies, our work is not restricted to radially symmetric densities. In the SCE framework, the exchange-correlation functional encodes the effects of the strong correlation regime by minimizing the pairwise Coulomb repulsion, resulting in an optimal transport problem. We give a mathematical derivation of the self-consistent Kohn-Sham-SCE equations, construct an efficient numerical discretization for this type of problem for N = 2 electrons, and apply it to the H2 molecule in its dissociating limit.
Yao, Kun
2015-01-01
We demonstrate a convolutional neural network trained to reproduce the Kohn-Sham kinetic energy of hydrocarbons from electron density. The output of the network is used as a non-local correction to the conventional local and semi-local kinetic functionals. We show that this approximation qualitatively reproduces Kohn-Sham potential energy surfaces when used with conventional exchange correlation functionals. Numerical noise inherited from the non-linearity of the neural network is identified as the major challenge for the model. Finally we examine the features in the density learned by the neural network to anticipate the prospects of generalizing these models.
Energy Technology Data Exchange (ETDEWEB)
Kapoor, Varun; Brics, Martins; Bauer, Dieter [Institut fuer Physik, Universitaet Rostock, 18051 Rostock (Germany)
2013-07-01
Autoionizing states are inaccessible to time-dependent density functional theory (TDDFT) using known, adiabatic Kohn-Sham (KS) potentials. We determine the exact KS potential for a numerically exactly solvable model Helium atom interacting with a laser field that is populating an autoionizing state. The exact single-particle density of the population in the autoionizing state corresponds to that of the energetically lowest quasi-stationary state in the exact KS potential. We describe how this exact potential controls the decay by a barrier whose height and width allows for the density to tunnel out and decay with the same rate as in the ab initio time-dependent Schroedinger calculation. However, devising a useful exchange-correlation potential that is capable of governing such a scenario in general and in more complex systems is hopeless. As an improvement over TDDFT, time-dependent reduced density matrix functional theory has been proposed. We are able to obtain for the above described autoionization process the exact time-dependent natural orbitals (i.e., the eigenfunctions of the exact, time-dependent one-body reduced density matrix) and study the potentials that appear in the equations of motion for the natural orbitals and the structure of the two-body density matrix expanded in them.
Mo, Yuxiang; Car, Roberto; Staroverov, Viktor N.; Scuseria, Gustavo E.; Tao, Jianmin
2017-01-01
Recently, Tao and Mo developed a semilocal exchange-correlation density functional. The exchange part of this functional is derived from a density-matrix expansion corrected to reproduce the fourth-order gradient expansion of the exchange energy in the slowly-varying-density limit, while the correlation part is based on the Tao-Perdew-Staroverov-Scuseria (TPSS) correlation functional, with a modification for the low-density limit. In the present paper, the Tao-Mo (TM) functional is assessed by computing various properties of solids and jellium surfaces. This includes 22 lattice constants and bulk moduli, 30 band gaps, seven cohesive energies, and jellium surface exchange and correlation energies for the density parameter rs in the range from 2 to 3 bohr. Our calculations show that the TM approximation can yield consistently high accuracy for most properties considered here, with mean absolute errors (MAEs) of 0.025 Å for lattice constants, 7.0 GPa for bulk moduli, 0.08 eV/atom for cohesive energies, and 35 erg /c m2 for surface exchange-correlation energies. The MAE in band gaps is larger than that of TPSS, but slightly smaller than the errors of the local spin-density approximation, Perdew-Burke-Ernzerhof generalized gradient approximation, and revised TPSS. However, band gaps are still underestimated, particularly for large-gap semiconductors, compared to the Heyd-Scuseria-Ernzerhof nonlocal screened hybrid functional.
Evaluating the Predictive Validity of Graduate Management Admission Test Scores
Sireci, Stephen G.; Talento-Miller, Eileen
2006-01-01
Admissions data and first-year grade point average (GPA) data from 11 graduate management schools were analyzed to evaluate the predictive validity of Graduate Management Admission Test[R] (GMAT[R]) scores and the extent to which predictive validity held across sex and race/ethnicity. The results indicated GMAT verbal and quantitative scores had…
Evaluating the Predictive Validity of Graduate Management Admission Test Scores
Sireci, Stephen G.; Talento-Miller, Eileen
2006-01-01
Admissions data and first-year grade point average (GPA) data from 11 graduate management schools were analyzed to evaluate the predictive validity of Graduate Management Admission Test[R] (GMAT[R]) scores and the extent to which predictive validity held across sex and race/ethnicity. The results indicated GMAT verbal and quantitative scores had…
Low hospital admission rates for respiratory diseases in children.
Uijen, J.H.J.M.; Schellevis, F.G.; Bindels, P.J.E.; Willemsen, S.P.; Wouden, J.C. van der
2010-01-01
BACKGROUND: Population-based data on hospital admissions for children aged 0-17 years concerning all respiratory diseases are scarce. This study examined hospital admissions in relation to the preceding consultations in general practice in this age group. METHODS: Data on children aged 0-17 years wi
Using Social Media "Smartly" in the Admissions Process
Parrot, Teresa Valerio; Tipton, Stacia
2010-01-01
Admissions officers around the country are hearing consistent calls to enhance their social media presence. Whether the pressure is from administrators, influential alumni, or peers across institutions, social media are touted as the next big thing in admissions marketing. But are social media strategies truly "strategic," or are they merely…
A Revised Admissions Standard for One Community College Nursing Program
Lown, Maris A.
2010-01-01
Predicting success on the NCLEX-RN is of paramount importance to nursing programs as they are held accountable for this outcome by accrediting agencies and by boards of nursing. This action research study examined the relationship between the NET admission test, anatomy and physiology grades, grade point average (GPA) on admission to the program…
4 CFR 25.3 - Admission to the GAO building.
2010-01-01
... 4 Accounts 1 2010-01-01 2010-01-01 false Admission to the GAO building. 25.3 Section 25.3 Accounts GOVERNMENT ACCOUNTABILITY OFFICE GENERAL PROCEDURES CONDUCT IN THE GOVERNMENT ACCOUNTABILITY OFFICE BUILDING AND ON ITS GROUNDS § 25.3 Admission to the GAO building. A person may be admitted to the GAO Building...
42 CFR 418.25 - Admission to hospice care.
2010-10-01
... 42 Public Health 3 2010-10-01 2010-10-01 false Admission to hospice care. 418.25 Section 418.25... (CONTINUED) MEDICARE PROGRAM HOSPICE CARE Eligibility, Election and Duration of Benefits § 418.25 Admission to hospice care. (a) The hospice admits a patient only on the recommendation of the medical...
A Revised Admissions Standard for One Community College Nursing Program
Lown, Maris A.
2010-01-01
Predicting success on the NCLEX-RN is of paramount importance to nursing programs as they are held accountable for this outcome by accrediting agencies and by boards of nursing. This action research study examined the relationship between the NET admission test, anatomy and physiology grades, grade point average (GPA) on admission to the program…
Using Social Media "Smartly" in the Admissions Process
Parrot, Teresa Valerio; Tipton, Stacia
2010-01-01
Admissions officers around the country are hearing consistent calls to enhance their social media presence. Whether the pressure is from administrators, influential alumni, or peers across institutions, social media are touted as the next big thing in admissions marketing. But are social media strategies truly "strategic," or are they merely…
29 CFR 458.71 - Procedure upon admission of facts.
2010-07-01
... 29 Labor 2 2010-07-01 2010-07-01 false Procedure upon admission of facts. 458.71 Section 458.71... facts. The admission of all the material allegations of fact in the complaint shall constitute a waiver... his recommended decision and order in which he shall adopt as his proposed findings of fact...
10 CFR 590.308 - Admissions of facts.
2010-01-01
... 10 Energy 4 2010-01-01 2010-01-01 false Admissions of facts. 590.308 Section 590.308 Energy... WITH RESPECT TO THE IMPORT AND EXPORT OF NATURAL GAS Procedures § 590.308 Admissions of facts. (a) At... proceeding that relate to statements or opinions of fact or of the application of law to fact. (b) A...
Strategic Enrollment Management's Ambassadors: The Changing Role of Admissions Counselors
Mathis, Daniel
2010-01-01
Road runner. File jockey. Advisor. Public speaker. Recruiter. At any given time, an admissions counselor fits one, some, or all of these descriptors. While all of these descriptors indicate an important function within a college or university, none reflects the increasingly complex nature of the role of an admissions counselor in strategic…
24 CFR 1720.425 - Presentation and admission of evidence.
2010-04-01
... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Presentation and admission of evidence. 1720.425 Section 1720.425 Housing and Urban Development Regulations Relating to Housing and Urban... PRACTICE Adjudicatory Proceedings Discovery and Evidence § 1720.425 Presentation and admission of...
An Evaluation of the Simulated Minority Admissions Exercise.
Sedlacek, William E.; Prieto, Dario O.
1982-01-01
The Simulated Minority Admissions Exercise, an educational technique that simulates a typical medical school admissions situation, is described. The main objective is to help medical schools to select potentially successful minority applicants and to improve their retention by ensuring that they enter medical school under positive circumstances.…
14 CFR 125.315 - Admission to flight deck.
2010-01-01
... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Admission to flight deck. 125.315 Section...,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Flight Operations § 125.315 Admission to flight deck. (a) No person may admit any person to the flight deck of an airplane unless...
28 CFR 541.47 - Admission to control unit.
2010-07-01
... the inmate's confinement in a control unit; (b) Notice of the type of personal property which is... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Admission to control unit. 541.47 Section... INMATE DISCIPLINE AND SPECIAL HOUSING UNITS Control Unit Programs § 541.47 Admission to control...
UCT's Admissions Policies: Is the Playing Field Level?
Favish, J.; Hendry, J.
2010-01-01
The article outlines how UCT's commitment to redress and diversity has officially guided the university's approach to admissions planning. In 2009 the Senate requested the Vice Chancellor to conduct a review of the admissions policy particularly to determine whether race continued to be an adequate proxy for disadvantage. This article analyses…
Affirmative Action in College and University Admissions: Yes.
Michaelson, Martin
1999-01-01
Argues in support of affirmative action in college and university admissions, noting the actual, relatively small effect of affirmative action on white admission and opportunity, and suggesting other possible reasons for the heated debate. Notes two related Supreme Court decisions made a century apart and reviews statistical studies in support of…
Communications Is from Mars, Admissions Is from Venus
Scully, Maura King
2010-01-01
Marketing communications and admissions often have very different needs, priorities, and ways of conducting business, but the two units work toward the same end goal. Brad Ward of BlueFuego, a marketing company that specializes in social Web tools for educational institutions, explains that admissions doesn't necessarily need to [talk] to…
Evaluating Admission Criteria Effects for Under-Represented Groups
Childs, Ruth A.; Ferguson, Amanda K.; Herbert, Monique B.; Broad, Kathryn; Zhang, Jingshun
2016-01-01
The effects that admission criteria may have for under-represented groups are an important concern for programs seeking to improve access to post-secondary education. Using data from a large preservice teacher education program in the Canadian province of Ontario, we demonstrate two approaches to evaluating the effects of admission criteria. The…
14 CFR 121.547 - Admission to flight deck.
2010-01-01
... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Admission to flight deck. 121.547 Section 121.547 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED... REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Flight Operations § 121.547 Admission to flight deck...
Environmental Scan of BC Post-Secondary Admissions: 2009
Heath, Nick
2009-01-01
In 2008, British Columbia Council on Admissions and Transfer (BCCAT) commissioned an environmental scan on the possible need for system-wide work on institutional admissions processes and practices. This scan is intended to seek system input and to provide guidance on the choice of research projects and other related work in the coming year. This…
Increasing the admission rate to upper secondary school
DEFF Research Database (Denmark)
Hoest, A.; Jensen, V.M.; Nielsen, L.P.
2013-01-01
the effects of a school intervention that introduces structured student career guidance in lower secondary school on upper secondary school admission. Disregarding the sunk-cost of implementation, the reform was cost-neutral. In a difference-in-difference framework, we find that the reform increases admission...
Psychiatric Inpatient Admissions of Adults with Intellectual Disabilities: Predictive Factors
Cowley, Amy; Newton, Jonathan; Sturmey, Peter; Bouras, Nick; Holt, Geraldine
2005-01-01
Information on admission to psychiatric inpatient units is lacking from the literature on contemporary services for people with intellectual disability and mental health needs. Here we report on predictors of admission for a cohort of 752 adults from this population living in community settings; 83 were admitted. We also report on two subsamples…
SOFTWARE OPTIMIZATION OF BUSINESS PROCESS “UNIVERSITY ADMISSION CAMPAIGN”
Directory of Open Access Journals (Sweden)
Victor V. Babenko
2015-01-01
Full Text Available Admission campaign is an important part of the main business processes system of the university. Admission campaign is analyzed on the base of different modeling tools. The conceptual basis of CRM-system as information support of the process is proposed. It should be significant optimizing resource of business process.
Transformation of admission interview to documentation for nursing practice
DEFF Research Database (Denmark)
Højskov, Ida E; Glasdam, Stinne
2014-01-01
by Ricoeur was conducted and consisted of five taped admission interviews, along with the written patient documentation subsequently worked out by the nurse. The findings were presented in four constructed themes: Admission interviews are the nurse's room rather than the patient's; Information on a surgical......The admission interview is usually the first structured meeting between patient and nurse. The interview serves as the basis for personalised nursing and care planning and is the starting point for the clinic's documentation of the patient and his course of treatment. In this way, admission...... interviews constitute a basis for reporting by each nurse on the patient to nursing colleagues. This study examined how, by means of the admission interview, nurses constructed written documentation of the patient and his course of treatment for use by fellow nurses. A qualitative case study inspired...
Admissibility, stable units and connected components
Xarez, J J
2011-01-01
Consider a reflection from a finitely-complete category $\\mathbb{C}$ into its full subcategory $\\mathbb{M}$, with unit $\\eta :1_\\mathbb{C}\\rightarrow HI$. Suppose there is a left-exact functor $U$ into the category of sets, such that $UH$ reflects isomorphisms and $U(\\eta_C)$ is a surjection, for every $C\\in\\mathbb{C}$. If, in addition, all the maps $\\mathbb{M}(T,M)\\rightarrow \\mathbf{Set}(1,U(M))$ induced by the functor $UH$ are surjections, where $T$ and 1 are respectively terminal objects in $\\mathbb{C}$ and $\\mathbf{Set}$, for every object $M$ in the full subcategory $\\mathbb{M}$, then it is true that: the reflection $H\\vdash I$ is semi-left-exact (admissible in the sense of categorical Galois theory) if and only if its connected components are "connected"; it has stable units if and only if any finite product of connected components is "connected". Where the meaning of "connected" is the usual in categorical Galois theory, and the definition of connected component with respect to the ground structure wil...
Involuntary admission: the case of anorexia nervosa.
Douzenis, Athanasios; Michopoulos, Ioannis
2015-01-01
Involuntary treatment of psychiatric disorders has always been controversial; this is especially true for eating disorders. Patients with anorexia nervosa of life threatening severity frequently refuse psychiatric hospitalization. Ambivalence toward treatment is characteristic of eating disorders and patients are often admitted to inpatient programs under pressure from family and doctors. In this article, we report research on the positive or negative impact of involuntary admission in the treatment of eating disorders, its application and effectiveness as well as the adverse consequences of coercive treatment in eating disorders. A literature review was done. From a total of 134 publications which were retrieved from the literature search, 50 studies were directly relevant to the scope of this review and fulfilled all inclusion criteria. There are trends and arguments for both sides; for and against involuntary treatment in anorexia nervosa. The scientific literature so far is inconclusive, although in the short term, involuntary hospitalization has benefits. This review has also shown that involuntary hospitalization can have adverse long-term consequences for the patient-therapist allegiance. We conclude that in some cases, involuntary treatment can save lives of young patients with anorexia nervosa; however, in other cases, it can break the psychotherapeutic relationship and make the patient abandon treatment. It is the clinician who has to decide for whom and when to approve involuntary treatment or not.
Admissibility of scientific evidence post-Daubert.
Masten, J; Strzelczyk, J J
2001-12-01
Proof of medical causation is the key element in cases involving alleged radiation injury. Until 1993, the use of scientific testimony in the courtroom was governed by the Frye doctrine requiring that a theory be "generally accepted" before it can be the basis of an expert's opinion. Applying that rule trial courts adopted a "let it all in" approach resulting in a near overdose of pseudoscience presented to juries. With its decision in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 113 S. Ct. 2786 (1993), the U.S. Supreme Court announced a new five-factor, non-exclusive test for federal district courts to consider when assessing the opinion of scientific experts. The Court further directed that the trial courts, acting as a gatekeeper for expert evidence, must evaluate whether there is an adequate "fit" between the expert's data and the opinion offered. This article examines how the Daubert standard has been implemented in federal court to combat junk science. Examples from recent case law dealing with operational health physics issues are presented as an illustration of the use of the five-factor test to challenge questionable testimony on causation. Guidance is offered to prospective expert witnesses in radiation-related litigation to insure that proposed testimony will be admissible in district court.
Harasym, P. H.; And Others
1995-01-01
The University of Calgary (Canada) medical school admissions process has been streamlined with the Student Admission to Medicine computer program, largely paperless, that creates a database from student applications. The database then converts grades to the university's standards and assists with administrative details, statistical analyses, and…
Hirano, Toshiyuki; Sato, Fumitoshi
2014-07-28
We used grid-free modified Cholesky decomposition (CD) to develop a density-functional-theory (DFT)-based method for calculating the canonical molecular orbitals (CMOs) of large molecules. Our method can be used to calculate standard CMOs, analytically compute exchange-correlation terms, and maximise the capacity of next-generation supercomputers. Cholesky vectors were first analytically downscaled using low-rank pivoted CD and CD with adaptive metric (CDAM). The obtained Cholesky vectors were distributed and stored on each computer node in a parallel computer, and the Coulomb, Fock exchange, and pure exchange-correlation terms were calculated by multiplying the Cholesky vectors without evaluating molecular integrals in self-consistent field iterations. Our method enables DFT and massively distributed memory parallel computers to be used in order to very efficiently calculate the CMOs of large molecules.
U.S. Environmental Protection Agency — Road density is generally highly correlated with amount of developed land cover. High road densities usually indicate high levels of ecological disturbance. More...
Sun, Jianwei; Perdew, John P.; Yang, Zenghui; Peng, Haowei
2016-05-01
The uniform electron gas and the hydrogen atom play fundamental roles in condensed matter physics and quantum chemistry. The former has an infinite number of electrons uniformly distributed over the neutralizing positively charged background, and the latter only one electron bound to the proton. The uniform electron gas was used to derive the local spin density approximation to the exchange-correlation functional that undergirds the development of the Kohn-Sham density functional theory. We show here that the ground-state exchange-correlation energies of the hydrogen atom and many other 1- and 2-electron systems are modeled surprisingly well by a different local spin density approximation (LSDA0). LSDA0 is constructed to satisfy exact constraints but agrees surprisingly well with the exact results for a uniform two-electron density in a finite, curved three-dimensional space. We also apply LSDA0 to excited or noded 1-electron densities, where it works less well. Furthermore, we show that the localization of the exact exchange hole for a 1- or 2-electron ground state can be measured by the ratio of the exact exchange energy to its optimal lower bound.
Forecasting paediatric malaria admissions on the Kenya Coast using rainfall.
Karuri, Stella Wanjugu; Snow, Robert W
2016-01-01
Malaria is a vector-borne disease which, despite recent scaled-up efforts to achieve control in Africa, continues to pose a major threat to child survival. The disease is caused by the protozoan parasite Plasmodium and requires mosquitoes and humans for transmission. Rainfall is a major factor in seasonal and secular patterns of malaria transmission along the East African coast. The goal of the study was to develop a model to reliably forecast incidences of paediatric malaria admissions to Kilifi District Hospital (KDH). In this article, we apply several statistical models to look at the temporal association between monthly paediatric malaria hospital admissions, rainfall, and Indian Ocean sea surface temperatures. Trend and seasonally adjusted, marginal and multivariate, time-series models for hospital admissions were applied to a unique data set to examine the role of climate, seasonality, and long-term anomalies in predicting malaria hospital admission rates and whether these might become more or less predictable with increasing vector control. The proportion of paediatric admissions to KDH that have malaria as a cause of admission can be forecast by a model which depends on the proportion of malaria admissions in the previous 2 months. This model is improved by incorporating either the previous month's Indian Ocean Dipole information or the previous 2 months' rainfall. Surveillance data can help build time-series prediction models which can be used to anticipate seasonal variations in clinical burdens of malaria in stable transmission areas and aid the timing of malaria vector control.
Impact of psychiatrists' qualifications on the rate of compulsory admissions.
Eytan, Ariel; Chatton, Anne; Safran, Edith; Khazaal, Yasser
2013-03-01
Despite efforts to reduce coercion in psychiatry, involuntary hospitalizations remain frequent, representing more than half of all admissions in some European regions. Since October 2006, only certified psychiatrists are authorized to require a compulsory admission to our facility, while before all physicians were, including residents. The aim of the present study is to assess the impact of this change of procedure on the proportion compulsory admissions. All medical records of patients admitted respectively 4 months before and 4 month after the implementation of the procedure were retrospectively analyzed. This search retrieved a total of 2,227 hospitalizations for 1,584 patients. The overall proportions of compulsory and voluntary admissions were 63.9 % and 36.1 % respectively. The average length of stay was 32 days (SD ± 64.4). During the study period, 25 % of patients experienced two hospitalizations or more. The most frequent patients' diagnoses were affective disorders (30 %), psychotic disorders (18.4 %) and substance abuse disorders (15.7 %). Compared with the period before October 2006, patients hospitalized from October 2006 up were less likely to be hospitalized on a compulsory basis (OR = 0.745, 95 % CI: 0.596-0.930). Factors associated with involuntary admission were young age (20 years or less), female gender, a diagnosis of psychotic disorder and being hospitalized for the first time. Our results strongly suggest that limiting the right to require compulsory admissions to fully certified psychiatrists can reduce the rate of compulsory versus voluntary admissions.
Admissions for personality disorders in Italy from 1988 to 1998
Directory of Open Access Journals (Sweden)
Barbui Corrado
2006-08-01
Full Text Available Abstract Background Personality disorders affect a substantial proportion of the population. It is unclear, however, whether the burden of personality disorders on modern mental health services has been increasing. To fill this gap, we analyzed trends in admissions for personality disorders in Italy from 1988 to 1998. Methods We used the yearly data from the Italian Central Institute of Statistics to analyse trends in the total number of admissions for personality disorders and in the total number of first admissions for personality disorders. Results The absolute number of admissions for personality disorders almost trebled from 1988 to 1998, as well as the proportion of all psychiatric admissions that were for personality disorders. Whilst there has been a marked increase in the absolute number of first admissions, the proportion of all first psychiatric admissions that were for personality disorders showed a steady but modest increase, from 5.7% to 7.6%. Conclusion In Italy, the burden of personality disorders on modern mental health services has been increasing. In terms of public health, these findings highlight the urgent need of developing policies to tackle the increasing demand of care of this difficult-to-treat patient population.
Low hospital admission rates for respiratory diseases in children
Directory of Open Access Journals (Sweden)
Willemsen Sten P
2010-10-01
Full Text Available Abstract Background Population-based data on hospital admissions for children aged 0-17 years concerning all respiratory diseases are scarce. This study examined hospital admissions in relation to the preceding consultations in general practice in this age group. Methods Data on children aged 0-17 years with respiratory diseases included in the Second Dutch National Survey of General Practice (DNSGP-2 were linked to all hospital admissions in the Dutch National Medical Registration. Admission rates for respiratory diseases were calculated. Data were analysed using multivariate logistic regression. Results Of all 79,272 children within the DNSGP-2, 1.8% were admitted to hospital for any respiratory diagnosis. The highest admission rates per 1000 children were for chronic disease of tonsils and adenoids (12.9; pneumonia and influenza (0.97; and asthma (0.92. Children aged 0-4 years and boys were admitted more frequently. Of children with asthma, 2.3% were admitted for respiratory diseases. For asthma, admission rates varied by urbanisation level: 0.47/1000 children/year in cities with ≤ 30,000 inhabitants, 1.12 for cities with ≥ 50,000 inhabitants, and 1.73 for the three largest cities (p = 0.002. Multivariate logistic regression showed that within two weeks after a GP consultation, younger age (OR 0.81, 95% CI 0.76-0.88 and more severe respiratory diseases (5.55, 95% CI 2.99-8.11 predicted hospital admission. Conclusions Children in the general population with respiratory diseases (especially asthma had very low hospital admission rates. In urban regions children were more frequently admitted due to respiratory morbidity. For effectiveness studies in a primary care setting, hospital admission rates should not be used as quality end-point.
Correlation of admission criteria with dental school performance and attrition.
Sandow, Pamela L; Jones, Anne C; Peek, Chuck W; Courts, Frank J; Watson, Ronald E
2002-03-01
This study was conducted to provide current information on the relationship between admission criteria and dental school performance, including the association of admission criteria and dental school outcomes such as remediation and attrition. Standard tests of bivariate association and multivariate regression models appropriate for continuous and discrete dependent variables were used to examine the relationship between multiple indicators of admission criteria and dental school performance for six recent classes at the University of Florida College of Dentistry (UFCD). The admission criteria included the undergraduate science grade point average (GPA), undergraduate non-science GPA, Dental Admissions Test (DAT) academic score, Perceptual Motor Aptitude Test (PMAT) score, and admission interview score. Measures of dental school performance were the National Dental Board Examination Part I and Part II (NB-I, NB-II) scores, yearly and final dental school GPA, and academic progress through the UFCD program. In general, most admission criteria were good bivariate indicators of dental school performance. Multivariate analyses indicated that students with higher undergraduate science GPAs and DAT academic scores were more likely to achieve higher NB-I and NB-II scores. The undergraduate science GPA and admission interview score were the most consistent determinants of dental school GPA. Students with lower undergraduate science GPAs, DAT academic scores, and PMAT scores were more likely to remediate, to repeat an academic year, or to be dismissed. Although bivariate differences were observed in several admission criteria of students who remediated one or more courses, repeated an academic year, or were dismissed only the undergraduate science GPA and the PMAT score were indicators of programmatic progress in the multivariate analysis.
Nonequilibrium Anderson model made simple with density functional theory
Kurth, S.; Stefanucci, G.
2016-12-01
The single-impurity Anderson model is studied within the i-DFT framework, a recently proposed extension of density functional theory (DFT) for the description of electron transport in the steady state. i-DFT is designed to give both the steady current and density at the impurity, and it requires the knowledge of the exchange-correlation (xc) bias and on-site potential (gate). In this work we construct an approximation for both quantities which is accurate in a wide range of temperatures, gates, and biases, thus providing a simple and unifying framework to calculate the differential conductance at negligible computational cost in different regimes. Our results mark a substantial advance for DFT and may inform the construction of functionals applicable to other correlated systems.
Linear density response function in the projector augmented wave method
DEFF Research Database (Denmark)
Yan, Jun; Mortensen, Jens Jørgen; Jacobsen, Karsten Wedel;
2011-01-01
We present an implementation of the linear density response function within the projector-augmented wave method with applications to the linear optical and dielectric properties of both solids, surfaces, and interfaces. The response function is represented in plane waves while the single......-particle eigenstates can be expanded on a real space grid or in atomic-orbital basis for increased efficiency. The exchange-correlation kernel is treated at the level of the adiabatic local density approximation (ALDA) and crystal local field effects are included. The calculated static and dynamical dielectric...... functions of Si, C, SiC, AlP, and GaAs compare well with previous calculations. While optical properties of semiconductors, in particular excitonic effects, are generally not well described by ALDA, we obtain excellent agreement with experiments for the surface loss function of graphene and the Mg(0001...
Energy Technology Data Exchange (ETDEWEB)
Tussupbayev, Samat; Govind, Niranjan; Lopata, Kenneth A.; Cramer, Christopher J.
2015-03-10
We assess the performance of real-time time-dependent density functional theory (RT-TDDFT) for the calculation of absorption spectra of 12 organic dye molecules relevant to photovoltaics and dye sensitized solar cells with 8 exchange-correlation functionals (3 traditional, 3 global hybrids, and 2 range-separated hybrids). We compare the calculations with traditional linear-response (LR) TDDFT. In addition, we demonstrate the efficacy of the RT-TDDFT approach to calculate wide absorption spectra of two large chromophores relevant to photovoltaics and molecular switches.
Schmeller, A.; Goñi, A. R.; Pinczuk, A.; Weiner, J. S.; Calleja, J. M.; Dennis, B. S.; Pfeiffer, L. N.; West, K. W.
1994-06-01
In inelastic light scattering experiments we observe for the first time clearly resolved one dimensional (1D) intersubband spin-density excitations. Together with new structure at energies close to the 2D intersubband transitions, these observations display the formation of 1D subbands. The depolarization shift ( Wdep) and the excitonic shift ( Wxc) can be deduced approximately from our experiments. These shifts are of special interest because they are related to the direct and exchange-correlation terms of the electron-electron interaction. We find ratios of the shifts ( Wxc/ Wdep) of up to 55%.
A scalable admission control scheme based on time label
Institute of Scientific and Technical Information of China (English)
杨松岸; 杨华; 杨宇航
2004-01-01
Resource reservation protocols allow communicating hosts to reserve resources such as bandwidth to offer guaranteed service. However, current resource reservation architectures do not scale well for a large number of flows. In this paper, we present a simple reservation protocol and a scalable admission control algorithm, which can provide QoS guarantees to individual flows without per-flow management in the network core. By mapping each flow to a definite time, this scheme addresses the problems that limit the effectiveness of current endpoint admission control schemes. The overall admission control process is described. Analysis is used to explain the reasonability of our scheme and simulation validates its performance.
Discovery of Association Rules from University Admission System Data
Directory of Open Access Journals (Sweden)
Abdul Fattah Mashat
2013-05-01
Full Text Available Association rules discovery is one of the vital data mining techniques. Currently there is an increasing interest in data mining and educational systems, making educational data mining (EDM as a new growing research community. In this paper, we present a model for association rules discovery from King Abdulaziz University (KAU admission system data. The main objective is to extract the rules and relations between admission system attributes for better analysis. The model utilizes an apriori algorithm for association rule mining. Detailed analysis and interpretation of the experimental results is presented with respect to admission office perspective.
Charge transfer in time-dependent density functional theory
Maitra, Neepa T.
2017-10-01
Charge transfer plays a crucial role in many processes of interest in physics, chemistry, and bio-chemistry. In many applications the size of the systems involved calls for time-dependent density functional theory (TDDFT) to be used in their computational modeling, due to its unprecedented balance between accuracy and efficiency. However, although exact in principle, in practise approximations must be made for the exchange-correlation functional in this theory, and the standard functional approximations perform poorly for excitations which have a long-range charge-transfer component. Intense progress has been made in developing more sophisticated functionals for this problem, which we review. We point out an essential difference between the properties of the exchange-correlation kernel needed for an accurate description of charge-transfer between open-shell fragments and between closed-shell fragments. We then turn to charge-transfer dynamics, which, in contrast to the excitation problem, is a highly non-equilibrium, non-perturbative, process involving a transfer of one full electron in space. This turns out to be a much more challenging problem for TDDFT functionals. We describe dynamical step and peak features in the exact functional evolving over time, that are missing in the functionals currently used. The latter underestimate the amount of charge transferred and manifest a spurious shift in the charge transfer resonance position. We discuss some explicit examples.
Łazarski, Roman; Burow, Asbjörn Manfred; Grajciar, Lukáš; Sierka, Marek
2016-10-30
A full implementation of analytical energy gradients for molecular and periodic systems is reported in the TURBOMOLE program package within the framework of Kohn-Sham density functional theory using Gaussian-type orbitals as basis functions. Its key component is a combination of density fitting (DF) approximation and continuous fast multipole method (CFMM) that allows for an efficient calculation of the Coulomb energy gradient. For exchange-correlation part the hierarchical numerical integration scheme (Burow and Sierka, Journal of Chemical Theory and Computation 2011, 7, 3097) is extended to energy gradients. Computational efficiency and asymptotic O(N) scaling behavior of the implementation is demonstrated for various molecular and periodic model systems, with the largest unit cell of hematite containing 640 atoms and 19,072 basis functions. The overall computational effort of energy gradient is comparable to that of the Kohn-Sham matrix formation. © 2016 Wiley Periodicals, Inc.
Spatial variation in nitrogen dioxide concentrations and cardiopulmonary hospital admissions
Dijkema, Marieke B A; van Strien, Robert T; van der Zee, Saskia C; Mallant, Sanne F; Fischer, Paul; Hoek, Gerard; Brunekreef, Bert; Gehring, Ulrike
2016-01-01
BACKGROUND: Air pollution episodes are associated with increased cardiopulmonary hospital admissions. Cohort studies showed associations of spatial variation in traffic-related air pollution with respiratory and cardiovascular mortality. Much less is known in particular about associations with cardi
A NEW ADMISSION CONTROL APPROACH BASED ON PREDICTION
Institute of Scientific and Technical Information of China (English)
Lu Kaining; Jin Zhigang; Zou Jun
2002-01-01
Admission control plays an important role in providing QoS to network users. Motivated by the measurement-based admission control algorithm, this letter proposed a new admission control approach for integrated service packet network based on traffic prediction. In the letter, FARIMA(p, d, q) models in the admission control algorithm is deployed. A method to simplify the FARIMA model fitting procedure and hence to reduce the time of traffic modeling and prediction is suggested. The feasibility-study experiments show that FARIMA models which have less number of parameters can be used to model and predict actual traffic on quite a large time scale. Simulation results validate the promising approach.
the admissibility of subregional courts' decisions before the african ...
African Journals Online (AJOL)
AbdiJA
(III). Art 7 empowers the African Court to apply the provisions of the African Charter .... November 1950 at Rome, entered into force on 3 September 1953. ..... admissibility criteria has been taken as one of the steps to reform the European.
49 CFR 1114.27 - Request for admission.
2010-10-01
... OF TRANSPORTATION RULES OF PRACTICE EVIDENCE; DISCOVERY Discovery § 1114.27 Request for admission. (a... of information or knowledge as a reason for failure to admit or deny unless he states that he...
16 CFR 1025.34 - Requests for admission.
2010-01-01
... PROCEEDINGS Discovery, Compulsory Process § 1025.34 Requests for admission. (a) Procedure for request. A party... and qualify or deny the remainder. An answering party may not give lack of information or knowledge...
49 CFR 386.44 - Request for admissions.
2010-10-01
... serve upon any other party a request for admission of any relevant matter or the authenticity of any... other proceeding. (c) If a party refuses to admit a matter or the authenticity of a document which...
Exploring Ethnic Inequalities in Admission to Russell Group Universities.
Boliver, Vikki
2016-04-01
This article analyses national university applications and admissions data to explore why ethnic minority applicants to Russell Group universities are less likely to receive offers of admission than comparably qualified white applicants. Contrary to received opinion, the greater tendency of ethnic minorities to choose highly numerically competitive degree subjects only partially accounts for their lower offer rates from Russell Group universities relative to white applicants with the same grades and 'facilitating subjects' at A-level. Moreover, ethnic inequalities in the chances of receiving an admissions offer from a Russell Group university are found to be greater in relation to courses where ethnic minorities make up a larger percentage of applicants. This latter finding raises the possibility that some admissions selectors at some Russell Group universities may be unfairly rejecting a proportion of their ethnic minority applicants in an attempt to achieve a more ethnically representative student body.
Relating Admissibility Standards for Digital Evidence to Attack Scenario Reconstruction
Directory of Open Access Journals (Sweden)
Changwei Liu
2014-09-01
Full Text Available Attackers tend to use complex techniques such as combining multi-step, multi-stage attack with anti-forensic tools to make it difficult to find incriminating evidence and reconstruct attack scenarios that can stand up to the expected level of evidence admissibility in a court of law. As a solution, we propose to integrate the legal aspects of evidence correlation into a Prolog based reasoner to address the admissibility requirements by creating most probable attack scenarios that satisfy admissibility standards for substantiating evidence. Using a prototype implementation, we show how evidence extracted by using forensic tools can be integrated with legal reasoning to reconstruct network attack scenarios. Our experiment shows this implemented reasoner can provide pre-estimate of admissibility on a digital crime towards an attacked network.
Premature discharge of children from hospital admission at Ahmadu ...
African Journals Online (AJOL)
Premature discharge of children from hospital admission at Ahmadu Bello University ... The commonest diagnoses were protein-energy malnutrition and pneumonia and ... Conclusion: Socio-economic factors were significant determinants of ...
Admissions Variables as Predictors of Performance in Basic Science Coursework.
Leonard, D. Lisa; Niebuhr, Bruce R.
1986-01-01
This study was designed to determine the relative contribution of several types of admissions data in predicting the success of junior occupational therapy students in the first term of a human anatomy and physiology course. (Author/CT)
Pattern of Diseases among Medical Admissions in Port Harcourt ...
African Journals Online (AJOL)
Pattern of Diseases among Medical Admissions in Port Harcourt, Nigeria. ... Nigerian Medical Practitioner. Journal Home · ABOUT · Advanced Search · Current Issue · Archives · Journal Home > Vol 51, No 3 (2007) >. Log in or ... Article Metrics.
Density Functional Theory with Spatial-Symmetry Breaking and Configuration Mixing
Lesinski, Thomas
2013-01-01
This article generalizes the notion of the local density of a many-body system to introduce collective coordinates as explicit degrees of freedom. It is shown that the energy of the system can be expressed as a functional of this object. The latter can in turn be factorized as the product of the square of a collective wave function and a normalized collective-coordinate-dependent density. Energy minimization translates into a set of coupled equations, i.e. a local Schr\\"odinger equation for the collective wave function and a set of Kohn-Sham equations for optimizing the normalized density at each point in the collective space. These equations reformulate the many-body problem exactly provided one is able to determine density- and collective-wave-function-dependent terms of the collective mass and potential which play a similar role to the exchange-correlation term in electronic Kohn-Sham density functional theory.
DEFF Research Database (Denmark)
Garnett, E S; Webber, C E; Coates, G
1977-01-01
The density of a defined volume of the human lung can be measured in vivo by a new noninvasive technique. A beam of gamma-rays is directed at the lung and, by measuring the scattered gamma-rays, lung density is calculated. The density in the lower lobe of the right lung in normal man during quiet...... breathing in the sitting position ranged from 0.25 to 0.37 g.cm-3. Subnormal values were found in patients with emphsema. In patients with pulmonary congestion and edema, lung density values ranged from 0.33 to 0.93 g.cm-3. The lung density measurement correlated well with the findings in chest radiographs...... but the lung density values were more sensitive indices. This was particularly evident in serial observations of individual patients....
Prediction of mortality 1 year after hospital admission.
LENUS (Irish Health Repository)
Kellett, J
2012-09-01
Hospital admission, especially for the elderly, can be a seminal event as many patients die within a year. This study reports the prediction of death within a year of admission to hospital of the Simple Clinical Score (SCS) and ECG dispersion mapping (ECG-DM). ECG-DM is a novel technique that analyzes low-amplitude ECG oscillations and reports them as the myocardial micro-alternation index (MMI).
A Supply and Demand Model of the College Admissions Problem
2009-01-01
We develop the first Bayesian model of decentralized college admissions, with heterogeneous students, costly portfolio applications, and noisy college evaluations. Students face a nontrivial portfolio choice, and colleges choose admissions standards that act like market-clearing prices. We derive the two college model equilibrium, deriving a “law of demand”. Surprisingly, the worse college might impose higher standards, and weaker students sometimes apply more aggressively. The lesser coll...
Kishi, Ryohei; Nakano, Masayoshi
2011-04-21
A novel method for the calculation of the dynamic polarizability (α) of open-shell molecular systems is developed based on the quantum master equation combined with the broken-symmetry (BS) time-dependent density functional theory within the Tamm-Dancoff approximation, referred to as the BS-DFTQME method. We investigate the dynamic α density distribution obtained from BS-DFTQME calculations in order to analyze the spatial contributions of electrons to the field-induced polarization and clarify the contributions of the frontier orbital pair to α and its density. To demonstrate the performance of this method, we examine the real part of dynamic α of singlet 1,3-dipole systems having a variety of diradical characters (y). The frequency dispersion of α, in particular in the resonant region, is shown to strongly depend on the exchange-correlation functional as well as on the diradical character. Under sufficiently off-resonant condition, the dynamic α is found to decrease with increasing y and/or the fraction of Hartree-Fock exchange in the exchange-correlation functional, which enhances the spin polarization, due to the decrease in the delocalization effects of π-diradical electrons in the frontier orbital pair. The BS-DFTQME method with the BHandHLYP exchange-correlation functional also turns out to semiquantitatively reproduce the α spectra calculated by a strongly correlated ab initio molecular orbital method, i.e., the spin-unrestricted coupled-cluster singles and doubles.
Śmiga, Szymon; Fabiano, Eduardo; Constantin, Lucian A; Della Sala, Fabio
2017-02-14
The development of semilocal models for the kinetic energy density (KED) is an important topic in density functional theory (DFT). This is especially true for subsystem DFT, where these models are necessary to construct the required non-additive embedding contributions. In particular, these models can also be efficiently employed to replace the exact KED in meta-Generalized Gradient Approximation (meta-GGA) exchange-correlation functionals allowing to extend the subsystem DFT applicability to the meta-GGA level of theory. Here, we present a two-dimensional scan of semilocal KED models as linear functionals of the reduced gradient and of the reduced Laplacian, for atoms and weakly bound molecular systems. We find that several models can perform well but in any case the Laplacian contribution is extremely important to model the local features of the KED. Indeed a simple model constructed as the sum of Thomas-Fermi KED and 1/6 of the Laplacian of the density yields the best accuracy for atoms and weakly bound molecular systems. These KED models are tested within subsystem DFT with various meta-GGA exchange-correlation functionals for non-bonded systems, showing a good accuracy of the method.
Ultra-nonlocality in density functional theory for photo-emission spectroscopy.
Uimonen, A-M; Stefanucci, G; van Leeuwen, R
2014-05-14
We derive an exact expression for the photocurrent of photo-emission spectroscopy using time-dependent current density functional theory (TDCDFT). This expression is given as an integral over the Kohn-Sham spectral function renormalized by effective potentials that depend on the exchange-correlation kernel of current density functional theory. We analyze in detail the physical content of this expression by making a connection between the density-functional expression and the diagrammatic expansion of the photocurrent within many-body perturbation theory. We further demonstrate that the density functional expression does not provide us with information on the kinetic energy distribution of the photo-electrons. Such information can, in principle, be obtained from TDCDFT by exactly modeling the experiment in which the photocurrent is split into energy contributions by means of an external electromagnetic field outside the sample, as is done in standard detectors. We find, however, that this procedure produces very nonlocal correlations between the exchange-correlation fields in the sample and the detector.
Semilocal exchange hole with an application to range-separated density functionals
Tao, Jianmin; Bulik, Ireneusz W.; Scuseria, Gustavo E.
2017-03-01
The exchange-correlation hole is a central concept in density functional theory. It not only provides justification for an exchange-correlation energy functional but also serves as a local ingredient for nonlocal range-separated density functionals. However, due to the nonlocal nature, modeling the conventional exact exchange hole presents a great challenge to density functional theory. In this work, we propose a semilocal exchange hole underlying the Tao-Perdew-Staroverov-Scuseria (TPSS) meta-generalized gradient approximation functional. Our model is distinct from previous ones not only at small separation between an electron and the hole around the electron but also in the way it interpolates between rapidly varying and slowly varying densities. Here the interpolation is determined by the wave-vector analysis on the infinite-barrier model for a jellium surface. Numerical tests show that our exchange-hole model mimics the conventional exact one quite well for atoms. As a simple application, we apply the hole model to construct a TPSS-based range-separated functional. We find that this range-separated functional can substantially improve the band gaps and barrier heights of TPSS, without losing much accuracy for atomization energies.
Hospital admissions: An examination of race and health insurance
Directory of Open Access Journals (Sweden)
Eric Gass
2008-06-01
Full Text Available This study examined the effects of racial differences and differences in insurance status on source of hospital admissions. The data source was the 2001 National Hospital Discharge Survey and included a sub-sample of 104,185 patients. 58.3% of patients were admitted through the emergency room, 75.0% of patients were White, 19.7% were Black, and 61.5% were on government insurance or uninsured. Black patients were found to have significantly higher levels of emergency room admissions (69.1%=p < .0001, regardless of insurance status (gov’t/self-pay, 73.7%=p < .0001, private insurance, 59.5%=p < .0001. Patients on government insurance or self-payment had significantly higher levels of emergency room admissions (65.8%=p < .0001. Regression analysis showed that both race and insurance type are significant predictors (p < .0001 of Source of Admission to the hospital. Percent probabilities confirmed this finding. Thus, it was concluded that racial differences witnessed in source of admission were not mediated by insurance type and that race and insurance type are significant, independent predictors of hospital admission source.
Hospital admissions: An examination of race and health insurance
Directory of Open Access Journals (Sweden)
Eric Gass
2008-06-01
Full Text Available This study examined the effects of racial differences and differences in insurance status on source of hospital admissions. The data source was the 2001 National Hospital Discharge Survey and included a sub-sample of 104,185 patients. 58.3% of patients were admitted through the emergency room, 75.0% of patients were White, 19.7% were Black, and 61.5% were on government insurance or uninsured. Black patients were found to have significantly higher levels of emergency room admissions (69.1%=p < .0001, regardless of insurance status (gov’t/self-pay, 73.7%=p < .0001, private insurance, 59.5%=p < .0001. Patients on government insurance or self-payment had significantly higher levels of emergency room admissions (65.8%=p < .0001. Regression analysis showed that both race and insurance type are significant predictors (p < .0001 of Source of Admission to the hospital. Percent probabilities confirmed this finding. Thus, it was concluded that racial differences witnessed in source of admission were not mediated by insurance type and that race and insurance type are significant, independent predictors of hospital admission source.
Towards an understanding of graduate admissions practices in physics
Potvin, Geoff; Chari, Deepa
2017-01-01
The APS bridge program works to improve the participation of students from traditionally under-represented groups in graduate physics. Related to this, we have undertaken research to improve our understanding of graduate admissions practices from the point of view of both students and faculty. Previously, we collected data on admission practices from over 75% of PhD-granting physics departments in the U.S., which highlighted the role of various criteria (including the GRE) in the admissions decisions faculty make, and identified the efforts (or lack thereof) made to recruit students from traditionally under-represented backgrounds. Currently, we are conducting a parallel study of upper division undergraduate physics majors to investigate their post-graduation career intentions, their perceptions of graduate admissions and perceived barriers to admissions, and to understand how undergraduate experiences influence students' career interests. Lastly, we are also studying, in depth, students who have been connected to physics bridge programs, to understand post-admission experiences and the enculturation process in physics departments. In this talk, we report on the collective results of these research efforts to date. NSF Award # 1143070.
Somnambulism: Emergency Department Admissions Due to Sleepwalking-Related Trauma
Sauter, Thomas C.; Veerakatty, Sajitha; Haider, Dominik G.; Geiser, Thomas; Ricklin, Meret E.; Exadaktylos, Aristomenis K.
2016-01-01
Introduction Somnambulism is a state of dissociated consciousness, in which the affected person is partially asleep and partially awake. There is pervasive public opinion that sleepwalkers are protected from hurting themselves. There have been few scientific reports of trauma associated with somnambulism and no published investigations on the epidemiology or trauma patterns associated with somnambulism. Methods We included all emergency department (ED) admissions to University Hospital Inselspital, Berne, Switzerland, from January 1, 2000, until August 11, 2015, when the patient had suffered a trauma associated with somnambulism. Demographic data (age, gender, nationality) and medical data (mechanism of injury, final diagnosis, hospital admission, mortality and medication on admission) were included. Results Of 620,000 screened ED admissions, 11 were associated with trauma and sleepwalking. Two patients (18.2%) had a history of known non-rapid eye movement parasomnias. The leading cause of admission was falls. Four patients required hospital admission for orthopedic injuries needing further diagnostic testing and treatment (36.4%). These included two patients with multiple injuries (18.2%). None of the admitted patients died. Conclusion Although sleepwalking seems benign in the majority of cases and most of the few injured patients did not require hospitalization, major injuries are possible. When patients present with falls of unknown origin, the possibility should be evaluated that they were caused by somnambulism. PMID:27833677
Mewes, Stefanie A; Plasser, Felix; Dreuw, Andreas
2015-11-01
Excited-state descriptors based on the one-particle transition density matrix referring to the exciton picture have been implemented for time-dependent density functional theory. State characters such as local, extended ππ(∗), Rydberg, or charge transfer can be intuitively classified by simple comparison of these descriptors. Strong effects of the choice of the exchange-correlation kernel on the physical nature of excited states can be found and decomposed in detail leading to a new perspective on functional performance and the design of new functionals.
Highly accurate local pseudopotentials of Li, Na, and Mg for orbital free density functional theory
Legrain, Fleur; Manzhos, Sergei
2015-02-01
We present a method to make highly accurate pseudopotentials for use with orbital-free density functional theory (OF-DFT) with given exchange-correlation and kinetic energy functionals, which avoids the compounding of errors of Kohn-Sham DFT and OF-DFT. The pseudopotentials are fitted to reference (experimental or highly accurate quantum chemistry) values of interaction energies, geometries, and mechanical properties, using a genetic algorithm. This can enable routine large-scale ab initio simulations of many practically relevant materials. Pseudopotentials for Li, Na, and Mg resulting in accurate geometries and energies of different phases as well as of vacancy formation and bulk moduli are presented as examples.
Excitons in solids with time-dependent density-functional theory: the bootstrap kernel and beyond
Byun, Young-Moo; Yang, Zeng-Hui; Ullrich, Carsten
Time-dependent density-functional theory (TDDFT) is an efficient method to describe the optical properties of solids. Lately, a series of bootstrap-type exchange-correlation (xc) kernels have been reported to produce accurate excitons in solids, but different bootstrap-type kernels exist in the literature, with mixed results. In this presentation, we reveal the origin of the confusion and show a new empirical TDDFT xc kernel to compute excitonic properties of semiconductors and insulators efficiently and accurately. Our method can be used for high-throughput screening calculations and large unit cell calculations. Work supported by NSF Grant DMR-1408904.
Reducing Systematic Errors in Oxide Species with Density Functional Theory Calculations
DEFF Research Database (Denmark)
Christensen, Rune; Hummelshøj, Jens S.; Hansen, Heine Anton
2015-01-01
Density functional theory calculations can be used to gain valuable insight into the fundamental reaction processes in metal−oxygen systems, e.g., metal−oxygen batteries. Here, the ability of a range of different exchange-correlation functionals to reproduce experimental enthalpies of formation...... for different types of alkali and alkaline earth metal oxide species has been examined. Most examined functionals result in significant overestimation of the stability of superoxide species compared to peroxides and monoxides, which can result in erroneous prediction of reaction pathways. We show that if metal...
DEFF Research Database (Denmark)
Olsen, Thomas; Thygesen, Kristian S.
2012-01-01
while chemical bond strengths and absolute correlation energies are systematically underestimated. In this work we extend the RPA by including a parameter-free renormalized version of the adiabatic local-density (ALDA) exchange-correlation kernel. The renormalization consists of a (local) truncation...... of the ALDA kernel for wave vectors q > 2kF, which is found to yield excellent results for the homogeneous electron gas. In addition, the kernel significantly improves both the absolute correlation energies and atomization energies of small molecules over RPA and ALDA. The renormalization can...
Density functional theory of the Seebeck coefficient in the Coulomb blockade regime
Yang, Kaike; Perfetto, Enrico; Kurth, Stefan; Stefanucci, Gianluca; D'Agosta, Roberto
2016-08-01
The Seebeck coefficient plays a fundamental role in identifying the efficiency of a thermoelectric device. Its theoretical evaluation for atomistic models is routinely based on density functional theory calculations combined with the Landauer-Büttiker approach to quantum transport. This combination, however, suffers from serious drawbacks for devices in the Coulomb blockade regime. We show how to cure the theory through a simple correction in terms of the temperature derivative of the exchange correlation potential. Our results compare well with both rate equations and experimental findings on carbon nanotubes.
Energy Technology Data Exchange (ETDEWEB)
Tao, Jianmin [Los Alamos National Laboratory; Perdew, John P [TULANE UNIV; Staroverov, Viktor N [UNIV OF WESTERN ONTARIO; Scuseria, Gustavo E [RICE UNIV
2008-01-01
We construct a nonlocal density functional approximation with full exact exchange, while preserving the constraint-satisfaction approach and justified error cancellations of simpler semilocal functionals. This is achieved by interpolating between different approximations suitable for two extreme regions of the electron density. In a 'normal' region, the exact exchange-correlation hole density around an electron is semilocal because its spatial range is reduced by correlation and because it integrates over a narrow range to -1. These regions are well described by popular semilocal approximations (many of which have been constructed nonempirically), because of proper accuracy for a slowly-varying density or because of error cancellation between exchange and correlation. 'Abnormal' regions, where non locality is unveiled, include those in which exchange can dominate correlation (one-electron, nonuniform high-density, and rapidly-varying limits), and those open subsystems of fluctuating electron number over which the exact exchange-correlation hole integrates to a value greater than -1. Regions between these extremes are described by a hybrid functional mixing exact and semi local exchange energy densities locally (i.e., with a mixing fraction that is a function of position r and a functional of the density). Because our mixing fraction tends to 1 in the high-density limit, we employ full exact exchange according to the rigorous definition of the exchange component of any exchange-correlation energy functional. Use of full exact exchange permits the satisfaction of many exact constraints, but the nonlocality of exchange also requires balanced nonlocality of correlation. We find that this nonlocality can demand at least five empirical parameters (corresponding roughly to the four kinds of abnormal regions). Our local hybrid functional is perhaps the first accurate size-consistent density functional with full exact exchange. It satisfies other known
Forecasting paediatric malaria admissions on the Kenya Coast using rainfall
Directory of Open Access Journals (Sweden)
Stella Wanjugu Karuri
2016-02-01
Full Text Available Background: Malaria is a vector-borne disease which, despite recent scaled-up efforts to achieve control in Africa, continues to pose a major threat to child survival. The disease is caused by the protozoan parasite Plasmodium and requires mosquitoes and humans for transmission. Rainfall is a major factor in seasonal and secular patterns of malaria transmission along the East African coast. Objective: The goal of the study was to develop a model to reliably forecast incidences of paediatric malaria admissions to Kilifi District Hospital (KDH. Design: In this article, we apply several statistical models to look at the temporal association between monthly paediatric malaria hospital admissions, rainfall, and Indian Ocean sea surface temperatures. Trend and seasonally adjusted, marginal and multivariate, time-series models for hospital admissions were applied to a unique data set to examine the role of climate, seasonality, and long-term anomalies in predicting malaria hospital admission rates and whether these might become more or less predictable with increasing vector control. Results: The proportion of paediatric admissions to KDH that have malaria as a cause of admission can be forecast by a model which depends on the proportion of malaria admissions in the previous 2 months. This model is improved by incorporating either the previous month's Indian Ocean Dipole information or the previous 2 months’ rainfall. Conclusions: Surveillance data can help build time-series prediction models which can be used to anticipate seasonal variations in clinical burdens of malaria in stable transmission areas and aid the timing of malaria vector control.
[Influence of postcode on paediatric admissions in Seville].
Tornero Patricio, Sebastián; Charris-Castro, Liliana; Granero Asencio, Mercedes; Daponte Codina, Antonio
2017-01-04
The postcode (where the home is situated) is an indicator of socioeconomic status and is associated with morbidity, mortality, and the use of health services. The aim of this study was to analyse its effects on paediatric admissions and to determine the rates of the most common causes of paediatric admissions in Seville. An observational cross-sectional study with two analysis units: under 15 year-old "admissions" in public hospitals in Seville (n=2,660) and "city districts" of Seville (n=11). The independent variable analysed was whether the postcode of the admitted patients was within a Regional Government designated "area with social transformation needs". The analysis of the admissions was performed using X(2)-test, Fisher test and Student-t test, with the description of rates using the calculation of crude and specific rates, and by rate ratio. Children living in districts with a lower socioeconomic status were on average 7 months younger (P<.001), and they were significantly more likely to be admitted via the emergency department (P<.001). There was no statistical difference detected in either the length of hospital stay or mortality. The crude admission rate ratio was higher in districts with a lower socioeconomic status (1.8), with a higher specific rate ratio detected in admissions due to asthma, respiratory infections, inguinal hernia, and epilepsy/convulsions. Paediatric hospital admission rates of the main diagnoses were higher in districts with a lower socioeconomic status. Children living in these districts were more likely to be admitted younger and via the emergency department. Copyright © 2016. Publicado por Elsevier España, S.L.U.
Hari Sutrisno
2016-01-01
This article is a theoritical approach to calculate the electronic structure of undoped- and non-metal anions doped-TiO2-anatase. The objective of the research is to calculate abinitio the band structure and the density of states (DOS) of undoped-, C-, N-, and S-doped TiO2-anatase. Kohn-Sham equations are performed with the density functional theory (DFT) using the local density approximation (LDA) for exchange-correlation functional. The first-principle calculations were done using supercell...
Handbook for the College Admissions Profession. The Greenwood Educators' Reference Collection.
Swann, Claire C., Ed.; Henderson, Stanley E., Ed.
The 19 chapters of this book on college admissions are divided into six sections on: (1) perspectives and history, (2) the admissions officer, (3) understanding enrollment management, (4) admissions tools, (5) admissions programs, and (6) perspectives on the twenty-first century. The papers are: "Perspectives on Educational Reform" (Donald…
Ryabinkin, Ilya G; Staroverov, Viktor N
2012-10-28
We present an accurate method for constructing the Kohn-Sham effective potential corresponding to a given electron density in one-dimensional and spherically symmetric systems. The method is based on the differential virial theorem--an exact relation between the effective potential, the electron density, and the kinetic energy density. A distinctive feature of the proposed technique is that it employs a size-consistent bosonic reference potential to ensure the correct asymptotic behavior of the resulting Kohn-Sham potential. We describe a practical implementation of our method and use it to obtain high-quality exchange-correlation and correlation potentials of the neon and argon atoms from ab initio densities generated in large Slater- and Gaussian-type basis sets.
Admissions file review: applying the multiple independent sampling (MIS) methodology.
Hanson, Mark D; Kulasegaram, Kulamakan Mahan; Coombs, Deborah L; Herold, Jodi
2012-10-01
Although multiple independent sampling (MIS) has been adapted for admissions interviews, its application for assessing written materials in the admissions file has been limited. Currently, admissions file review at the University of Toronto medical school involves one rater per file to enable holistic assessment, which may introduce a halo effect-that is, impressions of one component influencing the evaluation of other components. The authors examined whether MIS file review, through which multiple raters evaluate specific file components independently, may reduce this effect. The authors selected a stratified random sample of 300 applicant files from the 2010-2011 admissions cycle for rescoring by MIS. They divided each of the 300 applicant files into their four components (academic transcript, autobiographical sketch, personal statement, reference letters) and rebundled them into packages of 38 same-component items (purposely creating some overlap among packages to assess inter-rater reliability). The authors distributed each package to 1 of 36 raters; thus, each rater evaluated only one of four components across many applicants. The authors compared the inter-component reliability and factor analysis of MIS with that of holistic scoring. Ratings were returned for all applicants. Inter-component reliability (Cronbach alpha) was 0.69 for holistic scoring and 0.29 for MIS. Factor analysis showed all components loading heavily onto one factor in the holistic approach and onto three factors in the MIS method. Using MIS to assess the admissions file may reduce the halo effect and should be considered when evaluating applicants' written submissions.
Potential Utility of Non-Cognitive Constructs in Graduate Admissions
Miller, Casey
2015-03-01
It is becoming clear that the methods employed by many graduate admissions committees need updating. Regarding outcomes, we cannot select students that will actually graduate much better than would a coin toss. Further, the GRE is often misused. For example, the most recent GRE general test data (2006-2007) shows that for US citizens in the physical sciences, a cut-off score of ~64th percentile (700/155 on old/new test) would eliminate from eligibility: 63% of women vs 42% of men; 76% of all under-represented minorities vs 38% of Asian and 47% of White applicants. Fortunately, Organizational Psychologists have identified and validated several ``non-cognitive constructs'' for admissions: aspects of personality (conscientiousness); and self-management factors. Some intriguing facts about these parameters: they are measurable with the help of social scientists; they do not show race/ethnicity/gender performance differences; they are orthogonal to cognitive metrics measured by GPA and tests scores. These are proven to enhance both validity and diversity in admissions. My goals for this talk are to overview the non-cognitive constructs with the most potential for being used in physics graduate admissions, and to suggest example admissions protocols. Supported by the National Science Foundation.
Does mental health service integration affect compulsory admissions?
Directory of Open Access Journals (Sweden)
André I. Wierdsma
2009-09-01
Full Text Available Background: Over recent years, the number of compulsory admissions in many countries has increased, probably as a result of the shift from inpatient to outpatient mental health care. This might be mitigated by formal or collaborative relationships between services. Methods: In a retrospective record linkage study, we compared two neighboring districts, varying in level of service integration. Two periods were combined: 1991–1993 and 2001–2003. We included patients aged 18–60, who had a first emergency compulsory admission (n=830. Their psychiatric history was assessed, and service-use after admission was monitored over a 12-month follow-up. Results: Over a 10-year period, compulsory admission rates increased by 47%. Difference in relative increase between the integrated and non-integrated services was 14%. Patient characteristics showed different profiles in the two districts. Length of stay was >10 days shorter in the integrated district, where the proportion of involuntary readmissions decreased more, and where aftercare was swift and provided to about 10% more patients than in the non-integrated district. Conclusions: Services outcomes showed better results where mental healthcare was more integrated. However, limited effects were found and other factors than integration of services may be more important in preventing compulsory admissions.
Influence of ICU-bed availability on ICU admission decisions.
Robert, René; Coudroy, Rémi; Ragot, Stéphanie; Lesieur, Olivier; Runge, Isabelle; Souday, Vincent; Desachy, Arnaud; Gouello, Jean-Paul; Hira, Michel; Hamrouni, Mouldi; Reignier, Jean
2015-12-01
The potential influence of bed availability on triage to intensive care unit (ICU) admission is among the factors that may influence the ideal ratio of ICU beds to population: thus, high bed availability (HBA) may result in the admission of patients too well or too sick to benefit, whereas bed scarcity may result in refusal of patients likely to benefit from ICU admission. Characteristics and outcomes of patient admitted in four ICUs with usual HBA, defined by admission refusal rate less than 11 % because of bed unavailability, were compared to patients admitted in six ICUs with usual low bed availability (LBA), i.e., an admission refusal rate higher than 10 % during a 90-day period. Over the 90 days, the mean number of days with no bed available was 30 ± 16 in HBA units versus 48 ± 21 in LBA units (p Bed availability affected triage decisions. Units with HBA trend to admit patients too sick or too well to benefit.
Hoyer, Chad E; Gagliardi, Laura; Truhlar, Donald G
2015-11-05
Time-dependent Kohn-Sham density functional theory (TD-KS-DFT) is useful for calculating electronic excitation spectra of large systems, but the low-energy spectra are often complicated by artificially lowered higher-energy states. This affects even the lowest energy excited states. Here, by calculating the lowest energy spin-conserving excited state for atoms from H to K and for formaldehyde, we show that this problem does not occur in multiconfiguration pair-density functional theory (MC-PDFT). We use the tPBE on-top density functional, which is a translation of the PBE exchange-correlation functional. We compare to a robust multireference method, namely, complete active space second-order perturbation theory (CASPT2), and to TD-KS-DFT with two popular exchange-correlation functionals, PBE and PBE0. We find for atoms that the mean unsigned error (MUE) of MC-PDFT with the tPBE functional improves from 0.42 to 0.40 eV with a double set of diffuse functions, whereas the MUEs for PBE and PBE0 drastically increase from 0.74 to 2.49 eV and from 0.45 to 1.47 eV, respectively.
Energy Technology Data Exchange (ETDEWEB)
Silverstein, Daniel W.; Govind, Niranjan; van Dam, Hubertus J. J.; Jensen, Lasse
2013-12-10
A parallel implementation of analytical time-dependent density functional theory gradients is presented for the quantum chemistry program NWChem. The implementation is based on the Lagrangian approach developed by Furche and Ahlrichs. To validate our implementation, we first calculate the Stokes shifts for a range of organic dye molecules using a diverse set of exchange-correlation functionals (traditional density functionals, global hybrids, and range-separated hybrids) followed by simulations of the one-photon absorption and resonance Raman scattering spectrum of the phenoxyl radical, the well-studied dye molecule rhodamine 6G, and a molecular host–guest complex (TTFcCBPQT^{4+}). The study of organic dye molecules illustrates that B3LYP and CAM-B3LYP generally give the best agreement with experimentally determined Stokes shifts unless the excited state is a charge transfer state. Absorption, resonance Raman, and fluorescence simulations for the phenoxyl radical indicate that explicit solvation may be required for accurate characterization. For the host–guest complex and rhodamine 6G, it is demonstrated that absorption spectra can be simulated in good agreement with experimental data for most exchange-correlation functionals. Finally, however, because one-photon absorption spectra generally lack well-resolved vibrational features, resonance Raman simulations are necessary to evaluate the accuracy of the exchange-correlation functional for describing a potential energy surface.
A scalable admission control scheme based on time label
Institute of Scientific and Technical Information of China (English)
杨松岸; 杨华; 杨宇航
2004-01-01
Resource reservation protocols allow communicating hosts to reserve resources such as bandwidth to offer guaranteed service. However,current resource reservation architectures do not scale well for a large number of flows. In this paper,we present a simple reservation protocol and a scalable admission control algorithm,which can provide QoS guarantees to individual flows without per-flow management in the network core. By mapping each flow to a definite time,this scheme addresses the problems that limit the effectiveness of current endpoint admission control schemes. The overall admission control process is described. Analysis is used to explain the reasonability of our scheme and simulation validates its performance.
Adherence to inhaled therapy, mortality and hospital admission in COPD
DEFF Research Database (Denmark)
Vestbo, J; Anderson, J A; Calverley, P M A
2009-01-01
microg twice daily with placebo and each drug individually in 6112 patients with moderate to severe COPD over 3 years in the TORCH study were used. All-cause mortality and exacerbations leading to hospital admission were primary and secondary end points. The study of adherence was not specified a priori...... as an ancillary study. RESULTS: Of the 4880 patients (79.8%) with good adherence defined as >80% use of study medication, 11.3% died compared with 26.4% of the 1232 patients (20.2%) with poor adherence. The annual rates of hospital admission for exacerbations were 0.15 and 0.27, respectively. The association...... was more pronounced in patients with good adherence than in those with poor adherence. CONCLUSION: Adherence to inhaled medication is significantly associated with reduced risk of death and admission to hospital due to exacerbations in COPD. Further research is needed to understand these strong...
Hospital admissions and morbidity in people with intellectual developmental disorders
Directory of Open Access Journals (Sweden)
Rubén José Bernal-Celestino
2017-07-01
Full Text Available Objective. People with intellectual developmental disorders (IDD have worse health statuses in comparison with general population. The objective of this paper is to compare access and hospital morbimortality in people with IDD and general population. Material and methods. We conducted aretrospective cross-sectional analytical study and analyzed data on admissions and discharges between IDD patients and the rest of them, in Ciudad Real, España. Results. Out of 51 325 hospital admissions, 441 (0.9% belonged to the group of persons with IDD. The IDD group had fewer programmed hospitalization than the general population and fewer surgical interventions. They presented more admissions for mental disorders and respiratory system diseases. Conclusions.The data presented confirm TDI population have different patterns of disease. Furthermore, this study reveal potential difficulties in access to health care in this population.
Advanced Fuzzy Logic Based Admission Control for UMTS System
Directory of Open Access Journals (Sweden)
P. Kejik
2010-12-01
Full Text Available The capacity of CDMA (Code Division Multiple Access systems is interference limited. Therefore radio resources management (RRM functions are used. They are responsible for supplying optimum coverage, ensuring efficient use of physical resources, and providing the maximum planned capacity. This paper deals with admission control techniques for UMTS (Universal Mobile Telecommunication System. A UMTS system model and four fuzzy logic based admission control algorithms are presented in this paper. Two new versions of fuzzy logic based admission control algorithms are presented there. All algorithms are mutually compared via simulations. Simulations show that the novel advanced fuzzy algorithm outperforms the other simulated algorithms (in terms of blocking probability, dropping probability and the number of active UEs in cell.
An Intelligent Call Admission Control Decision Mechanism for Wireless Networks
S., Ramesh Babu H; S, Satyanarayana P
2010-01-01
The Call admission control (CAC) is one of the Radio Resource Management (RRM) techniques plays instrumental role in ensuring the desired Quality of Service (QoS) to the users working on different applications which have diversified nature of QoS requirements. This paper proposes a fuzzy neural approach for call admission control in a multi class traffic based Next Generation Wireless Networks (NGWN). The proposed Fuzzy Neural Call Admission Control (FNCAC) scheme is an integrated CAC module that combines the linguistic control capabilities of the fuzzy logic controller and the learning capabilities of the neural networks .The model is based on Recurrent Radial Basis Function Networks (RRBFN) which have better learning and adaptability that can be used to develop the intelligent system to handle the incoming traffic in the heterogeneous network environment. The proposed FNCAC can achieve reduced call blocking probability keeping the resource utilisation at an optimal level. In the proposed algorithm we have c...
Energetics of cyclohexane isomers: a density-functional study
Lee, C Y
1999-01-01
The binding energies and the geometric structures of conformational isomers of cyclohexane (C sub 6 H sub 1 sub 2) are determined from the density-functional theory combined with ultrasoft pseudopotentials and gradient-corrected nonlocal exchange-correlation functionals. The ground-state chair conformation is found to have a binding energy of 99.457 eV, and the metastable twist-boat conformation has 99.161 eV. The chair conformation converts to another conformation via a half-chair conformation with an energy barrier of 0.507 eV whereas the twist-boat conformation converts to another twist-boat conformation via a boat conformation with a much smaller energy barrier of 0.015 eV.
Band Anticrossing in Dilute Germanium Carbides Using Hybrid Density Functionals
Stephenson, Chad A.; O'brien, William A.; Qi, Meng; Penninger, Michael; Schneider, William F.; Wistey, Mark A.
2016-04-01
Dilute germanium carbides (Ge1- x C x ) offer a direct bandgap for compact silicon photonics, but widely varying properties have been reported. This work reports improved band structure calculations for Ge1- x C x using ab initio simulations that employ the HSE06 exchange-correlation density functional. Contrary to Vegard's law, the conduction band minimum at Γ is consistently found to decrease with increasing C content, while L and X valleys change much more slowly. The calculated Ge bandgap is within 11% of experimental values. A decrease in energy at the Γ conduction band valley of (170 meV ± 50)/%C is predicted, leading to a direct bandgap for x > 0.008. These results indicate a promising material for Group IV lasers.
Drug-related hospital admissions in a generic pharmaceutical system.
Zargarzadeh, A H; Emami, M H; Hosseini, F
2007-01-01
1. Generically based pharmaceutical systems exist in a few countries of the world, such as Iran. Most developed countries have free market pharmaceutical systems. Drug-related problems (DRP) have been reported mostly in the Western world but few data are available for generic systems. In this study, we tried to measure the prevalence of drug-related problems leading to hospital admissions in Isfahan, Iran. 2. One thousand consecutive hospital admissions in three major teaching hospitals were studied for a period of 6 months for the presence of DRP as a cause of hospital admissions. Two subcategories of DRP were considered: (i) drug therapy failure; and (ii) adverse drug reactions. Preventability and outcome measures were also assessed. Medications responsible for DRP were classified according to the Anatomic Therapeutic Chemical (ATC) classification of the World Health Organization. 3. Of the 1000 admissions studied, 115 (11.5%) were owing to DRP, 81% as a result of drug therapy failure and 19% as adverse drug reactions. A total of 106 out of the 115 DRP cases (92%) were either preventable or probably preventable, most of which had to do with either prescriber or patient error. An overview of DRP showed that 58.3% resulted in complete recovery, 33.9% in relative recovery and 7.8% in death. Close to 1% of hospital admissions resulted in DRP-related deaths. 4. The overall prevalence of hospital admissions caused by DRP is similar to that in free market pharmaceutical systems. The high preventability rate of these problems should alert clinicians and policy makers to design strategies to curtail this. Also, reasons for differences in subtypes of DRP between the results of this study and those of the literature from free market systems needs to be investigated further.
Toxicoepidemiology in Zimbabwe: admissions resulting from exposure to paraffin (kerosene).
Tagwireyi, D; Ball, D E; Nhachi, C F B
2006-01-01
Paraffin (kerosene) ingestion is the most common form of childhood poisoning in most developing countries. Despite this, there is a paucity of toxicoepidemiological data which could potentially be used in measures to reduce preventable exposures. This article reports on the patterns of hospital admissions resulting from paraffin exposure in Zimbabwe. All cases of paraffin ingestion admitted to eight major referral hospitals in Zimbabwe from January 1998 to December 1999 (inclusive), were identified using ICD-9 codes and ward registers and relevant information recorded on a standard data collection sheet. There were a total of 327 admissions due to oral exposure to paraffin. This represented 11.8% of all the poisoning admissions to the eight study hospitals. Most exposures (300; 91.7%) occurred accidentally, with only 6.7% resulting from deliberate ingestion of the chemical. The median age on admission was 2 years (interquartile range [IQR] 1-2 yrs) with over 85% of cases in the 0-5 year age range and less than 10% above the age of 12 years. The median age on admission was much higher for deliberate self poisoning (23 yrs; IQR 19-26 yrs) compared to that for accidental poisoning (1.5 yrs; IQR 1-2 yrs). Accidental poisoning from paraffin occurred throughout the year. Over three-quarters of patients received an antibiotic either alone, or in combination with another antibiotic or drug. Paracetamol (24.3%) was the next most commonly encountered treatment. The case fatality rate (CFR) was therefore 0.3 deaths per 100 admissions (95% Confidence Interval 0.0-1.7). Paraffin ingestion remains an important cause of poisoning morbidity in Zimbabwe throughout the year, particularly in children. Clinical management appears adequate with a low mortality, although there may be overuse of prophylactic antibiotics. Further study specific to this area is warranted to prevent unnecessary antibiotic use and wastage of resources.
Transformation of admission interview to documentation for nursing practice.
Højskov, Ida E; Glasdam, Stinne
2014-09-01
The admission interview is usually the first structured meeting between patient and nurse. The interview serves as the basis for personalised nursing and care planning and is the starting point for the clinic's documentation of the patient and his course of treatment. In this way, admission interviews constitute a basis for reporting by each nurse on the patient to nursing colleagues. This study examined how, by means of the admission interview, nurses constructed written documentation of the patient and his course of treatment for use by fellow nurses. A qualitative case study inspired by Ricoeur was conducted and consisted of five taped admission interviews, along with the written patient documentation subsequently worked out by the nurse. The findings were presented in four constructed themes: Admission interviews are the nurse's room rather than the patient's; Information on a surgical object; The insignificant but necessary contact; and Abnormalities must be medicated. It is shown how the nurse's documentation was based on the admission interview, the medical record details on the patient (facts that are essential to know in relation to disease and treatment), as well as the nurse's preconception of how to live a good life, with or without disease. Often, the patient tended to become an object in the nurse's report. It is concluded that in practice, the applied documentation system, VIPS, comes to act as the framework for what is important to the nurse to document rather than a tool that enables her to document what is important to the individual patient and his special circumstances and encounter with the health system. © 2013 Nordic College of Caring Science.
Admission Control Algorithm for Guaranteeing Real-Time Anycast Flow
Institute of Scientific and Technical Information of China (English)
Weijia Jia; Zhang Chuanlin
2002-01-01
In this paper, we study admission control algorithm for anycast flow with real-time constraints. With the given time requirement, when the result of this algorithm give succeed information, we find route for the anycast flow requesting. Therefore, what we need to do is testing if the corresponding path rj has enough bandwidth for coming anycast flow requirement at source S with end-to-end deadline D. This admission control is scalable in terms of the number of flows can be admitted through local information of the routes.
A lexicographic approach to constrained MDP admission control
Panfili, Martina; Pietrabissa, Antonio; Oddi, Guido; Suraci, Vincenzo
2016-02-01
This paper proposes a reinforcement learning-based lexicographic approach to the call admission control problem in communication networks. The admission control problem is modelled as a multi-constrained Markov decision process. To overcome the problems of the standard approaches to the solution of constrained Markov decision processes, based on the linear programming formulation or on a Lagrangian approach, a multi-constraint lexicographic approach is defined, and an online implementation based on reinforcement learning techniques is proposed. Simulations validate the proposed approach.
Duplex scanning on admission prevents unnecessary carotid endarterectomies.
Dalainas, I; Nano, G; Casana, R; Bianchi, P; Stegher, S; Malacrida, G; Tealdi, D G
2006-06-01
This retrospective single Institution study, aims to evaluate the performance of duplex scanning on admission of patients with carotid artery disease to avoid unnecessary carotid endarterectomies. From 1 January 1997 until 31 Decem-ber 2004, 1 504 patients were admitted to our Institution to undergo carotid endarterectomy. A duplex scan on admission was performed in all of them. A total of 1 369 from these patients (91%) underwent surgery, while 135 (9%) were dismissed because there was no indication for surgical treatment. They were put in conservative treatment and periodic duplex control appointments. In 9% of the patients, unnecessary carotid endarterectomy was avoided.
Prematurity, smallness-for-gestational age and later hospital admissions
DEFF Research Database (Denmark)
Á Rogvi, Rasmus; Forman, Julie Lyng; Greisen, Gorm
2015-01-01
hospital admissions later in life. METHODS: Using Danish nation-wide registries we created a cohort of 1,348,106 persons born 1974-1996 and assessed all unique diagnoses registered in the Danish Patient Registry (DPR) for hospital admissions in the period 1994-2007 (n=27,910,558). We determined the odds...... in life. CONCLUSION: Being born premature or SGA was associated with significantly altered risks of being admitted to a hospital with a wide range of diseases later in life, affecting almost all organ systems throughout childhood and early adulthood. Our findings may motivate testing in other cohorts...
Topological vector spaces admissible in economic equilibrium theory
DEFF Research Database (Denmark)
Keiding, Hans
2009-01-01
In models of economic equilibrium in markets with infinitely many commodities, the commodity space is an ordered topological vector space endowed with additional structure. In the present paper, we consider ordered topological vector spaces which are admissible (for equilibrium analysis) in the s......In models of economic equilibrium in markets with infinitely many commodities, the commodity space is an ordered topological vector space endowed with additional structure. In the present paper, we consider ordered topological vector spaces which are admissible (for equilibrium analysis...
Admissibility of false-confession testimony: know thy standard.
Quintieri, Peter; Weiss, Kenneth J
2005-01-01
The reliability of confessions is subject to a variety of factors, some of which give rise to expert testimony. To the degree that prosecutors construe the determination of reliability as an objective standard, they may attempt to bar testimony. Moreover, when the testimony is theoretical rather than clinical, there are additional challenges. Depending on jurisdiction, the admissibility of expert testimony on whether a confession was knowing, intelligent, and voluntary is subject to a legal threshold such as the Frye or Daubert standard. The authors review a 2002 New Jersey Superior Court ruling that illustrates the forces that shape the admissibility of confessions.
Temporal trends in the use of antithrombotics at admission
DEFF Research Database (Denmark)
Madsen, Christian Medom; Jantzen, Christopher; Lauritzen, Jes Bruun
2016-01-01
Background and purpose - Currently, no clear evidence exists on the pattern of use of antithrombotics at admission in hip fracture patients and how this has changed over time. We investigated temporal trends in-and factors associated with-the use of antithrombotics in patients admitted with a fra......Background and purpose - Currently, no clear evidence exists on the pattern of use of antithrombotics at admission in hip fracture patients and how this has changed over time. We investigated temporal trends in-and factors associated with-the use of antithrombotics in patients admitted...
Pediatric Type 1 Diabetes: Reducing Admission Rates for Diabetes Ketoacidosis
Choi, Steven; Rinke, Michael L.; Vandervoot, Kathy; Heptulla, Rubina A.
2016-01-01
Background: Diabetes ketoacidosis (DKA) is a life-threatening complication of type 1 diabetes mellitus (T1DM). Reducing DKA admissions in children with T1DM requires a coordinated, comprehensive management plan. We aimed to decrease DKA admissions, 30-day readmissions, and length of stay (LOS) for DKA admissions. Methods: A multipronged intervention was designed in 2011 to reach all patients: (1) increase insulin pump use and basal-bolus regimen versus sliding scales, (2) transform educational program, (3) increased access to medical providers, and (4) support for patients and families. A before-after study was conducted comparing performance outcomes in years 2007-2010 (preintervention) to 2012-2014 (postintervention) using administrative data and Wilcoxon rank sum and Fischer exact tests. Results: DKA admissions decreased by 44% postintervention (16.7 vs 9.3 per 100 followed patient-years; P = .006), unique patient 30-day readmissions decreased from 20% to 5% postintervention (P = .001), and median LOS significantly decreased postintervention (P < .0001). Although not an original goal of the study, median hemoglobin A1C of a subset of the population transitioned from sliding scale decreased, 10.3% to 8.9% (P < .02). Conclusions: When clinical and widespread program interventions were used, significant reductions in DKA hospitalizations, 30-day readmissions, and LOS occurred for pediatric T1DM. Continuous performance improvement efforts are needed for improving DKA outcomes. PMID:27749721
Power Admission Control with Predictive Thermal Management in Smart Buildings
DEFF Research Database (Denmark)
Yao, Jianguo; Costanzo, Giuseppe Tommaso; Zhu, Guchuan
2015-01-01
This paper presents a control scheme for thermal management in smart buildings based on predictive power admission control. This approach combines model predictive control with budget-schedulability analysis in order to reduce peak power consumption as well as ensure thermal comfort. First...
Hospital mortality is associated with ICU admission time
Kuijsten, H.A.J.M.; Brinkman, S.; Meynaar, I.A.; Spronk, P.E.; van der Spoel, J.I.; Bosman, R.J.; de Keizer, N.F.; Abu-Hanna, A.; de Lange, D.W.
2010-01-01
Previous studies have shown that patients admitted to the intensive care unit (ICU) after "office hours" are more likely to die. However these results have been challenged by numerous other studies. We therefore analysed this possible relationship between ICU admission time and in-hospital mortality
8 CFR 1101.1 - Presumption of lawful admission.
2010-01-01
... Section 1101.1 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE... the United States prior to July 1, 1924, provided that a record of his admission exists. (e) Chinese and Japanese aliens—(1) Prior to July 1, 1924. A Chinese alien for whom there exists a record of...
Coupling Admissions and Curricular Data to Predict Medical Student Outcomes
Sesate, Diana B.; Milem, Jeffrey F.; McIntosh, Kadian L.; Bryan, W. Patrick
2017-01-01
The relative impact of admissions factors and curricular measures on the first medical licensing exam (United States Medical Licensing Exam [USMLE] Step 1) scores is examined. The inclusion of first-year and second-year curricular measures nearly doubled the variance explained in Step 1 scores from the amount explained by the combination of…
Predicting MBA Student Success and Streamlining the Admissions Process
Pratt, William R.
2015-01-01
Within this study the author examines factors commonly employed as master of business administration applicant evaluation criteria to see if these criteria are important in determining an applicant's potential for success. The findings indicate that the Graduate Management Admissions Test (GMAT) is not a significant predictor of student success…
Continuous admission to primary school and mental health problems
Reijneveld, S.A.; Wiefferink, C.H.; Brugman, E.; Verhulst, F.C.; Verloove-Vanhorick, S.P.; Paulussen, T.G.W.
2006-01-01
Background: Younger children in a school class have higher rates of mental health problems if admission to primary school occurs once a year. This study examines whether this relative age effect also occurs if children are admitted to school continuously throughout the year. Methods: We assessed men
Should Universities Be Permitted to Set Their Own Admission Criteria?
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
For high school students in Shanghai, this year's college admission process is a bit different from that in previous years. Locally based Fudan University and Shanghai Jiaotong University (Jiaoda) have been allowed to make some changes in their enrollment procedures. In addition to taking an independently designed entrance exam
Rising rates of hospital admissions for atrial fibrillation
DEFF Research Database (Denmark)
Friberg, Jens; Buch, Nina Pernille Gardshodn; Scharling, Henrik;
2003-01-01
Atrial fibrillation is a common arrhythmia associated with excess morbidity and mortality. We studied temporal changes in hospital admission rates for atrial fibrillation using data from a prospective population-based cohort study spanning 2 decades (the Copenhagen City Heart Study)....
Predicting MBA Student Success and Streamlining the Admissions Process
Pratt, William R.
2015-01-01
Within this study the author examines factors commonly employed as master of business administration applicant evaluation criteria to see if these criteria are important in determining an applicant's potential for success. The findings indicate that the Graduate Management Admissions Test (GMAT) is not a significant predictor of student success…
42 CFR 32.86 - Admissions to Service facilities.
2010-10-01
... EXAMINATIONS MEDICAL CARE FOR PERSONS WITH HANSEN'S DISEASE AND OTHER PERSONS IN EMERGENCIES Persons with Hansen's Disease § 32.86 Admissions to Service facilities. Any person with Hansen's disease who presents... suitable for the accommodation of persons with Hansen's disease. ...
Increased Guillain-Barre Syndrome Admissions in Shiraz, Southern Iran
Directory of Open Access Journals (Sweden)
Seyed Taghi Heydari
2013-01-01
Full Text Available Background: Guillain-Barre syndrome (GBS is an acute immune-mediated peripheral neuropathy usually after an incident. This study was performed to investigate the basic epidemiologic features of GBS in south of Iran.Methods: We studied consecutive patients with GBS in Namazi Hospital of Shiraz, southern Iran. Demographic characteristics of the subjects, i.e. age, sex, and length of hospital stay were extracted. Information regarding yearly admissions for the entire hospital was also gathered. The prevalence of GBS per 10,000 hospital admissions was calculated and stratified by sex and year. Yearly prevalence was compared using the odds ratio (OR and 95% confidence intervals (CI.Results: From January 2000 to December 2009, 389 (232 males and 157 females patients with GBS were admitted in our center. The mean age of patients was 29.8 ± 23.0 years and their mean length of hospital stay was 12.9 ± 11.6 days. The overall mortality rate was 6%. The ratio of admissions due to GBS to the total admissions was significantly higher in 2009, the year of an influenza A (H1N1 virus pandemic.Conclusion: There appears to be an increase in the incidence of GBS in Shiraz. This is in parallel with the increasing trend of some other autoimmune diseases.
Confronting the Categories: Equitable Admissions without Apartheid Race Classification
Erasmus, Z.
2010-01-01
South Africa's government requires information on apartheid race classification to implement and monitor racial redress. This has sparked resistance to race classification as a criterion for redress in higher education admissions. I argue that (1) jettisoning apartheid race categories now in favour of either class or "merit" would set back the few…
Confronting the Categories: Equitable Admissions without Apartheid Race Classification
Erasmus, Z.
2010-01-01
South Africa's government requires information on apartheid race classification to implement and monitor racial redress. This has sparked resistance to race classification as a criterion for redress in higher education admissions. I argue that (1) jettisoning apartheid race categories now in favour of either class or "merit" would set…
Institutional Admissions Policies in Higher Education: A Widening Participation Perspective
Greenbank, Paul
2006-01-01
Purpose: This article analyses how higher education institutions (HEIs) have responded to government policy to increase the participation rates of students from lower social classes through their admissions policies. Design/methodology/approach: The article uses documentary evidence and interviews with institutional policy makers to examine HEI…
Admission and Attrition of Women in Graduate School.
Baranger, Elizabeth Urey
Reasons behind the fact that there are fewer women scientists than men scientists are explored in this paper. Data on the number of women Ph.D.'s in each field of science for the years 1966 through 1974 are presented and analyzed. Graduate school admissions policies and the greater attrition rate for women in graduate school compared to men are…
38 CFR 51.80 - Admission, transfer and discharge rights.
2010-07-01
... (CONTINUED) PER DIEM FOR NURSING HOME CARE OF VETERANS IN STATE HOMES Standards § 51.80 Admission, transfer... resident and, if known, a family member or legal representative of the resident of the transfer or..., address and telephone number of the State long term care ombudsman. (7) Orientation for transfer...
LGBT Applicants and Challenges for Admission: Five Cases
Baum, Benjamin S.
2012-01-01
Few professional processes are more personally intrusive than the college application. It demands information about your family, your finances, your interests, and your desires. For lesbian, gay, bisexual, and transgender (LGBT) applicants in their teenage years who may not be comfortable with their sexuality, admission officers need be sensitive…
78 FR 62415 - Refugee Admissions for Fiscal Year 2014
2013-10-21
... in the Federal Register. (Presidential Sig.) THE WHITE HOUSE, Washington, October 2, 2013 [FR Doc... Documents#0;#0; ] Presidential Determination No. 2014-01 of October 2, 2013 Refugee Admissions for Fiscal... up to 70,000 refugees to the United States during fiscal year (FY) 2014 is justified by...
Relationship Between Standardized Admissions Variables and Certain Interpersonal Skills
Hurst, Michael W.; Shatkin, Stephen D.
1974-01-01
An admissions model was developed that included standardized intellective and nonintellective variables. It was found that linear combinations of grade point average, quality of undergraduate college, major area of study, and recommendations and work experience were generally unrelated to pre- or post-training ratings of empathy, respect, and…
The effects of Montessori education: evidence from admission lotteries
Ruijs, N.
2014-01-01
Little is known about the effects of Montessori education, even though many students in many countries are educated in Montessori classrooms. This study investigates the causal effects of Montessori secondary education by exploiting admission lotteries in Dutch Montessori schools. The results
Using Technology in Undergraduate Admission: A Student Perspective
Lindbeck, Robin; Fodrey, Brian
2010-01-01
The relationship that currently exists between undergraduate admission, technology and the Millennial generation continues to be an area of constant change. As technology trends come-and-go and resources continue to be limited, what are colleges and universities doing to ensure they are being as effective and efficient as possible when it comes to…
Investigating the Reliability of the Medical School Admissions Interview
Kreiter, Clarence D.; Yin, Ping; Solow, Catherine; Brennan, Robert L.
2004-01-01
Purpose: Determining the valid and fair use of the interview for medical school admissions is contingent upon a demonstration of the reproducibility of interview scores. This study seeks to establish the generalizability of interview scores, first assessing the existing research evidence, and then analyzing data from a non-experimental independent…
42 CFR 483.12 - Admission, transfer and discharge rights.
2010-10-01
... State long term care ombudsman; (vi) For nursing facility residents with developmental disabilities, the... therapeutic leave, a nursing facility must provide to the resident and a family member or legal representative... 42 Public Health 5 2010-10-01 2010-10-01 false Admission, transfer and discharge rights. 483.12...
Hyponatraemia at hospital admission is a predictor of overall mortality
DEFF Research Database (Denmark)
Balling, L; Gustafsson, F; Goetze, J P;
2015-01-01
BACKGROUND: Hyponatraemia is a prognostic marker of increased mortality and morbidity in selected groups of hospitalised patients. The aim of the present study was to examine the prevalence and prognostic significance of hyponatraemia at hospital admission in an unselected population with a broad...
A Normative Code of Conduct for Admissions Officers
Hodum, Robert L.
2012-01-01
The increasing competition for the desired quantity and quality of college students, along with the rise of for-profit institutions, has amplified the scrutiny of behavior and ethics among college admissions professionals and has increased the need for meaningful ethical guidelines and codes of conduct. Many other areas of responsibility within…
Practices of Whiteness: Racialization in College Admissions Viewbooks
Osei-Kofi, Nana; Torres, Lisette E.; Lui, Joyce
2013-01-01
US colleges and universities today intensively market themselves in order to compete for prospective students. One of the most widespread marketing tools used to attract students are admissions viewbooks, which are designed to provide potential students with favorable impressions of the many institutions to which they may apply. In this study, we…
Increase in drug use after admission to Dutch nursing homes.
Koopmans, R.T.C.M.; Borgh, J.P. van der; Bor, J.H.J.; Hekster, Y.A.
2003-01-01
OBJECTIVE: To study changes in drug use after admission to Dutch nursing homes. SETTING: Six nursing homes near the city of Nijmegen, The Netherlands. DESIGN: Prospective longitudinal study. METHODS: All patients who had been newly admitted to the nursing home were included in the study. Age,
Admissibility and Refutation : Some Characterisations of Intermediate Logics
Goudsmit, J.P.
2014-01-01
Refutation systems are formal systems for inferring the falsity of formulae. These systems can, in particular, be used to syntactically characterise logics. In this paper, we explore the close connection between refutation systems and admissible rules. We develop technical machinery to construct ref
The effects of Montessori education: evidence from admission lotteries
Ruijs, N.
2014-01-01
Little is known about the effects of Montessori education, even though many students in many countries are educated in Montessori classrooms. This study investigates the causal effects of Montessori secondary education by exploiting admission lotteries in Dutch Montessori schools. The results indica
Student Attitudes toward Affirmative Action in College Admissions.
Arredondo, Marisol; Sax, Linda J.
1999-01-01
A national survey of 277,850 college freshmen examined attitudes toward affirmative action in college admissions for four racial/ethnic groups: Whites, African-Americans, Asian-Americans, and Mexican-Americans. The study analyzed the extent to which student opposition to affirmative action is driven by factors such as self-interest, political…
The Demise of Affirmative Action in College Admission.
Arredondo, David G.
2002-01-01
The legal activity in federal courts related to affirmative action indicates a strong possibility the Supreme Court will abolish affirmative action in college admission. Such a decision would inevitably alter the landscape of higher education. Campus diversity will have to be achieved without using race or ethnicity to offer preference to some at…
The Declining Significance of Race in College Admissions Decisions
Grodsky, Eric; Kalogrides, Demetra
2008-01-01
Using 18 years of data from more than 1,300 four-year colleges and universities in the United States, we investigate the extent to which institutional characteristics and contextual factors influence the propensity of colleges to indicate that they engage in affirmative action in their admissions decisions. Consideration of race/ethnicity in…
Objectivity in needs assessment practice : admission to a residential home
Jörg, F; Boeije, H R; Huijsman, R; de Weert, G H; Schrijvers, A J P; Jorg, Frederike
2002-01-01
In 1997, the Dutch government installed independent agencies to assess the long-term care needs of individual clients and to give advice on the allocation of appropriate services. Needs assessors assess, among other things, the eligibility of clients requesting admission to a residential home. Accor
Reflections on a Century of College Admissions Tests
Atkinson, Richard C.; Geiser, Saul
2009-01-01
The College Boards started as achievement tests designed to measure students' mastery of college preparatory subjects. Admissions testing has significantly changed since then with the introduction of the Scholastic Aptitude Test, Lindquist's creation of the ACT, renewed interest in subject-specific assessments, and current efforts to adapt K-12…
Modeling the effect of short stay units on patient admissions
Zonderland, Maartje E.; Boucherie, Richard J.; Carter, Michael W.; Stanford, David A.
2015-01-01
Two purposes of Short Stay Units (SSU) are the reduction of Emergency Department crowding and increased urgent patient admissions. At an SSU urgent patients are temporarily held until they either can go home or transferred to an inpatient ward. In this paper we present an overflow model to evaluate
28 CFR 549.41 - Voluntary admission and psychotropic medication.
2010-07-01
... medication. 549.41 Section 549.41 Judicial Administration BUREAU OF PRISONS, DEPARTMENT OF JUSTICE INSTITUTIONAL MANAGEMENT MEDICAL SERVICES Administrative Safeguards for Psychiatric Treatment and Medication § 549.41 Voluntary admission and psychotropic medication. (a) A sentenced inmate may be...
8 CFR 235.11 - Admission of conditional permanent residents.
2010-01-01
... alien entrepreneur (as defined in section 216A(f)(1) of the Act) or the spouse or unmarried minor child of an alien entrepreneur shall be admitted conditionally for a period of 2 years. At the time of admission, the alien shall be notified that the principal alien (entrepreneur) must file a Form...
8 CFR 1235.11 - Admission of conditional permanent residents.
2010-01-01
... immigrant visa as an alien entrepreneur (as defined in section 216A(f)(1) of the Act) or the spouse or unmarried minor child of an alien entrepreneur shall be admitted conditionally for a period of 2 years. At the time of admission, the alien shall be notified that the principal alien (entrepreneur) must file...
Differential Item Functioning on the Graduate Management Admission Test.
O'Neill, Kathleen A.; And Others
The purpose of this study was to identify differentially functioning items on operational administrations of the Graduate Management Admission Test (GMAT) through the use of the Mantel-Haenszel statistic. Retrospective analyses of data collected over 3 years are reported for black/white and female/male comparisons for the Verbal and Quantitative…
The Effects of Extrinsic Rewards on Admissions Counselors' Performance
Gardner-Engel, Miriam
2010-01-01
This study examines the best ways to motivate college admissions counselors. A review of literature revealed multiple perspectives on intrinsic and extrinsic as well as tangible and intangible rewards. Primary research was designed to examine the impact of tangible rewards and verbal reinforcements with a convenience sample of nine college…
Evaluation of the Early Admission to First Grade Program.
Hebbeler, Kathleen; And Others
This report presents findings from the first year of a pilot program permitting kindergarten age students to enter school at the first grade level (K-1 program for 5-year-olds). The purposes of the study were: (1) to compare the academic and social behavior of the early admissions (EA) students with that of the regular first graders; (2) to…
Predictors of Specialized Inpatient Admissions for Adults with Intellectual Disability
Modi, Miti; McMorris, Carly; Palucka, Anna; Raina, Poonam; Lunsky, Yona
2015-01-01
Individuals with intellectual disability (ID) have complex mental health needs and may seek specialized ID psychiatric services. This study reports on predictors of specialized inpatient admissions for 234 individuals with ID who received outpatient services at a psychiatric hospital. Overall, from 2007-2012, 55 of the 234 outpatients were triaged…
Job Admission and Resource Allocation in Distributed Streaming Systems
Wolf, Joel; Bansal, Nikhil; Hildrum, Kirsten; Parekh, Sujay; Rajan, Deepak; Wagle, Rohit; Wu, Kun-Lung
This paper describes a new and novel scheme for job admission and resource allocation employed by the SODA scheduler in System S. Capable of processing enormous quantities of streaming data, System S is a large-scale, distributed stream processing system designed to handle complex applications. The problem of scheduling in distributed, stream-based systems is quite unlike that in more traditional systems. And the requirements for System S, in particular, are more stringent than one might expect even in a “standard” stream-based design. For example, in System S, the offered load is expected to vastly exceed system capacity. So a careful job admission scheme is essential. The jobs in System S are essentially directed graphs, with software “processing elements” (PEs) as vertices and data streams as edges connecting the PEs. The jobs themselves are often heavily interconnected. Thus resource allocation of individual PEs must be done carefully in order to balance the flow. We describe the design of the SODA scheduler, with particular emphasis on the component, known as macroQ, which performs the job admission and resource allocation tasks. We demonstrate by experiments the natural trade-offs between job admission and resource allocation.
Scaled density functional theory correlation functionals.
Ghouri, Mohammed M; Singh, Saurabh; Ramachandran, B
2007-10-18
We show that a simple one-parameter scaling of the dynamical correlation energy estimated by the density functional theory (DFT) correlation functionals helps increase the overall accuracy for several local and nonlocal functionals. The approach taken here has been described as the "scaled dynamical correlation" (SDC) method [Ramachandran, J. Phys. Chem. A 2006, 110, 396], and its justification is the same as that of the scaled external correlation (SEC) method of Brown and Truhlar. We examine five local and five nonlocal (hybrid) DFT functionals, the latter group including three functionals developed specifically for kinetics by the Truhlar group. The optimum scale factors are obtained by use of a set of 98 data values consisting of molecules, ions, and transition states. The optimum scale factors, found with a linear regression relationship, are found to differ from unity with a high degree of correlation in nearly every case, indicating that the deviation of calculated results from the experimental values are systematic and proportional to the dynamic correlation energy. As a consequence, the SDC scaling of dynamical correlation decreases the mean errors (signed and unsigned) by significant amounts in an overwhelming majority of cases. These results indicate that there are gains to be realized from further parametrization of several popular exchange-correlation functionals.
Alam, Md. Mehboob; Knecht, Stefan; Fromager, Emmanuel
2016-07-01
Ensemble density-functional theory (eDFT) suffers from the so-called "ghost-interaction" error when approximate exchange-correlation functionals are used. In this work, we present a rigorous ghost-interaction correction (GIC) scheme in the context of range-separated eDFT. The method relies on an exact decomposition of the ensemble short-range exchange-correlation energy into a multideterminantal exact exchange term, which involves the long-range interacting ensemble density matrix, instead of the Kohn-Sham (KS) one, and a complementary density-functional correlation energy. A generalized adiabatic connection formula is derived for the latter. In order to perform practical calculations, the complementary correlation functional is simply modeled by its ground-state local density approximation (LDA), while long-range interacting ground- and excited-state wave functions are obtained self-consistently by combining a long-range configuration-interaction calculation with a short-range LDA potential. We show that the GIC reduces the curvature of approximate range-separated ensemble energies drastically while providing considerably more accurate excitation energies, even for charge-transfer and double excitations. Interestingly, the method performs well also in the context of standard KS-eDFT, which is recovered when the range-separation parameter is set to 0.
Admission glycaemia and outcome in patients with acute coronary syndrome.
Müdespacher, Damaris; Radovanovic, Dragana; Camenzind, Edoardo; Essig, Manfred; Bertel, Osmund; Erne, Paul; Eberli, Franz Robert; Gutzwiller, Felix
2007-12-01
Some studies of patients with acute myocardial infarction have reported that hyperglycaemia at admission may be associated with a worse outcome. This study sought to evaluate the association of blood glucose at admission with the outcome of unselected patients with acute coronary syndrome (ACS). Using the Acute Myocardial Infarction and unstable angina in Switzerland (AMIS Plus) registry, ACS patients were stratified according to their blood glucose on admission: group 1: 2.80-6.99 mmol/L, group 2: 7.00-11.09 mmol/L and group 3: > 11.10 mmol/L. Odds ratios for in-hospital mortality were calculated using logistic regression models. Of 2,786 patients, 73% were male and 21% were known to have diabetes. In-hospital mortality increased from 3% in group 1 to 7% in group 2 and to 15% in group 3. Higher glucose levels were associated with larger enzymatic infarct sizes (p<0.001) and had a weak negative correlation with angiographic or echographic left ventricular ejection fraction. High admission glycaemia in ACS patients remains a significant independent predictor of in-hospital mortality (adjusted OR 1.08; 95% confidence intervals [CI] 1.05-1.14, p<0.001) per mmol/L. The OR for in-hospital mortality was 1.04 (95% CI 0.99-1.1; p=0.140) per mmol/L for patients with diabetes but 1.21 (95% CI 112-1.30; p<0.001) per mmol/L for non-diabetic patients. In conclusion, elevated glucose level in ACS patients on admission is a significant independent predictor of in-hospital mortality and is even more important for patients who do not have known diabetes.
Specialty-specific admission: a cost-effective intervention?
LENUS (Irish Health Repository)
Slattery, E
2012-02-01
INTRODUCTION: Cost effectiveness of healthcare has become an important component in its delivery. Current practices need to be assessed and measured for variations that may lead to financial savings. Speciality specific admission is known not only to lead improved clinical outcomes but also to lead important cost reductions. METHODS: All patients admitted to an Irish teaching hospital via the emergency department over a 2-year period with a gastroenterology (GI) related illness were included in this analysis.GI illness was classified using the Disease related grouping (DRG) system. Mean length of stay (LOS) and patient level costing (PLC) were calculated. Differences between DRGs with respect to speciality (i.e. specialist vs. non-specialist) were calculated for the five commonest DRGs. RESULTS: Significant variations in LOS and PLC were demonstrated in the DRGs. Mean LOS varied with increasing complexity, from 3.2 days for non-complex GI haemorrhage to 14.4 days for complex alcohol related cirrhosis as expected. A substantial difference in LOS within DRG groups was demonstrated by large standard deviations in the mean (up to 8.1 days in some groups) and was independent of complexity of cases. PLC also varied widely in both complex and non-complex cases with standard deviations of up to
Hospital Admissions, Transfers and Costs of Guillain-Barre Syndrome.
Directory of Open Access Journals (Sweden)
Nikki van Leeuwen
Full Text Available Guillain-Barré syndrome (GBS has a highly variable clinical course, leading to frequent transfers within and between hospitals and high associated costs. We defined the current admissions, transfers and costs in relation to disease severity of GBS.Dutch neurologists were requested to report patients diagnosed with GBS between November 2009 and November 2010. Information regarding clinical course and transfers was obtained via neurologists and general practitioners.87 GBS patients were included with maximal GBS disability score of 1 or 2 (28%, 3 or 4 (53%, 5 (18% and 6 (1%. Four mildly affected GBS patients were not hospital admitted. Of the 83 hospitalized patients 68 (82% were initially admitted at a neurology department, 4 (5% at an ICU, 4 (5% at pediatrics, 4 (5% at pediatrics neurology and 3 (4% at internal medicine. Median hospital stay was 17 days (IQR 11-26 days, absolute range 1-133 days. Transfers between departments or hospitals occurred in 33 (40% patients and 25 (30% were transferred 2 times or more. From a cost-effectiveness perspective 21 (25% of the admissions was suboptimal. Median costs for hospital admission of GBS patients were 15,060 Euro (IQR 11,226-23,683. Maximal GBS disability score was significantly correlated with total length of stay, number of transfers, ICU admission and costs.Hospital admissions for GBS patients are highly heterogeneous, with frequent transfers and higher costs for those with more severe disease. Future research should aim to develop prediction models to early identify the most cost-effective allocation in individual patients.
Kinetic Energy of Hydrocarbons as a Function of Electron Density and Convolutional Neural Networks.
Yao, Kun; Parkhill, John
2016-03-01
We demonstrate a convolutional neural network trained to reproduce the Kohn-Sham kinetic energy of hydrocarbons from an input electron density. The output of the network is used as a nonlocal correction to conventional local and semilocal kinetic functionals. We show that this approximation qualitatively reproduces Kohn-Sham potential energy surfaces when used with conventional exchange correlation functionals. The density which minimizes the total energy given by the functional is examined in detail. We identify several avenues to improve on this exploratory work, by reducing numerical noise and changing the structure of our functional. Finally we examine the features in the density learned by the neural network to anticipate the prospects of generalizing these models.
Time-dependent density functional theory for many-electron systems interacting with cavity photons.
Tokatly, I V
2013-06-07
Time-dependent (current) density functional theory for many-electron systems strongly coupled to quantized electromagnetic modes of a microcavity is proposed. It is shown that the electron-photon wave function is a unique functional of the electronic (current) density and the expectation values of photonic coordinates. The Kohn-Sham system is constructed, which allows us to calculate the above basic variables by solving self-consistent equations for noninteracting particles. We suggest possible approximations for the exchange-correlation potentials and discuss implications of this approach for the theory of open quantum systems. In particular we show that it naturally leads to time-dependent density functional theory for systems coupled to the Caldeira-Leggett bath.
Towards efficient orbital-dependent density functionals for weak and strong correlation
Zhang, Igor Ying; Perdew, John P; Scheffler, Matthias
2016-01-01
We present a new paradigm for the design of exchange-correlation functionals in density-functional theory. Electron pairs are correlated explicitly by means of the recently developed second order Bethe-Goldstone equation (BGE2) approach. Here we propose a screened BGE2 (sBGE2) variant that efficiently regulates the coupling of a given electron pair. sBGE2 correctly dissociates H$_2$ and H$_2^+$, a problem that has been regarded as a great challenge in density-functional theory for a long time. The sBGE2 functional is then taken as a building block for an orbital-dependent functional, termed ZRPS, which is a natural extension of the PBE0 hybrid functional. While worsening the good performance of sBGE2 in H$_2$ and H$_2^{+}$, ZRPS yields a remarkable and consistent improvement over other density functionals across various chemical environments from weak to strong correlation.
Self-consistent density functional calculation of the image potential at a metal surface
Energy Technology Data Exchange (ETDEWEB)
Jung, J [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain); Alvarellos, J E [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain); Chacon, E [Instituto de Ciencias de Materiales de Madrid, Consejo Superior de Investigaciones CientIficas, E-28049 Madrid (Spain); GarcIa-Gonzalez, P [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain)
2007-07-04
It is well known that the exchange-correlation (XC) potential at a metal surface has an image-like asymptotic behaviour given by -1/4(z-z{sub 0}), where z is the coordinate perpendicular to the surface. Using a suitable fully non-local functional prescription, we evaluate self-consistently the XC potential with the correct image behaviour for simple jellium surfaces in the range of metallic densities. This allows a proper comparison between the corresponding image-plane position, z{sub 0}, and other related quantities such as the centroid of an induced charge by an external perturbation. As a by-product, we assess the routinely used local density approximation when evaluating electron density profiles, work functions, and surface energies by focusing on the XC effects included in the fully non-local description.
Magnetic properties of f-electron systems in spin-polarized relativistic density functional theory
Yamagami, H.; Mavromaras, A.; Kübler, J.
1997-12-01
The magnetic ground state of the series of lanthanide and actinide trivalent ions is investigated by means of spin-polarized relativistic spin-density functional theory. In the local density functional approximation (LDA) an internal effective magnetic field due to exchange and correlation couples to the spin degrees of freedom. The resulting set of coupled Dirac equations yields ground-state multiplets that obey the well-known Hund's rules. This remarkable result comes about by the coupling of the j = l + 1/2 with the j = l - 1/2 states due to the exchange - correlation potential that is, as usual, the functional derivative of the exchange - correlation energy with respect to the spin magnetic moment. The effect of the coupling is shown to depend on the varying relative strengths of spin - orbit coupling and exchange splitting within the f series. Since in the f levels the internal exchange splitting dominates rather than the spin - orbit splitting, the energy level scheme is that of the Paschen - Back effect, and thus features of the Russell - Saunders coupling persist in spite of relativistic effects.
Kahlenberg, Richard
This brief explores the pros and cons of three alternative approaches to college admissions policies: race-based preferences, which are backed by most Democrats; class-rank plans (admitting the top students in each high school), which is backed by the Bush administration; and economic affirmative action for the disadvantaged of all races, which…
Drug related hospital admissions in subspecialities of internal medicine.
Hallas, J
1996-04-01
It is well established in the literature that adverse drug reactions (ADRs) and drug non-compliance contribute substantially to the admissions at medical wards. Some important questions, however, remain unanswered. The purpose of this thesis was to characterise the drug-related hospital admissions (DRH) and to assess the magnitude of the problem seen in relation to the demographic parameters and drug use of the background population. In addition, an attempt was made to reduce the DRH incidence by an intervention program. The scope of the study program was adverse drug reactions, intended self-poisoning, non-compliance, underdosing and interactions. The material included 1999 admissions to six departments of internal medicine at Odense University Hospital. The patients were reviewed prospectively, while they were still in the wards, but use of standardised criteria fOR assessment of drug-ADR causality. With inclusion of a definite, probable and possible causal relationship, ADRs and toxic reactions were found as an important factor in 8.4% of all admissions. The incidense of ADR related admissions was 400 per 100,000 per year for the background population as a whole, but showing a strong increase with age. The drug-specific ADR incidences were generally small compared to the drug sales figures. Non-compliance contributed to 2.0% of admissions with diuretics and anti-asthmatics as the drugs most frequently involved. Two departments were re-investigated after an intervention program, primarily targetting general practitioners. The over-all incidence of DRHs was unaffected by the intervention, but the subset classified as avoidable DRHs showed a significant decline. The case material was subject to a blinded evaluation by an external peer group using the same criteria as the investigators. There was no indication that the observed decline in avoidable DRHs should be explained by a shift in the investigators' assessment of cases. It was concluded that the intervention
Alam, Md Mehboob; Fromager, Emmanuel
2016-01-01
Ensemble density-functional theory (eDFT) suffers from the "ghost-interaction" (GI) error when approximate exchange-correlation functionals are used. In this letter, we present a rigorous GI correction (GIC) in the context of multideterminantal range-separated eDFT. The method, which relies on a double generalized adiabatic connection for ensembles, is equally applicable to standard Kohn-Sham eDFT. We show that GIC reduces the curvature of approximate ensemble energies drastically while providing considerably more accurate excitation energies, even for charge-transfer and double excitations.
Directory of Open Access Journals (Sweden)
Jeffrey J. Guterman
2016-09-01
Full Text Available Introduction: Attending physician judgment is the traditional standard of care for emergency department (ED admission decisions. The extent to which variability in admission decisions affect cost and quality is not well understood. We sought to determine the impact of variability in admission decisions on cost and quality. Methods: We performed a retrospective observational study of patients presenting to a university-affiliated, urban ED from October 1, 2007, through September 30, 2008. The main outcome measures were admission rate, fiscal indicators (Medicaid-denied payment days, and quality indicators (15- and 30-day ED returns; delayed hospital admissions. We asked each Attending to estimate their inpatient admission rate and correlated their personal assessment with actual admission rates. Results: Admission rates, even after adjusting for known confounders, were highly variable (15.2%-32.0% and correlated with Medicaid denied-payment day rates (p=0.038. There was no correlation with quality outcome measures (30-day ED return or delayed hospital admission. There was no significant correlation between actual and self-described admission rate; the range of mis-estimation was 0% to 117%. Conclusion: Emergency medicine attending admission rates at this institution are highly variable, unexplained by known confounding variables, and unrelated to quality of care, as measured by 30-day ED return or delayed hospital admission. Admission optimization represents an important untapped potential for cost reduction through avoidable hospitalizations, with no apparent adverse effects on quality.
Implementation Strategies for Orbital-dependent Density Functionals
Bento, Marsal E.; Vieira, Daniel
2016-12-01
The development of density functional theory (DFT) has been focused primarily on two main pillars: (1) the pursuit of more accurate exchange-correlation (XC) density functionals; (2) the feasibility of computational implementation when dealing with many-body systems. In this context, this work is aimed on using one-dimensional quantum systems as theoretical laboratories to investigate the implementation of orbital functionals (OFs) of density. By definition, OFs are those which depend only implicitly on the density, via an explicit formulation in terms of Kohn-Sham orbitals. Typical examples are the XC functionals arising from the Perdew-Zunger self-interaction correction (PZSIC). Formally, via Kohn-Sham equations, the implementation of OFs must be performed by means of the optimized effective potential method (OEP), which is known by requiring an excessive computational effort even when dealing with few electrons systems. Here, we proceed a systematical investigation aiming to simplify or avoid the OEP procedure, taking as reference the implementation of the PZSIC correction applied to one-dimensional Hubbard chains.
Implementation Strategies for Orbital-dependent Density Functionals
Bento, Marsal E.; Vieira, Daniel
2016-10-01
The development of density functional theory (DFT) has been focused primarily on two main pillars: (1) the pursuit of more accurate exchange-correlation (XC) density functionals; (2) the feasibility of computational implementation when dealing with many-body systems. In this context, this work is aimed on using one-dimensional quantum systems as theoretical laboratories to investigate the implementation of orbital functionals (OFs) of density. By definition, OFs are those which depend only implicitly on the density, via an explicit formulation in terms of Kohn-Sham orbitals. Typical examples are the XC functionals arising from the Perdew-Zunger self-interaction correction (PZSIC). Formally, via Kohn-Sham equations, the implementation of OFs must be performed by means of the optimized effective potential method (OEP), which is known by requiring an excessive computational effort even when dealing with few electrons systems. Here, we proceed a systematical investigation aiming to simplify or avoid the OEP procedure, taking as reference the implementation of the PZSIC correction applied to one-dimensional Hubbard chains.
Kvaal, Simen; Helgaker, Trygve
2015-11-14
The relationship between the densities of ground-state wave functions (i.e., the minimizers of the Rayleigh-Ritz variation principle) and the ground-state densities in density-functional theory (i.e., the minimizers of the Hohenberg-Kohn variation principle) is studied within the framework of convex conjugation, in a generic setting covering molecular systems, solid-state systems, and more. Having introduced admissible density functionals as functionals that produce the exact ground-state energy for a given external potential by minimizing over densities in the Hohenberg-Kohn variation principle, necessary and sufficient conditions on such functionals are established to ensure that the Rayleigh-Ritz ground-state densities and the Hohenberg-Kohn ground-state densities are identical. We apply the results to molecular systems in the Born-Oppenheimer approximation. For any given potential v ∈ L(3/2)(ℝ(3)) + L(∞)(ℝ(3)), we establish a one-to-one correspondence between the mixed ground-state densities of the Rayleigh-Ritz variation principle and the mixed ground-state densities of the Hohenberg-Kohn variation principle when the Lieb density-matrix constrained-search universal density functional is taken as the admissible functional. A similar one-to-one correspondence is established between the pure ground-state densities of the Rayleigh-Ritz variation principle and the pure ground-state densities obtained using the Hohenberg-Kohn variation principle with the Levy-Lieb pure-state constrained-search functional. In other words, all physical ground-state densities (pure or mixed) are recovered with these functionals and no false densities (i.e., minimizing densities that are not physical) exist. The importance of topology (i.e., choice of Banach space of densities and potentials) is emphasized and illustrated. The relevance of these results for current-density-functional theory is examined.
Costa, D.W. da; Bouwense, S.A.; Schepers, N.J.; Besselink, M.G.; Santvoort, H.C. van; Brunschot, S. van; Bakker, O.J.; Bollen, T.L.; Dejong, C.H.; Goor, H. van; Boermeester, M.A.; Bruno, M.J.; Eijck, C.H. van; Timmer, R.; Weusten, B.L.; Consten, E.C.; Brink, M.A.; Spanier, B.W.; Bilgen, E.J.; Nieuwenhuijs, V.B.; Hofker, H.S.; Rosman, C.; Voorburg, A.M.; Bosscha, K.; Duijvendijk, P. van; Gerritsen, J.J.; Heisterkamp, J.; Hingh, I.H. de; Witteman, B.J.; Kruyt, P.M.; Scheepers, J.J.; Molenaar, I.Q.; Schaapherder, A.F.; Manusama, E.R.; Waaij, L.A. van der; Unen, J. van; Dijkgraaf, M.G.; Ramshorst, B. van; Gooszen, H.G.; Boerma, D.
2015-01-01
BACKGROUND: In patients with mild gallstone pancreatitis, cholecystectomy during the same hospital admission might reduce the risk of recurrent gallstone-related complications, compared with the more commonly used strategy of interval cholecystectomy. However, evidence to support same-admission
Da Costa, David W.; Bouwense, Stefan A.; Schepers, Nicolien J.; Besselink, Marc G.; van Santvoort, Hjalmar C.|info:eu-repo/dai/nl/304821721; Van Brunschot, Sandra; Bakker, Olaf J.|info:eu-repo/dai/nl/314099050; Bollen, Thomas L.; Dejong, Cornelis H.; Van Goor, Harry; Boermeester, Marja A.; Bruno, Marco J.; Van Eijck, Casper H.; Timmer, Robin; Weusten, Bas L.; Consten, Esther C.; Brink, Menno A.; Spanier, B. W Marcel; Bilgen, Ernst Jan Spillenaar; Nieuwenhuijs, Vincent B.; Hofker, H. Sijbrand; Rosman, Camiel; Voorburg, Annet M.; Bosscha, Koop; Van Duijvendijk, Peter; Gerritsen, Jos J.; Heisterkamp, Joos; De Hingh, Ignace H.; Witteman, Ben J.; Kruyt, Philip M.; Scheepers, Joris J.; Molenaar, I. Quintus|info:eu-repo/dai/nl/239093976; Schaapherder, Alexander F.; Manusama, Eric R.; Van Der Waaij, Laurens A.; Van Unen, Jacco; Dijkgraaf, Marcel G.; Van Ramshorst, Bert; Gooszen, Hein G.; Boerma, Djamila
2015-01-01
Background In patients with mild gallstone pancreatitis, cholecystectomy during the same hospital admission might reduce the risk of recurrent gallstone-related complications, compared with the more commonly used strategy of interval cholecystectomy. However, evidence to support same-admission
77 FR 19408 - Notice of Public Meeting on FY 2013 U.S. Refugee Admissions Program
2012-03-30
... Delicia Spruell, PRM/Admissions Program Officer at (202) 453-9257. Information about the U.S. Refugee Admissions Program may be found at http://www.state.gov/g/prm/ . Dated: March 22, 2012. David...
76 FR 19176 - Notice of Public Meeting on FY 2012 Refugee Admissions Program
2011-04-06
... contact Delicia Spruell, PRM/Admissions Program Officer at (202) 453-9257. Information about the U.S. Refugee Admissions Program may be found at http://www.state.gov/g/prm/ . Dated: March 30, 2011....
75 FR 20031 - Notice of Public Meeting on FY 2011 Refugee Admissions Program
2010-04-16
... contact Delicia Spruell, PRM/Admissions Program Officer at (202) 663-1006. Information about the Refugee Admissions Program may be found at http://www.state.gov/g/prm/ . Dated: April 12, 2010. David...
[Psychogeriatric emergency admissions in the area Eindhoven and the Kempen].
Schrijver, T L
1992-02-01
In the Netherlands a special arrangement between the Regional Institute for Outpatient Mental Health Care (RIAGG) and nursing homes exists in region Eindhoven to deal with emergency admissions of psychogeriatric patients. Such an arrangement is necessary, because of long waiting lists for psychogeriatric nursing homes. This article describes the circumstances of 47 patients, who were admitted by this special arrangement. The group which had not been known before the crisis by RIAGG or nursing home (n = 21) is compared to those who had already been waiting some time for admission (n = 26). It appears that in the latter group the burden on the care taker becomes too heavy due to behavioural disturbances of the patient, while in the first group the coping abilities of the system decline due to acute illness or death of the care taker.
Certain Aspects concerning Trial under Admission of Guilt
Directory of Open Access Journals (Sweden)
Mihai OLARIU
2014-03-01
Full Text Available The trial under admission of guilt is an abbreviated procedure relying on a guilty plea, and it may be applied if the conditions stipulated in the New Criminal Procedure Code are fulfilled. One of these conditions is for the defendant to fully admit of the deeds presented by the prosecutor in the indictment (he must not, however, admit the same upon the legal classification of offences. Pursuant to the simplified procedure, in the case of conviction or postponement of the application of the sanction, the punishment limits stipulated under the law are reduced by one third for imprisonment, and by one fourth for fine sanctions. The present article is a a continuation of the author’s own research and it represents a clear comment regarding trial under admission of guilt according to the New Criminal Procedure Code, in the purpose of understanding the legislator’s intention and how the new regulations will apply.
A structural comparison of measurement-based admission control algorithms
Institute of Scientific and Technical Information of China (English)
GU Yi-ran; WANG Suo-ping; WU Hai-ya
2006-01-01
Measurement-based admission control (MBAC)algorithm is designed for the relaxed real-time service. In contrast to traditional connection admission control mechanisms,the most attractive feature of MBAC algorithm is that it does not require a prior traffic model and that is very difficult for the user to come up with a tight traffic model before establishing a flow.Other advantages of MBAC include that it can achieve higher network utilization and offer quality service to users. In this article, the study of the equations in the MBAC shows that they can all be expressed in the same form. Based on the same form,some MBAC algorithms can achieve same performance only if they satisfy some conditions.
Factors related to monitoring during admission of acute patients
DEFF Research Database (Denmark)
Schmidt, Thomas; Bech, Camilla Louise Nørgaard; Brabrand, Mikkel
2017-01-01
one measurement were analyzed using quantile regression by looking at the impact of distance from nursing office, number of concurrent patients, wing type (medical/surgical), age, sex, comorbidities, and severity conditioned on how much patients were monitored during their admissions. We registered 11......,848 admissions, of which we were able to link patient monitor readings to 3149 (26.6 %) with 50 % being monitored nursing office had little influence on patients monitored ... the office reduced the level of monitoring. Higher levels of severity were related to higher degrees of monitoring, but being admitted to the surgical wing reduce how much patients were monitored, and periods with many concurrent patients lead to a small increase in monitoring. We found a significant...
NURSING ASSISTANCE FOR PATIENTS IN SURGICAL CENTER ADMISSION
Directory of Open Access Journals (Sweden)
Zulene Maria de Vasconcelos Varela
2002-06-01
Full Text Available We objectified in this study with qualitative handling, to analyze the nurse's care in the people'sadmission in Surgical Center, starting from this professional's assistematic observation, accomplishing thisprocedure. In the chosen institution, the space for admission is common to all the elements of the team, to thepeople's flow and customers, that stay close one of the other ones, generating erroneous interpretations in thecommunication, hindering of that the efective care. The nurse's concern, in developing the admission, as ownprerogative and humanização was evident. The continuity of that procedure, it is hindered by the surgical team,for the patient's liberation, what is leaving out the care alternatives and generating dissatisfaction in theprofessionals.
Admission Control of VL in AFDX Under HRT Constraints
Institute of Scientific and Technical Information of China (English)
ZHOU Qiang; QU Zhenliang; LIN Hengqing
2011-01-01
Avionics full duplex switched ethernet (AFDX) is a switched interconnection technology developed to provide reliable data exchange with strong data transmission time guarantees in internal communication of the spacecraft or aircraft. Virtual link (VL) is an important concept of AFDX to meet quality of service (QoS) requirements in terms of end-to-end message deadlines. A VL admission control algorithm in AFDX network under hard real-time (HRT) constraints is studied. Based on the scheduling principle of AFDX protocol, a packet scheduling scheme under HRT constraints is proposed, and after that an efficient VL admission control algorithm is presented. Analytical proof that the algorithm can effectively determine whether VL should be admitted is given. Finally simulative examples are presented to promote the conclusion.
Graduate admissions in clinical neuropsychology: the importance of undergraduate training.
Karazsia, Bryan T; Stavnezer, Amy Jo; Reeves, Jonathan W
2013-11-01
Discussions of and recommendations for the training of clinical neuropsychologists exist at the doctoral, internship, and post-doctoral level. With few exceptions, the literature on undergraduate preparations in clinical neuropsychology is sparse and lacks empirical evidence. In the present study, graduate-level faculty and current trainees completed surveys about graduate school preparations. Faculty expectations of minimum and ideal undergraduate training were highest for research methods, statistics, and assessment. Preferences for "goodness of fit" also emerged as important admissions factors. These results offer evidence for desirable undergraduate preparations for advanced study in clinical neuropsychology. Although undergraduate training in psychology is intentionally broad, results from this study suggest that students who desire advanced study in clinical neuropsychology need to tailor their experiences to be competitive in the application process. The findings have implications for prospective graduate students, faculty who train and mentor undergraduates, and faculty who serve on admissions committees.
Pharmacist-led medication review in an acute admissions unit
DEFF Research Database (Denmark)
Hansen, Trine Graabæk; Bonnerup, Dorthe Krogsgaard; Kjeldsen, Lene Juel
2015-01-01
Objectives Over the last decades, several papers have evaluated clinical pharmacy interventions in hospital settings with conflicting findings as results. Medication reviews are frequently a central component of these interventions. However, the term ‘medication review’ covers a plethora.......Methods A procedure was developed based on clinical experience and inspiration from previous studies and literature on medication review models. The procedure was developed to fit the busy workflow in acute admissions units.Results The procedure consists of five steps: (1) collection of clinical patient data, (2...... of principles and methodologies, and the practical procedure is seldom described in detail, which makes reproducing study findings difficult. The objective of this paper is to provide a detailed description of a procedure developed and used for pharmacist-led medication review in acute admissions units...
A Novel Admission Control Algorithm Based on Negotiation and Price
Institute of Scientific and Technical Information of China (English)
ZHANG Deng-yin; ZHANG Li; TANG Zhi-yun
2005-01-01
Admission control algorithm is a key component of a media server which supports Quality of Service(QoS).In this paper we present an admission control algorithm that exploits the elastic properties of the user requirements and the changing properties of system conditions.The characteristic of the algorithm can be expounded from these aspects:First,it provides multiple services to satisfy the different users' requirements regarding QoS and price.Second,it uses a worth function to select from media services with different QoS characteristics in the negotiation process.Finally,it employs a novel price policy to compute the charge for the service,which has a great effect on restricting the greediness of the users and therefore increase the overall user benefit.In the end of the paper,we compare the user benefit attained by our algorithm with that of other method.
Robust Admissible Analyse of Uncertain Singular Systems via Delta Operator Method
Institute of Scientific and Technical Information of China (English)
WANG Wen; WANG Hui
2016-01-01
This paper investigates the problem of robust admissible analysis for uncertain singular delta operator systems(SDOSs). Firstly, we introduce the definition of generalized quadratic admissibility to ensure robust admissibility. Then, by means of LMI, a necessary and sufficient condition is given to prove a uncertain SDOS is generalized quadratic admissible. Finally, a numerical example is provided to demonstrate the effectiveness of the results in this paper.
Viljoen, A; M.N. Saulez; C.M. Donnellan; Bester, L; B. Gummow
2009-01-01
Medical records of equine after-hours admissions from 1998 to 2007 are reviewed. Data extracted from the medical records included signalment, reason for admission, pre-admission treatment, clinical presentation, procedures performed, final diagnoses, complications occurring in hospital, length of stay and outcome. Eight hundred and twenty after-hours admissions were available of which 75 % were classified as emergencies. Most horses originated from Gauteng province (82 %), with Thoroughbred, ...
Probabilistic Tracklet Characterization and Prioritization Using Admissible Regions
2014-09-01
of deter- mining the potential threat of the object and obtaining further measurements. The solution to this problem is confounded in scenarios with...association and track initiation tasks. Well before their use in data association for asteroids and SOs, admissible regions have been used in stochastic...logic resource management.14 Milani et al.15 first proposed using ARs to assist in the optical detection and discrimination of asteroids . This work is
Intelligent Joint Admission Control for Next Generation Wireless Networks
Mohsen, Abdulqader M.; Al-Akwaa, Fadhl M.; Mohammed M. Alkhawlani
2012-01-01
The Heterogeneous Wireless Network (HWN) integrates different wireless networks into one common network. The integrated networks often overlap coverage in the same wireless service areas, leading to the availability of a great variety of innovative services based on user demands in a cost-efficient manner. Joint Admission Control (JAC) handles all new or handoff service requests in the HWN. It checks whether the incoming service request to the selected Radio Access Network (RAN) by the initia...
Interviewing strategically to elicit admissions from guilty suspects
Tekin, Serra; Granhag, Pär Anders; Strömwall, Leif; Giolla, Erik Mac; Vrij, Aldert; Hartwig, Maria
2015-01-01
In this article we introduce a novel interviewing tactic to elicit admissions from guilty suspects. By influencing the suspects’ perception of the amount of evidence the interviewer holds against them, we aimed to shift the suspects’ counterinterrogation strategies from less to more forthcoming. The proposed tactic (SUE-Confrontation) is a development of the Strategic Use of Evidence (SUE) framework and aims to affect the suspects’ perception by confronting them with statement-evidence incons...
Differential Weighting of Items to Improve University Admission Test Validity
Eduardo Backhoff Escudero; Felipe Tirado Segura; Norma Larrazolo Reyna
2001-01-01
This paper gives an evaluation of different ways to increase university admission test criterion-related validity, by differentially weighting test items. We compared four methods of weighting multiple-choice items of the Basic Skills and Knowledge Examination (EXHCOBA): (1) punishing incorrect responses by a constant factor, (2) weighting incorrect responses, considering the levels of error, (3) weighting correct responses, considering the item’s difficulty, based on the Classic Measur...
NURSING ASSISTANCE FOR PATIENTS IN SURGICAL CENTER ADMISSION
Zulene Maria de Vasconcelos Varela; Enêde Andrade da Cruz
2002-01-01
We objectified in this study with qualitative handling, to analyze the nurse's care in the people'sadmission in Surgical Center, starting from this professional's assistematic observation, accomplishing thisprocedure. In the chosen institution, the space for admission is common to all the elements of the team, to thepeople's flow and customers, that stay close one of the other ones, generating erroneous interpretations in thecommunication, hindering of that the efective care. The nurse's conc...
Yan, Zidan; Perdew, John P.; Kurth, Stefan
2000-03-01
Within a density functional context, the random phase approximation (RPA) for the correlation emergy makes a short-range error which is well-suited for correction by a local spin density or generalized gradient approximation (GGA). Here we construct a GGA for the short-range correction, following the same reliable procedure used earlier to construct the GGA for the whole exchange-correlation energy: real-space cutoff of the spurious long-range contribution to the gradient expansion of the hole around an electron. The resulting density functional is nearly local, and predicts a substantial correction to the RPA correlation energy of an atom but \\underlinevery small corrections to the RPA atomization energy of a molecule, which may by itself come close to "chemical accuracy", and to the RPA surface energy of a metal. A by-product of this work is a density functional for the system-averaged correlation hole within RPA.
Aggressive behavior during the first 24 hours of psychiatric admission
Directory of Open Access Journals (Sweden)
Vitor Crestani Calegaro
2014-09-01
Full Text Available OBJECTIVE: To investigate the association between aggression in the first 24 hours after admission and severity of psychopathology in psychiatric inpatients.METHODS: This cross-sectional study included psychiatric patients admitted to Hospital Universitário de Santa Maria, in Santa Maria, southern Brazil, from August 2012 to January 2013. At their arrival at the hospital, patients were interviewed to fill in the Brief Psychiatric Rating Scale (BPRS form, and any aggressive episodes in the first 24 hours after admission were recorded using the Overt Aggression Scale (OAS. The Mann-Whitney U test was used to compare patients according to aggressiveness: aggressive versus non-aggressive, hostile versus violent, and aggressive against others only versus self-aggressive.RESULTS: The sample was composed of 110 patients. Aggressive patients in general had higher BPRS total scores (p = 0.002 and individual component scores, and their results showed more activation (p < 0.001 and thinking disorders (p = 0.009, but less anxious-depression (p = 0.008. Violent patients had more severe psychomotor agitation (p = 0.027, hallucinations (p = 0.017 and unusual thought content (p = 0.020. Additionally, self-aggressive patients had more disorientation (p = 0.011 and conceptual disorganization (p = 0.007.CONCLUSIONS: Aggression in psychiatric patients in the first 24 hours after admission is associated with severity of psychopathology, and severity increases with severity of patient psychosis and agitation.
Correlation of admissions criteria with academic performance in dental students.
Curtis, Donald A; Lind, Samuel L; Plesh, Octavia; Finzen, Frederick C
2007-10-01
Our purpose was to compare admissions criteria as predictors of dental school performance in underachieving and normally tracking dental students. Underachieving dental students were identified by selecting ten students with the lowest class grade point average following the first year of dental school from five classes, resulting in a pool of fifty students. Normally tracking students served as a control and were randomly selected from students who had completed their first year of dental school not in the underachieving group. Admission measures of college grade point average (GPA), science grade point average (SGPA), academic average (AA), Perceptual Ability Test (PAT), college rigor, and academic load in college were evaluated with descriptive statistics, correlation, and regression analysis with first-year and graduating GPA as the dependent variables. Admissions criteria were generally weak predictors of first-year and graduating GPA. However, first-year dental school GPA was a strong predictor (R(2)=0.77) of graduating GPA for normally tracking students and a moderate predictor (R(2)=0.58) for underachieving students. Students who completed the first year of dental school having a low GPA tended to graduate with a low GPA. Therefore, remediation and monitoring would be important during the dental school experience for these students.
The full moon and admission to emergency rooms
Directory of Open Access Journals (Sweden)
Zargar Moosa
2004-05-01
Full Text Available OBJECTIVE: The purpose of this study was to investigate an ancient hypothesis; the moon effect might increase incidence of injuries and hence admission of patients with trauma to Emergency Rooms (ERs on full moon days. METHODS: During thirteen months, 58000 trauma patients admitted in three hospitals that had the highest load of trauma patients in Tehran were studied. Due to lack of complete data, 3543 patients (6.1% were excluded from the study, leaving 54457 cases for further analysis. We selected lunar calendar for our study, so dates of patients′ admissions were converted to lunar months and three day- periods with 15th as middle day were defined as full moon days. RESULTS: In our study the number of trauma patients was not increased during the full moon days against other days of lunar month. Statistical analyses of data didn′t exhibit a positive relation between full moon days and increasing of trauma patient admission to ERs. An association between assault and attempted suicide was not observed around the full moon days either. The results did not show significant reduction of GCS score of patients on full moon days and there was not any increase in severity of traumatic injury sustained during full moon days. CONCLUSIONS: It seems necessary to conduct studies regarding the probability of moon effect through on different database, geographic areas and for appropriate periods in order to reach a conclusive result.
Admission control with long-range dependence traffic input
Institute of Scientific and Technical Information of China (English)
RAO Yun-hua; ZOU Xue-cheng
2005-01-01
The admission control scheme is investigated for a FIFO self-similar queuing system with Quality of Service (QoS) performance guarantees. Since the self-similar queuing system performance analysis is often carried out under the condition of infinite buffer, it is difficult to deduce the upper boundary of buffer overflow probability. To overcome this shortcoming, a simple overflow condition is proposed, which defines a buffer overflow occurrence whenever the arrival rate exceeds the service rate. The analytic formula for the buffer overflow probability upper boundary is easily obtained under this condition. The required bandwidth upper boundary with long-range dependence input and determined overflow probability is then derived from this formula. Based on the above analytic formulas, the upper boundaries of the admission control regions for homogeneous and heterogeneous long-range dependence traffic sources are separately obtained. Finally, an effective admission control scheme for long-range dependence input is proposed. Simulation studies with real traffic have confirmed the validity of these results.
The full moon and admission to emergency rooms.
Zargar, Moosa; Khaji, Ali; Kaviani, Ahmad; Karbakhsh, Mojgan; Yunesian, Masud; Abdollahi, Morteza
2004-05-01
The purpose of this study was to investigate an ancient hypothesis; the moon effect might increase incidence of injuries and hence admission of patients with trauma to Emergency Rooms (ERs) on full moon days. During thirteen months, 58000 trauma patients admitted in three hospitals that had the highest load of trauma patients in Tehran were studied. Due to lack of complete data, 3543 patients (6.1%) were excluded from the study, leaving 54457 cases for further analysis. We selected lunar calendar for our study, so dates of patients' admissions were converted to lunar months and three day- periods with 15th as middle day were defined as full moon days. In our study the number of trauma patients was not increased during the full moon days against other days of lunar month. Statistical analyses of data didn't exhibit a positive relation between full moon days and increasing of trauma patient admission to ERs. An association between assault and attempted suicide was not observed around the full moon days either. The results did not show significant reduction of GCS score of patients on full moon days and there was not any increase in severity of traumatic injury sustained during full moon days. It seems necessary to conduct studies regarding the probability of moon effect through on different database, geographic areas and for appropriate periods in order to reach a conclusive result.
First Nations Pneumonia Admissions: Different Patients or Different Attitudes?
Directory of Open Access Journals (Sweden)
NR Anthonisen
2004-01-01
Full Text Available In this issue of the Canadian Respiratory Journal, Marrie et al (pages 336-342 present a database study of hospital admissions among First Nation Aboriginals (FNAs in Alberta that is fascinating, at least to me. They captured all hospital admissions for "status" FNAs from 1997 to 1999, along with data on where and how long they were hospitalized, the severity of the pneumonia, the number of comorbidities present, whether they were readmitted and the costs involved. They compared these finding with a group of age- and sex-matched non-FNAs who were also hospitalized for pneumonia. There are, of course, weaknesses in the study that commonly occur in most exercises using administrative databases. Pneumonia is a hospital record diagnosis (there is no information about chest x-rays, sputum cultures, etc. Pneumonia severity assessment relies on information regarding hospital transfers, intensive care unit admissions and events such as shock, artificial ventilation and death (there is no information available to apply an accepted grading system (1. Further, "status" FNAs were probably not entirely representative of FNAs in general; indeed, some nonstatus FNAs may well have been included in the control group. However, I strongly doubt that these or similar objections are substantial enough to greatly influence the findings of Marrie et al.
[Hospital admissions due to varicella in a tertiary hospital].
Guzmán Laura, K P; Periañez Vasco, A; Falcón Neyra, M D; Croche Santander, B
2014-06-01
Varicella (chickenpox) can cause serious complications and admission to hospital. Several countries included the varicella vaccine in their immunization schedules. A descriptive and retrospective study of hospitalizations due to varicella and its complications was conducted in a referral center from 2005 to 2011. A total of 1192 children with varicella were seen in the emergency room, of which 99 (8.5%) required admission. The annual incidence of admissions due to varicella and varicella complications was, 19.4 and 15.3 cases per 100,000 children under 14 years, respectively. Complications were more common in children under 5 years (79.5%), and with no underlying disease (78.2%). Infection of skin and soft tissue was the most common complication (62%). The mean hospital stay was 4.5 days (SD 4). Varicella causes high morbidity, and is more frequent in absolute terms in healthy children under 5 years of age. Therefore, routine vaccination recommended by the Immunization Advisory Committee should be mandatory. Copyright © 2013 Asociación Española de Pediatría. Published by Elsevier Espana. All rights reserved.
An Admissions Model for Monitoring Applicant Quality. AIR Forum 1981 Paper.
Rosenthal, Daniel J. A.; Tantillo, Charles
A college admissions system model is described that can be used to monitor applicants at each stage of the admissions process and to assist in planning and student recruitment. Examples are provided that demonstrate the model's broad applicability for the development of specialized admissions programs that can be targeted to accomplish…
The Medical School Admissions Process: A Review of the Literature 1955-1976. Special Report.
Cuca, Janet Melei; And Others
This document reviews the research on the medical school admissions process that has been completed during the past twenty years. The process is put into perspective by a historical overview chapter that traces trends in medical school admissions and highlights, where possible, relationships between the admissions process and institutional and…
Acute pulmonary admissions following implementation of a national workplace smoking ban.
LENUS (Irish Health Repository)
Kent, Brian D
2012-09-01
The implementation of workplace smoking bans has contributed to a significant reduction in the incidence of acute coronary syndrome admissions, but their influence on adult acute pulmonary disease admissions is unclear. We sought to assess the impact of a national smoking ban on nationwide admissions of individuals of working age with acute pulmonary illness.
42 CFR 442.118 - Denial of payments for new admissions to an ICF/MR.
2010-10-01
... 42 Public Health 4 2010-10-01 2010-10-01 false Denial of payments for new admissions to an ICF/MR... of payments for new admissions to an ICF/MR. (a) Basis for denial of payments. The Medicaid agency may deny payment for new admissions to an ICF/MR that no longer meets the applicable conditions of...
43 CFR 4.116 - Interrogatories to parties; inspection of documents; admission of facts.
2010-10-01
... documents; admission of facts. 4.116 Section 4.116 Public Lands: Interior Office of the Secretary of the...; admission of facts. Under appropriate circumstances, but not as a matter of course, the Board will entertain... serve upon the opposing party a request for the admission of specified facts. Such applications shall...
42 CFR 456.481 - Admission certification and plan of care.
2010-10-01
... Individuals Under Age 21: Admission and Plan of Care Requirements § 456.481 Admission certification and plan of care. If a facility provides inpatient psychiatric services to a recipient under age 21— (a) The... 42 Public Health 4 2010-10-01 2010-10-01 false Admission certification and plan of care....
Gatekeepers or Marketers: Reclaiming the Educational Role of Chief Admission Officers
McDonough, Patricia; Robertson, Larry
2012-01-01
The U.S. college admission environment has changed enormously over the last three decades. What have those changes meant for the profession of college admission officers? In this paper, the authors will describe the enormous changes that have taken place in high schools, colleges, and the entrepreneurial admission sector. They will describe how…
Why Preferences in College Admissions May Yield a More-Able Student Body
Li, Dong; Weisman, Dennis L.
2011-01-01
Critics of affirmative action policies contend that the elimination of racial preferences in college admissions would lead to a "more-able" student body. We develop a simple model comprised of three classes of college admissions--merit, race and legacy--to show that it is possible that a change in admissions policy that reduces racial preferences…
British Columbia Council on Admissions & Transfer Annual Report, 2008-09
British Columbia Council on Admissions and Transfer, 2009
2009-01-01
The role of the British Columbia Council on Admissions and Transfer (BCCAT) is to facilitate admission, articulation, and transfer arrangements in the BC post-secondary system. BCCAT carries out this work in various ways; for example, engaging in research on admissions and student transitions, evaluating the effectiveness of the transfer system…
Contribution of Renal Impairment to Potentially Preventable Medication-Related Hospital Admissions
Leendertse, Anne J.; van Dijk, Elisabeth A.; De Smet, Peter A. G. M.; Egberts, Toine C. G.; van den Bemt, Patricia M. L. A.
2012-01-01
BACKGROUND: Medication errors and renal impairment contribute to severe adverse drug events, which may lead to hospital admission. OBJECTIVE: To determine whether medication errors and renal impairment contribute to hospital admission and examine these errors for strategies to prevent admissions. ME
Analysis of the medication reconciliation process conducted at hospital admission
Directory of Open Access Journals (Sweden)
María Beatriz Contreras Rey
2016-07-01
Full Text Available Objective: To analyze the outcomes of a medication reconciliation process at admission in the hospital setting. To assess the role of the Pharmacist in detecting reconciliation errors and preventing any adverse events entailed. Method: A retrospective study was conducted to analyze the medication reconciliation activity during the previous six months. The study included those patients for whom an apparently not justified discrepancy was detected at admission, after comparing the hospital medication prescribed with the home treatment stated in their clinical hospital records. Those patients for whom the physician ordered the introduction of home medication without any specification were also considered. In order to conduct the reconciliation process, the Pharmacist prepared the best pharmacotherapeutical history possible, reviewing all available information about the medication the patient could be taking before admission, and completing the process with a clinical interview. The discrepancies requiring clarification were reported to the physician. It was considered that the reconciliation proposal had been accepted if the relevant modification was made in the next visit of the physician, or within 24-48 hours maximum; this case was then labeled as a reconciliation error. For the descriptive analysis, the Statistics® SPSS program, version 17.0, was used. Outcomes: 494 medications were reconciled in 220 patients, with a mean of 2.25 medications per patient. More than half of patients (59.5% had some discrepancy that required clarification; the most frequent was the omission of a medication that the patient was taking before admission (86.2%, followed by an unjustified modification in dosing or way of administration (5.9%. In total, 312 discrepancies required clarification; out of these, 93 (29.8% were accepted and considered as reconciliation errors, 126 (40% were not accepted, and in 93 cases (29,8% acceptance was not relevant due to a change in
Mo, Yuxiang; Tao, Jianmin
2016-01-01
Recently, Tao and Mo proposed an accurate meta-generalized gradient approximation for the exchange-correlation energy. The exchange part is derived from the density matrix expansion, while the correlation part is obtained by improving the TPSS correlation in the low-density limit. To better understand this exchange functional, in this work, we combine the TM exchange with the original TPSS correlation, which we call TMTPSS, and make a systematic assessment on molecular properties. The test sets include the 223 G3/99 enthalpies of formation, 58 electron affinities, 8 proton affinities, 96 bond lengths, 82 harmonic frequencies, and 10 hydrogen-bonded molecular complexes. Our calculations show that the TMTPSS functional is competitive with or even more accurate than TM functional for some properties. In particular, it is the most accurate nonempirical semilocal DFT for the enthalpies of formation and harmonic vibrational frequencies, suggesting the robustness of TM exchange.
Calculating the Lifetimes of Metastable States with Complex Density Functional Theory.
Zhou, Yongxi; Ernzerhof, Matthias
2012-07-19
Among other applications, complex absorbing potentials (CAPs) have proven to be useful tools in the theory of metastable states. They facilitate the conversion of unbound states of a finite lifetime into normalized bound states with a complex energy. Adding CAPs to a conventional Hamiltonian turns it into a non-Hermitian operator. Recently, we introduced a complex density functional theory (CODFT) that extends the Kohn-Sham method to the realm of non-Hermitian systems. Here, we combine CAPs with CODFT and present the first application of CODFT to metastable systems. In particular, we consider the negative ions of the beryllium atom and the nitrogen molecule. Using conventional exchange-correlation functionals as functionals of a complex density, the resonance positions and the resonance lifetimes are obtained, and they are in line with the findings of other studies.
First-principle Calculations of Equation of State for Metals at High Energy Density
Minakov, Dmitry; Levashov, Pavel; Khishchenko, Konstantin
2012-02-01
In this work, we present quantum molecular dynamics calculations of the shock Hugoniots of solid and porous samples as well as release isentropes and isentropic sound velocity behind the shock front for aluminum. Also we perform similar calculations for nickel and iron. We use the VASP code with ultrasoft and PAW pseudopotentials and GGA exchange-correlation functional. Up to 512 particles have been used in calculations. To calculate Hugoniots we solve the Hugoniot equation numerically. To obtain release isentropes, we use Zel'dovich's approach and integrate an ordinary differential equation for the temperature thus restoring all thermodynamic parameters. Isentropic sound velocity is calculated by differentiation of pressure along isentropes. The results of our calculations are in good agreement with experimental data at densities both higher and lower than the normal one. Thus, quantum molecular dynamics results can be effectively used for verification or calibration of semiempirical equations of state under conditions of lack of experimental information at high energy densities.
Density functional calculation of many-electron systems in cartesian coordinate grid
Roy, Amlan K
2011-01-01
A recently developed density functional method, within Hohenberg-Kohn-Sham framework, is used for faithful description of atoms, molecules in Cartesian coordinate grid, by using an LCAO-MO ansatz. Classical Coulomb potential is obtained by means of a Fourier convolution technique. All two-body potentials (including exchange-correlation (XC)) are constructed directly on real grid, while their corresponding matrix elements are computed from numerical integration. Detailed systematic investigation is made for a representative set of atoms/molecules through a number of properties like total energies, component energies, ionization energies, orbital energies, etc. Two nonlocal XC functionals (FT97 and PBE) are considered for pseudopotential calculation of 35 species while preliminary all-electron results are reported for 6 atoms using the LDA XC density functional. Comparison with literature results, wherever possible, exhibits near-complete agreement. This offers a simple efficient route towards accurate reliable...
Global hybrids from the semiclassical atom theory satisfying the local density linear response
Fabiano, E; Cortona, P; Della Sala, F
2015-01-01
We propose global hybrid approximations of the exchange-correlation (XC) energy functional which reproduce well the modified fourth-order gradient expansion of the exchange energy in the semiclassical limit of many-electron neutral atoms and recover the full local density approximation (LDA) linear response. These XC functionals represent the hybrid versions of the APBE functional [Phys. Rev. Lett. 106, 186406, (2011)] yet employing an additional correlation functional which uses the localization concept of the correlation energy density to improve the compatibility with the Hartree-Fock exchange as well as the coupling-constant-resolved XC potential energy. Broad energetical and structural testings, including thermochemistry and geometry, transition metal complexes, non-covalent interactions, gold clusters and small gold-molecule interfaces, as well as an analysis of the hybrid parameters, show that our construction is quite robust. In particular, our testing shows that the resulting hybrid, including 20\\% o...
Semilocal and Hybrid Density Embedding Calculations of Ground-State Charge-Transfer Complexes
Laricchia, S; Della Sala, F; 10.1063/1.4795825
2013-01-01
We apply the frozen density embedding method, using a full relaxation of embedded densities through a freeze-and-thaw procedure, to study the electronic structure of several benchmark ground-state charge-transfer complexes, in order to assess the merits and limitations of the approach for this class of systems. The calculations are performed using both semilocal and hybrid exchange-correlation (XC) functionals. The results show that embedding calculations using semilocal XC functionals yield rather large deviations with respect to the corresponding supermolecular calculations. Due to a large error cancellation effect, however, they can often provide a relatively good description of the electronic structure of charge-transfer complexes, in contrast to supermolecular calculations performed at the same level of theory. On the contrary, when hybrid XC functionals are employed, both embedding and supermolecular calculations agree very well with each other and with the reference benchmark results. In conclusion, fo...
Hafner, Jürgen
2010-09-29
During the last 20 years computer simulations based on a quantum-mechanical description of the interactions between electrons and atomic nuclei have developed an increasingly important impact on materials science, not only in promoting a deeper understanding of the fundamental physical phenomena, but also enabling the computer-assisted design of materials for future technologies. The backbone of atomic-scale computational materials science is density-functional theory (DFT) which allows us to cast the intractable complexity of electron-electron interactions into the form of an effective single-particle equation determined by the exchange-correlation functional. Progress in DFT-based calculations of the properties of materials and of simulations of processes in materials depends on: (1) the development of improved exchange-correlation functionals and advanced post-DFT methods and their implementation in highly efficient computer codes, (2) the development of methods allowing us to bridge the gaps in the temperature, pressure, time and length scales between the ab initio calculations and real-world experiments and (3) the extension of the functionality of these codes, permitting us to treat additional properties and new processes. In this paper we discuss the current status of techniques for performing quantum-based simulations on materials and present some illustrative examples of applications to complex quasiperiodic alloys, cluster-support interactions in microporous acid catalysts and magnetic nanostructures.
mBEEF: An accurate semi-local Bayesian error estimation density functional
Wellendorff, Jess; Lundgaard, Keld T.; Jacobsen, Karsten W.; Bligaard, Thomas
2014-04-01
We present a general-purpose meta-generalized gradient approximation (MGGA) exchange-correlation functional generated within the Bayesian error estimation functional framework [J. Wellendorff, K. T. Lundgaard, A. Møgelhøj, V. Petzold, D. D. Landis, J. K. Nørskov, T. Bligaard, and K. W. Jacobsen, Phys. Rev. B 85, 235149 (2012)]. The functional is designed to give reasonably accurate density functional theory (DFT) predictions of a broad range of properties in materials physics and chemistry, while exhibiting a high degree of transferability. Particularly, it improves upon solid cohesive energies and lattice constants over the BEEF-vdW functional without compromising high performance on adsorption and reaction energies. We thus expect it to be particularly well-suited for studies in surface science and catalysis. An ensemble of functionals for error estimation in DFT is an intrinsic feature of exchange-correlation models designed this way, and we show how the Bayesian ensemble may provide a systematic analysis of the reliability of DFT based simulations.
Time-Dependent Density Functional Theory Beyond Kohn-Sham Slater Determinants
Fuks, Johanna I; Ruggenthaler, Michael; Maitra, Neepa T
2016-01-01
When running time-dependent density functional theory (TDDFT) calculations for real-time simulations of non-equilibrium dynamics, the user has a choice of initial Kohn-Sham state, and typically a Slater determinant is used. We explore the impact of this choice on the exchange-correlation potential when the physical system begins in a 50:50 superposition of the ground and first-excited state of the system. We investigate the possibility of judiciously choosing a Kohn-Sham initial state that minimizes errors when adiabatic functionals are used. We find that if the Kohn-Sham state is chosen to have a configuration matching the one that dominates the interacting state, this can be achieved for a finite time duration for some but not all such choices. When the Kohn-Sham system does not begin in a Slater determinant, we further argue that the conventional splitting of the exchange-correlation potential into exchange and correlation parts has limited value, and instead propose a decomposition into a "single-particle...
Balakrishnan, Binod; Dasgupta, Mahua; Gajewski, Kim; Hoffmann, Raymond G; Simpson, Pippa M; Havens, Peter L; Hanson, Sheila J
2017-03-03
To investigate the association between low near infrared spectroscopy (NIRS) somatic oxygen saturation (admission and the need for lifesaving interventions (LSI) in the initial 24 h of a PICU admission. Retrospective chart review of all unplanned admissions to the pediatric intensive care unit (PICU) with NIRS somatic oxygen saturation data available within 4 h of admission, excluding admissions with a cardiac diagnosis. LSI data were collected for the first 24 h after admission. Hemodynamic parameters, laboratory values, illness severity scores and diagnoses were collected. Included PICU admissions were stratified by lowest NIRS value in the first 4 h after admission: low NIRS (admissions to the PICU of which 184 (44%) patients underwent NIRS monitoring. A higher proportion of patients who underwent somatic NIRS monitoring required LSIs compared to those without NIRS monitoring (36.4 vs 5.7% respectively, p medications were the most common LSIs. Multivariable modeling showed NIRS 2SD for age to be associated with LSIs. ROC curve analysis of the combination of NIRS 2SD for age had an area under the curve of 0.79 with 78% sensitivity and 76% specificity for association with LSI. Compared to the normal NIRS group, the low NIRS group had higher mortality (10.4 vs 0.7%, p = 0.005) and longer median hospital length of stay (2.9 vs 1.6 days, p admission is associated with need for higher number of subsequent lifesaving interventions up to 24 h after admission. Noninvasive, continuous, somatic NIRS monitoring may identify children at high risk of medical instability.
Maximal admissible faces and asymptotic bounds for the normal surface solution space
Burton, Benjamin A
2010-01-01
The enumeration of normal surfaces is a key bottleneck in computational three-dimensional topology. The underlying procedure is the enumeration of admissible vertices of a high-dimensional polytope, where admissibility is a powerful but non-linear and non-convex constraint. The main results of this paper are significant improvements upon the best known asymptotic bounds on the number of admissible vertices, using polytopes in both the standard normal surface coordinate system and the streamlined quadrilateral coordinate system. To achieve these results we examine the layout of admissible points within these polytopes. We show that these points correspond to well-behaved substructures of the face lattice, and we study properties of the corresponding "admissible faces". Key lemmata include upper bounds on the number of maximal admissible faces of each dimension, and a bijection between the maximal admissible faces in the two coordinate systems mentioned above.
Medical school dropout - testing at admission versus selection by highest grades as predictors
DEFF Research Database (Denmark)
O'Neill, Lotte Dyhrberg; Hartvigsen, Jan; Wallstedt, Birgitta;
2011-01-01
dropout. Methods This prospective cohort study followed six cohorts of medical students admitted to the medical school at the University of Southern Denmark during 2002-2007 (n = 1544). Half of the students were admitted based on their prior achievement of highest grades (Strategy 1) and the other half......Medical Education 2011: 45: 1111-1120 Context Very few studies have reported on the effect of admission tests on medical school dropout. The main aim of this study was to evaluate the predictive validity of non-grade-based admission testing versus grade-based admission relative to subsequent...... years after admission. Multivariate logistic regression analysis was used to model dropout. Results Strategy 2 (admission test) students had a lower relative risk for dropping out of medical school within 2 years of admission (odds ratio 0.56, 95% confidence interval 0.39-0.80). Only the admission...
Student characteristics, professional preferences, and admission to medical school
Directory of Open Access Journals (Sweden)
Kesternich, Iris
2017-02-01
Full Text Available Objectives: A potential new avenue to address the shortage of country doctors is to change the rules for admission to medical school. We therefore study the link between high-school grade point average and prospective physicians’ choice to work in rural areas. To further inform the discussion about rules for admission, we also study the effects of other predictors: a measure of students’ attitudes towards risk; whether they waited for their place of study (; whether their parents worked as medical doctors; and whether they have some practical experience in the medical sector.Methods: We conducted two internet surveys in 2012 and 2014. In the first survey, the sample comprised 701 students and in the second, 474 students. In both surveys, we asked students for their regional preferences; in the 2014 survey, we additionally asked students for their first, second, and third preferences among a comprehensive set of specializations, including becoming a general practitioner. In both surveys, we asked students for basic demographic information (age and gender, their parents’ occupation, a measure of subjective income expectations, a measure of risk attitudes, and their high-school grade point average (, and First National Boards Examination grade (. In 2014, we additionally asked for waiting periods ( as well as for prior professional experience in the health-care sector.Results: We find that three factors increase the probability of having a preference for working in a rural area significantly, holding constant all other influences: Moreover, we find that those willing to work in the countryside have significantly more experience in the medical sector before admission to medical school.Discussion: Our results suggest that a change in the selection process for medical school may increase the supply of country doctors. Instead of focusing on the high-school grade point average, universities could even more intensely screen for study motivation
Towards a threshold climate for emergency lower respiratory hospital admissions.
Islam, Muhammad Saiful; Chaussalet, Thierry J; Koizumi, Naoru
2017-02-01
Identification of 'cut-points' or thresholds of climate factors would play a crucial role in alerting risks of climate change and providing guidance to policymakers. This study investigated a 'Climate Threshold' for emergency hospital admissions of chronic lower respiratory diseases by using a distributed lag non-linear model (DLNM). We analysed a unique longitudinal dataset (10 years, 2000-2009) on emergency hospital admissions, climate, and pollution factors for the Greater London. Our study extends existing work on this topic by considering non-linearity, lag effects between climate factors and disease exposure within the DLNM model considering B-spline as smoothing technique. The final model also considered natural cubic splines of time since exposure and 'day of the week' as confounding factors. The results of DLNM indicated a significant improvement in model fitting compared to a typical GLM model. The final model identified the thresholds of several climate factors including: high temperature (≥27°C), low relative humidity (≤ 40%), high Pm10 level (≥70-µg/m(3)), low wind speed (≤ 2 knots) and high rainfall (≥30mm). Beyond the threshold values, a significantly higher number of emergency admissions due to lower respiratory problems would be expected within the following 2-3 days after the climate shift in the Greater London. The approach will be useful to initiate 'region and disease specific' climate mitigation plans. It will help identify spatial hot spots and the most sensitive areas and population due to climate change, and will eventually lead towards a diversified health warning system tailored to specific climate zones and populations. Copyright © 2016 Elsevier Inc. All rights reserved.
DEFF Research Database (Denmark)
Lau, Wallis C Y; Li, Xue; Wong, Ian C K
2017-01-01
BACKGROUND: Reducing 30-day hospital re-admission is a policy priority worldwide. Warfarin-related bleeding is among the most common cause of hospital admissions due to adverse drug events. Compared to warfarin, dabigatran achieve full anticoagulation effect more quickly following its initiation,...
Physics and the revised Medical College Admission Test
Hilborn, Robert C.
2014-05-01
Physics has played an important role in the preparation of future physicians and other health professionals for more than 100 years. Almost all pre-health students take a year of college-level physics as part of their preparation for medical, dental, and pharmacy school. In particular, the widely-used Medical College Admission Test (MCAT) contains a significant number of questions that require physics knowledge and skills. This paper describes the changes in the MCAT to be implemented in 2015, the role of physics in the revised MCAT, and implications for introductory physics courses for the life sciences.
New degradation call admission control for increasing WCDMA system capacity
Institute of Scientific and Technical Information of China (English)
Liu Ningqing; Lu Zhi; Gu Xuemai
2006-01-01
Propose a new degradation call admission control(DCAC)scheme, which can be used in wideband code division multiple access communication system. So-called degradation is that non-real time call has the characteristic of variable bit rate, so decreasing its bit rate can reduce the load of the system, consequently the system can admit new call which should be blocked when the system is close to full load, therefore new call's access probability increases. This paper brings forward design project and does system simulation, simulation proves that DCAC can effectively decrease calls' blocking probability and increase the total number of the on-line users.
TCP-Call Admission Control Interaction in Multiplatform Space Architectures
Directory of Open Access Journals (Sweden)
Georgios Theodoridis
2007-06-01
Full Text Available The implementation of efficient call admission control (CAC algorithms is useful to prevent congestion and guarantee target quality of service (QoS. When TCP protocol is adopted, some inefficiencies can arise due to the peculiar evolution of the congestion window. The development of cross-layer techniques can greatly help to improve efficiency and flexibility for wireless networks. In this frame, the present paper addresses the introduction of TCP feedback into the CAC procedures in different nonterrestrial wireless architectures. CAC performance improvement is shown for different space-based architectures, including both satellites and high altitude platform (HAP systems.
Business Intelligence Framework in Higher Education Admission Center (HEAC
Directory of Open Access Journals (Sweden)
Maryam Humaid Alwashahi
2015-12-01
Full Text Available - In recent year found that many organizations used Business Intelligence (BI in most of sectors in order to gather, consolidating, analyzing , and providing access to data to provide better decision-making to be faster than ever before by providing the right information to the right people at the right Time. This paper proposes Business Intelligence (BI framework for Higher Education Admission Centre (HEAC to simplify and integrate business critical data of a multi-schema database by using an Active database approach uses active rules, called EventCondition-Action (ECA rules. This paper explores the problem in HEAC, BI overview, BI component, BI features, BI framework, active DB.
Off-hours admission and quality of hip fracture care
DEFF Research Database (Denmark)
Kristiansen, Nina Sahlertz; Kristensen, Pia Kjær; Nørgård, Bente Mertz
2016-01-01
OBJECTIVE: Higher risks of adverse outcomes have been reported for patients admitted acutely during off-hours. However, in relation to hip fracture, the evidence is inconsistent. We examined whether time of admission influenced compliance with performance measures, surgical delay and 30-day...... mortality in patients with hip fracture. DESIGN: Cohort study. SETTING: Data from The Danish Multidisciplinary Hip Fracture Registry linked with data from Danish National Registries. PARTICIPANTS: Danish patients undergoing hip fracture surgery, aged >65 years, admitted 1 March 2010 to 30 November 2013 (N...