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Medical information systems and standards are increasingly based on principled models of at least three distinct sorts of information - patient data, concepts (terminology), and guidelines (decision support). Well defined interfaces are required between the three types of model to allow development to proceed independently. Two of the major issues to be dealt with in the defining of such interfaces are the interaction between ontological and inferential abstractions - how general notions such as 'abnormal cardiovascular finding' are abstracted from concrete data - and the management of the meaning of information in guidelines in different contexts. This paper explores these two issues and their ramifications.

The self-energy of the photo-hole in 2H-TaSe2 is measured by angle-resolved photoemission spectroscopy (ARPES) as a function of binding energy and temperature. In the charge-density wave (CDW) state, a structure in the self- energy is detected at ~ 65 meV that can not be explained by electron-phonon scattering. A reduction in the scattering rates below this energy indicates the collapse of a major scattering channel with the formation of the CDW state, accompanying the appearance of a bosonic "mode" in the excitation spectrum of the system., Comment: 4 pages, 4 eps figures, minor changes, references added

Recent instrumentation developments in photoemission are providing new insights into the physics of complex materials. With increased energy and momentum resolution, it has become possible to examine in detail different contributions to the self-energy or inverse lifetime of the photohole created in the photoexcitation process. Employing momentum distribution and energy distribution curves, a detailed study of the optimally doped cuprate, Bi2Sr2CaCu2O8+δ, shows that the material behaves like a non-Fermi liquid with no evidence for the quasi-particles characteristic of a Fermi liquid.

The photoemission line shapes of the optimally doped cuprate Bi 2 Sr 2 CaCu 2 O 8+δ were studied in the direction of a node in the superconducting order parameter by means of very high resolution photoemission spectroscopy. The peak width or inverse lifetime of the excitation displays a linear temperature dependence, independent of binding energy, for small energies, and a linear energy dependence, independent of temperature, for large binding energies. This behavior is unaffected by the superconducting transition, which is an indication that the nodal states play no role in the superconductivity. Temperature-dependent scaling suggests that the system displays quantum critical behavior.

Skeletal plans are a powerful way to reuse existing domain-specific procedural knowledge. In the Asgaard project, a set of tasks that support the design and the execution of skeletal plans by a human executing agent other than the original plan designer are designed. The underlying requirement to develop task-specific problem-solving methods is a modeling language. Therefore, within the Asgaard project, a time-oriented, intention-based language, called Asbru, was developed. During the design phase of plans, Asbru allows to express durative actions and plans caused by durative states of an observed agent. The intentions underlying these plans are represented explicitly as temporal patterns to be maintained, achieved or avoided. We will present the underlying idea of the Asgaard project and explain the time-oriented Asbru language. Finally, we show the benefits and limitations of the time-oriented, skeletal plan representation to be applicable in real-world, high-frequency domains.

This paper reports ongoing work in the project PRESTIGE: Guidelines in Healthcare. An approach has been developed to representing the knowledge content of clinical guideline and protocols, using a declarative model incorporating a lifecycle model of clinical acts and activities. We also encountered the need to analyse and model the healthcare processes in which the use of a clinical guideline is embedded. A business process re-engineering (BPRE) methodology, developed in the previous AIM programme project SHINE, has been used for this purpose, enabling the mapping of the knowledge components of a clinical guideline to the specific healthcare processes where they are applicable. We review the need for a combination of algorithmic and process-oriented views of guideline knowledge in order to enable effective delivery of guideline-based clinical decision support.

Publisher Summary This chapter reviews the different studies, both theoretical and experimental, of the properties of magnetic thin films with a particular emphasis on the electronic structure and studies of the latter using various electron spectroscopies. Over the past decade, the increasing demands for new information storage capabilities have lead to an enormous increase for research devoted to the study of the magnetic properties of surfaces and thin films. A number of technological developments allow new magnetic materials to be routinely fabricated and investigated on the atomic scale. Many of the discrepancies may be traced to structural problems relating to the growth procedure. Thus, island formation or inter diffusion often adds complexity to the problem. For both transition and noble metal over layers the polarization induced in the over layer reflects the interaction in the interface. The reflectivity's near the hybridization gaps in the substrate determine the level of confinement of the quantum well states and the associated spin polarization.

We report a combined photoemission and inverse-photoemission study of the quantum-well states formed in copper thin films deposited on a fcc Co(001) substrate. In particular, we examine the {ital k} point that would correspond to the Fermi-surface crossing that would allow the quantum-well states to mediate the short period of exchange coupling in the associated magnetic multilayers. The states do not display a strong intensity in photoemission, an effect that we attribute to interfacial roughness. {copyright} {ital 1996 The American Physical Society.}

Spin polarized photoemission is used to examine the development of the magnetic structure in Cr films deposited on an Fe(001) substrate at 50 {degree}C. The spin polarization of the Cr core levels provides a clear indication that within the initial monolayer the moments are antiferromagnetically aligned to those of the substrate. Through comparison with model tight-binding calculations it is shown that at the monolayer limit the Cr moments are of the order of 1.8{mu}{sub {ital B}} or larger. Subsequent Cr monolayers align antiferromagnetically with respect to the previous layer. The tight-binding calculations further indicate that as the Cr film thickness evolves the moment at the solid-vacuum interface is always enhanced.

A spin-polarized photoemission study of the Ni 3p core level reveals the spin polarization of the main line and the satellites. A detailed comparison with calculation confirms earlier assignments that the satellites have ${\mathit{d}}^{9}$ character. However, the measurement also reveals the role of spin-orbit and exchange interactions in determining the spin polarization of the main peak, which is shown to be composed of both ${\mathit{d}}^{9}$ and ${\mathit{d}}^{10}$ character. The study shows that the spin polarization in the leading edge of the main line reflects its ${\mathit{d}}^{9}$ character as a result of the hybridization between the different configurations.

We report a comprehensive study of orbital characters and tridimensional nature of the electronic bands of 111-family in Fe-pnictides superconductors, NaFe1−xCoxAs (x = 0 and 0.05), with angle-resolved photoemission spectroscopy. We determined the orbital characters and the kz dependence of the low-energy electronic structures by tuning the polarization and the energy of the incident photons. We observed two nearly two-dimensional hole-like Fermi surfaces (FS) near the Brillouin zone (BZ) center and two electron-like FS near BZ corner. The bands near the Fermi level (EF) are mainly derived from the Fe 3dxy, 3dyz, and 3dzx orbitals.

The authors show that the tunability of a femtosecond optical parametric amplifier combined with its high-repetition rate and short pulses provide a powerful tool for an alternate approach to conventional nonresonant band mapping by two-photon photoemission (2PPE). The authors demonstrate this 2PPE mapping via use of two model systems, i.e., the pair of sp surface and image states on flat Cu(111) and vicinal Cu(775) surfaces, over a photon energy range of 3.9–4.6 eV by making use of direct resonant band-to-band electronic transitions. Since the experimental excitation of the Cu image state from the surface state is comparable in time to the electron-electron equilibration time, the authors measure sharp resonant features in the electron energy distributions. In this approach, the authors track these resonant electronic transitions using 2PPE by varying the photon energy so as to achieve resonant excitation at each value of photoelectron emission angle over a large wavelength range on both types of surface...

Spin-resolved photoemission studies of the interface formed by depositing silver on an Fe(001) substrate show that the silver [ital d] bands show evidence of hybridization with the substrate [ital d] bands through the presence of a spin polarization for the initial monolayer of silver. Subsequent layers of silver show no evidence of spin polarization in the [ital d] bands. Studies of the dispersion of the interface or quantum-well states associated with these thin films reveal that their effective mass is enhanced due to hybridization with the substrate. This has implications for theoretical models of the exchange coupling in the associated magnetic multilayers, where the bulk band structure is often assumed for the noble-metal intervening layer.

A survey was designed to explore the relationship among elective time (ET), residency research requirement (RR), mandatory research rotation (MR), and academic productivity for the 1993 graduating residency class. Sixty-seven of the 75 rehabilitation residency program directors listed in the 1993 Directory of Graduate Medical Education Programs responded (89% response rate). Data from 60 programs, representing 283 graduating residents, were analyzed (80% usable response rate). A resident was operationally defined as "active" if that individual submitted either articles (SART) for publication or abstracts (SABS) for oral/poster presentation during the training years; residents with accepted articles (AART) and/or abstracts (AABS) were defined as "productive." Odds ratios and chi 2 statistics were calculated for each study risk variable (ET, RR, MR) and the corresponding outcome variables (SART, SABS, AART, AABS). One hundred and fifty-nine residents (56%) submitted abstracts; 86 (30%) submitted articles; of these residents, 134 (47%) and 54 (19%) had their work accepted, respectively. Research was required by 26/60 (43%) programs. Research elective time was available in 41/60 (68%) programs; only 44/203 (22%) residents used this time for research. Residents who had research required had a 1.9 times greater likelihood of submitting both abstracts (P < 0.008) and articles (P < 0.014). No other study relationship was found to be significant. The study results suggest that implementing a research requirement in the residency training curriculum may lead to an increase in resident research activity.

Spin-polarized photoemission experiments on expitaxial Ag overlayers on Fe(001) have shown that a minority-spin surface state of the bare substrate evolves into an interface state, moves to higher energies, and crosses the Fermi level ${\mathit{E}}_{\mathit{F}}$ between 3 and 4 Ag monolayers. Application of a phase accumulation model shows that this state is a quantum-well (QW) state characterized by the quantum number \ensuremath{\nu}=1, where \ensuremath{\nu}=m-n, and where n and m are the number of wave-function nodes and number of layers, respectively. Higher members of the QW series cross ${\mathit{E}}_{\mathit{F}}$ with a periodicity \ensuremath{\Delta}m=(1-${\mathit{k}}_{\mathit{F}}$/${\mathit{k}}_{\mathrm{BZ}}$${)}^{\mathrm{\ensuremath{-}}1}$ identical with that in recent theories for the alternation between ferromagnetic and antiferromagnetic coupling in magnetic multilayers. The QW model fails at low coverages. A tight-binding model captures the behavior at low coverages while reproducing QW behavior at high coverages.

In honor of this year's 100th anniversary of the discovery of superconductivity, this special issue of Reports on Progress in Physics is a dedicated issue to the 'iron-based superconductors'?a new class of high-temperature superconductors that were discovered in 2008. This is the first time the journal has generated a 'theme issue', and we provide this to the community to provide a 'snapshot' of the present status, both for researchers working in this fast-paced field, and for the general physics community. Reports on Progress in Physics publishes three classes of articles?comprehensive full Review Articles, Key Issues Reviews and, most recently, Reports on Progress articles that recount the current status of a rapidly evolving field, befitting of the articles in this special issue. It has been an exciting year for superconductivity?there have been numerous celebrations for this centenary recounting the fascinating history of this field, from seven Nobel prizes to life-saving discoveries that brought us medically useful magnetic resonance imaging. The discovery of a completely new class of high-temperature superconductors, whose mechanism remains as elusive as the cuprates discovered in 1986, has injected a new vitality into this field, and this year those new to the field were provided with the opportunity of interacting with those who have enjoyed a long history in superconductivity. Furthermore, as high-density current carriers with little or no power loss, high-temperature superconductors offer unique solutions to fundamental grid challenges of the 21st century and hold great promise in addressing our global energy challenges. The complexity and promise of these materials has caused our community to more freely share our ideas and results than ever before, and it is gratifying to see how we have grown into an enthusiastic global network to advance the field. This invited collection is true to this agenda and we are delighted to have received contributions from many of the world leaders for an initiative that is designed to benefit both newcomers and established researchers in superconductivity.

Spin polarized photoemission is used to examine the spin polarization of the quantum well states observed in copper films grown on a fcc Co(001) substrate. The states are observed to predominantly carry minority spin polarization and this is shown through comparison with calculation to reflect a preferential hybridization in the interface. The calculation also provides evidence that the quantum well states observed in the experiments are not only [ital sp] derived but also reflect the hybridization with the more localized copper [ital d] bands.

The C 1s photoelectron spectrum of CO has been measured with high resolution in the threshold region. The data exhibit hitherto unresolved vibrational structure on the C 1s main photoelectron line as well as new features in the satellite region. The vibrational energy of the CO + ion is 301±3 meV. The vibrational structure changes dramatically with photon energy due to the influence of the σ * shape resonance. The new satellite lines which are not present at high photon energies are attributed to conjugate shakeup processes

With spin polarized electron spectroscopies, we have investigated ordered Gd (0001) films deposited on W (110). The photoemission features of the gadolinium 5d surface state, the 4f levels, and the background exhibit considerable spin polarization along the same direction in the plane of the film, indicative of ferromagnetic coupling between the surface and the bulk. The 4f spin polarized photoemission data provides strong evidence that the surface 4f polarization differs from the bulk 4f polarization for Gd (000l). Our temperature dependent measurements with spin polarized secondary electron spectroscopy conclusively establishes that the surface of clean Gd (0001) possesses a perpendicular polarization component which persists to an enhanced surface Curie temperature. SMall amounts of contamination at the surface result in the disappearance of the perpendicular component and, therefore, a more perfect ferromagnetic coupling between the surface and the bulk.

Spin polarized photoemission is used to study the electronic structure of noble metals deposited on ferromagnetic substrates. Studies of Ag deposited on an Fe (001) substrate reveal a series of minority spin interface or quantum well states with binding energies dependent on the thickness of the silver. Similar behavior is observed for Cu films deposited on a fee Co (001) substrate. Tight-binding Modeling reproduces many of the observations and shows that hybridization of the sp-bands with the noble metal d-bands cannot be ignored.

This letter to the editor discusses an article that focused on analyzing the effect of PEPFAR in focus countries. It states that due to the belief that no evaluations have been done to date the U.S. government needs to be more proactive in disseminating and publicizing the PEPFAR evaluations particularly in peer-reviewed scientific literature. In addition the author encourages others to develop methods for measuring the success of PEPFAR and other efforts to mitigate the effect of the HIV epidemic worldwide.

The electronic and magnetic structure of metastable bcc nickel grown on Fe(001) has been investigated using spin-polarized angle-resolved photoemission. At the iron lattice constant bcc nickel is found to be ferromagnetic, with a moment of (0.4{plus minus}0.45){mu}{sub {ital B}} in reasonable agreement with theoretical predictions, and with a Curie temperature above 300 K. A 6-eV'' spin-polarized satellite is also observed, analogous to that seen for fcc nickel previously. The observation of spin polarization in this feature confirms the presence of long-range ferromagnetic order at the local nickel sites.

We report magnetoresistive and structural measurements of superconducting FeSe0.5Te0.5 epitaxial thin films grown by pulsed laser deposition. Enhanced onset superconducting transition temperature (∼17 K) is observed in some of these films. Structural analysis by x-ray diffraction and high resolution transmission electron microscopy reveal that these films generally have significantly shorter out-of-plane lattice constant c than the bulk value, suggesting that the out-of-plane changes have a dominating impact on the superconducting transition in iron-based superconductors. Our data also indicate that the upper critical field Hc2(0) of those films may reach as high as 50 T.

Studies of the formation of a nonmagnetic/magnetic silver/iron interface by spin-polarized photoemission identify magnetic interface states showing discrete binding energies dependent on the number of atomic layers in the overlayer. The results for one layer of silver on iron are in good agreement with a full-potential linearized-augmented-plane-wave calculation and tight-binding modeling allows us to reproduce qualitatively the layer-dependent binding energies for one, two, and three layers of silver on iron. The interface states appear to be related to a minority surface resonance on the iron surface.

Spin polarized photoemission is used to study the magnetic states associated with the clean iron (001) surface. These studies reveal evidence for a minority spin surface state in agreement with a first principles calculation. Studies of the same surface with silver and chromium epitaxial overlayers reveal evidence for interface states derived from this state found on the clean surface. In the case of the silver overlayer the binding energy of the new state is found to be dependent on the layer by layer thickness of the overlayer. With chromium overlayers the binding energy for the same interface state does not show the same thickness dependence. However a second interface state is observed immediately below the Fermi level. These changes in the interfacial electronic structure have implications for any modelling of magnetic coupling in multilayers dependent on the magnetic properties of the interface.

The electronic structure of $p$-type doped \BiTe is studied by angle resolved photoemission spectroscopy (ARPES) to experimentally confirm the mechanism responsible for the high thermoelectric figure of merit. Our ARPES study shows that the band edges are located off the $\Gamma$-Z line in the Brillouin zone, which provides direct observation that the spin-orbit interaction is a key factor to understand the electronic structure and the corresponding thermoelectric properties of \BiTe. Successive time dependent ARPES measurement also reveals that the electron-like bands crossing E$_F$ near the $\underline{\Gamma}$ point are formed in an hour after cleaving the crystals. We interpret these as surface states induced by surface band bending, possibly due to quintuple inter-layer distance change of \BiTe.

The combination of spin-polarization detection with core-level photoemission to give spin-polarized electron spectroscopy for chemical analysis provides new information on the oxidation of an iron surface. During the initial stage of oxidation the predominant phase is of a ferrimagnetic \ensuremath{\gamma}-${\mathrm{Fe}}_{2}$${\mathrm{O}}_{3}$ form. An observed antiferromagnetic coupling of this oxide with the iron substrate is attributed to a superexchange interaction, providing evidence for a possible site-exchange mechanism during the initial oxidation. Annealing transforms this oxide into an antiferromagnetic ${\mathrm{Fe}}_{\mathit{x}}$O form which is also present at the initial stage.

Spin-resolved angle-resolved photoemission spectra have been measured for the adsorption systems Fe(001)-p(1\ifmmode\times\else\texttimes\fi{}1)O and Fe(001)-c(2\ifmmode\times\else\texttimes\fi{}2)S. Adsorbate-induced features in the spectra display exchange splittings (\ensuremath{\Delta}E) and linewidths which vary with ${\mathit{k}}_{\mathrm{?}}$, with orbital symmetry (${\mathit{p}}_{\mathit{x}}$ or ${\mathit{p}}_{\mathit{z}}$), and with spin character. For adsorbate ${\mathit{p}}_{\mathit{z}}$ orbitals, the measured \ensuremath{\Delta}E is larger at the center of the surface Brillouin zone (1.3 eV for O, 0.5 eV for S) than at the zone boundary (0.25 and 0.2 eV, respectively). The results are compared with the predictions of tight-binding simulations and first-principles calculations.

The direct observation of magnetic surface states on Fe(001) is reported. A spin-polarized angle-resolved photoemission study identifies a minority surface resonance at {bar {Gamma}} (2.40-eV binding energy) and a minority surface state at {ital {bar X}} (2.25-eV binding energy) in the surface Brillouin zone. The majority counterpart of the minority surface resonance is not observed. Good agreement with 7- and 13-layer full-potential linearized-augmented-plane-wave calulations is found for the minority {bar {Gamma}} to {ital {bar X}} surface band. In addition, the 13-layer slab calculation is found to more correctly model the decay of the surface resonance into the bulk in contrast to the 7-layer slab where size effects play a role.

Spin polarized core level photoemision studies are capable of providing local site specific magnetic information. 3s core level photoemission spectra are characterized by a main peak and satellite whose separation reflects the exchange interaction between the core level and the net spin in the valence bands. However, there is currently considerable disagreement as to whether the splitting between these two peaks may be taken as a measure of the local moment. An alternative approach is to examine the intensities of the different peaks in the spectra. Indeed analysis of the multiplet intensities in the final state suggests that it should be possible to obtain a reasonable measure of the local magnetic moment through measurement of the spin dependent intensities in the multiplet structure. In detailed spin polarized photoemission studies of the 3s core level of Fe and Co films grown on Ag(001) and Cu(001) substrates, respectively, we find that this is indeed the case. This suggests that studies of the spin p...

A Comment on the Letter by I. Morrison [ital et] [ital al]., Phys. Rev. Lett. 71, 1083 (1993).

We describe the design and construction of an electron gun which produces a 1 mm focused beam with a 5° full width of angular convergence. The maximum achievable beam current depends on the energy, υ0, and is given as Imax ⋍ 0.1 (μA/V3/2) × V03/2. The gun is used in inverse photoelectron spectroscopy (IPES), and is operated at energies as low as 5 eV. The gun employs a BaO cathode operating at 850–1100°C. The low thermal energy spread of the beam (kT ≈ 0.1 eV) and the narrow convergence angle are ideal for momentum resolved IPES. The focused beam is well suited for use with a grating spectrograph IPES detector. The output beam parameters could easily be modified, within certain fundamental constraints, to suit purposes other than IPES. The design principles and the factors controlling beam parameters are discussed in detail.

The spin-polarized sulfur /ital L//sub 2,3/VV Auger spectrum isrecorded for the system /ital c/(2/times/2)S/Fe(001). Convolution of thecalculated spin-dependent projected local density of states gives goodagreement with the measured spectrum. As in previous studies a strong satelliteis observed in the Auger spectrum and this is shown to be due to the presenceof hybridized iron states at the sulfur site. The spectrum also shows anexchange splitting of 0.2 eV in reasonable agreement with the calculation. Theintegrated spin-up and spin-down Auger intensity gives an estimate of themagnetic moment of the sulfur adsorbate less than or equal to0.10..mu../sub /ital B//.

The proposed installation of an experimental beam line to exploit the photon flux from the FEL undulator on the Brookhaven VUV ring is described. It is shown that under the normal operating conditions of the VUV ring, the undulator should produce an intense flux of photons in a highly collimated beam in the energy range from 5–200 eV. It is intended to construct a beam line based on a McPherson 225 monochromator, which will allow an experimental program in the range 5–30 eV. The optical layout of the beamline is discussed with particular emphasis on the requirements of coupling a highly collimated source to such a monochromator. The experimental program is designed to utilize either the high photon flux with medium resolution, or a more modest flux, with the potential high resolution to be obtained from the monochromator. Planned experiments include high k -space resolution angle-resolved photoemission, high resolution gas phase studies and spin resolved photoemission from solid surfaces.

We describe a normal incidence grating spectrometer for use in inverse photoemission studies of surfaces. We show that by operating in a configuration where the source and image are displaced from the Rowland Circle it is possible to construct a useful spectrometer that can be attached to any existing surface science chamber. The device covers the range 10–30 eV in photon energy with a typical energy resolution of 150 meV. Capable of operating with relatively low incident currents, this instrument will be an excellent choice for spin‐polarized inverse photoemission experiments.