A Specialist-Led Care Model: Aligning the Patient and Specialist for the Greatest Impact.

In the previous paper, discussing "Risk and the Future of Musculoskeletal Care," we reviewed the basic concepts of the risk corridor, implications on health care overall if we maintain a fee-for-service model, and the need for musculoskeletal specialists to begin taking on/managing risk to reinforce our presence in a "value-based care" system. This paper discusses the successes and failures of recent value-based care models and provides the framework for the paradigm of a specialist-led care model. We posit that orthopedic surgeons are the most knowledgeable physicians to manage musculoskeletal conditions, create new and innovative models, and lead value-based care to the next level.

Risk Should Not Be a "Four-Letter Word" in Healthcare. Risk and the Future of Musculoskeletal Care.

Orthopaedics has seen a rapid transition to value-based care. As we transition away from fee-for-service models, healthcare systems, groups, and surgeons are being asked to take on an increasing amount of risk. While on the surface risk may have a negative connotation, managing risk allows surgeons to maintain autonomy while taking on value-based care to the next level.

Zeeman spectroscopy and crystal-field analysis of low symmetry centres in Nddoped YSiO.

We report on infrared to visible Zeeman absorption spectroscopy and parameterised crystal-field modelling of Ndcentres in YSiOthrough the use of experimentally inferred crystal-field energy levels and Zeeman directional electronicvalues. We demonstrate that good agreement between the calculated and experimental crystal-field energy levels as well as directional Zeemanvalues along all three crystallographic axes can be obtained. Further, we demonstrate that the addition of correlation crystal field effects successfully account for discrepancies that arise between the calculated and experimental values relevant to theH11/2(2) multiplet in a one-electron crystal field model.

Zeeman and laser site selective spectroscopy of Cpoint group symmetry Smcentres in YSiO: a parametrized crystal-field analysis for the 4configuration.

Parametrized crystal-field analyses are presented for both the six and seven fold coordinated, Csymmetry Smcentres in YSiO, based on extensive spectroscopic data spanning the infrared to optical regions. Laser site-selective excitation and fluorescence spectroscopy as well as Zeeman absorption spectroscopy performed along multiple crystallographic directions has been utilized, in addition to previously determinedtensors for theHZandGAstates. The resultant analyses give good approximation to the experimental energy levels and magnetic splittings, yielding crystal-field parameters consistent with the few other lanthanide ions for which such analyses are available.

Extending Phenomenological Crystal-Field Methods to C_{1} Point-Group Symmetry: Characterization of the Optically Excited Hyperfine Structure of ^{167}Er^{3+}:Y_{2}SiO_{5}.

We show that crystal-field calculations for C_{1} point-group symmetry are possible, and that such calculations can be performed with sufficient accuracy to have substantial utility for rare-earth based quantum information applications. In particular, we perform crystal-field fitting for a C_{1}-symmetry site in ^{167}Er^{3+}:Y_{2}SiO_{5}. The calculation simultaneously includes site-selective spectroscopic data up to 20 000  cm^{-1}, rotational Zeeman data, and ground- and excited-state hyperfine structure determined from high-resolution Raman-heterodyne spectroscopy on the 1.

Electron paramagnetic resonance enhanced crystal field analysis for low point-group symmetry systems: C sites in Sm:CaF/SrF.

We present a comprehensive spectroscopic study of C[Formula: see text] point-group symmetry sites in Sm[Formula: see text]:CaF[Formula: see text]/SrF[Formula: see text] codoped with either NaF or LiF. Data includes electron paramagnetic resonance measurements of Zeeman and hyperfine interactions for the ground state, as well as site-selective excitation and fluorescence spectroscopy up to the [Formula: see text]G[Formula: see text] multiplet. Inclusion of the EPR data allowed us to determine unique crystal-field parameters.

Evidence That the Anomalous Emission from CaF:Yb Is Not Described by the Impurity Trapped Exciton Model.

Yb-substituted CaF exhibits an anomalous red-shifted luminescence after UV excitation, attributed to the relaxation of impurity trapped excitons (ITE). CaF:Yb is the archetype system for this model, in which the Yb ions can be excited into a long-lived (ms) exciton state. Upon de-excitation, the emission intensity should be proportional to the Yb concentration, but that could not be checked when this model was first proposed.

X-ray Excitation Triggers Ytterbium Anomalous Emission in CaF:Yb but Not in SrF:Yb.

Materials that luminesce after excitation with ionizing radiation are extensively applied in physics, medicine, security, and industry. Lanthanide dopants are known to trigger crystal scintillation through their fast d-f emissions; the same is true for other important applications as lasers or phosphors for lighting. However, this ability can be seriously compromised by unwanted anomalous emissions often found with the most common lanthanide activators.

The determination of dopant ion valence distributions in insulating crystals using XANES measurements.

Ytterbium-doped wide-bandgap fluoride crystals CaF2, SrF2 and NaMgF3 have been measured using x-ray absorption near edge structure (XANES) on the L3 edge to determine the ratio of trivalent to divalent Yb ions present in the crystals. This study improves upon previous XANES measurements of dopant ion valency by taking into account the x-ray emission transition probabilities for the divalent and trivalent species instead of simply assuming that the relative concentrations may be determined by the ratio of the x-ray excitation band areas. Trivalent to divalent ratios as high as 5 are inferred even at low total dopant ion concentrations of 0.

Comprehensive Spectroscopic Determination of the Crystal Field Splitting in an Erbium Single-Ion Magnet.

The electronic structure of a novel lanthanide-based single-ion magnet, {C(NH2)3}5[Er(CO3)4]·11H2O, was comprehensively studied by means of a large number of different spectroscopic techniques, including far-infrared, optical, and magnetic resonance spectroscopies. A thorough analysis, based on crystal field theory, allowed an unambiguous determination of all relevant free ion and crystal field parameters. We show that inclusion of methods sensitive to the nature of the lowest-energy states is essential to arrive at a correct description of the states that are most relevant for the static and dynamic magnetic properties.

Pressure dependence of the emission in CaF2 : Yb(2+).

We present a detailed spectroscopic investigation of CaF2 doped with Yb(2+) performed at high hydrostatic pressure which is applied in a diamond anvil cell. At ambient pressure and at temperatures lower than 175 K, the luminescence consists of a single broad band peaked at 18 500 cm(-1), attributed to the recombination of impurity-trapped excitons. Increasing pressure causes the luminescence to be observable at higher temperature.

Effective Hamiltonian parameters for ab initio energy-level calculations of SrCl2:Yb2+ and CsCaBr3:Yb2+.

Calculated energy levels from recent ab initio studies of the electronic structure of SrCl2:Yb(2+) and CsCaBr3:Yb(2+) are fitted with a semi-empirical 'crystal-field' Hamiltonian, which acts within the model space 4f(14) + 4f(13)5d + 4f(13)6s. Parameters are obtained for the minima of the potential energy curves for each energy level and also for a range of anion-cation separations. The parameters are compared with published parameters fitted to experimental data and to atomic calculations.

Extraction of crystal-field parameters for lanthanide ions from quantum-chemical calculations.

A simple method for constructing effective Hamiltonians for the 4f(N) and 4f(N - 1)5d energy levels of lanthanide ions in crystals from quantum-chemical calculations is presented. The method is demonstrated by deriving crystal-field and spin-orbit parameters for Ce(3 + ) ions doped in LiYF(4), Cs(2)NaYCl(6), CaF(2), KY(3)F(10) and YAG host crystals from quantum-chemical calculations based on the DV-Xα method. Good agreement between calculated and fitted values of the crystal-field parameters is obtained.

Electronic spectra of Cs2NaYbF6 and crystal field analyses of YbX6(3-) (X = F, Cl, Br).

Detailed analysis of the vibronic structure in the electronic absorption spectrum of Cs2NaYbF6 at temperatures between 10 and 300 K enables the crystal field energy level diagram of Yb3+ in this cubic host to be deduced. Ultraviolet and visible laser excitation of Cs2NaYbF6, Cs2NaY(0.9)Yb(0.

Electronic structure of U3+ in Cs3Lu2Cl9 and Cs3Y2I9 single crystals.

Low-temperature emission and polarized absorption spectra have been recorded for U(3+) ions diluted in Cs(3)Lu(2)Cl(9) and Cs(3)Y(2)I(9) host crystals. The experimental crystal-field levels were fitted to 13 parameters of a semiempirical Hamiltonian representing the combined atomic, one-electron crystal field (CF) as well as two-particle correlation crystal-field (CCF) operators. The red shift of the first f-d transitions from approximately 14,800 cm(-1) in the spectrum of U(3+):Cs(3)Lu(2)Cl(9) to as low as 11,790 cm(-1) in that of U(3+):Cs(3)Y(2)I(9) has been attributed to an increase in the covalence of the U(3+)-X(-) bonds.

General calculation of 4f-5d transition rates for rare-earth ions using many-body perturbation theory.

The 4f-5d transition rates for rare-earth ions in crystals can be calculated with an effective transition operator acting between model 4f(N) and 4f(N-1)5d states calculated with effective Hamiltonian, such as semiempirical crystal Hamiltonian. The difference of the effective transition operator from the original transition operator is the corrections due to mixing in transition initial and final states of excited configurations from both the center ion and the ligand ions. These corrections are calculated using many-body perturbation theory.

Calculation of single-beam two-photon absorption rate of lanthanides: effective operator method and perturbative expansion.

Perturbative contributions to single-beam two-photon transition rates may be divided into two types. The first, involving low-energy intermediate states, require a high-order perturbation treatment, or an exact diagonalization. The other, involving high-energy intermediate states, only require a low-order perturbation treatment.

Conservation of connectivity of model-space effective interactions under a class of similarity transformation.

Effective interaction operators usually act on a restricted model space and give the same energies (for Hamiltonian) and matrix elements (for transition operators, etc.) as those of the original operators between the corresponding true eigenstates. Various types of effective operators are possible.

Simplified diagrammatic expansion for effective operators.

For a quantum many-body problem, effective Hamiltonians that give exact eigenvalues in reduced model space usually have different expressions, diagrams, and evaluation rules from effective transition operators that give exact transition matrix elements between effective eigenvectors in reduced model space. By modifying these diagrams slightly and considering the linked diagrams for all the terms of the same order, we find that the evaluation rules can be made the same for both effective Hamiltonian and effective transition operator diagrams, and in many cases it is possible to combine many diagrams into one modified diagram. We give the rules to evaluate these modified diagrams and show their validity.

Reappearance of fine structure as a probe of lifetime broadening mechanisms in the 4f(N) --> 4f(N-1)5d excitation spectra of Tb3+, Er3+, and Tm3+ in CaF2 and LiYF4.

High-energy transitions in the 4f(N) -->4f(N-1)5d excitation spectra of lanthanide ions in host crystals are usually broadened due to the short excited-state lifetimes, whereas low-energy transitions, with longer excited-state lifetimes, may show fine structure. We report the surprising observation that for some materials fine structure is observed not only for the low-energy excitation bands but also for some high-energy transitions. The excited states that display fine structure are those for which the 5d electron is in the lowest crystal-field level but the 4f(N-1) core is in a highly excited state, indicating that the broadening depends only on the energy of the 5d electron and not on the total energy of the 4f(N-1)5d excited state.

Wound infiltration with local anaesthetic after abdominal hysterectomy.

The study was performed to investigate if wound infiltration with 20 ml of 0.5% bupivacaine after abdominal hysterectomy improved analgesia and reduced morphine requirements from a patient-controlled analgesia system during the first 6 h after operation. Forty patients undergoing abdominal hysterectomy were allocated randomly to one of two groups.

Splenic artery aneurysm rupture in pregnancy.

A multigravid patient was admitted at 34 weeks with abdominal pain, signs of hypovolaemia and an intrauterine death. Ultrasonography and paracentesis revealed bleeding into the peritoneal cavity. The diagnosis of splenic artery aneurysm rupture was considered.