Space partitioning of exchange-correlation functionals with the projector augmented-wave method

We implement a Becke fuzzy cells type space partitioning scheme for the purposes of exchange-correlation within the GPAW projector augmented-wave method based density functional theory code. Space partitioning is needed in the situation where one needs to treat different parts of a combined system with different exchange-correlation functionals. For example, bulk and surface regions of a system could be treated with functionals that are specifically designed to capture the distinct physics of those regions. Here, we use the space partitioning scheme to implement the quasi-nonuniform exchange-correlation scheme, which is a useful practical approach for calculating metallic alloys on the generalized gradient approximation level. We also confirm the correctness of our implementation with a set of test calculations.

Motivational characteristics and resistance training in older adults: A randomized controlled trial and 1-year follow-up

The aim of this study was to investigate the effects of a 9-month supervised resistance training intervention on motivational and volitional characteristics related to exercise, and whether the absolute level and/or intervention-induced change in these characteristics predict self-directed continuation of resistance training 1 year after the intervention. Community dwelling older adults aged 65-75, who did not fulfill physical activity recommendations, were randomized into resistance training intervention groups: training once- (n = 26), twice- (n = 27), three-times-a-week (n = 28) or non-training control group (n = 25). Training groups participated in supervised resistance training for 9 months: during months 1-3 all groups trained twice-a-week and then with allocated frequencies during months 4-9. Exercise-related motivation, self-efficacy, and planning were measured with questionnaires at baseline, month-3 and month-9. The continuance of resistance training was determined by interviews 6 and 12 months after the end of the intervention. The intervention improved action and coping planning as well as intrinsic motivation (group × time P < .05). During 1-year follow-up, 54% of participants did not continue self-directed regular resistance training, 22% continued regular resistance training once-a-week, and 24% twice-a-week. Increases in exercise self-efficacy and intrinsic motivation related to training during the intervention predicted continuation of resistance training twice-a-week. Resistance training improved exercise-related motivational and volitional characteristics in older adults. These improvements were linked to continuing resistance training 1 year after the supervised intervention. The role of these characteristics should be taken into account when promoting long-term resistance training participation among older adults.

Quantitative description of short-range order and its influence on the electronic structure in Ag-Pd alloys

We investigate the effect of short-range order (SRO) on the electronic structure in alloys from the theoretical point of view using density of states (DOS) data. In particular, the interaction between the atoms at different lattice sites is affected by chemical disorder, which in turn is reflected in the fine structure of the DOS and, hence, in the outcome of spectroscopic measurements. We aim at quantifying the degree of potential SRO with a proper parameter. The theoretical modeling is done with the Korringa-Kohn-Rostoker Green's function method. Therein, the extended multi-sublattice non-local coherent potential approximation is used to include SRO. As a model system, we use the binary solid solution Ag c Pd1-c at three representative concentrations c  =  0.25, 0.5 and 0.75. The degree of SRO is varied from local ordering to local segregation through an intermediate completely uncorrelated state. We observe some pronounced features, which change over the whole energy range of the valence bands as a function of SRO in the alloy. These spectral variations should be traceable in modern photoemission experiments.

Adhesion of the iron-chromium oxide interface from first-principles theory

We determine the interface energy and the work of separation of the Fe/Cr2O3 interface using first-principles density functional theory. Starting from different structures, we put forward a realistic interface model that is suitable to study the complex metal-oxide interaction. This model has the lowest formation energy and corresponds to an interface between Fe and oxygen terminated Cr2O3. The work of separation is calculated to be smaller than the intrinsic adhesion energy of pure Fe or Cr2O3, suggesting that stainless steel surfaces should preferentially break along the metal-oxide interface. The relative stabilities and magnetic interactions of the different interfaces are discussed. Next we introduce Cr atoms into the Fe matrix at different positions relative to the interface. We find that metallic Cr segregates very strongly to the (FeCr)/Cr2O3 interface, and increases the separation energy of the interface, making the adhesion of the oxide scale mechanically more stable. The Cr segregation is explained by the enthalpy of formation.

First-principles atomistic study of surfaces of Fe-rich Fe-Cr

The surface properties of Fe-rich ferromagnetic Fe-Cr alloys are investigated using a first-principles quantum-mechanical method. In dilute alloys, the surfaces are dominated by Fe, whereas the Cr-containing surfaces become favorable when the bulk Cr concentration exceeds the limit of ∼ 10 atomic per cent. The abrupt change in the surface behavior is the consequence of complex competing magneto-chemical interactions between the alloying atoms. Considering the quantities of various features: equilibrium surface profiles, chemical potentials, segregation energies, surface energies, magnetic moments, mixing energies and pair interactions, within a wider range of bulk and surface concentrations enables us to build a comprehensive picture of the physics of Fe-Cr surfaces. Using the present achievements many previously controversial results can now be merged into a consistent model of Fe-rich Fe-Cr alloys.

Anomalous bismuth-stabilized (2x1) reconstructions on GaAs(100) and InP(100) surfaces

First-principles phase diagrams of bismuth-stabilized GaAs- and InP(100) surfaces demonstrate for the first time the presence of anomalous (2x1) reconstructions, which disobey the common electron counting principle. Combining these theoretical results with our scanning-tunneling-microscopy and photoemission measurements, we identify novel (2x1) surface structures, which are composed of symmetric Bi-Bi and asymmetric mixed Bi-As and Bi-P dimers, and find that they are stabilized by stress relief and pseudogap formation.

Transplanting the highly sensitized patient: The emory algorithm

Renal transplant patients sensitized to HLA antigens comprise nearly one-third of the UNOS wait-list and receive 14% of deceased donor (DD) transplants, a rate half that of unsensitized patients. Between 1999 and 2003, we performed 492 adult renal transplants from DD; 120 patients (approximately 25%) had a panel reactive antibody (PRA) of >30%, with nearly half (n = 58) having a PRA of >80%. Our approach is based upon high-resolution solid-phase HLA antibody analysis to identify class I/II antibodies and a 'virtual crossmatch' to predict compatible donor/recipient combinations. Recipients are excluded from the United Network for Organ Sharing match run if donors possess unacceptable antigens. Thus, when sensitized patients appear on the match run, they have a high probability of a negative final crossmatch. Here, we describe our 5-year experience with this approach. Five-year graft survival ranged from 66% to 70% among unsensitized (n = 272), moderately sensitized (PRA < 30%, n = 100) and highly sensitized (>30% PRA; n = 120) patients, equal to the average national graft survival (65.7%). The application of this approach (the Emory Algorithm) provides a logical and systematic approach to improve the access of sensitized patients to DD organs and promote more equitable allocation to a highly disadvantaged group of patients awaiting renal transplantation.

Aggression in childhood and long-term unemployment in adulthood: a cycle of maladaptation and some protective factors

The present study was designed to shed light on specific risk mechanisms and protective factors in the relation between aggression in childhood and long-term unemployment in adulthood. Participants were drawn from the ongoing Jyväskylä Longitudinal Study of Personality and Social Development; data gathered at the ages of 8 (N = 369), 14, 27, and 36 years (n = 311) were used in the present study. Teacher-rated aggression at age 8 was related to subsequent long-term unemployment through a cycle of maladaptation. Specifically, childhood aggression predicted school maladjustment at age 14, which was both directly and indirectly (via problem drinking and lack of occupational alternatives at age 27) related to long-term unemployment. Child-centered parenting and prosocial tendencies in an aggressive child significantly lowered his or her probability of becoming long-term unemployed in adulthood.

Case report: coexistence of acute calcific periarthritis and infection

Basic calcium phosphate (BCP) crystal deposition around the joints may sometimes lead to an acute inflammatory condition called calcific periarthritis. In this article, the authors describe a 62-year-old man with BCP crystal-induced periarthritis coexisting with an infection. Rheumatoid arthritis and crystal-induced synovitis complicated by infection has been described in the literature. To date, this is the first report of coexistent calcific periarthritis and an infection.