Spin crossover in ferropericlase from first-principles molecular dynamics.

Ferropericlase, (Mg,Fe)O, is the second-most abundant mineral of Earth's lower mantle. With increasing pressure, the Fe ions in the material begin to collapse from a magnetic to nonmagnetic spin state. We present a finite-temperature first-principles phase diagram of this spin crossover, finding a broad pressure range with coexisting magnetic and nonmagnetic ions due to favorable enthalpy of mixing of the two. Furthermore, we find the electrical conductivity of the mineral to reach semimetallic values inside Earth.

ADHD symptoms and maturity - a follow-up study in school children.

AIM: To test the hypothesis that there is a subgroup of children with attention deficit hyperactivity disorder (ADHD) who show a decline in ADHD-symptoms that is associated with signs of biological maturation, a phenomenon referred to as a 'maturation catch-up'. METHODS: The parents of 147 children who were given an examination in grades one and two 1999-2000 that included assessment of ADHD-symptoms and estimation of skeletal bone-age by use of hand radiographs (which was repeated in the eighth grade), were contacted 2008-2009 and were asked to answer questions concerning ADHD-symptoms and behavioural maturity in their children. The response frequency was 67%. A complete dataset was achieved in 57 children. A reduction of Conners scores for ADHD-symptoms of eight or more between the evaluations was defined as a marked reduction in symptoms. RESULTS: When the children with a marked symptom reduction (n = 6) were compared with children without such a reduction (n = 51), we found a significant difference in skeletal maturation (p < 0.05). CONCLUSION: This study gives support to the theory that there is a group of children with ADHD-symptoms who have a biological maturational-lag who will show a decrease in their ADHD-symptoms as they show a maturation catch-up with increasing age.

Serum bactericidal activity against Neisseria meningitidis in patients with C3 nephritic factors is dependent on IgG allotypes.

The main mechanisms of immune defense against Neisseria meningitidis are serum bactericidal activity (SBA) and opsonophagocytosis. Many complement deficiencies, among them acquired partial C3 deficiency due to stabilizing autoantibodies against the alternative pathway C3 convertase (C3 nephritic factors, C3 NeF); increase the risk of meningococcal infection. SBA against meningococci in patients with C3 NeF was determined along with allelic variants (GM alleles) of the immunoglobulin constant heavy G chain (IGHG) genes. In patients with C3 NeF and in control children, individuals homozygous for G1M*f and G3M*b showed higher SBA against meningococci than heterozygous individuals. Partial complement deficiency in early childhood might explain the influence of GM variants on SBA in control children. These novel findings imply that the IGHG genotype is important in defense against meningococci in individuals with low complement function and possibly in combination with other immunodeficiencies.

Adsorption of Water onto SrTiO3 from Periodic Møller-Plesset Second-Order Perturbation Theory.

Adsorption of water onto metal oxide surfaces is a long-standing problem motivated by relevance to many promising technological applications. In this work, we compute the adsorption energy of water on SrTiO3 using periodic Møller-Plesset second-order perturbation theory (MP2). We compare our MP2 results to density functional and hybrid density functional theory calculations with and without the widely used D3 dispersion correction. The MP2 ground-state adsorption energy of water on SrTiO3 (001) at one monolayer coverage is 0.9 eV on the TiO2 termination in the molecular configuration and 0.6 eV in the dissociative configuration, the corresponding results on the SrO termination being 0.9 eV for both modes of adsorption. These results are reproduced well by the PBE and PBE0 exchange-correlation functionals. Correcting for dispersion effects through the D3 dispersion correction leads to significantly overestimated adsorption energies for both PBE and PBE0 with respect to MP2. The D3 correction also fails to capture the difference in electron correlation between the molecular and dissociative adsorption states, similarly to the optB86b van der Waals density functional.

The interface of SrTiO3 and H2O from density functional theory molecular dynamics.

We use dispersion-corrected density functional theory molecular dynamics simulations to predict the ionic, electronic and vibrational properties of the SrTiO3/H2O solid-liquid interface. Approximately 50% of surface oxygens on the planar SrO termination are hydroxylated at all studied levels of water coverage, the corresponding number being 15% for the planar TiO2 termination and 5% on the stepped TiO2-terminated surface. The lateral ordering of the hydration structure is largely controlled by covalent-like surface cation to H2O bonding and surface corrugation. We find a featureless electronic density of states in and around the band gap energy region at the solid-liquid interface. The vibrational spectrum indicates redshifting of the O-H stretching band due to surface-to-liquid hydrogen bonding and blueshifting due to high-frequency stretching vibrations of OH fragments within the liquid, as well as strong suppression of the OH stretching band on the stepped surface. We find highly varying rates of proton transfer above different SrTiO3 surfaces, owing to differences in hydrogen bond strength and the degree of dissociation of incident water. Trends in proton dynamics and the mode of H2O adsorption among studied surfaces can be explained by the differential ionicity of the Ti-O and Sr-O bonds in the SrTiO3 crystal.

Cysteine residues are not essential for the catalytic activity of human class Mu glutathione transferase M1a-1a.

To investigate the possible involvement of a Cys thiol in the catalysis of the human glutathione transferase M1a-1a, we constructed mutants of this enzyme wherein the four Cys residues present in the native enzyme were replaced by Ala residues. Three mutants, one where all four Cys residues had been replaced and two mutants where three out of four Cys residues were changed into Ala, were characterized regarding their catalytic activities with three different substrates as well as by their binding of three different inhibitors. All three Cys-deficient mutant forms of glutathione transferase M1a-1a were catalytically active with the tested substrates and their binding of inhibitors, measured by I50, were not significantly different from the values previously obtained for the wild-type enzyme. We therefore conclude that none of the Cys residues in this class Mu glutathione transferase are directly involved in the catalysis performed by this enzyme.

Normal human serum depleted of C1q, factor D and properdin: its use in studies of complement activation.

Normal human sera were depleted of C1q, factor D (D) and properdin (P) by a simple and reproducible procedure providing reagents for analysis of complement-dependent functions. Classical pathway activity was restored with purified C1q, and alternative pathway activity with purified D and P. Since both activation pathways were abolished, antibodies and other components could be removed without loss of complement activity during immunoabsorption procedures. Synergism between the two pathways during haemolysis of rabbit erythrocytes was clearly demonstrated, and was also found on analysis of C3 cleavage in serum incubated with other alternative pathway activators such as zymosan and inulin. Experiments with a Neisseria meningitidis serogroup W-135 strain isolated from a patient with inherited P deficiency showed that both pathways were capable of supporting antibody-dependent killing of the bacteria in serum. The alternative pathway was possibly more efficient than the classical pathway in the assay system. In C1q,D,P-depleted serum with high concentrations of anticapsular IgG antibodies, the addition of D alone resulted in efficient alternative pathway-mediated killing. The alternative pathway was equally efficient in a C1q,D,P-depleted serum with low concentrations of anticapsular antibody, but in this case the reaction required both D and P.

Low back and neck/shoulder pain in construction workers: occupational workload and psychosocial risk factors. Part 1: Relationship to low back pain.

The prevalence rate of musculoskeletal problems, especially low back pain and severe low back pain in a randomly selected sample of 1,773 construction workers was studied. Its relationship to physical and psychosocial factors was analyzed. The workers answered a postal questionnaire. Workload was measured by means of eight manual materials handling indices and ten psychosocial indices, based on results from factor analyses. The 1-year prevalence rate of low back pain was 54% and of severe low back pain 7%. The relationship to heavy manual materials handling differed with age in such a manner that it could be interpreted as a healthy worker effect. Between severe low back pain and both stooping or kneeling a dose-response relationship was found. The most prominent of the psychosocial factors associated with low back pain and severe low back pain were the stress index and the psychosomatic and psychic indices. The age-standardized prevalence rate ratio of low back pain was 1.6 (95% confidence interval 1.4-1.8) and for severe low back pain 3.1 (95% confidence interval 2.3-4), when workers reporting "high" stress were compared to workers reporting "low" stress.

Low back and neck/shoulder pain in construction workers: occupational workload and psychosocial risk factors. Part 2: Relationship to neck and shoulder pain.

The prevalence rate of neck and shoulder trouble and considerable neck and shoulder pain in a randomly selected sample of 1773 construction workers were studied. The relationship to physical and psychosocial factors was analyzed. The workers answered a postal questionnaire. Workload was measured by means of eight manual materials handling indices and ten psychosocial indices, based on results from factor analyses. The 1-year prevalence rate of considerable neck and shoulder trouble was 56% and of neck and shoulder pain 12%. To work with hands above shoulder level showed a dose-response relationship to both neck and shoulder trouble and neck and shoulder pain. The psychosocial factors were more prominently associated with neck and shoulder trouble and neck and shoulder pain than the physical workload factors. The psychosocial indices; psychosomatic and psychic symptoms, stress and job satisfaction showed the highest age-standardized prevalence rate ratios for both neck and shoulder trouble and neck and shoulder pain.

Promising prospects: students choosing therapy as a career.

Careers in health fields are becoming increasingly popular among college students, and therapy (occupational, physical, and speech) is one of the fastest growing of these fields. To identify the characteristics of potential therapists, a group of subjects who had entered college as first-time, full-time freshmen in 1966 and who indicated in 1970 that they planned on a career in therapy were compared with aspirants to other health careers with respect to demographic characteristics, sources of college financing, academic achievement, and education/employment status as of 1970. In addition, their attitudes and values--as revealed by self-ratings, life goals, and reasons for choosing the career of therapy--were examined. Prospective therapists were found to have outstanding academic records, high rates of baccalaureate completion, and specific skills that seemed to qualify them for success in the career. They were stongly oriented toward working with people, had altruistic goals and values, and were highly confident of their interpersonal skills.

National commission meets the grass roots: concerns of program directors in allied health education.

An informal, open-ended survey was conducted by the National Commission on Allied Health Education for the purpose of learning what the directors of allied health programs in colleges and universities regard as the major problems facing allied health today and the major issues for the near future. The concerns of the respondents were found to cluster in 11 major areas: (1) definition (identity), (2) credentialing, (3) funding, (4) roles of educational settings, (5) clinical affiliations, (6) curriculum, (7) continuing education, (8) students, (9) faculty and administration, (10) delivery systems and consumer needs and (11) research and information needs. Even though consensus on problems was remarkable, there was no such general agreement on solutions. This initial "idea search" proved useful to the Commission in defining topic areas for documentation studies and in underscoring the necessity of looking for solutions.

A new parametrization of the Stillinger-Weber potential for an improved description of defects and plasticity of silicon.

A new parametrization of the widely used Stillinger-Weber potential is proposed for silicon, allowing for an improved modelling of defects and plasticity-related properties. The performance of the new potential is compared to the original version, as well as to another parametrization (Vink et al 2001 J. Non-Cryst. Solids, 282 248), in the case of several situations: point defects and dislocation core stability, threshold displacement energies, bulk shear, generalized stacking fault energy surfaces, fracture, melting temperature, amorphous structure, and crystalline phase stability. A significant improvement is obtained in the case of dislocation cores, bulk behaviour under high shear stress, the amorphous structure, and computation of threshold displacement energies, while most of the features of the original version (elastic constants, point defects) are retained. However, despite a slight improvement, a complex process like fracture remains difficult to model.

Ab initio method for locating characteristic potential-energy minima of liquids.

It is possible in principle to probe the many-atom potential surface using density functional theory (DFT). This will allow us to apply DFT to the Hamiltonian formulation of atomic motion in monatomic liquids by Wallace [Phys. Rev. E 56, 4179 (1997)]. For a monatomic system, analysis of the potential surface is facilitated by the random and symmetric classification of potential-energy valleys. Since the random valleys are numerically dominant and uniform in their macroscopic potential properties, only a few quenches are necessary to establish these properties. Here we describe an efficient technique for doing this. Quenches are done from easily generated "stochastic" configurations, in which the nuclei are distributed uniformly within a constraint limiting the closeness of approach. For metallic Na with atomic pair potential interactions, it is shown that quenches from stochastic configurations and quenches from equilibrium liquid molecular dynamics configurations produce statistically identical distributions of the structural potential energy. Again for metallic Na, it is shown that DFT quenches from stochastic configurations provide the parameters which calibrate the Hamiltonian. A statistical mechanical analysis shows how the underlying potential properties can be extracted from the distributions found in quenches from stochastic configurations.

High frequency of contact allergy to gold in patients with endovascular coronary stents.

BACKGROUND: Stent implantation is an effective method for treatment of atherosclerotic disease. Factors predisposing to in-stent restenosis are still largely unknown. Contact allergy to metal ions eluted from the stent has been suggested to be a risk factor. OBJECTIVES: To explore whether there is a possible induction of contact allergy to metals used in stents among patients with a stainless steel stent containing nickel (Ni stent) and patients with a gold-plated stent (Au stent). METHODS: Adults (n = 484) treated with coronary stent implantation participated in the study with patch testing. The study design was retrospective and cross-sectional with no assessment of contact allergy before stenting. Age- and sex-matched patch-tested patients with dermatitis (n = 447) served as controls. RESULTS: Of Au-stented patients, 54 of 146 (37%) were allergic to gold compared with 85 of 447 (19%) controls (P < 0.001). Within the stented population there were no statistically significant differences in contact allergy to gold or nickel between Ni-stented and Au-stented patients. In multivariate models where other risk factors for contact allergy to gold were considered, the Au stent showed a trend towards statistical significance (odds ratio 1.43, 95% confidence interval 0.95-2.16; P = 0.09). CONCLUSIONS: As the frequency of contact allergy to gold is higher in stented patients independent of stent type it suggests a previous sensitization. However, several pieces of circumstantial evidence as well as statistical analysis indicate the possibility of sensitization in the coronary vessel by the Au stent. Ni stents and Au stents should not be ruled out as risk factors for induction of contact allergy to these metals.

Knee kinematics and kinetics during gait, step and hop in males with a 16 years old ACL injury compared with matched controls.

The objective of this study was to compare subjects who sustained an ACL injury during soccer 16 years ago with a control group with regard to knee kinematics and kinetics of gait, step activity and cross over hop. Secondly, in the injured subjects, the purpose was to study the impact on kinematics and kinetics of characteristics such as operative status, meniscal resection, being symptomatic, having knee extensor weakness and of having radiographic knee OA. Data from a 3-dimensional gait analysis system (VICON) were used to calculate kinetics and kinematics during gait, step activity and cross over hop of 12 male subjects who had an anterior cruciate ligament injury 16 years earlier. Twelve uninjured subjects matched for age, sex, BMI and activity level served as controls. No significant differences in knee kinematics and kinetics between the ACL group and the control group were found. The variability of some parameters of step and all parameters of hop activity was generally larger in the ACL injured subjects compared with the controls. The ACL injured subjects had a significantly worse clinical status compared with the controls. Reduced knee extension strength was associated with joint moment reductions especially during step activity and cross over hop. Despite a significantly worse clinical status, as determined by self-report and isokinetic strength testing, no significant differences were seen in knee joint kinetics and kinematics in an ACL injured group 16 years after injury compared with a matched control group. The variation was larger among the ACL injured subjects indicating the need for larger study groups in gait and movement analysis in long-term follow-up of ACL injury.

Competing exchange interactions in magnetic multilayers.

We have studied alloying of the nonmagnetic spacer layer with a magnetic material as a method of tuning the interlayer coupling in magnetic multilayers. We have specifically studied the Fe/V(100) system by alloying the spacer V with various amounts of Fe. For some Fe concentrations in the spacer, it is possible to create a competition between antiferromagnetic Ruderman-Kittel-Kasuya-Yoshida exchange and direct ferromagnetic exchange coupling. The exchange coupling and transport properties for a large span of systems with different spacer concentrations and thicknesses were calculated and measured experimentally and good agreement between observations and theory was observed. A reduction in magnetoresistance of about 50% was observed close to the switchover from antiferromagnetic to ferromagnetic coupling.

Sample preserving deep interface characterization technique.

We propose a nondestructive technique based on atomic core-level shifts to characterize the interface quality of thin film nanomaterials. Our method uses the inherent sensitivity of the atomic core-level binding energies to their local surroundings in order to probe the layer-resolved binary alloy composition profiles at deeply embedded interfaces. From an analysis based upon high energy x-ray photoemission spectroscopy and density functional theory of a Ni/Cu fcc (100) model system, we demonstrate that this technique is a sensitive tool to characterize the sharpness of a buried interface. We performed controlled interface tuning by gradually approaching the diffusion temperature of the multilayer, which lead to intermixing. We show that core-level spectroscopy directly reflects the changes in the electronic structure of the buried interfaces, which ultimately determines the functionality of the nanosized material.

Effects of lumbar belts on trunk muscle strength and endurance: a follow-up study of construction workers.

The effects on maximal isometric trunk muscle strength and endurance after wearing a soft heat-retaining lumbar belt or a weightlifter's belt were studied. The soft belt (SB) study group comprised 12 construction workers with healthy backs, and the weightlifter's belt (WB) group comprised 24 construction workers with current or previous low back pain. The strength and endurance measurements were performed before the start of belt use, and after 1 and 2 months. The SB group increased the trunk flexor strength by 13% (p less than or equal to 0.01) after 2 months. The WB group increased the trunk flexor strength and endurance by 12% and 29%, respectively (p less than or equal to 0.001). No significant decrease of trunk muscle strength and endurance was found at the end of the follow-up period.

Low back pain--correspondence between questionnaire, interview and clinical examination.

The aim of this study was to analyse the correspondence between answers to a questionnaire about trouble from the musculoskeletal system, answers in a personal interview and clinical findings indicating low back disorder. The questionnaire was answered by 1,773 construction workers. Out of those, 206 workers underwent interview and clinical examination. Among those who reported no lifetime LBT in the questionnaire 63% gave the same report in the personal interview and those were all assessed negative at a blind clinical examination. Of those reporting current LBT in the interview 80% (47/59) were clinically positive. The clinical criteria used in the examination seemed to indicate lumbar painful structures. Answers to a question about functional impairment were in conformity with clinical findings. As regards answers to a question about frequency of pain and a question, in the specific Nordic questionnaire for the low back, concerning inability to do normal work the correlation to clinical findings was less apparent. Reported inability to do normal work in the questionnaire corresponded only to 43% with reported sick-leave in the interview.