Structure determination of the clean Co(110) surface by LEED

The atomic structure of the (11 0) surface of cobalt has been determined by LEED using six intensity spectra at normal incidence. The surface exhibits the truncated bulk structure with a contraction of the first interlayer spacing by about 8.5% with respect to the bulk value. Quantitative evaluation of the LEED spectra was done using Zanazzi and Jona's and Pendry's r-factors. The minimum averaged r-factors are and . No change of the interatomic distances within the plane could be detected and no rearrangement of the surface structure takes place up to temperatures shortly below the transition temperature

Two-photon interference with true thermal light

Two-photon interference and "ghost" imaging with entangled light have attracted much attention since the last century because of the novel features such as non-locality and sub-wavelength effect. Recently, it has been found that pseudo-thermal light can mimic certain effects of entangled light. We report here the first observation of two-photon interference with true thermal light.Comment: 4 pages, 5 figures, PRA72, 043805 (2005

Longitudinal excitations in quantum antiferromagnets

By extending our recently proposed magnon-density-waves to low dimensions, we investigate, using a microscopic many-body approach, the longitudinal excitations of the quasi-one-dimensional (quasi-1d) and quasi-2d Heisenberg antiferromagnetic systems on a bipartite lattice with a general spin quantum number. We obtain the full energy spectrum of the longitudinal mode as a function of the coupling constants in the original lattice Hamiltonian and find that it always has a non-zero energy gap if the ground state has a long-range order and becomes gapless for the pure isotropic 1d model. The numerical value of the minimum gap in our approximation agrees with that of a longitudinal mode observed in the quasi-1d antiferromagnetic compound KCuF${}_3$ at low temperature. It will be interesting to compare values of the energy spectrum at other momenta if their experimental results are available.Comment: 19 pages, 4 figure

Lab meets real life : a laboratory assessment of spontaneous thought and its ecological validity

People's minds frequently wander towards self-generated thoughts, which are unrelated to external stimuli or demands. These phenomena, referred to as "spontaneous thought" (ST) and "mind wandering" (MW), have previously been linked with both costs and benefits. Current assessments of ST and MW have predominantly been conducted in the laboratory, whereas studies on the ecological validity of such lab-related constructs and their interrelations are rare. The current study examined the stability of ST dimensions assessed in the lab and their predictive value with respect to MW, repetitive negative thought (uncontrollable rumination, RUM), and affect in daily life. Forty-three university students were assessed with the Amsterdam Resting State Questionnaire (2nd version) to assess ten ST dimensions during the resting state in two laboratory sessions, which were separated by five days of electronic ambulatory assessment (AA). During AA, individuals indicated the intensity of MW and RUM, as well as of positive and negative affect in daily life ten times a day. ST dimensions measured in the lab were moderately stable across one week. Five out of ten ST lab dimensions were predicted by mental health-related symptoms or by dispositional cognitive traits. Hierarchical linear models revealed that a number of ST lab dimensions predicted cognitive and affective states in daily life. Mediation analyses showed that RUM, but not MW per se, accounted for the relationship between specific ST lab dimensions and mood in daily life. By using a simple resting state task, we could demonstrate that a number of lab dimensions of spontaneous thought are moderately stable, are predicted by mental health symptoms and cognitive traits, and show plausible associations with categories of self-generated thought and mood in daily life

Description of an ancient social bee trapped in amber using diagnostic radioentomology

The application of non-invasive imaging technologies using X-radiation (diagnostic radioentomology, ‘DR’) is demonstrated for the study of amber-entombed social bees. Here, we examine the external and internal morphology of an Early Miocene (Burdigalian) stingless bee (Apinae: Meliponini) from the Dominican Republic using non-destructive X-ray microtomography analysis. The study permits the accurate reconstruction of features otherwise obscured or impossible to visualize without destroying the sample and allows diagnosis of the specimen as a new species, Proplebeia adbita Greco and Engel

A LEED structural analysis of the Co(100) surface

The structure of the clean Co(1010) surface has been analysed by LEED. Application of a recently developed computational scheme reveals the prevalence of the termination A in which the two topmost layers exhibit a narrow spacing of 0.62 Å, corresponding to a 12.8(±0.5)% contraction with respect to the bulk value, while the spacing between the second and third layer is slightly expanded by 0.8(±0.2)%

Die Rangfolge psychischer und sozialer Prädiktoren und Kriterien für die Prognose Herztransplantierter

Bei 44 Herztransplantierten wurden präoperativ und bis zu einem und drei Jahre postoperativ psychiatrisch/psychologische Untersuchungen durchgeführt und psychosoziale Daten erhoben. Die Prädiktoren und Kriterien für eine gute Prognose wurden ihrer Rangfolge nach hierarchisiert. Es ergab sich folgende Prädiktorrangfolge: 1. die eindeutige Motivation und der unauffällige psychopathologische Befund, 2. der gute soziale Rückhalt und die vor der Transplantation zum Ausdruck gebrachte positive Berufsperspektive, 3. das Bewußtsein der Geborgenheit durch die Familie und die reife psychologische Verarbeitung der Herzerkrankung und der bevorstehenden Herztransplantation, 4. der fortgeschrittene Schweregrad der Herzerkrankung (Schweregrad IV NYHA), 5. der relativ geringe Fernsehkonsum (weniger als an 4 Abenden), und 6. u. a. noch lebende Eltern und das Vorhandensein von Kindern. Für die 7 prognostischen Kriterien ließ sich folgendeKriterienrangfolge ermitteln: 1. die soziale Reintegration, 2. die Lebenszufriedenheit, 3. die Compliance und der psychopathologische Befund, 4. die berufliche Rehabilitation, und 5. die körperliche Belastbarkeit und der körperliche Zustand. Die Studie zeigt, daß es eine unterschiedliche Gewichtung psychosozialer Faktoren vor und nach der Herztransplantation gibt, und daß die soziale Reintegration der beste Indikator für eine erfolgreiche Herztransplantation ist.44 patients underwent psychiatric/psychological and psychosocial examinations before and for one to three years after heart transplantation. Predictors and prognostic criteria for a good result were established according to the rank of their significance. The rank sequence for the predictors were 1. strong motivation and absence of psychiatric symptomatology, 2. good social support and determination to return to work after transplantation, 3. the feeling of being cared for by the family and a mature psychological coping with the heart disease and the expected transplantation, 4. advanced heart failure (stage IV NYHA), 5. watching TV less than 4 evenings a week, 6. parents still living and having one’s own children. The rank sequence for the 7 prognostic criteria for a good result after heart transplantation were 1. social reintegration, 2. being content with life. 3. good compliance and absence of psychopathology, 4. returning to work, and 5. physical exercise tolerance and general physical condition. The study shows that there is a different magnitude of significance for psychosocial factors before and after heart transplantation and that social reintegration is the best indicator for a good result after heart transplantation

Quasi-1D spin-1/2 Heisenberg magnets in their ordered phase: correlation functions

We study weakly coupled antiferromagnetic spin chains in their ordered phase by combinining an exact solution of the single-chain problem with an RPA analysis of the interchain interaction. A single chain is described by a quantum Sine-Gordon model and dynamical staggered susceptibilities are determined by employing the formfactor approach to quantum correlation functions. We consider both antiferromagnetic order encountered in quasi-1D materials like $KCuF_3$ and spin-Peierls order as found in $CuGeO_3$.Comment: 16 pages of revtex, 12 figure

Uptake of home-based voluntary HIV testing in sub-Saharan Africa: a systematic review and meta-analysis

Improving access to HIV testing is a key priority in scaling up HIV treatment and prevention services. Home-based voluntary counselling and testing (HBT) as an approach to delivering wide-scale HIV testing is explored here