Exchange-correlation potentials for inhomogeneous electron systems in two dimensions from exact diagonalization: comparison with the local-spin-density approximation

We consider electronic exchange and correlation effects in density-functional calculations of two-dimensional systems. Starting from wave function calculations of total energies and electron densities of inhomogeneous model systems, we derive corresponding exchange-correlation potentials and energies. We compare these with predictions of the local-spin-density approximation and discuss its accuracy. Our data will be useful as reference data in testing, comparing and parametrizing exchange and correlation functionals for two-dimensional electronic systems.Comment: Submitted to Physical Review B on January 3, 2012. Second revised version submitted on April 13, 201

Development of office-hours use of primary health centers in the early years of the 21st century : a 13-year longitudinal follow-up study

This study, conducted in a Finnish city, examined whether a long-lasting observed trend in Finnish primary health care, namely, a decreasing rate of office-hour visits to general practitioners (GPs), would lead to reduced services for specific gender, diagnosis or age groups. This was an observational retrospective follow-up study. The annual number of visits to office-hour primary care GPs in different gender, diagnosis and age groups was recorded during a 13-year follow-up period. The effect of the decreasing visit rate on the annual mortality rate in different age and gender groups was also studied. The total number of monthly visits to office-hour GPs decreased slowly over the whole study period. This decrease was stronger in women and older people. The proportion of recorded infectious diseases (Groups A and J and especially diagnoses related to infections of respiratory airways) decreased. Proportions of recorded chronic diseases increased (Group I, cardiovascular diseases, diabetes and osteoarthrosis) during the follow-up. The annual rate of visits to office-hour GP/per GP decreased. There was a decrease in the mortality in two of the age groups (20-64, 65+ years) and no change in the youngest population (0-19 years). The decrease in the office-hours GP activity does not seem to increase mortality either.Peer reviewe

Development of the use of primary health care emergency departments after interventions aimed at decreasing overcrowding : a longitudinal follow-up study

Background This study, conducted in a Finnish city, examined whether decreasing emergency department (ED) services in an overcrowded primary care ED and corresponding direction to office-hours primary care would modify service usage for specific gender, age or diagnosis groups. Methods This was an observational retrospective study carried out by gradually decreasing ED services in primary care. The interventions aimed at decreasing use of EDs were a) application of ABCDE-triage combined with public guidance on the proper use of EDs, b) closure of a minor supplementary ED, and finally, c) application of "reverse triage" with enhanced direction of the public to office-hours services and away from the remaining ED The annual number of visits to office-hours primary care GPs in different gender, age and diagnosis groups (International Classification of Diseases (ICD - 10) were recorded during a 13-year follow-up period. Results The total number of monthly visits to EDs decreased slowly over the whole study period. This decrease was similar in women and men. The decrease was stronger in the youngest age groups (0-19 years). GPs treated decreasing proportions of ICD-10 groups. Recorded infectious diseases (Groups A and J, and especially diagnoses related to infections of respiratory airways) tended to decrease. However, visits due to injuries and symptomatic diagnoses increased. Conclusion Decreasing services in a primary health care ED with the described interventions seemed to reduce the use of services by young people. The three interventions mentioned above had the effect of making the primary care ED under study appear to function more like a standard ED driven by specialized health care.Peer reviewe

Critical points in low-energy positron-atom scattering

Critical points, which represent minima in differential scattering cross sections as a function of scattering angle and incident projectile energy, are theoretically predicted for elastic scattering of low-energy positrons by Ar, Kr, and Xe. It is demonstrated that these points arise due to low-energy positron diffraction effects

The effect of electronic reminders on the recording of diagnoses in primary care : A quasi-experimental before and after study

Objectives: This study examined whether using electronic reminders leads to an increase in the rate of diagnosis recordings in the electronic health record system following visits to a general practitioner. The impact of electronic reminders was studied in the primary health care of a Finnish city. Methods: This observational quasi-experimental study based on a before-and-after design was carried out by installing an electronic reminder to improve the recording of diagnoses in the computerized electronic health record system. The quantity of the recorded diagnoses was observed before and after the intervention. The effect of this intervention on the distribution of different diagnoses was also studied. Results: Before intervention, 33%-46% of visits (to general practitioners/month) had recorded diagnose in the primary health care units. After 4 years, the recording rate had risen to 87%-95% (p <0.001). The rate of change in the recording of diagnoses was highest during the first year of intervention and plateaued about 3.5 years after application reminders. In the present study, most of the visits concerned mild respiratory infections, elevated blood pressure, low back pain and type 2 diabetes. Conclusion: An electronic reminder is likely to improve the recording of diagnoses during the visits to general practitioners. The distribution of diagnoses was in line with former reports concerning diagnoses in Finnish primary care.Peer reviewe

Recording of diagnoses in public primary oral health care in a retrospective longitudinal observational study in a Finnish town: Underrepresentation of periodontitis diagnoses

Abstract Objectives This study investigates which oral diagnoses public primary dental care dentists record. Methods An observational register-based retrospective follow-up study was performed in the public primary oral health care of a Finnish town after the dentists were advised to mark the diagnoses in their practices. The rate of recorded diagnoses resulting from visits to the public primary care dentists was studied. The assessed diagnoses were recorded with the 10th revision of the International Classification of Diseases. The distribution of diagnoses was recorded during a 2-year follow-up period. Results The most frequent diagnosis groups were dental caries (K02, 38.6%), other diseases of dental hard tissues (K03, 14.9%), diseases of pulp and periapical tissues (K04, 11.4%), periodontal diseases (K05, 9.7%), and different types of bone fractures (S02, 8.1%). Periodontitis was underrepresented. Conclusions In public primary oral health care, there may be difficulties in adequate recording of certain chronic diseases.Peer reviewe

Applicability of Modified Effective-Range Theory to positron-atom and positron-molecule scattering

We analyze low-energy scattering of positrons on Ar atoms and N2 molecules using Modified Effective-Range Theory (MERT) developped by O'Malley, Spruch and Rosenberg [Journal of Math. Phys. 2, 491 (1961)]. We use formulation of MERT based on exact solutions of Schroedinger equation with polarization potential rather than low-energy expansions of phase shifts into momentum series. We show that MERT describes well experimental data, provided that effective-range expansion is performed both for s- and p-wave scattering, which dominate in the considered regime of positron energies (0.4 - 2 eV). We estimate the values of the s-wave scattering lenght and the effective range for e+ - Ar and e+ - N2 collisions.Comment: RevTeX, 4 pages, 2 figure

Scattering of positrons and electrons by alkali atoms

Absolute total scattering cross sections (Q sub T's) were measured for positrons and electrons colliding with sodium, potassium, and rubidium in the 1 to 102 eV range, using the same apparatus and experimental approach (a beam transmission technique) for both projectiles. The present results for positron-sodium and -rubidium collisions represent the first Q sub T measurements reported for these collision systems. Features which distinguish the present comparisons between positron- and electron-alkali atom Q sub T's from those for other atoms and molecules (room-temperature gases) which have been used as targets for positrons and electrons are the proximity of the corresponding positron- and electron-alkali atom Q sub T's over the entire energy range of overlap, with an indication of a merging or near-merging of the corresponding positron and electron Q sub T's near (and above) the relatively low energy of about 40 eV, and a general tendency for the positron-alkali atom Q sub T's to be higher than the corresponding electron values as the projectile energy is decreased below about 40 eV

Palaeoecological evidence of changes in vegetation and climate during the Holocene in the pre-Polar Urals, northeast European Russia

This study investigated Holocene tree-line history and climatic change in the pre-Polar Urals, northeast European Russia. A sediment core from Mezhgornoe Lake situated at the present-day alpine tree-line was studied for pollen, plant macrofossils, Cladocera and diatoms. A peat section from Vangyr Mire in the nearby mixed mountain taiga zone was analysed for pollen. The results suggest that the study area experienced a climatic optimum in the early Holocene and that summer temperatures were at least 2°C warmer than today. Tree birch immigrated to the Mezhgornoe Lake area at the onset of the Holocene. Mixed spruce forests followed at ca. 9500-9000 14C yr BP. Climate was moist and the water level of Mezhgornoe Lake rose rapidly. The hypsithermal phase lasted until ca. 5500-4500 14C yr BP, after which the mixed forest withdrew from the Mezhgornoe catchment as a result of the climate cooling. The gradual altitudinal downward shift of vegetation zones resulted in the present situation, with larch forming the tree-line

Trapping hot quasi-particles in a high-power superconducting electronic cooler

The performance of hybrid superconducting electronic coolers is usually limited by the accumulation of hot quasi-particles in their superconducting leads. This issue is all the more stringent in large-scale and high-power devices, as required by the applications. Introducing a metallic drain connected to the superconducting electrodes via a fine-tuned tunnel barrier, we efficiently remove quasi-particles and obtain electronic cooling from 300 mK down to 130 mK with a 400 pW cooling power. A simple thermal model accounts for the experimental observations.Peer reviewe