Results of Russian geomagnetic observatories in the 19th century: magnetic activity, 1841–1862

Hourly (spot readings) magnetic data (H- and D-components) were digitized from Russian yearbook tables for the years 1850–1862 from four observatories. The pdf pictures for digitization were taken by a normal digital camera. The database obtained consists of about 900 000 single data points. The time series of hourly magnetic values reveal slow secular variations (declination only) as well as transient and regular geomagnetic variations of external origin. The quality and homogeneity of the data is satisfactory. Daily Ak-indices were calculated using the index algorithm that has been earlier applied to 19th century data from Helsinki (Finland) as well as modern magnetic observatory recordings. The activity index series derived from the Russian data is consistent with earlier activity index series for 1850–1862. The digitized index data series derived in this study was extended back to 1841 by including magnetic <I>C</I>9 activity index data available from a Russian observatory (St. Petersburg). Magnetic data rescued here is well suitable for various reconstructions for studies of the long-term variation of the space weather in the 19th century

Supported magnetic nanoclusters: Softlanding of Pd clusters on a MgO surface

Low-energy deposition of neutral Pd_N clusters (N=2-7 and 13) on a MgO(001) surface F-center (FC) was studied by spin-density-functional molecular dynamics simulations. The incident clusters are steered by an attractive "funnel" created by the FC, resulting in adsorption of the cluster, with one of its atoms bonded atop of the FC. The deposited Pd_2-Pd_6 clusters retain their gas-phase structures, while for N>6 surface-commensurate isomers are energetically more favorable. Adsorbed clusters with N > 3 are found to remain magnetic at the surface.Comment: 5 pages, 2 figs, Phys.Rev.Lett., accepte

Electronic structure and dimerization of a single monatomic gold wire

The electronic structure of a single monatomic gold wire is presented for the first time. It has been obtained with state-of-the-art ab-initio full-potential density-functional (DFT) LMTO (linearized muffin-tin orbital) calculations taking into account relativistic effects. For stretched structures in the experimentally accessible range the conduction band is exactly half-filled, whereas the band structures are more complex for the optimized structure. By studying the total energy as a function of unit-cell length and of a possible bond-length alternation we find that the system can lower its total energy by letting the bond lengths alternate leading to a structure containing separated dimers with bond lengths of about 2.5 \AA, largely independent of the stretching. However, first for fairly large unit cells (above roughly 7 \AA), is the total-energy gain upon this dimerization comparable with the energy costs upon stretching. We propose that this together with band-structure effects is the reason for the larger interatomic distances observed in recent experiments. We find also that although spin-orbit couplings lead to significant effects on the band structure, the overall conclusions are not altered, and that finite Au_2, Au_4, and Au_6 chains possess electronic properties very similar to those of the infinite chain.Comment: (14 pages, 5 figures; Elsevier Preprint style elsart.sty

Energy relaxation in graphene and its measurement with supercurrent

We study inelastic energy relaxation in graphene for low energies to find out how electrons scatter with acoustic phonons and other electrons. By coupling the graphene to superconductors, we create a strong dependence of the measured signal, i.e.,\ critical Josephson current, on the electron population on different energy states. Since the relative population of high- and low-energy states is determined by the inelastic scattering processes, the critical current becomes an effective probe for their strength. We argue that the electron-electron interaction is the dominant relaxation method and, in our model of two-dimensional electron-electron scattering, we find a scattering time $\tau_{e-e}=5... 13$ ps at T=500 mK, 1-2 orders of magnitude smaller than predicted by theory.Comment: 10 pages, 13 figures submitted to Physical Review

Multi-shell gold nanowires under compression

Deformation properties of multi-wall gold nanowires under compressive loading are studied. Nanowires are simulated using a realistic many-body potential. Simulations start from cylindrical fcc(111) structures at T=0 K. After annealing cycles axial compression is applied on multi-shell nanowires for a number of radii and lengths at T=300 K. Several types of deformation are found, such as large buckling distortions and progressive crushing. Compressed nanowires are found to recover their initial lengths and radii even after severe structural deformations. However, in contrast to carbon nanotubes irreversible local atomic rearrangements occur even under small compressions.Comment: 1 gif figure, 5 ps figure

Structure and Magnetism of Neutral and Anionic Palladium Clusters

The properties of neutral and anionic Pd_N clusters were investigated with spin-density-functional calculations. The ground state structures are three-dimensional for N>3 and they are magnetic with a spin-triplet for 2<=N<=7 and a spin nonet for N=13 neutral clusters. Structural- and spin-isomers were determined and an anomalous increase of the magnetic moment with temperature is predicted for a Pd_7 ensemble. Vertical electron detachment and ionization energies were calculated and the former agree well with measured values for anionic Pd_N clusters.Comment: 5 pages, 3 figures, fig. 2 in color, accepted to Phys. Rev. Lett. (2001

Tules-kurssien standardien kehittäminen : Suositukset standardiin

Tutkimuksen tavoitteena oli tuottaa tietoa Kelan Tules-kurssien standardien kehittämistä varten. Kelan kuntoutusryhmän aloitteesta toteutettu tutkimus tukee standardien kehittämistä sekä tutkimusnäytön perusteella, että kuulemalla palveluntuottajia ja palveluja käyttäneitä asiakkaita. Standardien kehittämisen tarkoituksena on, että Kelan järjestämät kuntoutuspalvelut voisivat olla entistä vaikuttavampia. Tutkimus koostui viidestä osatutkimuksesta (kirjallisuuskatsaus, kuntoutujien fokusryhmät, palveluntuottajien haastattelut, GAS-tavoitteiden analyysi ja hyvät kuntoutuskäytännöt -kysely). Osatutkimuksista kootun ja analysoidun tutkimustiedon perusteella koottiin suosituksia sisällöistä, joita standardien kehittämisessä voisi huomioida. Suositukset esiteltiin palveluntuottajien edustajille Kelan kuntoutusryhmän järjestämässä työkokouksessa. Yhdeksässä tutkimustietoon pohjautuvassa suosituksessa kiinnitetään huomiota seuraaviin, nykyisessä standardissakin esiintyvien teemojen sisältöihin: tavoitteen asettelu, mittausten määrä, aloitusjakson rakenne ja resurssit, ryhmät, sisällöt, välityöskentely, työelämäyhteys, asiakkaan osallistaminen ja kuntoutuksen seuranta. Osatutkimuksissa tuotettua tietoa voidaan soveltaa hyvinä kuntoutuskäytäntöinä päivittäisessä työssä kuntoutujien kanssa. Kelan kuntoutusryhmän vastuulla on arvioida, millä tavalla tutkimuksessa esille tuodut suositukset voidaan huomioida, muiden standardin laatimiseen vaikuttavien tekijöiden ohella, tulevissa Tules-kurssien standardeissa. Tutkimus on ensimmäinen Kelan vakiintuneen toiminnan standardien kehittämisen tueksi toteutettu tutkimus. Tutkimuksellisesti eri lähestymistavoilla kerätty tieto on täydentänyt toisiaan ja osoittanut, että standardien kehittämisen tueksi nostetut suositukset saavat vahvistusta useamman näkökulman kautta. Tutkimuksessa käytettyä toimintamallia voi soveltaa muidenkin Kelan vakiintuneen toiminnan standardien kehittämiseen

Structure of aluminum atomic chains

First-principles density functional calculations reveal that aluminum can form planar chains in zigzag and ladder structures. The most stable one has equilateral triangular geometry with four nearest neighbors; the other stable zigzag structure has wide bond angle and allows for two nearest neighbors. An intermediary structure has the ladder geometry and is formed by two strands. All these planar geometries are, however, more favored energetically than the linear chain. We found that by going from bulk to a chain the character of bonding changes and acquires directionality. The conductance of zigzag and linear chains is 4e^2/h under ideal ballistic conditions.Comment: modified detailed version, one new structure added, 4 figures, modified figure1, 1 tabl

RNA sequencing-based single sample predictors of molecular subtype and risk of recurrence for clinical assessment of early-stage breast cancer

BackgroundMultigene expression assays for molecular subtypes and biomarkers can aid clinical management of early invasive breast cancer. Based on RNA-sequencing we aimed to develop single-sample predictor (SSP) models for conventional clinical markers, molecular intrinsic subtype and risk of recurrence (ROR).MethodsA uniformly accrued breast cancer cohort of 7743 patients with RNA-sequencing data from fresh tissue was divided into a training set and a reserved test set. We trained SSPs for PAM50 molecular subtypes and ROR assigned by nearest-centroid (NC) and SSPs for conventional clinical markers from histopathology data. Additionally, SSP classifications were compared with Prosigna® in two external cohorts. Prognostic value was assessed using distant recurrence-free interval.ResultsIn the test set, agreement between SSP and NC classifications for PAM50 (five subtypes) and Subtype (four subtypes) was high (85%, Kappa=0.78) and very high (90%, Kappa=0.84) respectively. Accuracy for ROR risk category was high (84%, Kappa=0.75, weighted Kappa=0.90). The prognostic value for SSP and NC was assessed as equivalent. Agreement for SSP and histopathology was very high or high for receptor status, while moderate and poor for Ki67 status and Nottingham histological grade, respectively. SSP concordance with Prosigna® was high for subtype and moderate and high for ROR risk category. In pooled analysis, concordance between SSP and Prosigna® for emulated treatment recommendation for chemotherapy (yes vs. no) was high (85%, Kappa=0.66). In postmenopausal ER+/HER2-/N0 patients SSP application suggested changed treatment recommendations for up to 17% of patients, with nearly balanced escalation and de-escalation of chemotherapy.ConclusionsSSP models for histopathological variables, PAM50, and ROR classifications can be derived from RNA-sequencing that closely matches clinical tests. Agreement and outcome analyses suggest that NC and SSP models are interchangeable on a group-level and nearly so on a patient level. Retrospective evaluation in postmenopausal ER+/HER2-/N0 patients suggested that molecular testing could lead to a changed therapy recommendation for almost one-fifth of patients

Common Origin for Surface Reconstruction and the Formation of Chains of Metal Atoms

During the fracture of nanocontacts gold spontaneously forms freely suspended chains of atoms, which is not observed for the iso-electronic noble metals Ag and Cu. Au also differs from Ag and Cu in forming reconstructions at its low-index surfaces. Using mechanically controllable break junctions we show that all the 5d metals that show similar reconstructions (Ir, Pt and Au) also form chains of atoms, while both properties are absent in the 4d neighbor elements (Rh, Pd, Ag), indicating a common origin for these two phenomena. A competition between s and d bonding is proposed as an explanation