Anomalous magnetic ordering in PrBa_2Cu_3O_{7-y} single crystals: Evidence for magnetic coupling between the Cu and Pr sublattices

In Al-free PrBa_2Cu_3O_{7-y} single crystals the kink in the temperature dependence of magnetic susceptibility chi_{ab}(T), connected with Pr antiferromagnetic ordering, disappears after field cooling (FC) in a field H || ab-plane. The kink in chi_c(T) remains unchanged after FC in H || c-axis. As a possible explanation, freezing of the Cu magnetic moments, lying in the ab-plane, caused by FC in H || ab, hinders their reorientation and, due to coupling between the Pr and Cu(2) sublattices, ordering of the Pr^{3+} moments. A field induced phase transition and a field dependence of the Pr^{3+} ordering temperature have been found for both H || c and H || ab.Comment: 11 pages (LaTex with elsart.sty), 5 EPS figs. Accepted to Physica

Large halloween asteroid at lunar distance

The near-Earth asteroid (NEA) 2015 TB had a very close encounter with Earth at 1.3 lunar distances on October 31, 2015. We obtained 3-band mid-infrared observations of this asteroid with the ESO VLT-VISIR instrument covering approximately four hours in total. We also monitored the visual lightcurve during the close-encounter phase. The NEA has a (most likely) rotation period of 2.939 ± 0.005 h and the visual lightcurve shows a peak-to-peak amplitude of approximately 0.12 ± 0.02 mag. A second rotation period of 4.779 ± 0.012 h, with an amplitude of the Fourier fit of 0.10 ± 0.02 mag, also seems compatible with the available lightcurve measurements. We estimate a V-R colour of 0.56 ± 0.05 mag from different entries in the MPC database. A reliable determination of the object's absolute magnitude was not possible. Applying different phase relations to the available R-/V-band observations produced H = 18.6 mag (standard H-G calculations) or H = 19.2 mag and H = 19.8 mag (via the H-G procedure for sparse and low-quality data), with large uncertainties of approximately 1 mag. We performed a detailed thermophysical model analysis by using spherical and partially also ellipsoidal shape models. The thermal properties are best explained by an equator-on (± 30°) viewing geometry during our measurements with a thermal inertia in the range 250-700 J m s K (retrograde rotation) or above 500 J m s K (prograde rotation). We find that the NEA has a minimum size of approximately 625 m, a maximum size of just below 700 m, and a slightly elongated shape with a/b 1.1. The best match to all thermal measurements is found for: (i) thermal inertia Γ = 900 J m s K; D = 644 m, p = 5.5% (prograde rotation with 2.939 h); regolith grain sizes of 50-100 mm; (ii) thermal inertia Γ = 400 J m s K; D = 667 m, p = 5.1% (retrograde rotation with 2.939 h); regolith grain sizes of 10-20 mm. A near-Earth asteroid model (NEATM) confirms an object size well above 600 m (best NEATM solution at 690 m, beaming parameter η = 1.95), significantly larger than early estimates based on radar measurements. In general, a high-quality physical and thermal characterisation of a close-encounter object from two-week apparition data is not easily possible. We give recommendations for improved observing strategies for similar events in the future. © ESO, 2017.The research leading to these results has received funding from the European Union's Horizon 2020 Research and Innovation Programme, under Grant Agreement No. 687378. Funding from Spanish grant AYA-2014-56637-C2-1-P is acknowledged. Hungarian funding from the NKFIH grant GINOP-2.3.2-15-2016-00003 is also acknowledged. R.D. acknowledges the support of MINECO for his Ramon y Cajal Contract.Peer Reviewe

Thermal Infrared Imaging Experiments of C-Type Asteroid 162173 Ryugu on Hayabusa2

The thermal infrared imager TIR onboard Hayabusa2 has been developed to investigate thermo-physical properties of C-type, near-Earth asteroid 162173 Ryugu. TIR is one of the remote science instruments on Hayabusa2 designed to understand the nature of a volatile-rich solar system small body, but it also has significant mission objectives to provide information on surface physical properties and conditions for sampling site selection as well as the assessment of safe landing operations. TIR is based on a two-dimensional uncooled micro-bolometer array inherited from the Longwave Infrared Camera LIR on Akatsuki (Fukuhara et al., 2011). TIR takes images of thermal infrared emission in 8 to 12 μm with a field of view of 16×12∘ and a spatial resolution of 0.05∘ per pixel. TIR covers the temperature range from 150 to 460 K, including the well calibrated range from 230 to 420 K. Temperature accuracy is within 2 K or better for summed images, and the relative accuracy or noise equivalent temperature difference (NETD) at each of pixels is 0.4 K or lower for the well-calibrated temperature range. TIR takes a couple of images with shutter open and closed, the corresponding dark frame, and provides a true thermal image by dark frame subtraction. Data processing involves summation of multiple images, image processing including the StarPixel compression (Hihara et al., 2014), and transfer to the data recorder in the spacecraft digital electronics (DE). We report the scientific and mission objectives of TIR, the requirements and constraints for the instrument specifications, the designed instrumentation and the pre-flight and in-flight performances of TIR, as well as its observation plan during the Hayabusa2 mission

4pi Models of CMEs and ICMEs

Coronal mass ejections (CMEs), which dynamically connect the solar surface to the far reaches of interplanetary space, represent a major anifestation of solar activity. They are not only of principal interest but also play a pivotal role in the context of space weather predictions. The steady improvement of both numerical methods and computational resources during recent years has allowed for the creation of increasingly realistic models of interplanetary CMEs (ICMEs), which can now be compared to high-quality observational data from various space-bound missions. This review discusses existing models of CMEs, characterizing them by scientific aim and scope, CME initiation method, and physical effects included, thereby stressing the importance of fully 3-D ('4pi') spatial coverage.Comment: 14 pages plus references. Comments welcome. Accepted for publication in Solar Physics (SUN-360 topical issue

On practical problems to compute the ghost propagator in SU(2) lattice gauge theory

In SU(2) lattice pure gauge theory we study numerically the dependence of the ghost propagator G(p) on the choice of Gribov copies in Lorentz (or Landau) gauge. We find that the effect of Gribov copies is essential in the scaling window region, however, it tends to decrease with increasing beta. On the other hand, we find that at larger beta-values very strong fluctuations appear which can make problematic the calculation of the ghost propagator.Comment: 15 pages, 5 postscript figures. 2 Figures added Revised version as to be published in Phys.Rev.

Monopole characteristics in various Abelian gauges

Renormalization group (RG) smoothing is employed on the lattice to investigate and to compare the monopole structure of the SU(2) vacuum as seen in different gauges (maximally Abelian (MAG), Polyakov loop (PG) and Laplacian gauge (LG)). Physically relevant types of monopoles (LG and MAG) are distinguished by their behavior near the deconfining phase transition. For the LG, Abelian projection reproduces well the gauge independent monopole structure encoded in an auxiliary Higgs field. Density and localization properties of monopoles, their non-Abelian action and topological charge are studied. Results are presented confirming the Abelian dominance with respect to the non-perturbative static potential for all gauges considered.Comment: 36 pages, 12 figure

Photocaged Hoechst enables subnuclear visualization and cell selective staining of DNA in vivo

Selective targeting of DNA by means of fluorescent labelling has become a mainstay in the life sciences. While genetic engineering serves as a powerful technique and allows for the visualization of nucleic acid by using DNA-targeting fluorescent fusion proteins in a cell-type and subcellular specific manner, it relies on the introduction of foreign genes. On the other hand, DNA-binding small fluorescent molecules can be used without genetic engineering but they are not spatially restricted. Here, we report a photocaged version of the DNA dye Hoechst33342 (pcHoechst), which can be uncaged using UV to blue light for the selective staining of chromosomal DNA in subnuclear regions of live cells. Expanding its application to a vertebrate model organism, we demonstrate uncaging in epithelial cells and short-term cell tracking  in vivo  in zebrafish. We envision pcHoechst as a valuable tool for targeting and interrogating DNA with precise spatiotemporal resolution in living cells and wild-type organisms

Colossal dielectric constants in transition-metal oxides

Many transition-metal oxides show very large ("colossal") magnitudes of the dielectric constant and thus have immense potential for applications in modern microelectronics and for the development of new capacitance-based energy-storage devices. In the present work, we thoroughly discuss the mechanisms that can lead to colossal values of the dielectric constant, especially emphasising effects generated by external and internal interfaces, including electronic phase separation. In addition, we provide a detailed overview and discussion of the dielectric properties of CaCu3Ti4O12 and related systems, which is today's most investigated material with colossal dielectric constant. Also a variety of further transition-metal oxides with large dielectric constants are treated in detail, among them the system La2-xSrxNiO4 where electronic phase separation may play a role in the generation of a colossal dielectric constant.Comment: 31 pages, 18 figures, submitted to Eur. Phys. J. for publication in the Special Topics volume "Cooperative Phenomena in Solids: Metal-Insulator Transitions and Ordering of Microscopic Degrees of Freedom

Shared Genetic Etiology Between Alcohol Dependence and Major Depressive Disorder

The clinical comorbidity of alcohol dependence (AD) and major depressive disorder (MDD) is well established, whereas genetic factors influencing co-occurrence remain unclear. A recent study using polygenic risk scores (PRS) calculated based on the first-wave Psychiatric Genomics Consortium MDD meta-analysis (PGC-MDD1) suggests a modest shared genetic contribution to MDD and AD. Using a (∼10 fold) larger discovery sample, we calculated PRS based on the second wave (PGC-MDD2) of results, in a severe AD case–control target sample. We found significant associations between AD disease status and MDD-PRS derived from both PGC-MDD2 (most informative P-threshold=1.0, P=0.00063, R2=0.533%) and PGCMDD1 (P-threshold=0.2, P=0.00014, R2=0.663%) metaanalyses; the larger discovery sample did not yield additional predictive power. In contrast, calculating PRS in a MDD target sample yielded increased power when using PGC-MDD2 (P-threshold=1.0, P=0.000038, R2=1.34%) versus PGC-MDD1 (P-threshold=1.0, P=0.0013, R2=0.81%). Furthermore, when calculating PGC-MDD2 PRS in a subsample of patients with AD recruited explicitly excluding comorbid MDD, significant associations were still found (n=331; P-threshold=1.0, P=0.042, R2=0.398%). Meanwhile, in the subset of patients in which MDD was not the explicit exclusion criteria, PRS predicted more variance (n=999; P-threshold=1.0, P=0.0003, R2=0.693%). Our findings replicate the reported genetic overlap between AD and MDD and also suggest the need for improved, rigorous phenotyping to identify true shared cross-disorder genetic factors. Larger target samples are needed to reduce noise and take advantage of increasing discovery sample size

TNOs are cool: a survey of the transneptunian region

Over one thousand objects have so far been discovered orbiting beyond Neptune. These trans-Neptunian objects (TNOs) represent the primitive remnants of the planetesimal disk from which the planets formed and are perhaps analogous to the unseen dust parent-bodies in debris disks observed around other main-sequence stars. The dynamical and physical properties of these bodies provide unique and important constraints on formation and evolution models of the Solar System. While the dynamical architecture in this region (also known as the Kuiper Belt) is becoming relatively clear, the physical properties of the objects are still largely unexplored. In particular, fundamental parameters such as size, albedo, density and thermal properties are difficult to measure. Measurements of thermal emission, which peaks at far-IR wavelengths, offer the best means available to determine the physical properties. While Spitzer has provided some results, notably revealing a large albedo diversity in this population, the increased sensitivity of Herschel and its superior wavelength coverage should permit profound advances in the field. Within our accepted project we propose to perform radiometric measurements of 139 objects, including 25 known multiple systems. When combined with measurements of the dust population beyond Neptune (e.g. from the New Horizons mission to Pluto), our results will provide a benchmark for understanding the Solar debris disk, and extra-solar ones as well