Anisotropic strains, metal-insulator transition, and magnetoresistance of La0.7_{0.7}Ca0.3_{0.3}MnO3_{3} films

Thin films of perovskite manganite La$_{0.7}$Ca$_{0.3}$MnO$_{3}$ were grown epitaxially on various substrates by either the pulsed laser deposition method or laser molecular beam epitaxy. The substrates change both the volume and symmetry of the unit cell of the films. It is revealed that the symmetry as well as the volume of the unit cell have strong influence on the metal-insulator transition temperature and the size of magnetoresistance.Comment: 6 pages, 3 figure

Magnetic Properties of Dilute Alloys: Equations for Magnetization and its Structural Fluctuations

The dilute Heisenberg ferromagnet is studied taking into account fluctuations of magnetization caused by disorder. A self-consistent system of equations for magnetization and its mean quadratic fluctuations is derived within the configurationally averaged two-time temperature Green's function method. This system of equations is analised at low concentration of non-magnetic impurities. Mean relative quadratic fluctuations of magnetization are revealed to be proportional to the square of concentration of impurities.Comment: 16 pages, LaTe

Charge ordering, ferroelectric, and magnetic domains in LuFe2O4 observed by scanning probe microscopy

LuFe2O4 is a multiferroic system which exhibits charge order, ferroelectricity, and ferrimagnetism simultaneously below similar to 230 K. The ferroelectric/charge order domains of LuFe2O4 are imaged with both piezoresponse force microscopy (PFM) and electrostatic force microscopy (EFM), while the magnetic domains are characterized by magnetic force microscopy (MFM). Comparison of PFM and EFM results suggests that the proposed ferroelectricity in LuFe2O4 is not of usual displacive type but of electronic origin. Simultaneous characterization of ferroelectric/charge order and magnetic domains by EFM and MFM, respectively, on the same surface of LuFe2O4 reveals that both domains have irregular patterns of similar shape, but the length scales are quite different. The domain size is approximately 100 nm for the ferroelectric domains, while the magnetic domain size is much larger and gets as large as 1 mu m. We also demonstrate that the origin of the formation of irregular domains in LuFe2O4 is not extrinsic but intrinsic. (c) 2015 AIP Publishing LLC.open11116sciescopu

Cdk5 Phosphorylates Dopamine D2 Receptor and Attenuates Downstream Signaling

The dopamine D2 receptor (DRD2) is a key receptor that mediates dopamine-associated brain functions such as mood, reward, and emotion. Cyclin-dependent kinase 5 (Cdk5) is a proline-directed serine/threonine kinase whose function has been implicated in the brain reward circuit. In this study, we revealed that the serine 321 residue (S321) in the third intracellular loop of DRD2 (D2i3) is a novel regulatory site of Cdk5. Cdk5-dependent phosphorylation of S321 in the D2i3 was observed in in vitro and cell culture systems. We further observed that the phosphorylation of S321 impaired the agonist-stimulated surface expression of DRD2 and decreased G protein coupling to DRD2. Moreover, the downstream cAMP pathway was affected in the heterologous system and in primary neuronal cultures from p35 knockout embryos likely due to the reduced inhibitory activity of DRD2. These results indicate that Cdk5-mediated phosphorylation of S321 inhibits DRD2 function, providing a novel regulatory mechanism for dopamine signaling.X111111sciescopu

Influence of ambient water intrusion on coral reef acidification in the Chuuk lagoon, located in the coral-rich western Pacific Ocean

Weekly carbonate chemistry condition data recorded between 2008 and 2014 in the Chuuk lagoon (7.3 degrees N and 151.5 degrees E) of the Federated States of Micronesia, located in the western Pacific Ocean, were analyzed. The results showed that, during periods of weak intrusion of ambient seawater from the surrounding open ocean, two internal biological processes (calcification and respiration) reinforced each other and together lowered the pH of the reef water for extended periods, ranging from a few to several months. The analysis indicated that reduced intrusion of ambient water is associated with periods of low wind speeds. Such conditions increase the residence time of reef water, thus promoting acidification by respiration and calcification. This phenomenon likely affects many other areas of the coral-rich western Pacific Ocean, which contains 50% of global coral reefs and in which the degree of ambient water intrusion into the atolls has been shown to be closely associated with the El Nino-Southern Oscillation-induced wind speed change.1111Ysciescopu

Metal insulator transition and magnetotransport anomalies in perovskite SrIr0.5Ru0.5O3 thin films

We investigated the nature of transport and magnetic properties in SrIr0.5Ru0.5O3 (SIRO), which has characteristics intermediate between a correlated non-Fermi liquid state and an itinerant Fermi liquid state, by growing perovskite thin films on various substrates (e.g., SrTiO3 (001), (LaAlO3)(0.3)(Sr2TaAlO6)(0.7) (001), and LaAlO3 (001)). We observed systematic variation of underlying substrate dependent metal-to-insulator transition temperatures (T-MIT similar to 80K on SrTiO3, similar to 90 K on (LaAlO3)(0.3)(Sr2TaAlO6)(0.7), and similar to 100K on LaAlO3) in resistivity. At temperature 300K >= T >= T-MIT, SIRO is metallic and its resistivity follows a T-3/2 power law, whereas insulating nature at T 25 K, with negative MR proportional to B-1/2 and positive MR proportional to B-2; consistent with the localized-to-normal transport crossover dynamics. Furthermore, observed spin glass like behavior of SIRO on SrTiO3 (001) at T < 25 K in the localized regime validates the hypothesis that (Anderson) localization favors glassy ordering. These remarkable features provide a promising approach for future applications and of fundamental interest in oxide thin films. (C) 2015 AIP Publishing LLC.open1186sciescopu

Risk of Atrial Fibrillation and Adverse Outcomes in Patients With Cardiac Implantable Electronic Devices.

Background and objectives: Comprehensive epidemiological data are lacking on the incident atrial fibrillation (AF) in patients with cardiac implantable electronic devices (CIEDs). This study aimed to examine the incidence, risk factors, and AF-related adverse outcomes of patients with CIEDs.Methods: This was an observational cohort study that analyzed patients without prevalent AF who underwent CIED implantation in 2009-2018 using a Korean nationwide claims database. The subjects were divided into three groups by CIED type and indication: pacemaker (n=21,438), implantable cardioverter defibrillator (ICD)/cardiac resynchronization therapy (CRT) with heart failure (HF) (n=3,450), and ICD for secondary prevention without HF (n=2,146). The incidence of AF, AF-associated predictors, and adverse outcomes were evaluated.Results: During follow-up, the incidence of AF was 4.3, 7.3, and 5.1 per 100 person-years in the pacemaker, ICD/CRT with HF, and ICD without HF cohorts, respectively. Across the three cohorts, older age and valvular heart disease were commonly associated with incident AF. Incident AF was consistently associated with an increased risk of ischemic stroke (3.8-11.4-fold), admission for HF (2.6-10.5-fold), hospitalization for any cause (2.4-2.7-fold), all-cause death (4.1-5.0-fold), and composite outcomes (3.4-5.7-fold). Oral anticoagulation rates were suboptimal in patients with incident AF (pacemaker, 51.3%; ICD/CRT with HF, 51.7%; and ICD without HF, 33.8%, respectively).Conclusions: A substantial proportion of patients implanted CIED developed newly diagnosed AF. Incident AF was associated with a higher risk of adverse events. The importance of awareness, early detection, and appropriate management of AF in patients with CIED should be emphasized

Terahertz spin-orbital excitations in the paramagnetic state of multiferroic Sr2FeSi2O7

We studied the novel multiferroic material Sr2FeSi2O7 and found three absorption modes above the magnetic ordering transition temperature using time-domain terahertz spectroscopy. These absorption modes can be explained as the optical transitions between the spin-orbit coupling and crystal-field split 3d(6) Fe2+ ground-state term in this material. Consideration of the compressed tetrahedral environment of the Fe2+ site is crucial to understand the excitations. We point out, however, discrepancies between the single-site atomic picture and the experimental results.1133Ysciescopu