Field Effect and Magnetically Induced Capacitive Tuning in Hole Doped La1-xSRXMnO3

Electrostatic modulation of interface conduction between semiconductors and insulating oxides is the foundation of semiconductor technology. This field effect concept can be applied on complex oxides, such as high temperature superconductors and colossal magnetoresistive manganites, in order to create new electronic and magnetic phases. Competition and coexistence of multiple nanoscale phases make them exciting to study around phase transitions. This study on hole doped La1-xSrxMnO3 systems has a two-fold purpose. One is the demonstration of the field effect on La1-xSrxMnO3 (x = 0.125, 0.2, 0.3, 0.5) thin films. It is an important step towards electrostatic control of material properties; however, a challenging task because of their charge carrier densities of 0.01-1 hole/unit cell, a few orders of magnitude larger than in doped semiconductors. Control by linear dielectrics needs huge, constantly applied bias. Energy efficient tuning with low voltages requires highly polar ferroelectric. Pb(Zr0.2Ti0.8)O3 was chosen, whose remanence provides 0.5 charge carrier/unit cell on the manganite/ferroelectric interface. La1-xSrxMnO3/Pb(Zr0.2Ti0.8)O3 heterostructures were synthesized by pulsed laser epitaxy and remarkable conduction modifications were observed in the La1-xSrxMnO3. This can be a strong foundation of a new tool to research electronic oxides. The second purpose of this work is to utilize the phase separation in manganites. There has been extensive research on multiferroic materials, in which dielectric and magnetic responses are controlled by magnetic and electric field, respectively. In order to demonstrate magnetically tuned capacitance, insulating La7/8Sr1/8MnO3 was studied. Drastic capacitance change in magnetic field was shown through a phase transitions and explained in the framework of electronic phase separation. It makes this material eligible for high frequency magnetoelectric applications. Modulating charge carriers, mobility and magnetism in magnetic oxides, superconductors and superlattices has a great impact on the emerging field of oxide electronics. These compounds overcome the scaling limitations of conventional semiconductors; using low operation voltage oxide ferroelectrics lowers energy consumption. This thesis shows that changing fundamental physical properties of complex oxides on the atomic scale is possible by ferroelectric field effect. This technique is proposed as a tool to study thin films, artificially stacked structures and to induce and optimize novel phases and phenomena

An analogue of a theorem of Steinitz for ball polyhedra in R-3

Steinitz's theorem states that a graph G is the edge-graph of a 3-dimensional convex polyhedron if and only if, G is simple, plane and 3-connected. We prove an analogue of this theorem for ball polyhedra, that is, for intersections of finitely many unit balls in R-3

The complex role of physical exercise and reactive oxygen species on brain

AbstractReactive oxygen species (ROS) are continuously generated during aerobic metabolism and at moderate level. They play a role in redox signaling, but in significant concentration they cause oxidative damage and neurodegeneration. Because of the enhanced sensitivity of brain to ROS, it is especially important to maintain the normal redox state in different types of neuron cells. In last decade it became clear that regular exercise beneficially affects brain function, and can play an important preventive and therapeutic role in stroke, Alzheimer, and Parkinson diseases. The effects of exercise appear to be very complex and could include neurogenesis via neurotrophic factors, increased capillariszation, decreased oxidative damage, and increased proteolytic degradation by proteasome and neprilysin. Data from our and other laboratories indicate that exercise-induced modulation of ROS levels plays a role in the protein content and expression of brain-derived neurotrophic factor, tyrosine-related kinase B (TrkB), and cAMP response element binding protein, resulting in better function and increased neurogenesis. Therefore, it appears that exercise-induced modulation of the redox state is an important means, by which exercise benefits brain function, increases the resistance against oxidative stress, facilitates recovery from oxidative stress, and attenuates age-associated decline in cognition

Serum procalcitonin level and leukocyte antisedimentation rate as early predictors of respiratory dysfunction after oesophageal tumour resection

INTRODUCTION: Postoperative care after oesophageal tumour resection holds a high risk of respiratory complications. We therefore aimed to determine the value of systemic inflammatory markers in predicting arterial hypoxaemia as the earliest sign of developing lung injury after oesophageal tumour resection. METHODS: In a prospective observational study, 33 consecutive patients were observed for three days (T1–T3) after admission (T0) to an intensive care unit following oesophageal tumour resection. The daily highest values of the heart rate, axillary temperature, leukocyte count and PaCO(2 )were recorded. Serum C-reactive protein and procalcitonin concentrations and the leukocyte antisedimentation rate (LAR) were determined at T1 and T2. Respiratory function was monitored 6-hourly measurement of the PaO(2)/FIO(2 )ratio, and the lowest value was recorded at T3. Patients were categorised as normoxaemic or hypoxaemic using the cutoff value of 300 mmHg for PaO(2)/FIO(2). RESULTS: Seventeen out of 33 patients were classified as hypoxaemic and 16 patients as normoxaemic at T3. Increases of temperature at T0 and of the procalcitonin and LAR values at T2 were predictive of hypoxaemia at T3 (P < 0.05, P < 0.01 and P < 0.001, respectively). The area under the receiver-operating characteristic curve was 0.65 for the temperature at T0, which was significantly lower than that for the procalcitonin level at T2 (0.83; 95% confidence interval, 0.69–0.97; P < 0.01) and that for LAR at T2 (0.89; 95% confidence interval, 0.77–1.00; P < 0.001). CONCLUSION: These results suggest that an elevated LAR (>15%) and an elevated procalcitonin concentration (>2.5 ng/ml) measured on the second postoperative day can predict next-day arterial hypoxaemia (PaO(2)/FIO(2 )< 300 mmHg) after oesophageal tumour resection

Giant Dielectric Permittivity and Magnetocapacitance in La\u3csub\u3e0.875\u3c/sub\u3eSr\u3csub\u3e0.125\u3c/sub\u3eMnO\u3csub\u3e3\u3c/sub\u3e Single Crystals

We report the observation of extremely high dielectric permittivity exceeding 109 and magnetocapacitance of the order of 104% in La0.875Sr0.125MnO3 single crystal. This phenomenon is observed below 270 K, and it exhibits a history dependence. These effects may be the consequence of strong competition and interplay among the charge, orbital, and spin degrees of freedom, resulting in nanoscale charge and spin dynamic inhomogeneities in the prepercolation regime of the phase segregation

Prepregből autoklávban gyártott kompozit lemezek rétegközi tulajdonságainak alakulása a térhálósítás során alkalmazott technológiai paraméterek függvényében

Munkánk során a felfűtés sebességének, a ciklus során a kompozitra kifejtett nyomás mértékének, illetve a plató alkalmazásának hatásait vizsgáltuk üvegszál/epoxi kompozit lemezek autoklávos gyártása esetén. Ehhez különböző paraméterekkel állítottunk elő lemezeket, majd meghatároztuk ezek száltartalmát, sűrűségét és egyes mechanikai tulajdonságait, különös tekintettel a rétegközi tulajdonságokra. A vizsgálatok eredményei alapján elemeztük az adatlapon szereplő paraméterektől való eltérések következményeit

Információelmélet és alkalmazásai = Information theory and its applications

a) Többfelhasználós modellek titkossági kapacitásáról publikáció megjelent. Összefoglaló dolgozat készült több-bemenetű csatornákról (megjelent) és az információmennyiségek axiomatikus vizsgálatáról (közlésre elfogadva). Megoldottunk egy kvantum-információelméleti problémát, a pub. megjelent. b) Távolság-divergencia egyenlőtlenséget bizonyítottunk kontraktív Markov-láncokra; segítségével távolság-divergencia egyenlőtlenségeket lehet bizonyítani Gibbs mértékekre. Két előadás nemzetközi konferencián, folyóiratpubl. előkészületben. c) Általánosított maximum likelihood becslésekről publikáció megjelent. Vizsgálatainkat kiterjesztettük általános entrópiafunkcionálok minimalizálására és Bregman divergenciák szerinti vetületekre, több nemzetközi konferencián előadás, folyóiratpubl. előkészületben. d) Gráfokra bevezettünk egy gráfkapacitás jellegű új paramétert, segítségével új becslést adtunk egy Körner és Malvenuto által korábban vizsgált problémára; publ. megjelent. Vizsgáltuk az előbbi gráfparaméter egy általánosítását végtelen gráfokra, több esetre meghatároztuk az értékét és megmutattuk, hogy a Shannon kapacitás speciális esetként értelmezhető. Publ. benyújtva. A gráfok lokális kromatikus számának topologikus módszerrel való becslésére vonatkozó korábbi eredményeinket javítva több új esetre pontos eredményt adtunk. Publ. elfogadva. A topologikus módszerrel új eredményt bizonyítottunk az ún. necklace bisection problémára is. Publ. megjelent. | a) Solution of a quantum information theory problem. Survey papers on multiple access channels and on axiomatic approach. b) A distance-divergence inequality for contractive Markov chains. c) Extension of previous information geometry results to general entropy functionals and Bregman distances. d) Introduction and study of a graph parameter for finite graphs, and an extension of it to infinite graphs. Improved lower bounds on local chromatic number via a topological method, and a new result on the necklace problem

Mitochondrial biogenesis-associated factors underlie the magnitude of response to aerobic endurance training in rats

Trainability is important in elite sport and in recreational physical activity, and the wide range for response to training is largely dependent on genotype. In this study, we compare a newly developed rat model system selectively bred for low and high gain in running distance from aerobic training to test whether genetic segregation for trainability associates with differences in factors associated with mitochondrial biogenesis. Low response trainer (LRT) and high response trainer (HRT) rats from generation 11 of artificial selection were trained five times a week, 30 min per day for 3 months at 70 % VO2max to study the mitochondrial molecular background of trainability. As expected, we found significant differential for the gain in running distance between LRT and HRT groups as a result of training. However, the changes in VO2max, COX-4, redox homeostasis associated markers (reactive oxygen species (ROS)), silent mating-type information regulation 2 homolog (SIRT1), NAD+/NADH ratio, proteasome (R2 subunit), and mitochondrial network related proteins such as mitochondrial fission protein 1 (Fis1) and mitochondrial fusion protein (Mfn1) suggest that these markers are not strongly involved in the differences in trainability between LRT and HRT. On the other hand, according to our results, we discovered that differences in basal activity of AMP-activated protein kinase alpha (AMPKα) and differential changes in aerobic exercise-induced responses of citrate synthase, carbonylated protein, peroxisome proliferator-activated receptor gamma coactivator-1α (PGC1-α), nuclear respiratory factor 1 (NRF1), mitochondrial transcription factor A (TFAM), and Lon protease limit trainability between these selected lines. From this, we conclude that mitochondrial biogenesis-associated factors adapt differently to aerobic exercise training in training sensitive and training resistant rats