Structural study on Pr0.55(Ca[1-y]Sr[y])0.45MnO3 thin films on perovskite (011) substrate

Structural study on the photo-switching system Pr{0.55}(Ca{1-y}Sr y){0.45}MnO3 thin films on perovskite (011) substrate has been made with synchrotron radiation diffraction experiment. The insulating phase of y=0.20 sample was found to be an antiferro-orbital ordered phase with large lattice distortion and the ferromagnetic metallic phase of y=0.40 film show no distinct lattice distortion from the paramagnetic phase, which are very similar with (Nd,Pr)0.5Sr0.5MnO3 films. A striking contrast of the orbital ordered phase of y=0.20 film to (Nd,Pr)0.5Sr0.5MnO3 films was its untwinned structure.Comment: 8 pages, 4 figures. To be published in European Journal of Physics Special Topic

Severe thermoregulatory deficiencies in mice with a gene deletion in titin

Muscular dystrophy with myositis (mdm) mice, which carry a deletion in the muscle protein titin, shiver at a lower than expected frequency for their body size, have body temperatures that decrease below ambient temperatures of 34°C, and have reduced active muscle stiffness in vivo compared to their wild type siblings. The impairment in shivering thermogenesis could be due to the N2A deletion in the titin protein leading to more compliant muscles and lower shivering frequency. I hypothesized that the ability of mdm mice to use the other heat production mechanism, nonshivering thermogenesis (NST), may also be impaired and contribute to their hypothermic state. To assess the response to cold exposure, body temperature and metabolic rate were measured in wild type and mdm mice using open-flow respirometry at four ambient temperature ranges: 19-21°C, 23-25°C, 27-30°C, and 33-35°C. Following the temperature experiment, NST was maximally stimulated by administering 1.2 mg kg-1 of norepinephrine subcutaneously. In the temperature experiment, there was a significant interaction between genotype and temperature, with mdm mice having significantly higher metabolic rates at 27-30°C and lower metabolic rates at 23-25°C compared to wild type mice. After correcting metabolic rate for Q10 effects, mdm mice had lower metabolic rates compared to size-matched Perognathus longimembris (little pocket mouse). In addition, the capacity for NST estimated by area underneath the metabolic response curve was also reduced in mdm mice compared to wild type littermates. When comparing mdm mice to other mice with similar body mass (7g), the effects of low metabolic rate and capacity for NST were exacerbated because predicted values of metabolic rate and capacity for NST are larger for smaller animals. These results indicate that a deletion in N2A titin causes severe thermoregulatory defects at every level of thermoregulation, including NST. Direct effects of the titin mutation likely lead to the lower shivering frequency observed. Indirect effects likely lead to a lower capacity for NST and metabolism in general. Future studies should investigate effects on oxidative phosphorylation or other signaling pathways

Forecasting Global Temperature Variations by Neural Networks

Global temperature variations between 1861 and 1984 are forecast usingsregularization networks, multilayer perceptrons and linearsautoregression. The regularization network, optimized by stochasticsgradient descent associated with colored noise, gives the bestsforecasts. For all the models, prediction errors noticeably increasesafter 1965. These results are consistent with the hypothesis that thesclimate dynamics is characterized by low-dimensional chaos and thatsthe it may have changed at some point after 1965, which is alsosconsistent with the recent idea of climate change.

Direct Observation of Sub-picosecond Hole Injection from Lead Halide Perovskite by Differential Transient Transmission Spectroscopy

Efficient charge separation at the interfaces between the perovskite and with the carrier transport layers is crucial for perovskite solar cells to achieve high power conversion efficiency. We systematically investigate the hole injection dynamics from MAPbI$_3$ perovskite to three typical hole transport materials (HTMs) PEDOT:PSS, PTAA and NiO$_x$ by means of pump-probe transmission measurements. We photoexcite only near the MAPbI$_3$/HTM interface or near the back surface, and measure the differential transient transmission between the two excitation configurations to extract the carrier dynamics directly related to the hole injection. The differential transmission signals directly monitor the hole injections to PTAA and PEDOT:PSS being complete within 1 and 2 ps, respectively, and that to NiO$_x$ exhibiting an additional slow process of 40 ps time scale. The obtained injection dynamics are discussed in comparison with the device performance of the solar cells containing the same MAPbI$_3$/HTM interfaces.Comment: 5 pages, 5 figure

Strangeness production in antiproton-nucleus collisions

Antiproton annihilations on nuclei provide a very interesting way to study the behaviour of strange particles in the nuclear medium. In low energy $\bar p$ annihilations, the hyperons are produced mostly by strangeness exchange mechanisms. Thus, hyperon production in $\bar p A$ interactions is very sensitive to the properties of the antikaon-nucleon interaction in nuclear medium. Within the Giessen Boltzmann-Uehling-Uhlenbeck transport model (GiBUU), we analyse the experimental data on $\Lambda$ and $K^0_S$ production in $\bar p A$ collisions at $p_{\rm lab}=0.2-4$ GeV/c. A satisfactory overall agreement is reached, except for the $K^0_S$ production in $\bar p+^{20}$Ne collisions at $p_{\rm lab}=608$ MeV/c, where we obtain substantially larger $K^0_S$ production rate. We also study the $\Xi$ hyperon production, important in view of the forthcoming experiments at FAIR and J-PARC.Comment: 8 pages, 4 figures, invited talk given by A.B. Larionov at the 10th International Conference on Low Energy Antiproton Physics (LEAP2011), Vancouver, Canada, Apr 27 - May 1, 2011, Hyperfine Interact. in pres

Map location of ace-5.

Map location of ace-5

Polar Antiferromagnets Produced with Orbital-Order

Polar magnetic states are realized in pseudocubic manganite thin films fabricated on high-index substrates, in which a Jahn-Teller (JT) distortion remains an active variable. Several types of orbital-orders were found to develop large optical second harmonic generation, signaling broken-inversion-symmetry distinct from their bulk forms and films on (100) substrates. The observed symmetry-lifting and first-principles calculation both indicate that the modified JT q2 mode drives Mn-site off-centering upon orbital order, leading to the possible cooperation of "Mn-site polarization" and magnetism.Comment: 5 pages, 4 figure

NP-hardness of the sorting buffer problem on the uniform metric

AbstractAn instance of the sorting buffer problem (SBP) consists of a sequence of requests for service, each of which is specified by a point in a metric space, and a sorting buffer which can store up to a limited number of requests and rearrange them. To serve a request, the server needs to visit the point where serving a request p following the service to a request q requires the cost corresponding to the distance d(p,q) between p and q. The objective of SBP is to serve all input requests in a way that minimizes the total distance traveled by the server by reordering the input sequence. In this paper, we focus our attention to the uniform metric, i.e., the distance d(p,q)=1 if p≠q, d(p,q)=0 otherwise, and present the first NP-hardness proof for SBP on the uniform metric