Coupling of atomic quadrupole transitions with resonant surface plasmons

We report on the coupling of an electric quadrupole transition in atom with plasmonic excitation in a nanostructured metallic metamaterial. The quadrupole transition at 685 nm in the gas of Cesium atoms is optically pumped, while the induced ground state population depletion is probed with light tuned on the strong electric dipole transition at 852 nm. We use selective reflection to resolve the Doppler-free hyperfine structure of Cesium atoms. We observed a strong modification of the reflection spectra at the presence of metamaterial and discuss the role of the spatial variation of the surface plasmon polariton on the quadrupole coupling.Comment: 6 pages, 5 figure

Irak después de Saddam Hussein y su descomposición socioeconómica

Desde la caída de Saddam Hussein, Irak que ya estaba soportando estoicamente la desgracia de verse invadido por fuerzas de ocupación que dieron por tierra su derecho a la autodeterminación, experimenta día a día la quiebra de su economía, debido a la corrupción, la violencia destructiva y la mala administración generalizada. La corrupción que existe en todos los niveles, hacen responsable en este asunto, tanto al actual gobierno iraquí como a las autoridades de ocupación, incapaces de proteger su propio presupuesto e impedir que les roben sus fondos. De la ínfima ayuda externa que llega (a pesar de que donantes internacionales anunciaron el envío de miles de millones de dólares para proyectos de reconstrucción), la mayor parte va a parar a los bolsillos de funcionarios corruptos, quienes pretenden compensar el déficit reduciendo subsidios y suprimiendo paulatinamente las raciones alimenticias con las que cuentan muchos de los iraquíes pobres para sobrevivir.Instituto de Relaciones Internacionales (IRI

Irak después de Saddam Hussein y su descomposición socioeconómica

Desde la caída de Saddam Hussein, Irak que ya estaba soportando estoicamente la desgracia de verse invadido por fuerzas de ocupación que dieron por tierra su derecho a la autodeterminación, experimenta día a día la quiebra de su economía, debido a la corrupción, la violencia destructiva y la mala administración generalizada. La corrupción que existe en todos los niveles, hacen responsable en este asunto, tanto al actual gobierno iraquí como a las autoridades de ocupación, incapaces de proteger su propio presupuesto e impedir que les roben sus fondos. De la ínfima ayuda externa que llega (a pesar de que donantes internacionales anunciaron el envío de miles de millones de dólares para proyectos de reconstrucción), la mayor parte va a parar a los bolsillos de funcionarios corruptos, quienes pretenden compensar el déficit reduciendo subsidios y suprimiendo paulatinamente las raciones alimenticias con las que cuentan muchos de los iraquíes pobres para sobrevivir.Instituto de Relaciones Internacionales (IRI

Irak después de Saddam Hussein y su descomposición socioeconómica

Desde la caída de Saddam Hussein, Irak que ya estaba soportando estoicamente la desgracia de verse invadido por fuerzas de ocupación que dieron por tierra su derecho a la autodeterminación, experimenta día a día la quiebra de su economía, debido a la corrupción, la violencia destructiva y la mala administración generalizada. La corrupción que existe en todos los niveles, hacen responsable en este asunto, tanto al actual gobierno iraquí como a las autoridades de ocupación, incapaces de proteger su propio presupuesto e impedir que les roben sus fondos. De la ínfima ayuda externa que llega (a pesar de que donantes internacionales anunciaron el envío de miles de millones de dólares para proyectos de reconstrucción), la mayor parte va a parar a los bolsillos de funcionarios corruptos, quienes pretenden compensar el déficit reduciendo subsidios y suprimiendo paulatinamente las raciones alimenticias con las que cuentan muchos de los iraquíes pobres para sobrevivir.Instituto de Relaciones Internacionales (IRI

Spin and lattice excitations of a BiFeO3 thin film and ceramics

We present a comprehensive study of polar and magnetic excitations in BiFeO3 ceramics and a thin film epitaxially grown on an orthorhombic (110) TbScO3 substrate. Infrared reflectivity spectroscopy was performed at temperatures from 5 to 900 K for the ceramics and below room temperature for the thin film. All 13 polar phonons allowed by the factor-group analysis were observed in theceramic samples. The thin-film spectra revealed 12 phonon modes only and an additional weak excitation, probably of spin origin. On heating towards the ferroelectric phase transition near 1100 K, some phonons soften, leading to an increase in the static permittivity. In the ceramics, terahertz transmission spectra show five low-energy magnetic excitations including two which were not previously known to be infrared active; at 5 K, their frequencies are 53 and 56 cm-1. Heating induces softening of all magnetic modes. At a temperature of 5 K, applying an external magnetic field of up to 7 T irreversibly alters the intensities of some of these modes. The frequencies of the observed spin excitations provide support for the recently developed complex model of magnetic interactions in BiFeO3 (R.S. Fishman, Phys. Rev. B 87, 224419 (2013)). The simultaneous infrared and Raman activity of the spin excitations is consistent with their assignment to electromagnons

Deletions in the N-terminal segment of the plasma membrane Ca2+ pump impair the expression of a correctly folded functional enzyme

Mutant cDNAs encoding h4 plasma membrane Ca2+ pumps with deletions in the N-terminal segment have been constructed and expressed in COS cells. As judged by immunoblotting, each construct was expressed at a high level similar to that of the wild-type enzyme. The removal of the first six amino acids had no effect on the Ca2+ transport activity, but deletions in the segment 15-75 reduced the activity to undetectable levels. The d(43-56)h4 mutant, lacking amino acids 43-56, was also efficiently expressed in stable form in CHO cells. The Ca2+ transport activity of d(43-56)h4 in this system was about 40% of that of the wild type. The d(43-56)h4 enzyme exhibited a similar affinity for Ca2+, a slightly increased apparent affinity for ATP, and a slightly lower sensitivity to inhibition by vanadate than the wild-type enzyme. Analysis of the phosphoenzyme intermediate formed in the presence of lanthanum showed that the phosphorylation reaction was not affected, but the maximum amount of phosphoenzyme was reduced to the same extent as the Ca2+ transport activity. These results suggest that the expressed d(43-56)h4 was a mixture of fully active and inactive enzyme. The d(43-56)h4 enzyme was more easily degraded by proteases and had a higher sensitivity to heat inactivation than the wild type suggesting that the loss of function was due to the improper folding and instability, of the mutant protein. On the basis of these findings, it appears that the N-terminal segment of the plasma membrane Ca2+ pump is neither essential for synthesis nor for catalytic activity but is critical for the expression of a correctly folded functional enzyme.Fil: Adamo, Hugo Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Grimaldi, Mirta E.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Garcia Arguinzonis, Maisa I.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentin

The Snapshot Hubble U-Band Cluster Survey (SHUCS) II. Star Cluster Population of NGC 2997

We study the star cluster population of NGC 2997, a giant spiral galaxy located at 9.5 Mpc and targeted by the Snapshot Hubble U-band Cluster Survey (SHUCS). Combining our U-band imaging from SHUCS with archival BVI imaging from HST, we select a high confidence sample of clusters in the circumnuclear ring and disk through a combination of automatic detection procedures and visual inspection. The cluster luminosity functions in all four filters can be approximated by power-laws with indices of $-1.7$ to $-2.3$. Some deviations from pure power-law shape are observed, hinting at the presence of a high-mass truncation in the cluster mass function. However, upon inspection of the cluster mass function, we find it is consistent with a pure power-law of index $-2.2\pm0.2$ despite a slight bend at $\sim$$2.5\times10^{4}$ M$_{\odot}$. No statistically significant truncation is observed. From the cluster age distributions, we find a low rate of disruption ($\zeta\sim-0.1$) in both the disk and circumnuclear ring. Finally, we estimate the cluster formation efficiency ($\Gamma$) over the last 100 Myr in each region, finding $7\pm2$% for the disk, $12\pm4$% for the circumnuclear ring, and $10\pm3$% for the entire UBVI footprint. This study highlights the need for wide-field UBVI coverage of galaxies to study cluster populations in detail, though a small sample of clusters can provide significant insight into the characteristics of the population.Comment: 31 pages, 9 figures, accepted to the A

Anthocyanins protect the gastrointestinal tract from high fat diet-induced alterations in redox signaling, barrier integrity and dysbiosis.

The gastrointestinal (GI) tract can play a critical role in the development of pathologies associated with overeating, overweight and obesity. We previously observed that supplementation with anthocyanins (AC) (particularly glycosides of cyanidin and delphinidin) mitigated high fat diet (HFD)-induced development of obesity, dyslipidemia, insulin resistance and steatosis in C57BL/6J mice. This paper investigated whether these beneficial effects could be related to AC capacity to sustain intestinal monolayer integrity, prevent endotoxemia, and HFD-associated dysbiosis. The involvement of redox-related mechanisms were further investigated in Caco-2 cell monolayers. Consumption of a HFD for 14 weeks caused intestinal permeabilization and endotoxemia, which were associated with a decreased ileum expression of tight junction (TJ) proteins (occludin, ZO-1 and claudin-1), increased expression of NADPH oxidase (NOX1 and NOX4) and NOS2 and oxidative stress, and activation of redox sensitive signals (NF-κB and ERK1/2) that regulate TJ dynamics. AC supplementation mitigated all these events and increased GLP-2 levels, the intestinal hormone that upregulates TJ protein expression. AC also prevented, in vitro, tumor necrosis factor alpha-induced Caco-2 monolayer permeabilization, NOX1/4 upregulation, oxidative stress, and NF-κB and ERK activation. HFD-induced obesity in mice caused dysbiosis and affected the levels and secretion of MUC2, a mucin that participates in intestinal cell barrier protection and immune response. AC supplementation restored microbiota composition and MUC2 levels and distribution in HFD-fed mice. Thus, AC, particularly delphinidin and cyanidin, can preserve GI physiology in HFD-induced obesity in part through redox-regulated mechanisms. This can in part explain AC capacity to mitigate pathologies, i.e. insulin resistance and steatosis, associated with HFD-associated obesity