Using galaxy pairs as cosmological tracers

The Alcock-Paczynski (AP) effect uses the fact that, when analyzed with the correct geometry, we should observe structure that is statistically isotropic in the Universe. For structure undergoing cosmological expansion with the background, this constrains the product of the Hubble parameter and the angular diameter distance. However, the expansion of the Universe is inhomogeneous and local curvature depends on density. We argue that this distorts the AP effect on small scales. After analyzing the dynamics of galaxy pairs in the Millennium simulation, we find an interplay between peculiar velocities, galaxy properties and local density that affects how pairs trace cosmological expansion. We find that only low mass, isolated galaxy pairs trace the average expansion with a minimum "correction" for peculiar velocities. Other pairs require larger, more cosmology and redshift dependent peculiar velocity corrections and, in the small-separation limit of being bound in a collapsed system, do not carry cosmological information.Comment: 15 pages, 14 figures, 1 tabl

Organometallic rhodium(iii) and iridium(iii) cyclopentadienyl complexes with curcumin and bisdemethoxycurcumin co-ligands

A series of half-sandwich cyclopentadienyl rhodium(iii) and iridium(iii) complexes of the type [Cp*M(curc/bdcurc)Cl] and [Cp*M(curc/bdcurc)(PTA)][SO3CF3], in which Cp* = pentamethylcyclopentadienyl, curcH = curcumin and bdcurcH = bisdemethoxycurcumin as O^O-chelating ligands, and PTA = 1,3,5-triaza-7-phosphaadamantane, is described. The X-ray crystal structures of three of the complexes, i.e. [Cp*Rh(curc)(PTA)][SO3CF3] (5), [Cp*Rh(bdcurc)(PTA)][SO3CF3] (6) and [Cp*Ir(bdcurc)(PTA)][SO3CF3] (8), confirm the expected "piano-stool" geometry. With the exception of 5, the complexes are stable under pseudo-physiological conditions and are moderately cytotoxic to human ovarian carcinoma (A2780 and A2780cisR) cells and also to non-tumorigenic human embryonic kidney (HEK293) cells, but lack the cancer cell selectivity observed for related arene ruthenium(ii) complexes

Steric and Electronic Effects Responsible for N, O- or N, N-Chelating Coordination of Pyrazolones Containing a Pyridine Ring in Ruthenium Arene Systems

Structural and electronic factors are crucial to rationalize the different N,O or N,N chelating coordination of pyrazolones containing a pyridine ring. The reactivity of proligand 3-phenyl-1-(pyridin-2-yl)-5-pyrazolone (HLpy,ph) with the (arene)Ru(II) fragment was explored. Neutral and ionic (arene)Ru(II) complexes were obtained and fully characterized, also by X-ray diffraction, revealing the ligand to coordinate in an unusual N,O-chelating fashion. Other ruthenium complexes were also synthesized with 3-methyl-1-(pyridin-2-yl)-5-pyrazolone (HLpy,me) and 3-methyl-1-(pyridin-2-yl)-4-trifluoroacetyl-5-pyrazolone (HQpy,CF3). In these complexes the ligands adopt the preferred N,N-chelating mode. Ligands and complexes were theoretically analyzed by density functional theory (DFT). The most stable tautomer of HLpy,phmatched well with the experimental behavior of this proligand and the structures of Ru-complexes were well described by calculations. The thermodynamic stability of the N,O- and N,N-coordination modes was analyzed and a proposal for the achievement of the N,O-coordination mode in complexes 1-4 was proposed. Cytotoxicity tests were performed against human ovarian carcinoma (A2780 and Cisplatin-resistant A2780cis) and nontumorigenic human embryonic kidney (HEK293T) cell lines, showing the free ligands to be more cytotoxic that the ensuing (arene)Ru(II) complexes

Evidence of an association between poly(3-hydroxybutyrate) accumulation and phosphotransbutyrylase expression in Bacillus megaterium

Molecular analysis of a genomic region of Bacillus megaterium, a polyhydroxybutyrate (PHB)- producing microorganism, revealed the presence of a gene coding for the enzyme phosphotransbutyrylase (Ptb). Enzyme activity was measured throughout the different growth phases of B. megaterium and was found to correlate with PHB accumulation during the late-exponential growth phase. Ptb expression was repressed by glucose and activated by the branched amino acids isoleucine and valine. Overexpression of ActBm, a σ 54 regulator from B. megaterium whose gene is located upstream from ptb, caused an increase in Ptb activity and PHB accumulation in B. megaterium

Raman scattering reveals strong LO-phonon-hole-plasmon coupling in nominally undoped GaAsBi: optical determination of carrier concentration

We report room-temperature Raman scattering studies of nominally undoped (100) GaAs1−xBix epitaxial layers exhibiting Biinduced (p-type) longitudinal-optical-plasmon coupled (LOPC) modes for 0.018≤x≤0.048. Redshifts in the GaAs-like optical modes due to alloying are evaluated and are paralleled by strong damping of the LOPC. The relative integrated Raman intensities of LO(Γ) and LOPC ALO/ALOPC are characteristic of heavily doped p-GaAs, with a remarkable near total screening of the LO(Γ) phonon (ALO/ALOPC →0) for larger Bi concentrations. A method of spectral analysis is set out which yields estimates of hole concentrations in excess of 5 × 1017 cm−3 and correlates with the Bi molar fraction. These findings are in general agreement with recent electrical transport measurements performed on the alloy, and while the absolute size of the hole concentrations differ, likely origins for the discrepancy are discussed. We conclude that the damped LO-phonon-hole-plasmon coupling phenomena plays a dominant role in Raman scattering from unpassivated nominally undoped GaAsBi

Herramientas para el seguimiento de procesos de interactividad mediatizados por facebook en educación superior

Esta ponencia presenta diversas herramientas para el seguimiento y evaluación de procesos de interactividad mediatizados por Facebook que pueden utilizarse para el análisis de propuestas educativas de nivel superior. A tal fin, fue necesario precisar y profundizar los conceptos de redes sociales y sus herramientas de análisis existentes. Enmarcados en la noción de Dispositivo Hipermedial Dinámico como una propuesta innovadora para construir aprendizajes significativos, abordamos dichos instrumentos tecnológicos con la clara finalidad de analizar su utilización y su capacidad real. Aunque Facebook tuvo su origen en un ambiente específicamente universitario, se evidencia que la mayoría de estas aplicaciones carecen de especificidad para un enfoque educativo y orientan su finalidad a contextos comerciales o de mercado. Sin embargo, existe un grupo reducido de estas cuyos resultados pueden aportar elementos de análisis, como así también algunos desarrollos a nivel prototipo que podrían aportar soluciones originales.Eje: Workshop Tecnología informática aplicada en educación (WTIAE)Red de Universidades con Carreras en Informática (RedUNCI

DUF3380 domain from a Salmonella phage endolysin shows potent N -acetylmuramidase activity

Bacteriophage-encoded endolysins are highly diverse enzymes that cleave the bacterial peptidoglycan layer. Current research focuses on their potential applications in medicine, in food conservation, and as biotechnological tools. Despite the wealth of applications relying on the use of endolysin, little is known about the enzymatic properties of these enzymes, especially in the case of endolysins of bacteriophages infecting Gram-negative species. Automated genome annotations therefore remain to be confirmed. Here, we report the biochemical analysis and cleavage site determination of a novel Salmonella bacteriophage endolysin, Gp110, which comprises an uncharacterized domain of unknown function (DUF3380; pfam11860) in its C terminus and shows a higher specific activity (34,240 U/μM) than that of 14 previously characterized endolysins active against peptidoglycan from Gram-negative bacteria (corresponding to 1.7- to 364-fold higher activity). Gp110 is a modular endolysin with an optimal pH of enzymatic activity of pH 8 and elevated thermal resistance. Reverse-phase high-performance liquid chromatography (RP-HPLC) analysis coupled to mass spectrometry showed that DUF3380 has N-acetylmuramidase (lysozyme) activity cleaving the β-(1,4) glycosidic bond between N-acetylmuramic acid and N-acetylglucosamine residues. Gp110 is active against directly cross-linked peptidoglycans with various peptide stem compositions, making it an attractive enzyme for developing novel antimicrobial agents

1,1′,1′′-{[4-(3,4-Ethyl­ene­dioxy­thio­phen-2-yl)phen­yl]methane­tri­yl}tris­(1H-pyra­zole)

In the title complex, C22H18N6O2S, two of the pyrazole rings are disordered over two sets of sites with ratios of refined occupancies of 0.58 (2):0.42 (2) and 0.517 (12):0.483 (12). The dioxane ring is in a half-chair conformation and the two –CH2– groups of this ring are disordered over two sets of sites, the ratio of refined occupancies being 0.855 (19):0.145 (19). The essentially planar thio­phene ring [largest deviation = 0.0444 (2) Å] forms a dihedral angle of 19.59 (3)° with the benzene ring

Tris(5-methyl-3-phenyl-1H-pyrazol-1-yl)methane

The first crystal structure of a second-generation tris­(pyrazol­yl)methane, namely the title compound, C31H28N6, is reported. The mol­ecule exhibits a helical conformation with an average twist of 35.1°. In addition, there are C—H⋯π inter­actions of 3.202 (2) Å between the pyrazole C—H group and neighbouring phenyl groups