Determination of Angle of Light Deflection in Higher-Derivative Gravity Theories

Gravitational light deflection is known as one of three classical tests of general relativity and the angle of deflection may be computed explicitly using approximate or exact solutions describing the gravitational force generated from a point mass. In various generalized gravity theories, however, such explicit determination is often impossible due to the difficulty with obtaining an exact expression for the deflection angle. In this work, we present some highly effective globally convergent iterative methods to determine the angle of semiclassical gravitational deflection in higher- and infinite-derivative formalisms of quantum gravity theories. We also establish the universal properties that the deflection angle always stays below the classical Einstein angle and is a strictly decreasing function of the incident photon energy, in these formalisms.Comment: 32 pages, 8 figure

The Galactic Isotropic γ\gamma-ray Background and Implications for Dark Matter

We present an analysis of the radial angular profile of the galacto-isotropic (GI) $\gamma$-ray flux--the statistically uniform flux in circular annuli about the Galactic center. Two different approaches are used to measure the GI flux profile in 85 months of Fermi-LAT data: the BDS statistic method which identifies spatial correlations, and a new Poisson ordered-pixel method which identifies non-Poisson contributions. Both methods produce similar GI flux profiles. The GI flux profile is well-described by an existing model of bremsstrahlung, $\pi^0$ production, inverse Compton scattering, and the isotropic background. Discrepancies with data in our full-sky model are not present in the GI component, and are therefore due to mis-modeling of the non-GI emission. Dark matter annihilation constraints based solely on the observed GI profile are close to the thermal WIMP cross section below 100 GeV, for fixed models of the dark matter density profile and astrophysical $\gamma$-ray foregrounds. Refined measurements of the GI profile are expected to improve these constraints by a factor of a few.Comment: 20 pages, 15 figures, references adde

Invasion and dissemination of <i>S</i>. <i>flexneri</i> bacteria expressing type 1 fimbriae.

<p>(A) Confluent monolayers of TC7 cells were infected with M90T/pACYC184 or M90/pSH2 at multiplicities of infection (MOI) of 0.01 (upper row) or 0.001 (lower row), overlaid with gentamicin-containing agar, incubated at 37°C for 72 h, fixed and stained with Giemsa. (B) The graph indicates the number of plaques formed in the monolayer infected with either M90T harboring pACYC184 (vector) or pSH2 (carrying the <i>fim</i> operon), as calculated using different MOIs. Values are the means and SD of three independent experiments, each performed in triplicate at a MOI of 0.001; ** indicates P-value between 0.001 and 0.01. (C) Confluent monolayers of TC7 cells were infected with M90T/pACYC184 or M90/pSH2 at a MOI of 0.001 in the absence or in the presence of 0.2 mM mannose during the first 2 h (entry step).</p

Determination of the orientation of the <i>fimS</i> invertible element.

<p>Schematic representations of the region encompassing <i>fimS</i> in the ON and OFF orientations are shown in panels A and B, respectively; positions of <i>fimS</i> (box), inverted repeats (IR) on both sides of <i>fimS</i>, the promoter of the <i>fim</i> operon (small open arrow), the 5' end of <i>fimA</i> (large grey arrow), primers Inv-1 and Inv-2 (small black arrows), the <i>Sna</i>BI cleavage site and sizes of the <i>Sna</i>BI digestion products of the PCR fragment amplified by using Inv-1 and Inv-2 are indicated for each orientation. (C) The region encompassing <i>fimS</i> was amplified by PCR by using primers Inv-1 and Inv-2 and digested with <i>Sna</i>BI and restriction fragments were resolved on a 2% agarose gel; lane 1, M90T/pSH2 after growth for 24 h in static conditions; lane 2, M90T/pACYC184 after growth for 24 h in static conditions; lane 3, M90T/pSH2 after growth for 48 h in static conditions. The <i>fimS</i> region is carried by both the chromosome and the plasmid pSH2 in M90T/pSH2 and only by the chromosome in M90T/pACYC184; due to the higher copy number of pSH2 as compared to the chromosome, <i>fimS</i> was preferentially amplified from the pSH2 plasmid in M90T/pSH2. Diagrams on panels A and B were adapted from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121785#pone.0121785.ref044" target="_blank">44</a>].</p

Primers used for the characterization of the GI <i>leuX</i>.

<p>Primers used for the characterization of the GI <i>leuX</i>.</p

Characterization of the GI <i>leuX</i> in <i>S</i>. <i>flexneri</i>.

<p>The genetic organization of the ~23-kb GI inserted at the <i>leuX</i> locus in the <i>S</i>. <i>flexneri</i> reference strain 2457T is shown (drawn to scale). The <i>gntP</i> and <i>leuX</i>-<i>yjgB</i> genes flanking the GI are indicated by hatched arrows, <i>fim</i> genes by white arrows, <i>yjhATS</i> genes by dark-gray arrows and other genes present in the GI by pale-gray arrows. The position of IS<i>1</i> in <i>fimD</i> is indicated by a black box. The position and sizes of the six PCR fragments generated for the tiling PCR are indicated below the genetic map; the expected sizes of PCR fragment 2 corresponding to <i>fimD</i> with and without IS<i>1</i> are indicated. For the sake of clarity, other IS elements and phage remnants are not indicated.</p

Adhesion of S. <i>flexneri</i> bacteria expressing type 1 fimbriae to HeLa cells.

<p>HeLa cells infected for 30 min with M90T/pACYC184 or M90T/pSH2 in the absence or in the presence of 0.2 mM mannose were fixed with ethanol and stained with Giemsa. Numbers of bacteria per cell are shown in (A). Data are the means of three independent experiments performed in duplicate; *** denotes P-value < 0.001. Representative pictures of Giemsa stained cells are shown in (B); scale bar, 40 μm.</p

Distribution of inactivation events of the <i>fim</i> cluster among <i>S</i>. <i>flexneri</i> Chilean clinical isolates clinical and reference strains.

<p>^a Reference strains (ref) are 2457T and Sf301 (serotype 2a), M90T (serotype 5a) and Sf8401 (serotype 5b). Clinical strains (clin) were isolated from patients in Chile during the period 2004–2006.</p><p>^b For clinical isolates, the nonsense mutation at codon 162 of <i>fimB</i> was tested by restriction analysis of PCR fragment 3 using <i>Bfa</i>I.</p><p>^c PCR fragment 3 was not amplified from one of the 44 strains tested.</p><p>Distribution of inactivation events of the <i>fim</i> cluster among <i>S</i>. <i>flexneri</i> Chilean clinical isolates clinical and reference strains.</p

Characterization of type 1 fimbriae production in derivatives of the <i>S</i>. <i>flexneri</i> strain M90T.

<p>Representative electron microscopy pictures of derivatives of <i>S</i>. <i>flexneri</i> strain M90T harboring pACYC184 (vector) or pSH2 (carrying the <i>fim</i> operon) are shown in panels A and B, respectively. Scale bar, 1 μm. Results of an haemagglutination assays performed in the absence or in the presence of 0.2 mM mannose with the <i>S</i>. <i>flexneri</i> strain M90T harboring either pSH2 or pACYC184 are shown in panel C.</p

Genomic organization of the GI <i>leuX</i> in <i>E</i>. <i>coli</i> K12 and representative members of <i>Shigella</i> spp.

<p>A schematic representation (drawn to scale) of the main gene clusters present in the GI <i>leuX</i> is shown for the <i>E</i>. <i>coli</i> K-12 strain MG1655, the <i>S</i>. <i>flexneri</i> strain 2457T, the <i>S</i>. <i>sonnei</i> strain Ss046, the <i>S</i>. <i>dysenteriae</i> strain Sd197, the <i>S</i>. <i>boydii</i> strains CDC 3083–94 and Sb227, the <i>S</i>. <i>dysenteriae</i> strain 155–74, the <i>S</i>. <i>boydii</i> strain CIP52-54 and the EIEC strain 53638; the phylogenetic group to which each strain belongs is indicated in parenthesis. The GI encompasses the region located between <i>uxuABR-gntP</i> and <i>leuX</i>-<i>yjgB</i>. For the sake of clarity, IS (including IS inserted in <i>fim</i> genes) and phage remnants are not indicated.</p