Identification of non-dot/icm suppressors of the Legionella pneumophila △dotL lethality phenotype

Legionella pneumophila, a causative agent of bacterial pneumonia, survives inside phagocytic cells by avoiding rapid targeting to the lysosome. This bacterium utilizes a type IVB secretion system, encoded by the dot/icm genes, to replicate inside host cells. DotL, a critical component of the Dot/Icm secretion apparatus, functions as the type IV coupling protein. In contrast to most dot/icm genes, which are dispensable for growth on bacteriological media, dotL is required for the viability of wild-type L. pneumophila. Previously we reported that ΔdotL lethality could be suppressed by inactivation of the Dot/Icm complex via mutations in other dot/icm genes. Here we report the isolation of non-dot/icm suppressors of this phenotype. These ΔdotL suppressors include insertions that disrupt the function of the L. pneumophila homologs of cpxR, djlA, lysS, and two novel open reading frames, lpg0742 and lpg1594, that we have named ldsA and ldsB for lethality of ΔdotL suppressor. In addition to suppressing ΔdotL lethality, inactivation of these genes in a wild-type strain background causes a range of defects in L. pneumophila virulence traits, including intracellular growth, implicating these factors in the proper function of the Dot/Icm complex. Consistent with previous data showing a role for the cpx system in regulating expression of several dot/icm genes, the cpxR insertion mutant produced decreased levels of three Dot/Icm proteins, DotA, IcmV, and IcmW. The remaining four suppressors did not affect the steady-state levels of any Dot/Icm protein and are likely to represent the first identified factors necessary for assembly and/or activation of the Dot/Icm secretion complex

Extracting equation of state parameters from black hole-neutron star mergers. I. Nonspinning black holes

The late inspiral, merger, and ringdown of a black hole-neutron star (BHNS) system can provide information about the neutron-star equation of state (EOS). Candidate EOSs can be approximated by a parametrized piecewise-polytropic EOS above nuclear density, matched to a fixed low-density EOS; and we report results from a large set of BHNS inspiral simulations that systematically vary two parameters. To within the accuracy of the simulations, we find that, apart from the neutron-star mass, a single physical parameter Lambda, describing its deformability, can be extracted from the late inspiral, merger, and ringdown waveform. This parameter is related to the radius, mass, and l=2 Love number, k_2, of the neutron star by Lambda = 2k_2 R^5/3M_{NS}^5, and it is the same parameter that determines the departure from point-particle dynamics during the early inspiral. Observations of gravitational waves from BHNS inspiral thus restrict the EOS to a surface of constant Lambda in the parameter space, thickened by the measurement error. Using various configurations of a single Advanced LIGO detector, we find that neutron stars are distinguishable from black holes of the same mass and that Lambda^{1/5} or equivalently R can be extracted to 10-40% accuracy from single events for mass ratios of Q=2 and 3 at a distance of 100 Mpc, while with the proposed Einstein Telescope, EOS parameters can be extracted to accuracy an order of magnitude better.Comment: 21 pages, 14 figures, submitted to PR

Framing the neoliberal canon: resisting the market myth via literary enquiry

here is widespread recognition that neoliberal rhetoric about ‘free markets’ stands in considerable tension with ‘really existing’ neoliberalizing processes. However, the oft-utilized analytical distinction between ‘pure’ economic and political theory and ‘messy’ empirical developments takes for granted that neoliberalism, at its core, valorizes free markets. In contrast, the paper explores whether neoliberal intellectuals ever made such an argument. Using Friedrich Hayek and Milton Friedman as exemplars, our reading of canonical neoliberal texts focuses on author framing gestures, particular understandings of the term ‘science’, techniques of characterization, and constructions of epistemological legitimacy. This enables us to avoid the trap of assuming that these texts are about free markets and instead enquires into their constitution as literary artefacts. As such, we argue that the remaking of states and households rather than the promotion of free markets is at the core of neoliberalism. Our analysis has significant implications. For example, it means that authoritarian neoliberalism is not a departure from but actually more in line with the ‘pure’ neoliberal canon than in the past. Therefore, neoliberalism ought to be critiqued not for its rhetorical promotion of free markets but instead for seeking to reorganize societies in coercive, non-democratic and unequal ways. This also enables us to acknowledge that households are central to resistance to neoliberalism as well as to the neoliberal worldview itself

Self-interest And Public Interest: The Motivations Of Political Actors

Self-Interest and Public Interest in Western Politics showed that the public, politicians, and bureaucrats are often public spirited. But this does not invalidate public-choice theory. Public-choice theory is an ideal type, not a claim that self-interest explains all political behavior. Instead, public-choice theory is useful in creating rules and institutions that guard against the worst case, which would be universal self-interestedness in politics. In contrast, the public-interest hypothesis is neither a comprehensive explanation of political behavior nor a sound basis for institutional design

Learning a Factor Model via Regularized PCA

We consider the problem of learning a linear factor model. We propose a regularized form of principal component analysis (PCA) and demonstrate through experiments with synthetic and real data the superiority of resulting estimates to those produced by pre-existing factor analysis approaches. We also establish theoretical results that explain how our algorithm corrects the biases induced by conventional approaches. An important feature of our algorithm is that its computational requirements are similar to those of PCA, which enjoys wide use in large part due to its efficiency

The Young and the Dustless: Interpreting Radio Observations of UltraViolet Luminous Galaxies

Ultraviolet Luminous Galaxies (UVLGs) have been identified as intensely star-forming, nearby galaxies. A subset of these, the supercompact UVLGs, are believed to be local analogs of high redshift Lyman Break Galaxies. Here we investigate the radio continuum properties of this important population for the first time. We have observed 42 supercompact UVLGs with the VLA, all of which have extensive coverage in the UV/optical by GALEX and SDSS. Our analysis includes comparison samples of multiwavelength data from the Spitzer First Look Survey and from the SDSS-Galex matched catalogs. In addition we have Spitzer MIPS data for 24 of our galaxies and find that they fall on the radio-FIR correlation of normal star-forming galaxies. We find that our galaxies have lower radio-to-UV ratios and lower Balmer decrements than other local galaxies with similar (high) star formation rates. Optical spectra show they have lower Dn(4000) and HdeltaA indices, higher Hbeta emission-line equivalents widths, and higher [OIII]5007/Hbeta emission-line ratios than normal star forming galaxies. Comparing these results to galaxy spectral evolution models we conclude that supercompact UVLGs are distinguished from normal star forming galaxies firstly by their high specific star formation rates. Moreover, compared to other types of galaxies with similar star formation rates, they have significantly less dust attenuation. In both regards they are similar to Lyman Break Galaxies. This suggests that the process that causes star formation in the supercompact UVLGs differs from other local star forming galaxies, but may be similar to Lyman Break Galaxies.Comment: 37 pages, 13 figures, accepted and scheduled to appear in ApJS December 2007 (GALEX Special Issue