Transcriptomic, Functional, and Network Analyses Reveal Novel Genes Involved in the Interaction between \u3ci\u3eCaenorhabditis elegans\u3c/i\u3e and \u3ci\u3eStenotrophomonas maltophilia\u3c/i\u3e

The bacterivorous nematode Caenorhabditis elegans is an excellent model for the study of innate immune responses to a variety of bacterial pathogens, including the emerging nosocomial bacterial pathogen Stenotrophomonas maltophilia. The study of this interaction has ecological and medical relevance as S. maltophilia is found in association with C. elegans and other nematodes in the wild and is an emerging opportunistic bacterial pathogen. We identified 393 genes that were differentially expressed when exposed to virulent and avirulent strains of S.maltophilia and an avirulent strain of E. coli. We then used a probabilistic functional gene network model (WormNet) to determine that 118 of the 393 differentially expressed genes formed an interacting network and identified a set of highly connected genes with eight or more predicted interactions.We hypothesized that these highly connected genes might play an important role in the defense against S. maltophila and found that mutations of six of seven highly connected genes have a significant effect on nematode survival in response to these bacteria. Of these genes, C48B4.1, mpk-2, cpr-4, clec-67, and lys-6 are needed for combating the virulent S. maltophilia JCMS strain, while dod-22 was solely involved in response to the avirulent S. maltophilia K279a strain. We further found that dod-22 and clec-67 were up regulated in response to JCMS vs. K279a, while C48B4.1, mpk-2, cpr-4, and lys-6 were down regulated. Only dod-22 had a documented role in innate immunity, which demonstrates the merit of our approach in the identification of novel genes that are involved in combating S. maltophilia infection

Why stellar feedback promotes disc formation in simulated galaxies

We study how feedback influences baryon infall onto galaxies using cosmological, zoom-in simulations of haloes with present mass $M_{vir}=6.9\times10^{11} M_{\odot}$ to $1.7\times10^{12} M_{\odot}$. Starting at z=4 from identical initial conditions, implementations of weak and strong stellar feedback produce bulge- and disc-dominated galaxies, respectively. Strong feedback favours disc formation: (1) because conversion of gas into stars is suppressed at early times, as required by abundance matching arguments, resulting in flat star formation histories and higher gas fractions; (2) because 50% of the stars form in situ from recycled disc gas with angular momentum only weakly related to that of the z=0 dark halo; (3) because late-time gas accretion is typically an order of magnitude stronger and has higher specific angular momentum, with recycled gas dominating over primordial infall; (4) because 25-30% of the total accreted gas is ejected entirely before z~1, removing primarily low angular momentum material which enriches the nearby inter-galactic medium. Most recycled gas roughly conserves its angular momentum, but material ejected for long times and to large radii can gain significant angular momentum before re-accretion. These processes lower galaxy formation efficiency in addition to promoting disc formation.Comment: 23 pages, 29 figures, accepted for publication in MNRA

The photochemical isomerisation and acid/base rectivity of pyrazolotriazole azomethine dyes.

This thesis deals with two aspects of the chemistry of pyrazolotriazole azomethine dyes (PT dyes): a), the kinetics and yield of photoinduced isomerisation and b). the kinetics of dye hydrolysis in acidic and basic media. Microsecond flash photolysis has been used to investigate the effects of solvent, excitation wavelength and oxygen on the yields of photoinduced isomerisation for a range of pyrazolotriazole azomethine dyes substituted at the 6-position. The rates of thermal relaxation show no obvious dependence on solvent solvatochromic parameters examined; this suggests that solvent factors such as dielectric properties and basicity are not uniquely significant in determining the relaxation times of the dye isomers. The isomer yields for the two dyes examined with substituents which contained the carbonyl group, i.e. 6CO2Et-PT and 2COPh-PT show an unexpected dependency on excitation wavelength and on the presence or absence of oxygen. It is tentatively suggested that this is a consequence of the availability of substituent localised carbonyl excited states for these dyes. It is suggested that these states are populated by uv excitation to give a localised carbonyl triplet state which can undergo energy transfer into the pyrazolotriazole azomethine triplet state leading to relatively efficient isomerisation via the triplet manifold. There was no change observed in isomer yield when using ethyl-iodide in a nitrogen saturated solution with either 6CO2Et-PT or 6COPh-PT dyes indicating no effective external heavy atom effect from this solvent. In acid media, the pyrazolotriazole azomethine dyes undergo hydrolysis with first order kinetics. Arrhenius constants and pre-exponential constants were measured for a number of different dyes. Base hydrolyses of the 6CO2Et-PT and 6COPh-PT dyes showed second order kinetics. Preliminary investigations of acid catalysed decomposition using millisecond stopped flow suggest a complex reaction scheme involving, possibly, three successive reactions

Single-photon threshold photoionization of NO

Single‐photon threshold photoionization spectra for jet‐cooled NO have been measured for the v^+=0 and 1 vibrational levels of the X ^1Σ^+ ground state of NO^+. The NO^+ rotational state distribution for the v^+=0 level is shown to be perturbed by nearby autoionizing levels, whereas the v^+=1 level exhibits a cation rotational distribution which is in near quantitative agreement with calculated spectra near threshold. Only small changes in total angular momentum are observed (‖ΔJ‖=‖J^+ − J‘‖≤5/2) even though a wide range of photoelectron angular momenta (l=0–3) are predicted to contribute to the near‐threshold photoelectron continua. The present results are also discussed in light of recently published two‐photon threshold photoionization spectra of NO which exhibit nearly identical NO^+ rotational state distributions

Dynamical evolution of globular cluster systems in clusters of galaxies I. The case of NGC 1404 in the Fornax cluster

We investigate, via numerical simulations, the tidal stripping and accretion of globular clusters (GCs). In particular, we focus on creating models that simulate the situation for the GC systems of NGC 1404 and NGC 1399 in the Fornax cluster, which have poor (specific frequency $S_{\rm N}$ $\sim$ 2) and rich ($S_{\rm N}$ $\sim$ 10) GC systems respectively. We initially assign NGC 1404 in our simulation a typical $S_{\rm N}$ ($\sim$ 5) for cluster ellipticals, and find that its GC system can only be reduced through stripping to the presently observed value, if its orbit is highly eccentric (with orbital eccentricity of $>$ 0.5) and if the initial scale length of the GCs system is about twice as large as the effective radius of NGC 1404 itself. These stripped GCs can be said to have formed a `tidal stream' of intracluster globular clusters (ICGCs) orbiting the centre of Fornax cluster (many of which would be assigned to NGC 1399 in an imaging study). The physical properties of these GCs (e.g., number, radial distribution) depend on the orbit and initial distribution of GCs in NGC 1404. Our simulations also predict a trend for $S_{\rm N}$ to rise with increasing clustercentric distance - a trend for which there is some observational support in the Fornax cluster.Comment: 12 pages 12 figures, MNRAS in pres

Polymerisable octahedral rhenium cluster complexes as precursors for photo/electroluminescent polymers

New polymerisable photoluminescent octahedral rhenium cluster complexes trans-[{Re₆Q₈}(TBP)₄VB)₂] (Q = S or Se; TBP – p-tert-butylpyridine; VB – vinyl benzoate) have been synthesised, characterised and used to construct rhe-nium cluster-organic polymer hybrid materials. These novel polymer systems are solution-processable and the rhenium clusters retain their photoluminescent properties within the polymer environment. Notably, when the rhenium cluster complexes are incorporated into the matrix of the electroluminescent polymer poly(N-vinylcarbazole), the resultant cluster polymer hybrid combined properties of both components and was used successfully in the construc-tion of a polymer light emitting diode (PLED). These prototype devices are the first PLEDs to incorporate octahedral rhenium clusters and provide the first direct evidence of the electroluminescent properties of rhenium clusters and indeed, to the best of our knowledge, of any member of the family of 24-electron hexanuclear cluster complexes of molybdenum, tungsten or rhenium

Semileptonic BcB_c Decay and Heavy Quark Spin Symmetry

Semileptonic decay of the $B_c$ meson is studied in the heavy quark limit. The six possible form factors for $B_c \rightarrow B_s (B^0),B_s^* (B^{*0})$ semileptonic decay are determined by two invariant functions. Only one of these functions contributes at zero recoil, where it is calculable to lowest order in an operator product expansion in terms of the meson decay constant $f_B$ and the $B_c$ wavefunction. A similar result is found for $B_c \rightarrow D^0,D^{*0}$ and for $B_c\rightarrow\eta_c,J/\psi$ semileptonic decay for a restricted kinematic region. Semileptonic $B_c$ decay provides a means for determining the KM mixing angle $|V_{ub}|$.Comment: (12 Pages, no figures

Development of Occupant-Preferred Landing Profiles for Personal Aerial Vehicles

With recent increased interest in autonomous vehicles and the associated technology, the prospect of realizing a personal aerial vehicle (PAV) seems closer than ever. However, there is likely to be a continued requirement for any occupant of an air vehicle to be comfortable with both the automated portions of the flight and their ability to take manual control as and when required. This paper, using the approach to landing as an example maneuver, examines what a comfortable trajectory for PAV occupants might look like. Based upon simulated flight data, a ‘natural’ flight trajectory was designed and then compared to constant deceleration and constant optic flow descent profiles. It was found that PAV occupants with limited flight training and no artificial guidance followed the same longitudinal trajectory as had been found for professionally trained helicopter pilots. Further, the final stages of the approach to hover could be well described using Tau Theory. For automatic flight, PAV occupants preferred a constant deceleration profile. For approaches flown manually, the newly designed natural profile was preferred

Telemetric Observations of Foraging Ozark Big-Eared Bats in Arkansas

Ozark big-eared bat (Corynorhinus townsendii ingens) foraging activities were studied during 1995 in Marion County, Arkansas. Adult bats were equipped with radiotransmitters and tracked during June and July. Foraging activities were generally within 1 kilometer (km) of the roost cave. Male bats ranged farther than females with the exception of one female that flew 2.5 km into a different watershed. Male big-eared bats and northern long-eared bats (Myotis septentrionalis) were also found within the maternity colony