Luminescence spectroscopy of matrix-isolated z 6P state atomic manganese

The relaxation of electronically excited atomic manganese isolated in solid rare gas matrices is observed from recorded emission spectra, to be strongly site specific. z 6P state excitation of Mn atoms isolated in the red absorption site in Ar and Kr produces narrow a 4D and a 6D state emissions while blue-site excitation produces z 6P state fluorescence and broadened a 4D and a 6D emissions. Mn/Xe exhibits only a single thermally stable site whose emission at 620 nm is similar to the broad a 6D bands produced with blue-site excitation in Ar and Kr. Thus in ArsKrd, excitation of the red site at 393 s400d nm produces narrow line emissions at 427.5 s427.8d and 590 s585.7d nm. From their spectral positions, linewidths, and long decay times, these emission bands are assigned to the a 4D7/2 and a 6D9/2 states, respectively. Excitation of the blue site at 380 s385.5d nm produces broad emission at 413 s416d nm which, because of its nanosecond radiative lifetime, is assigned to resonance z 6P!a 6S fluorescence. Emission bands at 438 s440d and 625 s626.8d nm, also produced with blue-site excitation, are broader than their red-site equivalents at 427.5 and 590 nm s427.8 and 585.7 nm in Krd but from their millisecond and microsecond decay times are assigned to the a 4D and a 6D states. The line features observed in high resolution scans of the red-site emission at 427.5 and 427.8 nm in Mn/Ar and Mn/ Kr, respectively, have been analyzed with the Wp optical line shape function and identified as resolved phonon structure originating from very weak sS=0.4d electron-phonon coupling. The presence of considerable hot-phonon emission seven in 12 K spectrad and the existence of crystal field splittings of 35 and 45 cmâ1 on the excited a 4D7/2 level in Ar and Kr matrices have been identified in Wp line shape fits. The measured matrix lifetimes for the narrow red-site a 6D state emissions s0.29 and 0.65 msd in Ar and Kr are much shorter than the calculated s3 sd gas phase value. With the lifetime of the metastable a 6D9/2 state shortened by four orders of magnitude in the solid rare gases, it is clear that the probability of the âforbiddenâ a 6D!a 6S atomic transition is greatly enhanced in the solid state. A novel feature identified in the present work is the large width and shifted 4D and 6D emissions produced for Mn atoms isolated in the blue sites of Ar and Kr. In contrast, these states produce narrow, unshifted sgas-phase-liked 4D and 6D state emissions from the red site

Anthrax Toxin Receptor 2 Determinants that Dictate the pH Threshold of Toxin Pore Formation

The anthrax toxin receptors, ANTXR1 and ANTXR2, act as molecular clamps to prevent the protective antigen (PA) toxin subunit from forming pores until exposure to low pH. PA forms pores at pH ∼6.0 or below when it is bound to ANTXR1, but only at pH ∼5.0 or below when it is bound to ANTXR2. Here, structure-based mutagenesis was used to identify non-conserved ANTXR2 residues responsible for this striking 1.0 pH unit difference in pH threshold. Residues conserved between ANTXR2 and ANTXR1 that influence the ANTXR2-associated pH threshold of pore formation were also identified. All of these residues contact either PA domain 2 or the neighboring edge of PA domain 4. These results provide genetic evidence for receptor release of these regions of PA as being necessary for the protein rearrangements that accompany anthrax toxin pore formation

Controlled eutrophication system and process

A controlled eutrophication system and process are disclosed. The system includes the combination of a partitioned aquaculture system in conjunction with an anaerobic digester. Wastewater containing pollutants, such as nitrogen and phosphorus, are fed to the partitioned aquaculture system. Algae within the system converts the pollutants into algal biomass. Fish populations, in turn, control the algal populations. The fish populations may then be periodically harvested for human or animal consumption. A polishing chamber is contained in the system in which aquatic organisms remove substantial amounts of the algae from batch fed additions of water. The water is then discharged to an external water source containing virtually no pollutants. In one embodiment, the biomass excreted by the aquatic organisms in the system are collected and fed to a digester. In the digester, the biomass is converted to a hydrocarbon gas and collected for its fuel value, while the liquid fraction is collected for its fertilizer value

Sub-m s−1^{-1} upper limits from a deep HARPS-N radial-velocity search for planets orbiting HD 166620 and HD 144579

Minimising the impact of stellar variability in Radial Velocity (RV) measurements is a critical challenge in achieving the 10 cm s$^{-1}$ precision needed to hunt for Earth twins. Since 2012, a dedicated programme has been underway with HARPS-N, to conduct a blind RV Rocky Planets Search (RPS) around bright stars in the Northern Hemisphere. Here we describe the results of a comprehensive search for planetary systems in two RPS targets, HD 166620 and HD 144579. Using wavelength-domain line-profile decorrelation vectors to mitigate the stellar activity and performing a deep search for planetary reflex motions using a trans-dimensional nested sampler, we found no significant planetary signals in the data sets of either of the stars. We validated the results via data-splitting and injection recovery tests. Additionally, we obtained the 95th percentile detection limits on the HARPS-N RVs. We found that the likelihood of finding a low-mass planet increases noticeably across a wide period range when the inherent stellar variability is corrected for using scalpels U-vectors. We are able to detect planet signals with $M\sin i \leq 1$ M$_\oplus$ for orbital periods shorter than 10 days. We demonstrate that with our decorrelation technique, we are able to detect signals as low as 54 cm s$^{-1}$, which brings us closer to the calibration limit of 50 cm s$^{-1}$ demonstrated by HARPS-N. Therefore, we show that we can push down towards the RV precision required to find Earth analogues using high-precision radial velocity data with novel data-analysis techniques.Comment: 7 tables, 24 figures (including those in appendix

AVERT2(a very early rehabilitation trial, a very effective reproductive trigger): retrospective observational analysis of the number of babies born to trial staff

Objective: To report the number of participants needed to recruit per baby born to trial staff during AVERT, a large international trial on acute stroke, and to describe trial management consequences. Design: Retrospective observational analysis. Setting: 56 acute stroke hospitals in eight countries. Participants: 1074 trial physiotherapists, nurses, and other clinicians. Outcome measures: Number of babies born during trial recruitment per trial participant recruited. Results: With 198 site recruitment years and 2104 patients recruited during AVERT, 120 babies were born to trial staff. Births led to an estimated 10% loss in time to achieve recruitment. Parental leave was linked to six trial site closures. The number of participants needed to recruit per baby born was 17.5 (95% confidence interval 14.7 to 21.0); additional trial costs associated with each birth were estimated at 5736 Australian dollars on average. Conclusion: The staff absences registered in AVERT owing to parental leave led to delayed trial recruitment and increased costs, and should be considered by trial investigators when planning research and estimating budgets. However, the celebration of new life became a highlight of the annual AVERT collaborators’ meetings and helped maintain a cohesive collaborative group

Aryl Hydrocarbon Receptor–Independent Toxicity of Weathered Crude Oil during Fish Development

Polycyclic aromatic hydrocarbons (PAHs), derived largely from fossil fuels and their combustion, are pervasive contaminants in rivers, lakes, and nearshore marine habitats. Studies after the Exxon Valdez oil spill demonstrated that fish embryos exposed to low levels of PAHs in weathered crude oil develop a syndrome of edema and craniofacial and body axis defects. Although mechanisms leading to these defects are poorly understood, it is widely held that PAH toxicity is linked to aryl hydrocarbon receptor (AhR) binding and cytochrome P450 1A (CYP1A) induction. Using zebrafish embryos, we show that the weathered crude oil syndrome is distinct from the well-characterized AhR-dependent effects of dioxin toxicity. Blockade of AhR pathway components with antisense morpholino oligonucleotides demonstrated that the key developmental defects induced by weathered crude oil exposure are mediated by low-molecular-weight tricyclic PAHs through AhR-independent disruption of cardiovascular function and morphogenesis. These findings have multiple implications for the assessment of PAH impacts on coastal habitats

HST Observations of Heavy Elements in Metal-Poor Galactic Halo Stars

We present new abundance determinations of neutron-capture elements Ge, Zr, Os, Ir, and Pt in a sample of 11 metal-poor (-3.1 <= [Fe/H] <= -1.6) Galactic halo giant stars, based on Hubble Space Telescope UV and Keck I optical high-resolution spectroscopy. The stellar sample is dominated by r-process-rich stars such as the well-studied CS 22892-052 and bd+173248, but also includes the r-process-poor, bright giant HD 122563. Our results demonstrate that abundances of the 3rd r-process peak elements Os, Ir and Pt in these metal-poor halo stars are very well-correlated among themselves, and with the abundances of the canonical r-process element Eu (determined in other studies), thus arguing for a common origin or site for r-process nucleosynthesis of heavier (Z>56) elements. However, the large (and correlated) scatters of [Eu,Os,Ir,Pt/Fe] suggests that the heaviest neutron-capture r-process elements are not formed in all supernovae. In contrast, the Ge abundances of all program stars track their Fe abundances, very well. An explosive process on iron-peak nuclei (e.g., the alpha-rich freeze-out in supernovae), rather than neutron capture, appears to have been the dominant synthesis mechanism for this element at low metallicities -- Ge abundances seem completely uncorrelated with Eu.Comment: 35 pages, 5 tables, 7 figures; To appear in the Astrophysical Journa

Anthrax Toxin Receptor 2–Dependent Lethal Toxin Killing In Vivo

Anthrax toxin receptors 1 and 2 (ANTXR1 and ANTXR2) have a related integrin-like inserted (I) domain which interacts with a metal cation that is coordinated by residue D683 of the protective antigen (PA) subunit of anthrax toxin. The receptor-bound metal ion and PA residue D683 are critical for ANTXR1-PA binding. Since PA can bind to ANTXR2 with reduced affinity in the absence of metal ions, we reasoned that D683 mutant forms of PA might specifically interact with ANTXR2. We show here that this is the case. The differential ability of ANTXR1 and ANTXR2 to bind D683 mutant PA proteins was mapped to nonconserved receptor residues at the binding interface with PA domain 2. Moreover, a D683K mutant form of PA that bound specifically to human and rat ANTXR2 mediated killing of rats by anthrax lethal toxin, providing strong evidence for the physiological importance of ANTXR2 in anthrax disease pathogenesis

Novel pathogenic COX20 variants causing dysarthria, ataxia, and sensory neuropathy.

COX20/FAM36A encodes a mitochondrial complex IV assembly factor important for COX2 activation. Only one homozygous COX20 missense mutation has been previously described in two separate consanguineous families. We report four subjects with features that include childhood hypotonia, areflexia, ataxia, dysarthria, dystonia, and sensory neuropathy. Exome sequencing in all four subjects identified the same novel COX20 variants. One variant affected the splice donor site of intron-one (c.41A&gt;G), while the other variant (c.157+3G&gt;C) affected the splice donor site of intron-two. cDNA and protein analysis indicated that no full-length cDNA or protein was generated. These subjects expand the phenotype associated with COX20 deficiency

The Rise of the s-Process in the Galaxy

From newly-obtained high-resolution, high signal-to-noise ratio spectra the abundances of the elements La and Eu have been determined over the stellar metallicity range -3<[Fe/H]<+0.3 in 159 giant and dwarf stars. Lanthanum is predominantly made by the s-process in the solar system, while Eu owes most of its solar system abundance to the r-process. The changing ratio of these elements in stars over a wide metallicity range traces the changing contributions of these two processes to the Galactic abundance mix. Large s-process abundances can be the result of mass transfer from very evolved stars, so to identify these cases, we also report carbon abundances in our metal-poor stars. Results indicate that the s-process may be active as early as [Fe/H]=-2.6, alalthough we also find that some stars as metal-rich as [Fe/H]=-1 show no strong indication of s-process enrichment. There is a significant spread in the level of s-process enrichment even at solar metallicity.Comment: 64 pages, 15 figures; ApJ 2004 in pres