Super-solar N/C in the NLS1 Galaxy Markarian 1044

Narrow-Line Seyfert 1s (NLS1s) are known to have extreme values of a number of properties compared to Active Galactic Nuclei (AGN) as a class. In particular, previous emission-line studies have suggested that NLS1s are unusually metal rich compared to broad-line AGN of comparable luminosity. We present low- and medium-resolution spectroscopic observations of the NLS1 Markarian 1044 with the Hubble Space Telescope Imaging Spectrometer (STIS). We identify two blueshifted intrinsic absorption systems at -1145 and -295 km/s relative to the systemic velocity of the galaxy. Using a simple photoionization model of the absorbing gas, we find that the strongest and best-measured of the absorption systems has N/C approximately 6.96 times the solar value. We also report on the discovery of three new Ly-alpha forest lines with neutral Hydrogen column density log greater than 12.77 in the log. This number is consistent with the 2.6 expected in the path length to the source redshift of Mrk 1044.Comment: Submitted to ApJ. 21 pages including 4 figures & 5 table

Sand stress as a non-determinant of habitat segregation of indigenous (Perna perna) and invasive (Mytilus galloprovincialis) mussels in South Africa

Periodical sand inundation influences diversity and distribution of intertidal species throughout the world. This study investigates the effect of sand stress on survival and on habitat segregation of the two dominant mussel species living in South Africa, the invasive Mytilus galloprovincialis and the indigenous Perna perna. P. perna occupies a lower intertidal zone which, monthly surveys over 1.5 years showed, is covered by sand for longer periods than the higher M. galloprovincialis zone. Despite this, when buried under sand, P. perna mortality rates were significantly higher than those of M. galloprovincialis in both laboratory and in field experiments. Under anoxic condition, P. perna mortality rates were still significantly higher than those for M. galloprovincialis, but both species died later than when exposed to sand burial, underlining the importance of the physical action of sand on mussel internal organs. When buried, both species accumulate sediments within the shell valves while still alive, but the quantities are much greater for P. perna. This suggests that P. perna gills are more severely damaged by sand abrasion and could explain its higher mortality rates. M. galloprovincialis has longer labial palps than P. perna, indicating a higher particle sorting ability and consequently explaining its lower mortality rates when exposed to sand in suspension. Habitat segregation is often explained by physiological tolerances, but in this case, such explanations fail. Although sand stress strongly affects the survival of the two species, it does not explain their vertical zonation. Contrary to our expectations, the species that is less well adapted to cope with sand stress maintains dominance in a habitat where such stress is high

Neurological complications of sickle cell disease in Africa: protocol for a systematic review

INTRODUCTION: Sickle cell disease (SCD) is highly prevalent in Africa. Considered as a public health problem, it is associated with high morbidity and mortality. Neurological complications of SCD can cause significant disability with important socioeconomic and psychological impact on the patients and their families, and can even lead to death if not properly managed. There are important knowledge gaps regarding the burden of neurological complications of SCD in African populations. We propose to conduct the first systematic review to summarise the epidemiological data available on neurological complications of SCD in Africa. METHODS AND ANALYSIS: We will search PubMed, MEDLINE, EMBASE and the African Index Medicus from 1 January 1950 to 31 May 2016 for studies of neurological complications of SCD in Africa. After study selection, full-text paper acquisition, data extraction and synthesis, we will assess all studies for quality, risk of bias and heterogeneity. Appropriate methods of meta-analysis will be used to pool prevalence estimates from studies with similar features, globally and in major subgroups. This protocol complies with the 2015 Preferred Reporting Items for Systematic reviews and Meta-Analysis protocols (PRISMA-P) guidelines. ETHICS AND DISSEMINATION: The proposed study will use published data. Therefore, there is no requirement for ethical approval. This review is expected to provide relevant data to help quantify the burden of neurological complications of SCD in African populations, inform policymakers and identify further research topics. The final report of the systematic review will be published in a peer-reviewed journal and presented at conferences. REVIEW REGISTRATION NUMBER: CRD42016039574

Chandra Observation of 3C 212: a New Look at the X-ray and UV Absorbers

The red quasar 3C 212 (z=1.049) is one of the most distant and most luminous AGN which has shown evidence of an X-ray warm absorber. In order to further investigate this unusual quasar, we used Chandra/ACIS-S to observe 3C 212 for 19.5 ksec, resulting in a net detection of ~4000 counts. The Chandra data confirm the presence of an excess absorbing column N_H ~ 4 x 10^21 cm^-2 at the quasar redshift, but we find no compelling evidence for a warm absorber. Using both the Chandra and archival ROSAT PSPC data, we obtain very good fits for both a partially covered neutral absorber and a low-ionization (U = 0.03) photo-ionized absorber. In the ultraviolet, 3C 212 shows a strong associated MgII absorber. Based on a moderate resolution (80 km/s) MMT spectrum we show that the absorber is highly saturated and has a covering fraction less than 60%, implying that the absorber is truly intrinsic to the quasar. Photo-ionization modeling of the MgII absorber yields a constraint on the ionization parameter of U < 0.03, inconsistent with a warm UV/X-ray absorber. In addition to our spectral analysis, we find evidence in the ACIS image data for weak extended emission surrounding the quasar as well as emission corresponding to the radio lobes at a distance of 5 arcsec from 3C 212. The statistical significance of these features is low, but we briefly explore the implications if the detections are valid.Comment: 8 pages, 6 figures, Accepted for publication in the Astrophysical Journa

The distinct RNA-interaction modes of a small ZnF domain underlay TUT4(7) diverse action in miRNA regulation

TUT4 and the closely related TUT7 are non-templated poly(U) polymerases required at different stages of development, and their mis-regulation or mutation has been linked to important cancer pathologies. While TUT4(7) interaction with its pre-miRNA targets has been characterized in detail, the molecular bases of the broader target recognition process are unclear. Here, we examine RNA binding by the ZnF domains of the protein. We show that TUT4(7) ZnF2 contains two distinct RNA binding surfaces that are used in the interaction with different RNA nucleobases in different targets, i.e that this small domain encodes diversity in TUT4(7) selectivity and molecular function. Interestingly and unlike other well-characterized CCHC ZnFs, ZnF2 is not physically coupled to the flanking ZnF3 and acts independently in miRNA recognition, while the remaining CCHC ZnF of TUT4(7), ZnF1, has lost its intrinsic RNA binding capability. Together, our data suggest that the ZnFs of TUT4(7) are independent units for RNA and, possibly, protein-protein interactions that underlay the protein’s functional flexibility and are likely to play an important role in building its interaction network

X-Ray Light Curves of Gamma-ray Bursts Detected with the All-Sky Monitor on RXTE

We present X-ray light curves (1.5-12 keV) for fifteen gamma-ray bursts (GRBs) detected by the All-Sky Monitor on the Rossi X-ray Timing Explorer. We compare these soft X-ray light curves with count rate histories obtained by the high-energy (>12 keV) experiments BATSE, Konus-Wind, the BeppoSAX Gamma-Ray Burst Monitor, and the burst monitor on Ulysses. We discuss these light curves within the context of a simple relativistic fireball and synchrotron shock paradigm, and we address the possibility of having observed the transition between a GRB and its afterglow. The light curves show diverse morphologies, with striking differences between energy bands. In several bursts, intervals of significant emission are evident in the ASM energy range with little or no corresponding emission apparent in the high-energy light curves. For example, the final peak of GRB 970815 as recorded by the ASM is only detected in the softest BATSE energy bands. We also study the duration of bursts as a function of energy. Simple, singly-peaked bursts seem consistent with the E^{-0.5} power law expected from an origin in synchrotron radiation, but durations of bursts that exhibit complex temporal structure are not consistent with this prediction. Bursts such as GRB 970828 that show many short spikes of emission at high energies last significantly longer at low energies than the synchrotron cooling law would predict.Comment: 15 pages with 20 figures and 2 tables. In emulateapj format. Accepted by ApJ