Detection of neutral hydrogen in early-type dwarf galaxies of the Sculptor Group

We present our results of deep 21 cm line (HI) observations of five early and mixed-type dwarf galaxies in the nearby Sculptor group using the ATNF 64m Parkes Radio Telescope. Four of these objects, ESO294-G010, ESO410-G005, ESO540-G030, and ESO540-G032, were detected in HI with neutral hydrogen masses in the range of 2-9x10^5 M_{\odot} ($M_{HI}/L_{B}$ = 0.08, 0.13, 0.16, and 0.18, respectively). These HI masses are consistent with the gas mass expected from stellar outflows over a large period of time. Higher resolution radio data from the Australia Telescope Compact Array were further analysed to measure more accurate positions and the distribution of the HI gas. In the cases of dwarfs ESO294-G010 and ESO540-G030, we find significant offsets of 290 pc and 460 pc, respectively, between the position of the HI peak flux and the center of the stellar component. These offsets are likely to have internal cause such as the winds from star-forming regions. The fifth object, the spatially isolated dwarf elliptical Scl-dE1, remains undetected at our 3\sigma limit of 22.5 mJy km/s and thus must contain less than 10^5 M_{\odot} of neutral hydrogen. This leaves Scl-dE1 as the only Sculptor group galaxy known where no interstellar medium has been found to date. The object joins a list of similar systems including the Local Group dwarfs Tucana and Cetus that do not fit into the global picture of the morphology-density relation where gas-rich dwarf irregulars are in relative isolation and gas-deficient dwarf ellipticals are satellites of more luminous galaxies.Comment: 21 pages, 4 figures, to be published in AJ (accepted

Interstellar medium disruption in the Centaurus A group

We present the results of a 21 cm neutral hydrogen (HI) line detection experiment in the direction of 18 low luminosity dwarf galaxies of the Centaurus A group, using the Australia Telescope National Facility 64m Parkes Radio Telescope and the Australia Telescope Compact Array. Five dwarfs have HI masses between M_HI=4x10^5 to M_HI=2.1x10^7 Msol and 0.04<M_HI/L_B<1.81 Msol L_{sol, B}^-1. The other 13 have upper-limits between M_HI<5x10^5 and M_HI<4x10^6 Msol (M_HI}/L_B<0.24 Msol L_{sol, B}^-1). Two of the mixed-morphology dwarfs remain undetected in HI, a situation that is in contrast to that of similar Local Group and Sculptor group objects where all contain significant amounts of neutral gas. There is a discontinuity in the HI properties of Centaurus A group low luminosity dwarfs that is unobserved amongst Sculptor group dwarfs. All objects fainter than M_B=-13 have either M_HI>10^7 Msol or M_HI<10^6 Msol. This gap may be explained by the ram pressure stripping mechanism at work in this dense environment where all galaxies with M_HI<10^7 Msol have been stripped of their gas. The required intergalactic medium density to achieve this is ~10^-3 cm^-3.Comment: 7 figures, 2 table

Fast growth of magnetic fields in galaxy clusters: a self-accelerating dynamo

We propose a model of magnetic-field growth in galaxy clusters whereby the field is amplified by a factor of about 10^8 over a cosmologically short time of ~10^8 yr. Our model is based on the idea that the viscosity of the intracluster medium during the field-amplification epoch is determined not by particle collisions but by plasma microinstabilities: these give rise to small-scale fluctuations, which scatter particles, increasing their effective collision rate and, therefore, the effective Reynolds number. This gives rise to a bootstrap effect as the growth of the field triggers the instabilities which increase the Reynolds number which, in turn, accelerates the growth of the field. The growth is explosive and the result is that the observed field strength is reached over a fraction of the cluster lifetime independent of the exact strength of the seed field (which only needs to be above ~10^{-15} G to trigger the explosive growth).Comment: latex (AN style), 5 pages, 2 figure

The tale of two centres

We study motion in the field of two fixed centres described by a family of Einstein-dilaton-Maxwell theories. Transitions between regular and chaotic motion are observed as the dilaton coupling is varied.Comment: 20 pages, RevTeX, 7 figures included, TeX format change

Properties regulating the nature of the plasmacytoid dendritic cell response to Toll-like receptor 9 activation

Human plasmacytoid dendritic cells (PDCs) can produce interferon (IFN)-α and/or mature and participate in the adaptive immune response. Three classes of CpG oligonucleotide ligands for Toll-like receptor (TLR)9 can be distinguished by different sequence motifs and different abilities to stimulate IFN-α production and maturation of PDCs. We show that the nature of the PDC response is determined by the higher order structure and endosomal location of the CpG oligonucleotide. Activation of TLR9 by the multimeric CpG-A occurs in transferrin receptor (TfR)-positive endosomes and leads exclusively to IFN-α production, whereas monomeric CpG-B oligonucleotides localize to lysosome-associated membrane protein (LAMP)-1–positive endosomes and promote maturation of PDCs. However, CpG-B, when complexed into microparticles, localizes in TfR-positive endosomes and induces IFN-α from PDCs, whereas monomeric forms of CpG-A localize to LAMP-1–positive endosomes accompanied by the loss of IFN-α production and a gain in PDC maturation activity. CpG-C sequences, which induce both IFN-α and maturation of PDCs, are distributed in both type of endosomes. Encapsulation of CpG-C in liposomes stable above pH 5.75 completely abrogated the IFN-α response while increasing PDC maturation. This establishes that the primary determinant of TLR9 signaling is not valency but endosomal location and demonstrates a strict compartmentalization of the biological response to TLR9 activation in PDCs

Intragenic Meiotic Crossovers Generate Novel Alleles with Transgressive Expression Levels

Meiotic recombination is an evolutionary force that generates new genetic diversity upon which selection can act. Whereas multiple studies have assessed genome-wide patterns of recombination and specific cases of intragenic recombination, few studies have assessed intragenic recombination genome-wide in higher eukaryotes. We identified recombination events within or near genes in a population of maize recombinant inbred lines (RILs) using RNA-sequencing data. Our results are consistent with case studies that have shown that intragenic crossovers cluster at the 5\u27 ends of some genes. Further, we identified cases of intragenic crossovers that generate transgressive transcript accumulation patterns, that is, recombinant alleles displayed higher or lower levels of expression than did nonrecombinant alleles in any of ~100 RILs, implicating intragenic recombination in the generation of new variants upon which selection can act. Thousands of apparent gene conversion events were identified, allowing us to estimate the genome-wide rate of gene conversion at SNP sites (4.9 X 10-5). The density of syntenic genes (i.e., those conserved at the same genomic locations since the divergence of maize and sorghum) exhibits a substantial correlation with crossover frequency, whereas the density of nonsyntenic genes (i.e., those which have transposed or been lost subsequent to the divergence of maize and sorghum) shows little correlation, suggesting that crossovers occur at higher rates in syntenic genes than in nonsyntenic genes. Increased rates of crossovers in syntenic genes could be either a consequence of the evolutionary conservation of synteny or a biological process that helps to maintain synteny

Opinion: Why Protect Nature? Rethinking Values and the Environment

A cornerstone of environmental policy is the debate over protecting nature for humans’ sake (instrumental values) or for nature’s (intrinsic values) (1). We propose that focusing only on instrumental or intrinsic values may fail to resonate with views on personal and collective well-being, or “what is right,” with regard to nature and the environment. Without complementary attention to other ways that value is expressed and realized by people, such a focus may inadvertently promote worldviews at odds with fair and desirable futures. It is time to engage seriously with a third class of values, one with diverse roots and current expressions: relational values. By doing so, we reframe the discussion about environmental protection, and open the door to new, potentially more productive policy approaches

Ethical Considerations for the Participation of Children of Minor Parents in Clinical Trials.

Children of minor parents are under-represented in clinical trials. This is largely because of the ethical, legal, and regulatory complexities in the enrolment, consent, and appropriate access of children of minor parents to clinical research. Using a case-based approach, we examine appropriate access of children of minor parents in an international vaccine trial. We first consider the scientific justification for inclusion of children of minor parents in a vaccine trial. Laws and regulations governing consent generally do not address the issue of minor parents. In their absence, local community and cultural contexts may influence consent processes. Rights of the minor parent include dignity in their role as a parent and respect for their decision-making capacity in that role. Rights of the child include the right to have decisions made in their best interest and the right to the highest attainable standard of health. Children of minor parents may have vulnerabilities related to the age of their parent, such as increased rates of poverty, that have implications for consent. Neuroscience research suggests that, by age 12-14 years, minors have adult-level capacity to make research decisions in situations with low emotion and low distraction. We conclude with a set of recommendations based on these findings to facilitate appropriate access and equity related to the participation of children of minor parents in clinical research

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO