73 research outputs found
New Classification of the Dictyostelids
Traditional morphology-based taxonomy of dictyostelids is rejected by molecular phylogeny. A new classification is presented based on monophyletic entities with consistent and strong molecular phylogenetic support and that are, as far as possible, morphologically recognizable. All newly named clades are diagnosed with small subunit ribosomal RNA (18S rRNA) sequence signatures plus morphological synapomorphies where possible. The two major molecular clades are given the rank of order, as Acytosteliales ord. nov. and Dictyosteliales. The two major clades within each of these orders are recognized and given the rank of family as, respectively, Acytosteliaceae and Cavenderiaceae fam. nov. in Acytosteliales, and Dictyosteliaceae and Raperosteliaceae fam. nov. in Dictyosteliales. Twelve genera are recognized: Cavenderia gen. nov. in Cavenderiaceae, Acytostelium, Rostrostelium gen. nov. and Heterostelium gen. nov. in Acytosteliaceae, Tieghemostelium gen. nov., Hagiwaraea gen. nov., Raperostelium gen. nov. and Speleostelium gen. nov. in Raperosteliaceae, and Dictyostelium and Polysphondylium in Dictyosteliaceae. The polycephalum complex is treated as Coremiostelium gen. nov. (not assigned to family) and the polycarpum complex as Synstelium gen. nov. (not assigned to order and family). Coenonia, which may not be a dictyostelid, is treated as a genus incertae sedis. Eighty-eight new combinations are made at species and variety level, and Dictyostelium ammophilum is validated
An expanded phylogeny of social amoebas (Dictyostelia) shows increasing diversity and new morphological patterns
<p>Abstract</p> <p>Background</p> <p>Social Amoebae or Dictyostelia are eukaryotic microbes with a unique life cycle consisting of both uni- and multicellular stages. They have long fascinated molecular, developmental and evolutionary biologists, and <it>Dictyostelium discoideum </it>is now one of the most widely studied eukaryotic microbial models. The first molecular phylogeny of Dictyostelia included most of the species known at the time and suggested an extremely deep taxon with a molecular depth roughly equivalent to Metazoa. The group was also shown to consist of four major clades, none of which correspond to traditional genera. Potential morphological justification was identified for three of the four major groups, on the basis of which tentative names were assigned.</p> <p>Results</p> <p>Over the past four years, the Mycetozoan Global Biodiversity Survey has identified many new isolates that appear to be new species of Dictyostelia, along with numerous isolates of previously described species. We have determined 18S ribosomal RNA gene sequences for all of these new isolates. Phylogenetic analyses of these data show at least 50 new species, and these arise from throughout the dictyostelid tree breaking up many previously isolated long branches. The resulting tree now shows eight well-supported major groups instead of the original four. The new species also expand the known morphological diversity of the previously established four major groups, violating nearly all previously suggested deep morphological patterns.</p> <p>Conclusions</p> <p>A greatly expanded phylogeny of Dictyostelia now shows even greater morphological plasticity at deep taxonomic levels. In fact, there now seem to be no obvious deep evolutionary trends across the group. However at a finer level, patterns in morphological character evolution are beginning to emerge. These results also suggest that there is a far greater diversity of Dictyostelia yet to be discovered, including novel morphologies.</p
First-year Sloan Digital Sky Survey-II (SDSS-II) Supernova Results: Hubble Diagram and Cosmological Parameters
We present measurements of the Hubble diagram for 103 Type Ia supernovae
(SNe) with redshifts 0.04 < z < 0.42, discovered during the first season (Fall
2005) of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. These data
fill in the redshift "desert" between low- and high-redshift SN Ia surveys. We
combine the SDSS-II measurements with new distance estimates for published SN
data from the ESSENCE survey, the Supernova Legacy Survey, the Hubble Space
Telescope, and a compilation of nearby SN Ia measurements. Combining the SN
Hubble diagram with measurements of Baryon Acoustic Oscillations from the SDSS
Luminous Red Galaxy sample and with CMB temperature anisotropy measurements
from WMAP, we estimate the cosmological parameters w and Omega_M, assuming a
spatially flat cosmological model (FwCDM) with constant dark energy equation of
state parameter, w. For the FwCDM model and the combined sample of 288 SNe Ia,
we find w = -0.76 +- 0.07(stat) +- 0.11(syst), Omega_M = 0.306 +- 0.019(stat)
+- 0.023(syst) using MLCS2k2 and w = -0.96 +- 0.06(stat) +- 0.12(syst), Omega_M
= 0.265 +- 0.016(stat) +- 0.025(syst) using the SALT-II fitter. We trace the
discrepancy between these results to a difference in the rest-frame UV model
combined with a different luminosity correction from color variations; these
differences mostly affect the distance estimates for the SNLS and HST
supernovae. We present detailed discussions of systematic errors for both
light-curve methods and find that they both show data-model discrepancies in
rest-frame -band. For the SALT-II approach, we also see strong evidence for
redshift-dependence of the color-luminosity parameter (beta). Restricting the
analysis to the 136 SNe Ia in the Nearby+SDSS-II samples, we find much better
agreement between the two analysis methods but with larger uncertainties.Comment: Accepted for publication by ApJ
Errors, biases, and corrections for weighing gauge precipitation measurements from WMO-SPICE
Presentación realizada en: American Meteorological Society Annual Meeting (2017) celebrado en Seattle (Washington) del 22 al 26 de enero de 2017
Errors, Biases, and Corrections for Weighing Gauge Precipitation Measurements from the WMO Solid Precipitation Intercomparison Experiment
Comunicación presentada en: TECO-2016 (Technical Conference on Meteorological and Environmental Instruments and Methods of Observation) celebrada en Madrid, del 27 al 30 de septiembre de 2016.Although precipitation has been measured for many centuries, precipitation measurements are still beset with significant biases and errors. Solid precipitation is particularly difficult to measure accurately, and biases between winter-time precipitation measurements from different measurement networks or different regions can exceed 100%. Using precipitation gauge results from the WMO Solid Precipitation Intercomparison Experiment (WMO-SPICE), errors in precipitation measurement caused by gauge uncertainty, spatial variability in precipitation, hydrometeor type, and wind are quantified. The methods used to calculate gauge catch efficiency and correct known biases are described briefly. Transfer functions describing catch efficiency as a function of air temperature and wind speed are also presented. In addition, the biases and errors associated with the use of a single transfer function to correct gauge undercatch at multiple sites are discussed
The Tully-Fisher relations of the Eridanus group of galaxies
The Tully-Fisher (TF) or the luminosity line-width relations of the galaxies
in the Eridanus group are constructed using the HI rotation curves and the
luminosities in the optical and in the near-infrared bands. The slopes of the
TF relations (absolute magnitude vs log2V_{flat}) are -8.6\pm1.1, -10.0\pm1.5,
-10.7\pm2.1, and -9.7\pm1.3 in the R, J, H, and K bands respectively for
galaxies having flat HI rotation curves. These values of the slopes are
consistent with those obtained from studies of other groups and clusters. The
scatter in the TF relations is in the range 0.5 - 1.1 mag in different bands.
This scatter is considerably larger compared to those observed in other groups
and clusters. It is suggested that the larger scatter in the TF relations for
the Eridanus group is related to the loose structure of the group. If the TF
relations are constructed using the baryonic mass (stellar + HI + Helium mass)
instead of the stellar luminosity, nearly identical slopes are obtained in the
R and in the near-infrared bands. The baryonic TF (baryonic mass vs
log2V_{flat}) slope is in the range 3.5 - 4.1.Comment: 20 pages, 3 figures, Submitted to Journal of Astrophysics & Astronomy
(Revised after referee's comments
The Solar Neighborhood XXIII CCD Photometric Distance Estimates of SCR Targets -- 77 M Dwarf Systems within 25 Parsecs
We present CCD photometric distance estimates of 100 SCR (SuperCOSMOS RECONS)
systems with 0\farcs18/yr, 28 of which are new discoveries
previously unpublished in this series of papers. These distances are estimated
using a combination of new photometry acquired at CTIO and
magnitudes extracted from 2MASS. The estimates are improvements over those
determined using photographic plate magnitudes from SuperCOSMOS plus
, as presented in the original discovery papers. In total, 77 of the 100
systems investigated are predicted to be within 25 pc. If all 77 systems are
confirmed to have 40 milliarcseconds, this sample would
represent a 23% increase in M dwarf systems nearer than 25 pc in the southern
sky.Comment: 34 pages, 8 figure
Influenza Infection in Wild Raccoons
Raccoons can transmit avian and human influenza Influenza Infection in Wild Raccoon
A Novel Anti-Influenza Copper Oxide Containing Respiratory Face Mask
Protective respiratory face masks protect the nose and mouth of the wearer from vapor drops carrying viruses or other infectious pathogens. However, incorrect use and disposal may actually increase the risk of pathogen transmission, rather than reduce it, especially when masks are used by non-professionals such as the lay public. Copper oxide displays potent antiviral properties. A platform technology has been developed that permanently introduces copper oxide into polymeric materials, conferring them with potent biocidal properties.. The copper oxide containing masks successfully passed Bacterial Filtration Efficacy, Differential Pressure, Latex Particle Challenge, and Resistance to Penetration by Synthetic Blood tests designed to test the filtration properties of face masks in accordance with the European EN 14683:2005 and NIOSH N95 standards.Impregnation of copper oxide into respiratory protective face masks endows them with potent anti-influenza biocidal properties without altering their physical barrier properties. The use of biocidal masks may significantly reduce the risk of hand or environmental contamination, and thereby subsequent infection, due to improper handling and disposal of the masks
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