4,323 research outputs found
A new species of Monanthotaxis from Gabon with a unique inflorescence type for Annonaceae
Monanthotaxis Baillon (1890: 878) currently consists of 56 species (Rainer & Chatrou 2006) confined to tropical Africa and Madagascar and is the second most species-rich genus of Annonaceae in Africa after Uvaria Linnaeus (1753: 536). Both genera belong to the tribe Uvarieae Hooker & Thomson (1855: 91, 92). Circumscription of this tribe has recently been modified to comply with the principle of monophyly, and it now almost exclusively consists of climbing species, all from the Old World tropics (Chatrou et al. 2012). Generic circumscription within Uvarieae has been in disarray for considerable time. Delimitation of Uvaria and related genera has recently been modified based on phylogenetic relationships (Zhou et al. 2010, Zhou et al. 2009). Monanthotaxis was monophyletic in Wang et al. (2012), based on a limited sampling of seven species. Subsequent study with increased sampling (Hoekstra, unpub.) has revealed that the African species of Friesodielsia van Steenis (1948: 458) and Exellia Boutique (1951b: 117) are nested in Monanthotaxis. Whatever the solution and taxonomic consequences, the name Monanthotaxis with the type Monanthotaxis congoensis Baillon (1890: 879) will be retained as it is the oldest valid generic name. Along with phylogenetic analysis, we are conducting a taxonomic revision. The last revision of Monanthotaxis and allied genera was published over a century ago by Engler & Diels (1901). Since then, only contributions to local floras have been published (e.g. Boutique 1951a, Le Thomas 1969, Robson 1960, Verdcourt 1971a). While studying the material of Monanthotaxis, we encountered a remarkable new species, which differs from all other species of Annonaceae in its large and lax panicle-like inflorescence. Panicle-like inflorescences are rare in Annonaceae, and those that have been recorded are either congested, as in e.g. Unonopsis and Guatteria (Erkens et al. 2008, Maas et al. 2007), or with only a few flowers, as in Monanthotaxis le-testui Pellegrin (1950: 75). This new species is probably closely related to M. congoensis since they share several characters. Verdcourt (1971b) divided the genus in three subgenera and five sections. In his classification, this new species would join M. congoensis in the typical section Monanthotaxis, which is easily distinguished by having flowers with the four to six petals in a single whorl and less than 17 stamens. Because it is so similar to M. congoensis, our new species will almost certainly be classified within Monanthotaxis, and we decided to publish it before a new generic classification has been completed
A nonet of novel species of Monanthotaxis (Annonaceae) from around Africa
As part of an ongoing revision of the genus Monanthotaxis Baill. (Annonaceae), nine new species are described and one variety is reinstated to species rank. Two new species from West Africa (Monanthotaxis aquila P.H. Hoekstra, sp. nov. and Monanthotaxis atewensis P.H. Hoekstra, sp. nov.), four new species from Central Africa (Monanthotaxis couvreurii P.H. Hoekstra, sp. nov., Monanthotaxis latistamina P.H. Hoekstra, sp. nov., Monanthotaxis tripetala P.H. Hoekstra, sp. nov. and Monanthotaxis zenkeri P.H. Hoekstra, sp. nov.), one new species from Tanzania (Monanthotaxis filipes P.H. Hoekstra, sp. nov.), one new species from the area around Maputo (Monanthotaxis maputensis P.H. Hoekstra, sp. nov.), one new species from the Comoro Islands (Monanthotaxis komorensis P.H. Hoekstra, sp. nov.) and Monanthotaxis klainei (Engl.) Verdc. var. angustifolia (Boutique) Verdc. is raised to species level leading to the replacement name Monanthotaxis atopostema P.H. Hoekstra, nom. nov. (not Monanthotaxis angustifolia (Exell) Verdc.). Complete descriptions, comparisons with related species, ecological information and IUCN conservation assessments are given for the new species. Five species were classified as critical endangered, two species as endangered, one as vulnerable and one as least concern, warranting the need of further collecting and studying those species
PKS 1004+13: A High-Inclination, Highly-Absorbed Radio-Loud QSO -- The First Radio-Loud BAL QSO at Low Redshift?
The existence of BAL outflows in only radio-quiet QSOs was thought to be an
important clue to mass ejection and the radio-loud - radio-quiet dichotomy.
Recently a few radio-loud BAL QSOs have been discovered at high redshift. We
present evidence that PKS 1004+13 is a radio-loud BAL QSO. It would be the
first known at low-redshift (z = 0.24), and one of the most radio luminous. For
PKS 1004+13, there appear to be broad absorption troughs of O VI, N V, Si IV,
and C IV, indicating high-ionization outflows up to about 10,000 km/s. There
are also two strong, broad (~500 km/s), high-ionization, associated absorption
systems that show partial covering of the continuum source. The strong UV
absorption we have detected suggests that the extreme soft-X-ray weakness of
PKS 1004+13 is primarily the result of absorption. The large radio-lobe
dominance indicates BAL and associated gas at high inclinations to the central
engine axis, perhaps in a line-of-sight that passes through an accretion disk
wind.Comment: To appear in Ap.J. Letters, 1999 (June or July); 4 pages, 5 figure
Joint Analysis of Cluster Observations: II. Chandra/XMM-Newton X-ray and Weak Lensing Scaling Relations for a Sample of 50 Rich Clusters of Galaxies
We present a study of multiwavelength X-ray and weak lensing scaling
relations for a sample of 50 clusters of galaxies. Our analysis combines
Chandra and XMM-Newton data using an energy-dependent cross-calibration. After
considering a number of scaling relations, we find that gas mass is the most
robust estimator of weak lensing mass, yielding 15 +/- 6% intrinsic scatter at
r500 (the pseudo-pressure YX has a consistent scatter of 22%+/-5%). The scatter
does not change when measured within a fixed physical radius of 1 Mpc. Clusters
with small BCG to X-ray peak offsets constitute a very regular population whose
members have the same gas mass fractions and whose even smaller <10% deviations
from regularity can be ascribed to line of sight geometrical effects alone.
Cool-core clusters, while a somewhat different population, also show the same
(<10%) scatter in the gas mass-lensing mass relation. There is a good
correlation and a hint of bimodality in the plane defined by BCG offset and
central entropy (or central cooling time). The pseudo-pressure YX does not
discriminate between the more relaxed and less relaxed populations, making it
perhaps the more even-handed mass proxy for surveys. Overall, hydrostatic
masses underestimate weak lensing masses by 10% on the average at r500; but
cool-core clusters are consistent with no bias, while non-cool-core clusters
have a large and constant 15-20% bias between r2500 and r500, in agreement with
N-body simulations incorporating unthermalized gas. For non-cool-core clusters,
the bias correlates well with BCG ellipticity. We also examine centroid shift
variance and and power ratios to quantify substructure; these quantities do not
correlate with residuals in the scaling relations. Individual clusters have for
the most part forgotten the source of their departures from self-similarity.Comment: Corrects an error in the X-ray luminosities (erratum
submitted)---none of the other results are affected. Go to
http://sfstar.sfsu.edu/jaco for an electronic fitter and updated quick data
download link
Intrinsic galaxy shapes and alignments II: Modelling the intrinsic alignment contamination of weak lensing surveys
Intrinsic galaxy alignments constitute the major astrophysical systematic of
forthcoming weak gravitational lensing surveys but also yield unique insights
into galaxy formation and evolution. We build analytic models for the
distribution of galaxy shapes based on halo properties extracted from the
Millennium Simulation, differentiating between early- and late-type galaxies as
well as central galaxies and satellites. The resulting ellipticity correlations
are investigated for their physical properties and compared to a suite of
current observations. The best-faring model is then used to predict the
intrinsic alignment contamination of planned weak lensing surveys. We find that
late-type galaxy models generally have weak intrinsic ellipticity correlations,
marginally increasing towards smaller galaxy separation and higher redshift.
The signal for early-type models at fixed halo mass strongly increases by three
orders of magnitude over two decades in galaxy separation, and by one order of
magnitude from z=0 to z=2. The intrinsic alignment strength also depends
strongly on halo mass, but not on galaxy luminosity at fixed mass, or galaxy
number density in the environment. We identify models that are in good
agreement with all observational data, except that all models over-predict
alignments of faint early-type galaxies. The best model yields an intrinsic
alignment contamination of a Euclid-like survey between 0.5-10% at z>0.6 and on
angular scales larger than a few arcminutes. Cutting 20% of red foreground
galaxies using observer-frame colours can suppress this contamination by up to
a factor of two.Comment: 23 pages, 14 figures; minor changes to match version published in
MNRA
Quality of Life After Axillary or Groin Sentinel Lymph Node Biopsy, With or Without Completion Lymph Node Dissection, in Patients With Cutaneous Melanoma
The aim of this study was to asses quality of life (QoL) after axillary or inguinal sentinel lymph node biopsy (SLNB) with or without completion lymph node dissection (CLND) in patients with cutaneous melanoma by comparing patients to a norm group of the general population and by comparing QoL between four patient groups depending on surgical procedure and location, i.e., patients receiving an axillary or groin SLNB, or an axillary or groin CLND.Between 1995 and 2003, a total of 242 axillary and inguinal SLNBs were performed. Of the 127 patients eligible for the study, 116 patients participated (91%). QoL was measured by the 30-item European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30), the McGill Pain Questionnaire and the Groningen Activity Restriction Scale.Median age at diagnosis was 50 (range, 18-77) years; median Breslow thickness 2.0 (range, 1-13) mm; median follow-up 56 (range, 4-94) months. SLNB only was performed in 89 patients (77%): 48 in the groin and 41 in the axilla. CLND was performed in 27 patients (23%): 13 in the axilla and 14 in the groin. More postoperative complications (13 vs. 5; P <0.001) and lymphedema (10 vs. 8; P <0.001) occurred in the CLND group than in the SLNB group. The total group of patients reported better physical (P <0.001), role (P <0.001), emotional (P <0.001), and social functioning (P = 0.049), global QoL (P <0.001), and less fatigue (P <0.001) and pain (P <0.001) than a German norm group. Analysis of variance revealed significant differences in role functioning (P = 0.02) and tendencies toward physical problems (P = 0.051) and fatigue (P = 0.051) between the four groups. Post hoc Bonferroni tests showed that the axillary CLND group had more problems than the axillary and inguinal SLNB groups. Kruskal-Wallis tests showed that the axillary CLND group reported most pain.QoL in melanoma survivors after axillary or inguinal SLNB with or without CLND was better than that in a norm group. Patients who underwent CLND in the axilla after SLNB reported most problems.</p
Finding halo streams with a pencil-beam survey: new wraps in the Sagittarius stream
We use data from two CFHT-MegaCam photometric pencil-beam surveys in the g'
and the r' bands to measure distances to the Sagittarius, the Palomar 5 and the
Orphan stream. We show that, using a cross-correlation algorithm to detect the
turnoff point of the main sequence, it is possible to overcome the main
limitation of a two-bands pencil-beam survey, namely the lack of adjacent
control-fields that can be used to subtract the foreground and background stars
to enhance the signal on the colour-magnitude diagrams (CMDs). We describe the
cross-correlation algorithm and its implementation. We combine the resulting
main sequence turnoff points with theoretical isochrones to derive photometric
distances to the streams. Our results (31 detections on the Sagittarius stream
and one each for the Palomar 5 and the Orphan streams) confirm the findings by
previous studies, expand the distance trend for the Sagittarius faint southern
branch and, for the first time, trace the Sagittarius faint branch of the
northern-leading arm out to 56 kpc. In addition, they show evidence for new
substructure: we argue that these detections trace the continuation of the
Sagittarius northern-leading arm into the southern hemisphere, and find a
nearby branch of the Sagittarius trailing wrap in the northern hemisphere.Comment: 16 pages, 15 figures, 2 table
A skewer survey of the Galactic halo from deep CFHT and INT images
We study the density profile and shape of the Galactic halo using deep
multicolour images from the MENeaCS and CCCP projects, over 33 fields selected
to avoid overlap with the Galactic plane. Using multicolour selection and PSF
homogenization techniques we obtain catalogues of F stars (near-main sequence
turnoff stars) out to Galactocentric distances up to 60kpc. Grouping nearby
lines of sight, we construct the stellar density profiles through the halo in
eight different directions by means of photometric parallaxes. Smooth halo
models are then fitted to these profiles. We find clear evidence for a
steepening of the density profile power law index around R=20 kpc, from -2.50
+- 0.04 to -4.85 +- 0.04, and for a flattening of the halo towards the poles
with best-fit axis ratio 0.63 +- 0.02. Furthermore, we cannot rule out a mild
triaxiality (w>=0.8). We recover the signatures of well-known substructure and
streams that intersect our lines of sight. These results are consistent with
those derived from wider but shallower surveys, and augur well for upcoming,
wide-field surveys of comparable depth to our pencil beam surveys.Comment: 14 pages, 8 figures, 6 table
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