366 research outputs found
Revision of the New World Heteromeringia (Diptera: Clusiidae: Clusiodinae).
Die 18 neuweltlichen Arten von Heteromeringia Czerny, 1903 werden revidiert inklusive Beschreibung von 10 neuen Arten (H. apholis sp. n. (Mexiko), H. aphotisma sp. n. (Brasilien), H. decora sp. n. (Mexiko), H. lateralis sp. n. (Costa Rica), H. mediana sp. n. (Brasilien), H. nanella sp. n. (Brasilien), H. nervosa sp. n. (Costa Rica), H. quadriseta sp. n. (Ecuador, Peru), H. volcana sp. n. (Costa Rica) und H. zophina sp. n. (Mexiko)). Die nearktische Unterart H. nitida nigripes Melander & Argo, 1924 wird zur Art erhoben. Die H. nitida-Artengruppe und die H. czernyi-Artengruppe werden aufgestellt, und die Verwandtschaftsverhältnisse der letzteren (ausschließlich neotropischen) Gruppe werden diskutiert. Sobarocephala subfasciata Curran, 1939 wird synonymisiert mit H. czernyi Kertesz, 1903. Heteromeringia dimidiata Hennig, 1938 wird in die Gattung Sobarocephala Czerny, 1903 comb. n. gestellt. Heteromeringia tephrinos nomen nov. wird als Ersatzname vorgeschlagen für die afrotropische H. nigrifrons Lamb, 1914, ein jüngeres primäres Homonym von H. nigrifrons Kertesz, 1903. Die Biologie von Heteromeringia wird diskutiert und ein Bestimmungsschlüssel für die neuweltlichen Arten wird vorgestellt. Zum ersten Mal wird aggressives Verhalten innerhalb der Gattung beschrieben: Männchen von H. nitida benutzen ihre zweifarbigen Vorderbeine zur Verteidigung von Paarungsrevieren.StichwörterHeteromeringia, H. czernyi species group, H. nitida species group, Clusiidae, Diptera, New World, revision, new species, stat. n., syn. n., comb. n., nomen n., biology, behaviour.Nomenklatorische Handlungenapholis Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.aphotisma Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.decora Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.flavipes (Williston, 1896) (Heteromeringia), Lectotype described as Heteroneura flavipeslateralis Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.mediana Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.nanella Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.nervosa Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.nigripes Melander & Argo, 1924 (Heteromeringia), stat. n. described as Heteromeringia nitida var. nigripesquadriseta Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.tephrinos Lonsdale & Marshall, 2007 (Heteromeringia), nom. n. pro Heteromeringia nigrifrons Lamb, 1914, nec Kertesz, 1903volcana Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.zophina Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.dimidiata (Hennig, 1938) (Sobarocephala), comb. n. hitherto Heteromeringia dimidiatasubfasciata Curran, 1939 (Sobarocephala), syn. n. of Heteromeringia czernyi Kertesz, 1903The 18 New World species of Heteromeringia Czerny, 1903 are revised, with 10 species described as new: H. apholis sp. n. (Mexico), H. aphotisma sp. n. (Brazil), H. decora sp. n. (Mexico), H. lateralis sp. n. (Costa Rica), H. mediana sp. n. (Brazil), H. nanella sp. n. (Brazil), H. nervosa sp. n. (Costa Rica), H. quadriseta sp. n. (Ecuador, Peru), H. volcana sp. n. (Costa Rica) and H. zophina sp. n. (Mexico). The Nearctic H. nitida nigripes Melander & Argo, 1924 is raised from subspecies to species. The H. nitida species group and the H. czernyi species group are erected, and species relationships are discussed for the latter (entirely neotropical) group. Sobarocephala subfasciata Curran, 1939 is included as a junior synonym of H. czernyi Kertesz, 1903. Heteromeringia dimidiata Hennig, 1938 is moved to Sobarocephala Czerny, 1903 comb. n. Heteromeringia tephrinos nomen n. is provided as a replacement name for the Afrotropical H. nigrifrons Lamb, 1914, which is a junior primary homonym of H. nigrifrons Kertesz, 1903. The biology of Heteromeringia is discussed, and a key is provided for all New World species. Agonistic interactions are described for this genus for the first time, with H. nitida Johnson, 1913 males recorded as using bicoloured forelegs to defend mating territories.KeywordsHeteromeringia, H. czernyi species group, H. nitida species group, Clusiidae, Diptera, New World, revision, new species, stat. n., syn. n., comb. n., nomen n., biology, behaviour.Nomenclatural Actsapholis Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.aphotisma Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.decora Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.flavipes (Williston, 1896) (Heteromeringia), Lectotype described as Heteroneura flavipeslateralis Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.mediana Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.nanella Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.nervosa Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.nigripes Melander & Argo, 1924 (Heteromeringia), stat. n. described as Heteromeringia nitida var. nigripesquadriseta Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.tephrinos Lonsdale & Marshall, 2007 (Heteromeringia), nom. n. pro Heteromeringia nigrifrons Lamb, 1914, nec Kertesz, 1903volcana Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.zophina Lonsdale & Marshall, 2007 (Heteromeringia), spec. n.dimidiata (Hennig, 1938) (Sobarocephala), comb. n. hitherto Heteromeringia dimidiatasubfasciata Curran, 1939 (Sobarocephala), syn. n. of Heteromeringia czernyi Kertesz, 190
Far-Infrared Properties of Spitzer-selected Luminous Starbursts
We present SHARC-2 350 micron data on 20 luminous z ~ 2 starbursts with
S(1.2mm) > 2 mJy from the Spitzer-selected samples of Lonsdale et al. and
Fiolet et al. All the sources were detected, with S(350um) > 25 mJy for 18 of
them. With the data, we determine precise dust temperatures and luminosities
for these galaxies using both single-temperature fits and models with power-law
mass--temperature distributions. We derive appropriate formulae to use when
optical depths are non-negligible. Our models provide an excellent fit to the
6um--2mm measurements of local starbursts. We find characteristic
single-component temperatures T1 ~ 35.5+-2.2 K and integrated infrared (IR)
luminosities around 10^(12.9+-0.1) Lsun for the SWIRE-selected sources.
Molecular gas masses are estimated at 4 x 10^(10) Msun, assuming
kappa(850um)=0.15 m^2/kg and a submillimeter-selected galaxy (SMG)-like
gas-to-dust mass ratio. The best-fit models imply >~2 kpc emission scales. We
also note a tight correlation between rest-frame 1.4 GHz radio and IR
luminosities confirming star formation as the predominant power source. The
far-IR properties of our sample are indistinguishable from the purely
submillimeter-selected populations from current surveys. We therefore conclude
that our original selection criteria, based on mid-IR colors and 24 um flux
densities, provides an effective means for the study of SMGs at z ~ 1.5--2.5.Comment: 13 pages, 4 figures, edited to match published version in ApJ 717,
29-39 (2010
The Deep SWIRE Field. IV. First properties of the sub-mJy galaxy population: redshift distribution, AGN activity and star formation
We present a study of a 20cm selected sample in the Deep SWIRE VLA Field,
reaching a limiting flux density of ~13.5 uJy at the image center. In a 0.6x0.6
square degrees field, we are able to assign an optical/IR counterpart to 97% of
the radio sources. Up to 11 passbands from the NUV to 4.5um are then used to
sample the spectral energy distribution (SED) of these counterparts in order to
investigate the nature of the host galaxies. By means of an SED template
library and stellar population synthesis models we estimate photometric
redshifts, stellar masses, and stellar population properties, dividing the
sample in three sub-classes of quiescent, intermediate and star-forming
galaxies. We focus on the radio sample in the redshift range 0.3<z<1.3 where we
estimate to have a redshift completeness higher than 90%, and study the
properties and redshift evolution of these sub-populations. We find that, as
expected, the relative contributions of AGN and star-forming galaxies to the
uJy population depend on the flux density limit of the sample. At all flux
levels a significant population of "green-valley" galaxies is observed. While
the actual nature of these sources is not definitely understood, the results of
this work may suggest that a significant fraction of faint radio sources might
be composite (and possibly transition) objects, thus a simple "AGN vs
star-forming" classification might not be appropriate to fully understand what
faint radio populations really are.Comment: 18 pages, 16 figures, accepted for publication in Ap
School physical activity intervention effect on adolescents' performance in mathematics
Purpose: The primary aim of this study was to test the effect of a school-based physical activity intervention on adolescents’ performance in mathematics. A secondary aim was to explore potential mechanisms that might explain the intervention effect.
Methods: The Activity and Motivation in Physical EDucation intervention was evaluated using a two-arm cluster randomized controlled trial in 14 secondary schools located in low socioeconomic areas of Western Sydney, Australia. Study participants (n = 1173) were grade 8 students (mean age = 12.94 yr, SD = 0.54). The multicomponent intervention was designed to help teachers maximize students’ opportunities for moderate-to-vigorous physical activity (MVPA) during physical education (PE) and enhance students’ motivation toward PE. Mathematics performance was assessed as part of national testing in grade 7, which was the year before the trial began and then again in grade 9. Potential mediators were: (i) proportion of PE lesson time that students spent in MVPA and leisure time MVPA (%), measured using Actigraph GT3X+ accelerometers, and (ii) students’ self-reported engagement (behavioral, emotional, and cognitive) during mathematics lessons. Mediators were assessed at baseline (grade 8) and follow-up (grade 9, 14–15 months after baseline).
Results: The effect of the intervention on mathematics performance was small-to-medium (β = 0.16, P < 0.001). An intervention effect was observed for MVPA% in PE (β = 0.59, P < 0.001), but not for leisure time MVPA or any of the engagement mediators. There were no significant associations between changes in potential mediators and mathematics performance.
Conclusions: The Activity and Motivation in Physical EDucation intervention had a significant positive effect on mathematics performance in adolescents. However, findings should be interpreted with caution as the effect was small and not associated with changes in hypothesized mediators
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The SWIRE/Chandra Survey: The X-ray Sources
We report a moderate-depth (70 ks), contiguous 0.7 deg^2 Chandra survey in the Lockman Hole Field of the Spitzer/SWIRE Legacy Survey coincident with a completed, ultra-deep VLA survey with deep optical and near-infrared imaging in-hand. The primary motivation is to distinguish starburst galaxies and active galactic nuclei (AGNs), including the significant, highly obscured (log N_H > 23) subset. Chandra has detected 775 X-ray sources to a limiting broadband (0.3-8 keV) flux ~4 × 10^(–16) erg cm^(–2) s^(–1). We present the X-ray catalog, fluxes, hardness ratios, and multi-wavelength fluxes. The log N versus log S agrees with those of previous surveys covering similar flux ranges. The Chandra and Spitzer flux limits are well matched: 771 (99%) of the X-ray sources have infrared (IR) or optical counterparts, and 333 have MIPS 24 μm detections. There are four optical-only X-ray sources and four with no visible optical/IR counterpart. The very deep (~2.7 μJy rms) VLA data yield 251 (>4σ) radio counterparts, 44% of the X-ray sources in the field. We confirm that the tendency for lower X-ray flux sources to be harder is primarily due to absorption. As expected, there is no correlation between observed IR and X-ray fluxes. Optically bright, type 1, and red AGNs lie in distinct regions of the IR versus X-ray flux plots, demonstrating the wide range of spectral energy distributions in this sample and providing the potential for classification/source selection. Many optically bright sources, which lie outside the AGN region in the optical versus X-ray plots (f_r /f_x >10), lie inside the region predicted for red AGNs in IR versus X-ray plots, consistent with the presence of an active nucleus. More than 40% of the X-ray sources in the VLA field are radio-loud using the classical definition, R_L . The majority of these are red and relatively faint in the optical so that the use of R_L to select those AGNs with the strongest radio emission becomes questionable. Using the 24 μm to radio flux ratio (q_(24)) instead results in 13 of the 147 AGNs with sufficient data being classified as radio-loud, in good agreement with the ~10% expected for broad-lined AGNs based on optical surveys. We conclude that q_(24) is a more reliable indicator of radio-loudness. Use of R_L should be confined to the optically selected type 1 AGN
Infrared-Faint Radio Sources: A Cosmological View - AGN Number Counts, the Cosmic X-Ray Background and SMBH Formation
Context. Infrared Faint Radio Sources (IFRS) are extragalactic emitters
clearly detected at radio wavelengths but barely detected or undetected at
optical and infrared wavelengths, with 5 sigma sensitivities as low as 1 uJy.
Aims. Recent SED-modelling and analysis of their radio properties shows that
IFRS are consistent with a population of (potentially extremely obscured)
high-redshift AGN at 3<z<6. We demonstrate some astrophysical implications of
this population and compare them to predictions from models of galaxy evolution
and structure formation.
Methods. We compiled a list of IFRS from four deep extragalactic surveys and
extrapolated the IFRS number density to a survey-independent value of (30.8 +-
15.0) per square degree. We computed the IFRS contribution to the total number
of AGN in the Universe to account for the Cosmic X-ray Background. By
estimating the black hole mass contained in IFRS, we present conclusions for
the SMBH mass density in the early universe and compare it to relevant
simulations of structure formation after the Big Bang.
Results. The number density of AGN derived from the IFRS density was found to
be about 310 deg^-2, which is equivalent to a SMBH mass density of the order of
10^3 M_sun Mpc^-3 in the redshift range 3<z<6. This produces an X-ray flux of 9
10^-16 W m^-2 deg^-2 in the 0.5-2.0 keV band and 3 10^-15 W m^-2 deg^-2 in the
2.0-10 keV band, in agreement with the missing unresolved components of the
Cosmic X-ray Background. Concerning the problem of SMBH formation after the Big
Bang we find evidence for a scenario involving both halo gas accretion and
major mergers.Comment: 8 pages, 4 figures, accepted for publication in A&
A Deep 1.2 mm Map of the Lockman Hole North Field
We present deep 1.2 mm continuum mapping of a 566 arcmin^2 area within the
Lockman Hole North field, previously a target of the Spitzer Wide-area Infrared
Extragalactic (SWIRE) survey and extremely deep 20 cm mapping with the Very
Large Array, which we have obtained using the Max-Planck millimeter bolometer
(MAMBO) array on the IRAM 30 m telescope. After filtering, our full map has an
RMS sensitivity ranging from 0.45 to 1.5 mJy/beam, with an average of 0.75
mJy/beam. Using the pixel flux distribution in a map made from our best data,
we determine the shape, normalization, and approximate flux density cutoff for
1.2 mm number counts well below our nominal sensitivity and confusion limits.
After validating our full dataset through comparison with this map, we
successfully detect 41 1.2 mm sources with S/N > 4.0 and S(1.2 mm)\simeq 2-5
mJy. We use the most significant of these detections to directly determine the
integral number counts down to 1.8 mJy, which are consistent with the results
of the pixel flux distribution analysis. 93% of our 41 individual detections
have 20 cm counterparts, 49% have Spitzer/MIPS 24 micron counterparts, and one
may have a significant Chandra X-ray counterpart. We resolve \simeq 3% of the
cosmic infrared background (CIB) at 1.2 mm into significant detections, and
directly estimate a 0.05 mJy faint-end cutoff for the counts that is consistent
with the full intensity of the 1.2 mm CIB. The median redshift of our 17
detections with spectroscopic or robust photometric redshifts is z(median)=2.3,
and rises to z(median)=2.9 when we include redshifts estimated from the
radio/far-infrared spectral index. By using a nearest neighbor and angular
correlation function analysis, we find evidence that our S/N>4.0 detections are
clustered at the 95% confidence level.Comment: 40 pages, 25 figures, accepted for publication in Ap
MAMBO 1.2mm observations of luminous starbursts at z~2 in the SWIRE fields
We report on--off pointed MAMBO observations at 1.2 mm of 61 Spitzer-selected
star-forming galaxies from the SWIRE survey. The sources are selected on the
basis of bright 24um fluxes (f_24um>0.4mJy) and of stellar dominated
near-infrared spectral energy distributions in order to favor z~2 starburst
galaxies. The average 1.2mm flux for the whole sample is 1.5+/-0.2 mJy. Our
analysis focuses on 29 sources in the Lockman Hole field where the average
1.2mm flux (1.9+/-0.3 mJy) is higher than in other fields (1.1+/-0.2 mJy). The
analysis of the sources multi-wavelength spectral energy distributions
indicates that they are starburst galaxies with far-infrared luminosities
~10^12-10^13.3 Lsun, and stellar masses of ~0.2-6 x10^11 M_sun. Compared to
sub-millimeter selected galaxies (SMGs), the SWIRE-MAMBO sources are among
those with the largest 24um/millimeter flux ratios. The origin of such large
ratios is investigated by comparing the average mid-infrared spectra and the
stacked far-infrared spectral energy distributions of the SWIRE-MAMBO sources
and of SMGs. The mid-infrared spectra exhibit strong PAH features, and a warm
dust continuum. The warm dust continuum contributes to ~34% of the mid-infrared
emission, and is likely associated with an AGN component. This constribution is
consistent with what is found in SMGs. The large 24um/1.2mm flux ratios are
thus not due to AGN emission, but rather to enhanced PAH emission compared to
SMGs. The analysis of the stacked far-infrared fluxes yields warmer dust
temperatures than typically observed in SMGs. Our selection favors warm
ultra-luminous infrared sources at high-z, a class of objects that is rarely
found in SMG samples. Our sample is the largest Spitzer-selected sample
detected at millimeter wavelengths currently available.Comment: Accepted for publication in ApJ (51 pages; 16 figures). The quality
of some figures has been degraded for arXiv purposes. Full resolution version
available at this
http://www.iasf-milano.inaf.it/~polletta/mambo_swire/lonsdale08_ApJ_accepted.pd
The star catalogues of Ptolemaios and Ulugh Beg: Machine-readable versions and comparison with the modern Hipparcos Catalogue
In late antiquity and throughout the middle ages, the positions of stars on
the celestial sphere were obtained from the star catalogue of Ptolemaios. A
catalogue based on new measurements appeared in 1437, with positions by Ulugh
Beg, and magnitudes from the 10th-century astronomer al-Sufi. We provide
machine-readable versions of these two star catalogues, based on the editions
by Toomer (1998) and Knobel (1917), and determine their accuracies by
comparison with the modern Hipparcos Catalogue. The magnitudes in the
catalogues correlate well with modern visual magnitudes; the indication `faint'
by Ptolemaios is found to correspond to his magnitudes 5 and 6. Gaussian fits
to the error distributions in longitude / latitude give widths sigma ~ 27
arcmin / 23 arcmin in the range |Delta lambda, Delta beta|<50 arcmin for
Ptolemaios and sigma ~ 22 arcmin /18 arcmin in Ulugh Beg. Fits to the range
|Delta lambda, Delta beta|<100 arcmin gives 10-15 per cent larger widths,
showing that the error distributions are broader than gaussians. The fraction
of stars with positions wrong by more than 150 arcmin is about 2 per cent for
Ptolemaios and 0.1 per cent in Ulugh Beg; the numbers of unidentified stars are
1 in Ptolemaios and 3 in Ulugh Beg. These numbers testify to the excellent
quality of both star catalogues (as edited by Toomer and Knobel).Comment: to be published in Astronomy and Astrophysics; 34 pages with 57
Figures. Note changed address and email address of first autho
A new list of extra-galactic radio jets
A catalogue of extra-galactic jets is very useful both in observational and
theoretical studies of active galaxies. With the use of new powerful radio
instruments, the detailed structures of very compact or weak radio sources are
investigated observationally and many new radio jets are detected. In this
paper, we give a list of 661 radio sources with detected radio jets known to us
prior to the end of December 2000. All references are collected for the
observations of jets in radio, IR, optical, UV and X-ray wave-bands.Comment: 43 pages, 1 figur
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