539 research outputs found
A Far-Ultraviolet View of Starburst Galaxies
Recent observational and theoretical results on starburst galaxies related to
the wavelength regime below 1200 A are discussed. The review covers stars,
dust, as well as hot and cold gas. This wavelength region follows trends
similar to those seen at longer wavelengths, with several notable exceptions.
Even the youngest stellar populations show a turn-over in their spectral energy
distributions, and line-blanketing is much more pronounced. Furthermore, the O
VI line allows one to probe gas at higher temperatures than possible with lines
at longer wavelengths. Molecular hydrogen lines (if detected) provide a glimpse
of the cold phase. I cover the crucial wavelength regime below 912 A and the
implications of recent attempts to detect the escaping ionizing radiation.Comment: 8 pages, 3 figures, Invited Talk, Starbursts--From 30 Doradus to
Lyman-Break Galaxies, ed. R. de Grijs & R. M. Gonzalez Delgado (Dordrecht:
Kluwer
North American wetlands and mosquito control
© The Author(s), 2012. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in International Journal of Environmental Research and Public Health 9 (2012): 4537-4605, doi:10.3390/ijerph9124537.Wetlands are valuable habitats that provide important social, economic, and ecological services such as flood control, water quality improvement, carbon sequestration, pollutant removal, and primary/secondary production export to terrestrial and aquatic food chains. There is disagreement about the need for mosquito control in wetlands and about the techniques utilized for mosquito abatement and their impacts upon wetlands ecosystems. Mosquito control in wetlands is a complex issue influenced by numerous factors, including many hard to quantify elements such as human perceptions, cultural predispositions, and political climate. In spite of considerable progress during the last decades, habitat protection and environmentally sound habitat management still remain inextricably tied to politics and economics. Furthermore, the connections are often complex, and occur at several levels, ranging from local businesses and politicians, to national governments and multinational institutions. Education is the key to lasting wetlands conservation. Integrated mosquito abatement strategies incorporate many approaches and practicable options, as described herein, and need to be well-defined, effective, and ecologically and economically sound for the wetland type and for the mosquito species of concern. The approach will certainly differ in response to disease outbreaks caused by mosquito-vectored pathogens versus quality of life issues caused by nuisance-biting mosquitoes. In this contribution, we provide an overview of the ecological setting and context for mosquito control in wetlands, present pertinent information on wetlands mosquitoes, review the mosquito abatement options available for current wetlands managers and mosquito control professionals, and outline some necessary considerations when devising mosquito control strategies. Although the emphasis is on North American wetlands, most of the material is applicable to wetlands everywhere.Publication of this article was funded in
part by the University of Florida Open Access Publishing Fund
Parental bonding and identity style as correlates of self-esteem among adult adoptees and nonadoptees
Adult adoptees (n equals 100) and non-adoptees (n equals 100) were compared with regard to selfesteem, identity processing style, and parental bonding. While some differences were found with regard to self-esteem, maternal care, and maternal overprotection, these differences were
qualified by reunion status such that only reunited adoptees differed significantly from nonadoptees.
Moreover, hierarchical regression analyses indicated that parental bonding and identity processing style were more important than adoptive status per se in predicting self esteem. Implications for practitioners who work with adoptees are discussed
Seasonal Patterns in Stable Isotope and Fatty Acid Profiles of Southern Stingrays (Hypanus americana) at Stingray City Sandbar, Grand Cayman
Ecotourism opportunities in the marine environment often rely heavily on provisioning to ensure the viewing of cryptic species by the public. However, intentional feeding of wildlife can impact numerous aspects of an animals’ behavior and ecology. Southern stingrays (Hypanus americana) provisioned at Stingray City Sandbar (SCS) in Grand Cayman have altered diel activity patterns and decreased measures of health. This study looked at seasonal changes in stable isotope (SI) and fatty acid (FA) profiles of provisioned stingrays at SCS. Plasma δ15N was higher in male stingrays (11.86 ± 1.71‰) compared to females (10.70 ± 1.71‰). Lower values for δ15N in males and females were measured in October during low tourist season, suggesting stingrays may be forced to rely on native prey items to supplement the decreased amount of provisioned squid available during this time. Plasma FA profiles were significantly different between sexes and across sampling time points, with FAs 22:6n3, 16:0, 20:5n3, 18:1n3C, 18:0 and 18:1n9T contributing to dissimilarity scores between groups. Dietary FAs primarily contributed to differences between males and females lending further evidence to differences in foraging patterns at SCS, likely due to intraspecific competition. Further, canonical analysis of principal coordinates (CAP) analysis of FA profiles suggest similar diets during peak tourist season and differences in diet between males and females during the low season. This study demonstrates alterations in feeding ecology in stingrays at SCS which is of critical importance for effective management of the SCS aggregation
Particularly Efficient Star Formation in M33
The Star Formation (SF) rate in galaxies is an important parameter at all
redshifts and evolutionary stages of galaxies. In order to understand the
increased SF rates in intermediate redshift galaxies one possibility is to
study star formation in local galaxies with properties frequently found at this
earlier epoch like low metallicity and small size. We present sensitive
observations of the molecular gas in M 33, a small Local Group spiral at a
distance of 840 kpc which shares many of the characteristics of the
intermediate redshift galaxies. The observations were carried out in the
CO(2--1) line with the HERA heterodyne array on the IRAM 30 m telescope. A
11\arcmin22\arcmin region in the northern part of M 33 was observed,
reaching a detection threshold of a few 10 \msol. The correlation in this
field between the CO emission and tracers of SF (8\mum, 24\mum, \Ha, FUV) is
excellent and CO is detected very far North, showing that molecular gas forms
far out in the disk even in a small spiral with a subsolar metallicity. One
major molecular cloud was discovered in an interarm region with no HI peak and
little if any signs of SF -- without a complete survey this cloud would never
have been found. The radial dependence of the CO emission has a scale length
similar to the dust emission, less extended than the \Ha or FUV. If, however,
the \ratioo ratio varies inversely with metallicity, then the scale length of
the H becomes similar to that of the \Ha or FUV. Comparing the SF rate to
the H mass shows that M 33, like the intermediate redshift galaxies it
resembles, has a significantly higher SF efficiency than large local universe
spirals.Comment: 16 pages, 15 figure
A multi-scale study of infrared and radio emission from Scd galaxy M33
We investigate the energy sources of the infrared (IR) emission and their
relation to the radio continuum emission at various spatial scales within the
Scd galaxy M33. We use the wavelet transform to analyze IR data at the Spitzer
wavelengths of 24, 70, and 160m, as well as recent radio continuum data at
3.6cm and 20cm. An H map serves as a tracer of the star forming regions
and as an indicator of the thermal radio emission. We find that the dominant
scale of the 70m emission is larger than that of the 24m emission,
while the 160m emission shows a smooth wavelet spectrum. The radio and
H maps are well correlated with all 3 MIPS maps, although their
correlations with the 160m map are weaker. After subtracting the bright
HII regions, the 24 and 70m maps show weaker correlations with the 20cm
map than with the 3.6cm map at most scales. We also find a strong correlation
between the 3.6cm and H emission at all scales. Comparing the results
with and without the bright HII regions, we conclude that the IR emission is
influenced by young, massive stars increasingly with decreasing wavelength from
160 to 24m. The radio-IR correlations indicate that the warm dust-thermal
radio correlation is stronger than the cold dust-nonthermal radio correlation
at scales smaller than 4kpc. A perfect 3.6cm-H correlation implies that
extinction has no significant effect on H emitting structures.Comment: 15 pages, 10 figures, accepted for publication in the Astronomy and
Astrophysics Journa
Continuum Halos in Nearby Galaxies -- an EVLA Survey (CHANG-ES) -- II: First Results on NGC 4631
We present the first results from the CHANG-ES survey, a new survey of 35
edge-on galaxies to search for both in-disk as well as extra-planar radio
continuum emission. The motivation and science case for the survey are
presented in a companion paper (Paper I). In this paper (Paper II), we outline
the observations and data reduction steps required for wide-band calibration
and mapping of EVLA data, including polarization, based on C-array test
observations of NGC 4631.
With modest on-source observing times (30 minutes at 1.5 GHz and 75 minutes
at 6 GHz for the test data) we have achieved best rms noise levels of 22 and
3.5 Jy beam at 1.5 GHz and 6 GHz, respectively. New disk-halo
features have been detected, among them two at 1.5 GHz that appear as loops in
projection. We present the first 1.5 GHz spectral index map of NGC 4631 to be
formed from a single wide-band observation in a single array configuration.
This map represents tangent slopes to the intensities within the band centered
at 1.5 GHz, rather than fits across widely separated frequencies as has been
done in the past and is also the highest spatial resolution spectral index map
yet presented for this galaxy. The average spectral index in the disk is
indicating that the emission is
largely non-thermal, but a small global thermal contribution is sufficient to
explain a positive curvature term in the spectral index over the band. Two
specific star forming regions have spectral indices that are consistent with
thermal emission. Polarization results (uncorrected for internal Faraday
rotation) are consistent with previous observations and also reveal some new
features. On broad scales, we find strong support for the notion that magnetic
fields constrain the X-ray emitting hot gas.Comment: Accepted to the Astronomical Journal, Version 2 changes: Added
acknowledgement to NRA
Modern Electronic Techniques Applied to Physics and Engineering
Contains reports on three research projects
HI clouds in the proximity of M33
Neutral hydrogen clouds are found in the Milky Way and Andromeda halo both as
large complexes and smaller isolated clouds. Here we present a search for Hi
clouds in the halo of M33, the third spiral galaxy of the Local Group. We have
used two complementary data sets: a 3^o x 3^o map of the area provided by the
Arecibo Legacy Fast ALFA (ALFALFA) survey and deeper pointed observations
carried out with the Arecibo telescope in two fields that permit sampling of
the north eastern and south-western edges of the HI disc. The total amount of
Hi around M33 detected by our survey is M. At least 50%
of this mass is made of HI clouds that are related both in space and velocity
to the galaxy. We discuss several scenarios for the origin of these clouds
focusing on the two most interesting ones: dark-matter dominated gaseous
satellites, debris from filaments flowing into M33 from the intergalactic
medium or generated by a previous interaction with M31. Both scenarios seem to
fit with the observed cloud properties. Some structures are found at anomalous
velocities, particularly an extended HI complex previously detected by Thilker
et al. (2002). Even though the ALFALFA observations seem to indicate that this
cloud is possibly connected to M33 by a faint gas bridge, we cannot firmly
establish its extragalactic nature or its relation to M33. Taking into account
that the clouds associated with M33 are likely to be highly ionised by the
extragalactic UV radiation, we predict that the total gas mass associated with
them is > 5 x 10^7 M. If the gas is steadily falling towards the M33
disc it can provide the fuel needed to sustain a current star formation rate of
0.5 M yr.Comment: 16 pages, 19 figures. Accepted for publication in A&
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