38 research outputs found

    The relation between 13CO(2-1) line width in molecular clouds and bolometric luminosity of associated IRAS sources

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    We search for evidence of a relation between properties of young stellar objects (YSOs) and their parent molecular clouds to understand the initial conditions of high-mass star formation. A sample of 135 sources was selected from the Infrared Astronomical Satellite (IRAS) Point Source Catalog, on the basis of their red color to enhance the possibility of discovering young sources. Using the Kolner Observatorium fur SubMillimeter Astronomie (KOSMA) 3-m telescope, a single-point survey in 13CO(2-1) was carried out for the entire sample, and 14 sources were mapped further. Archival mid-infrared (MIR) data were compared with the 13CO emissions to identify evolutionary stages of the sources. A 13CO observed sample was assembled to investigate the correlation between 13CO line width of the clouds and the luminosity of the associated YSOs. We identified 98 sources suitable for star formation analyses for which relevant parameters were calculated. We detected 18 cores from 14 mapped sources, which were identified with eight pre-UC HII regions and one UC HII region, two high-mass cores earlier than pre-UC HII phase, four possible star forming clusters, and three sourceless cores. By compiling a large (360 sources) 13CO observed sample, a good correlation was found between the 13CO line width of the clouds and the bolometric luminosity of the associated YSOs, which can be fitted as a power law: lg(dV13/km/s)=-0.023+0.135lg(Lbol/Lsolar). Results show that luminous (>10^3Lsolar) YSOs tend to be associated with both more massive and more turbulent (dV13>2km/s) molecular cloud structures.Comment: Accepted by Astronomy and Astrophysics; this version: sent to publisher; 13 pages, 4 figures, 2 tables, 1 online appendi

    The BLAST Survey of the Vela Molecular Cloud: Physical Properties of the Dense Cores in Vela-D

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    The Balloon-borne Large-Aperture Submillimeter Telescope (BLAST) carried out a 250, 350 and 500 micron survey of the galactic plane encompassing the Vela Molecular Ridge, with the primary goal of identifying the coldest dense cores possibly associated with the earliest stages of star formation. Here we present the results from observations of the Vela-D region, covering about 4 square degrees, in which we find 141 BLAST cores. We exploit existing data taken with the Spitzer MIPS, IRAC and SEST-SIMBA instruments to constrain their (single-temperature) spectral energy distributions, assuming a dust emissivity index beta = 2.0. This combination of data allows us to determine the temperature, luminosity and mass of each BLAST core, and also enables us to separate starless from proto-stellar sources. We also analyze the effects that the uncertainties on the derived physical parameters of the individual sources have on the overall physical properties of starless and proto-stellar cores, and we find that there appear to be a smooth transition from the pre- to the proto-stellar phase. In particular, for proto-stellar cores we find a correlation between the MIPS24 flux, associated with the central protostar, and the temperature of the dust envelope. We also find that the core mass function of the Vela-D cores has a slope consistent with other similar (sub)millimeter surveys.Comment: Accepted for publication in the Astrophysical Journal. Data and maps are available at http://blastexperiment.info

    Captive breeding of European freshwater mussels as aconservation tool: A review

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    1. Freshwater mussels are declining throughout their range. Their importantecological functions along with insufficient levels of natural recruitment haveprompted captive breeding for population augmentation and questions about the usefulness and applicability of such measures. 2. This article reviews the current state of captive breeding and rearing programmes for freshwater mussels in Europe. It considers the various species, strategies, andtechniques of propagation, as well as the different levels of effort requiredaccording to rearing method, highlighting the key factors of success. 3. Within the last 30 years, 46 breeding activities in 16 European countries have been reported, mainly of Margaritifera margaritifera and Unio crassus. Some facilities propagate species that are in a very critical situation, such as Pseudunio auricularius, Unio mancus, and Unio ravoisieri, or multiple species concurrently. Insome streams, the number of released captive-bred mussels already exceeds the size of the remaining natural population. 4. Rearing efforts range from highly intensive laboratory incubation to lowerintensity methods using in-river mussel cages or silos. Most breeding efforts are funded by national and EU LIFE(+) grants, are well documented, and consider the genetic integrity of the propagated mussels. Limited long-term funding perspectives, the availability of experienced staff, water quality, and feeding/survival during early life stages are seen as the most important challenges. 5. Successful captive breeding programmes need to be combined with restoration ofthe habitats into which the mussels are released. This work will benefit from anevidence-based approach, knowledge exchange among facilities, and an overall breeding strategy comprising multiple countries and conservation units. aquaculture, captive breeding, conservation translocation, freshwater mussel culturing, Margaritifera margaritifera, propagation, reintroduction, Unio crassusCaptive breeding of European freshwater mussels as aconservation tool: A reviewpublishedVersio

    Erythroid-Specific Expression of β-globin from Sleeping Beauty-Transduced Human Hematopoietic Progenitor Cells

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    Gene therapy for sickle cell disease will require efficient delivery of a tightly regulated and stably expressed gene product to provide an effective therapy. In this study we utilized the non-viral Sleeping Beauty (SB) transposon system using the SB100X hyperactive transposase to transduce human cord blood CD34+ cells with DsRed and a hybrid IHK–β-globin transgene. IHK transduced cells were successfully differentiated into multiple lineages which all showed transgene integration. The mature erythroid cells had an increased β-globin to γ-globin ratio from 0.66±0.08 to 1.05±0.12 (p = 0.05), indicating expression of β-globin from the integrated SB transgene. IHK–β-globin mRNA was found in non-erythroid cell types, similar to native β-globin mRNA that was also expressed at low levels. Additional studies in the hematopoietic K562 cell line confirmed the ability of cHS4 insulator elements to protect DsRed and IHK–β-globin transgenes from silencing in long-term culture studies. Insulated transgenes had statistically significant improvement in the maintenance of long term expression, while preserving transgene regulation. These results support the use of Sleeping Beauty vectors in carrying an insulated IHK–β-globin transgene for gene therapy of sickle cell disease

    Etude comparée de l’écologie de deux espèces jumelles de Chiroptères (Mammalia : Chiroptera ) en Belgique: l’oreillard roux (Plecotus auritus) (Linn., 1758) et l’oreillard gris (Plecotus austriacus ) (Fischer, 1829).

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    Introduction The purpose of this study is to verify one of the principal rules of ecology: the principle of exclusive competition, by using the sibling species of long-eared bats present in Belgium as a model: the brown long-eared bat (Plecotus auritus) and the grey long-eared bat (Plecotus austriacus). Two similar species present in the same region and, what is more, share the same roost, must differ according to certain aspects of their ecological niche in order to be able to co-exist (MacNab 1971). In order to determine the resource sharing mechanisms between the two species, we have compared the three important dimensions of their ecological requirements: the use of trophic resources by means of faecal analysis and the use of space and time by radio-tracking. Trophic resources One hundred and thirty samples (4688 droppings, 6388 occurrences) taken from 5 single-species colonies of P. austriacus, 5 single-species colonies of P. auritus and from a mixed colony have been taken into account in the analysis of the summer diet. With the help of a first model constructed with the aid of generalized linear regressions, we have shown that, independently of the cohabitation conditions (single-species and mixed colonies), the two species have similar dietary requirements. Qualitatively, the same types of prey are consumed : Lepidoptera, Diptera (Craneflies, Cyclorrhapha and others Diptera), Coleoptera, Arachnids and Dermaptera. Small quantitative differences of between 3% to 8%, were seen to exist : P. austriacus consumes slightly more Coleoptera and Lepidoptera and fewer Craneflies than P. auritus. With the help of a second model enabling interspecific comparison of the diet according to whether the animal belonged to the single-species colonies or the mixed colony, we were able to show that the differences were more marked. When P. austriacus belong to single-species colonies, with reference to single-species colonies of P. auritus, predicted value indicate that they consume more Coleoptera (+ 5,0 %, p = 0,001) Lepidoptera (+ 14,4 %, p < 0,0005) and fewer Arachnids (- 8,3 %, p < 0,0005), Dermaptera (- 8,8%, p < 0,0005) and Craneflies (- 9,5 %, p = 0,009). This leads us to believe that the proportion of non-flying or diurnal prey gleaned by P. auritus is 2,5 times greater than that of P. austriacus. On the other hand, when P. austriacus belongs to the mixed colony, in reference to the P. austriacus single-species colonies, it changed its feeding behaviour. The predicted consumption of Arachnids and Dermaptera is higher, 14,5 % (p < 0,0005) and 11,3 % (p < 0,0005) respectively, while the consumption of Lepidoptera is much less (- 25,6 %, p < 0,0005). The syntopic P. austriacus also consume more craneflies (+ 7,9 %, p = 0,034) but fewer Coleoptera (-11,1 %, p = 0,009). This shows that P. austriacus posesses surprising adaptation abilities. The diet of the P. auritus of the mixed colony in relation to the single-species P. auritus, only showed slight variations on the other hand : - 7% (p = 0,006) for the Cyclorrhapha and - 4% (p = 0,002) for the Dermaptera. In syntopy, the study of seasonal variations has shown that the quantitative differences were significant at the end of gestation and lactation when the energy requirement is at its highest. In June, P. austriacus consumes more Arachnids (p = 0,046), in July, more Arachnids (p = 0,020) and fewer Lepidoptera (p = 0,020). In August, they consume more Dermaptera (p = 0.019), fewer Coleoptera (p = 0.032) and Lepidoptera (p = 0.034). Winter trophic ecology Our study has also led to the discovery of a little-known aspect of the ecology of chiroptera: winter trophic ecology. The results have shown that long-eared bats consume at least 70% of their prey which they capture by gleaning (Spiders, Dermaptera, Cyclorrhapha). These results have made it possible to confirm that the two species possess the ability to glean their prey. Spatial and temporal resources Twenty-two Plecotus were used for the analysis : seven P. auritus in Gozin, six P. austriacus in Gembes, five P. auritus and four P. austriacus in Pondrome (mixed colony). Eighty-four nights of monitoring corresponding to the discovery of 111 hunting grounds were used for the analyses. The results show that the use of space by P. auritus and P. austriacus contain similarities. The distance of the hunting grounds, the number of grounds visited per night, the duration of their use, their surface and the individual area of daily activity are similar. In the same way, contrary to what the literature suggests, it seems that P. auritus possesses the ability to exploit the open or semi-open areas like the meadows surrounded by linear woodland elements, while P. austriacus possesses the ability to exploit equally well the closed areas such as woods. In syntopy, the two species showed a different selection of habitats (grasslands, leafy woods,, gardens, edges for P. auritus and leafy or coniferous woods, gardens and edges for P. austriacus), P. auritus spending 64% of hunting time above the grassland against 83% in the woods for P. austriacus. On the other hand, in comparison with the two single-species colonies, the division of hunting time around the roost is more spread out in terms of space and the number of hunting grounds visited by night is more important. No difference in the exploitation of temporal resources was detected; the later departures from the Gozin colony were attributed to the presence of artificial lighting placed in front of the roost. The mechanisms allowing resources partitioning In the case of single-species colonies we have shown the existence of trophic resources partitioning. In fact, P. austriacus showed a diet less rich in Arachnids, Dermaptera, Craneflies and richer in Coeloptera and Lepidoptera than P. auritus. However, in syntopy, P. austriacus clearly modified its diet by consuming more Arachnids and Dermaptera to the detriment of Coleoptera and Lepidoptera. The consumption in Arachnids and Dermaptera remains higher than those of single-species P. auritus. Whether for single-species colonies or mixed colonies, trophic resources partitioning is quite evident. As requirements in terms of syntopy were modified, the results lead us to assume that inter-specific competition exists between this sibling species. The differences observed in the diet are probably dictated by a different use of the habitats. Indeed, in relation with the ecology of prey, the results of habitats use have made it possible to show that habitat partitioning occurs between the two species of long-eared bat. Our results therefore constitute a good illustration of the principle of competitive exclusion. Whether in the case of single-species colonies or mixed colonies, the two species share the trophic and spatial resources which allow them to co-exist. Recommendations for the conservation of the species To satisfy the requirements of the summer diet, it is necessary to maintain a network of diverse habitats composed of gardens, meadowlands, humid zones, hedges, bushes, tree alignments, leafy or mixed woodlands, preferably hygrophilous, allowing for the development of undergrowth and clearings. The results of the selection of surface habitats have globally confirmed the importance of these habitats used as hunting grounds. The selection of linear habitats such as tree-lines, hedges, bushes and edges also show the importance of ecological networks and the potentially damaging effects of the fragmentation of habitats on the bat population. In order to integrate the spatial requirements of P. austriacus, we recommend the establishment of a minimum protection perimeter of 3500 metres around the nest. With regard to P. auritus, it would be judicious to protect a minimum perimeter of a radius of 2000 metres

    Comparison between two techniques to study habitat use by serotine bats (Eptesicus serotinus): radiotracking and bat detectors used simultaneously

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    peer reviewedDuring the course of a study on the use of habitat by the common serotine bat in Belgium, we have had recourse to radiotracking and the prospecting with an ultrasonic detector. The results obtained with the two techniques used have been compared. The preferred habitats of the bats were found identical with the two techniques, with a preferece for leafy environments. However, the interpretation of the results affords different information depending on the technique adopted. We have thus compared the limits of each of the two techniques. In conclusion, the results obtained by radiotracking and with the ultrasonic detector are at the same time virtually the same but also complementary
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