289 research outputs found

    Herschel-HIFI observations of H2O, NH3 and N2H+ toward high-mass starless and proto-stellar clumps identified by the Hi-GAL survey

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    Our present understanding of high-mass star formation still remains very schematic. In particular, it is not yet clear how much of the difference between low-mass and high-mass star formation occurs during the earliest star formation phases. The chemical characteristics of massive cold clumps, and the comparison with those of their low-mass counterparts, could provide crucial clues about the exact role that chemistry plays in differentiating the early phases of low-mass and high-mass star formation. Water, in particular, is a unique probe of physical and chemical conditions in star-forming regions. Using the HIFI instrument of Herschel we have observed the ortho-NH3 (1_0-0_0) (572GHz), ortho-H2O (1_10-1_01) (557GHz) and N2H+ (6-5) (559GHz) lines toward a sample of high-mass starless and proto-stellar clumps selected from the "Herschel} Infrared Galactic Plane Survey" (Hi-GAL). We compare our results to previous studies of low-mass and high-mass proto-stellar objects. At least one of the three molecular lines was detected in 4 (out of 35) and 7 (out of 17) objects in the l=59deg and l=30deg galactic regions, respectively. All detected sources are proto-stellar. The water spectra are complex and consist of several kinematic components, identified through a Gaussian decomposition, and in a few sources inverse and regular P-Cygni profiles have been detected. All water line profiles of the l=59deg region are dominated by a broad Gaussian emission feature, indicating that the bulk of the water emission arises in outflows. No such broad emission is detected toward the l=30deg objects. The ammonia line in some cases also shows line wings and an inverse P-Cygni profile, thus confirming that NH3 rotational transitions can be used to probe the dynamics of high-mass star forming regions. Both bolometric and water line luminosity increase with the continuum temperature.Comment: This paper includes 7 main figures and 6 tables, in addition to the figures with the spectra of the individual sources which are presented as on-line material. Accepted for publication on Astronomy and Astrophysic

    Mass and motion of globulettes in the Rosette Nebula

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    We have investigated tiny molecular clumps in the Rosette Nebula. Radio observations were made of molecular line emission from 16 globulettes identified in a previous optical survey. In addtion, we collected images in the NIR broad-band JHKs and narrow-band Paschen beta and H2. Ten objects, for which we collected information from several transitions in 12CO and 13CO were modelled using a spherically symmetric model. The best fit to observed line ratios and intensities was obtained by assuming a model composed of a cool and dense centre and warm and dense surface layer. The average masses derived range from about 50 to 500 Jupiter masses, which is similar to earlier estimates based on extinction measures. The globulettes selected are dense, with very thin layers of fluorescent H2 emission. The NIR data shows that several globulettes are very opaque and contain dense cores. Because of the high density encountered already at the surface, the rims become thin, as evidenced by our P beta images. We conclude that the entire complex of shells, elephant trunks, and globulettes in the northern part of the nebula is expanding with nearly the same velocity of ~22 km/s, and with a very small spread in velocity among the globulettes. Some globulettes are in the process of detaching from elephant trunks and shells, while other more isolated objects must have detached long ago and are lagging behind in the general expansion of the molecular shell. The suggestion that some globulettes might collapse to form planetary-mass objects or brown dwarfs is strengthened by our finding of dense cores in several objects.Comment: 15 pages, 15 figures Astronomy and Astrophysics 201

    Herschel-HIFI observations of H2O, NH3, and N2H+ toward high-mass starless and protostellar clumps identified by the Hi-GAL survey

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    Context. Our present understanding of high-mass star formation still remains very schematic. In particular, it is not yet clear how much of the difference between low-mass and high-mass star formation occurs during the earliest star formation phases. Aims. The chemical characteristics of massive cold clumps, and the comparison with those of their low-mass counterparts, could provide crucial clues about the exact role that chemistry plays in differentiating the early phases of low-mass and high-mass star formation. Water, in particular, is a unique probe of physical and chemical conditions in star-forming regions. Methods. Using the HIFI instrument of Herschel, we have observed the ortho−NH3 (10 −00 ) (572 GHz), ortho−H2 O (110 −101 ) (557 GHz), and N2 H+ (6−5) (559 GHz) lines toward a sample of high-mass starless and protostellar clumps selected from the Herschel Infrared Galactic Plane Survey (Hi-GAL). We compare our results to previous studies of low-mass and high-mass protostellar objects. Results. At least one of the three molecular lines was detected in 4 (out of 35) and 7 (out of 17) objects in the l = 59° and l = 30° galactic regions, respectively. All detected sources are protostellar. The water spectra are complex and consist of several kinematic components, identified through a Gaussian decomposition, and we detected inverse and regular P-Cygni profiles in a few sources. All water line profiles of the l = 59° region are dominated by a broad Gaussian emission feature, indicating that the bulk of the water emission arises in outflows. No such broad emission is detected toward the l = 30° objects. The ammonia line in some cases also shows line wings and an inverse P-Cygni profile, thus confirming that NH3 rotational transitions can be used to probe the dynamics of high-mass, star-forming regions. Both bolometric and water line luminosity increase with the continuum temperature. Conclusions. The higher water abundance toward the l = 59° sources, characterized by the presence of outflows and shocks, supports a scenario in which the abundance of this molecule is linked to the shocked gas. Various indicators suggest that the detected sources toward the l = 30° region are in a somewhat later evolutionary phase compared to the l = 59° field, although a firm conclusion is limited by the small number of observed sources. We find many similarities with studies carried out toward low-mass protostellar objects, but there are indications that the level of infall and turbulence in the high-mass protostars studied here could be significantly higher

    Science stories: researchers\u27 experiences of writing science communication and the implications for training future scientists

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    This study investigates tenured academics\u27 experiences of science communication-popularization of science, dissemination of scientific knowledge, and collaboration outside academia. Specifically, the study spotlights the written aspect of science communication and explores how scientists approach writing addressing audiences \u27beyond academia\u27. Adopting an ethnographic narrative interview approach, we explore what four researchers in different STEM fields write, how they do it and why, their perceptions about the value and the role of science communication, and the place and space it takes in their career. After presenting their individual experiences, we discuss the common themes that link their personal \u27stories\u27 of science communication. First, their motives align with the notion of scholarship of engagement: as a means to educate and share scientific knowledge, science communication has a democratic value. Secondly, they engage in a wide range of writing practices and genres, based on the nature of their work and their field of expertise. Additionally, while they personally value writing science communication, this engagement takes time away from their academic writing and other types of scientific work. We conclude with suggestions for further research and the development of training programs for future scientists that build on established writing pedagogies

    Comparison of Measurements of Autoantibodies to Glutamic Acid Decarboxylase and Islet Antigen-2 in Whole Blood Eluates from Dried Blood Spots Using the RSR-Enzyme Linked Immunosorbent Assay Kits and In-House Radioimmunoassays

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    To evaluate the performance of dried blood spots (DBSs) with subsequent analyses of glutamic acid decarboxylase (GADA) and islet antigen-2 (IA-2A) with the RSR-ELISAs, we selected 80 children newly diagnosed with type 1 diabetes and 120 healthy women. DBSs from patients and controls were used for RSR-ELISAs while patients samples were analysed also with in-house RIAs. The RSR-ELISA-GADA performed well with a specificity of 100%, albeit sensitivity (46%) was lower compared to in RIA (56%; P = .008). No prozone effect was observed after dilution of discrepant samples. RSR-ELISA-IA-2A achieved specificity of 69% and sensitivity was lower (59%) compared with RIA (66%; P < .001). Negative or low positive patients and control samples in the RSR-ELISA-IA-2A increased after dilution. Eluates from DBS can readily be used to analyse GADA with the RSR-ELISA, even if low levels of autoantibodies were not detected. Some factor could disturb RSR-ELISA-IA-2A analyses

    The Nicaraguan Health and Demographic Surveillance Site, HDSS-Leon: a platform for public health research.

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    AIM: To describe the Health and Demographic Surveillance System (HDSS) in León, Nicaragua and to present results from the 2002-2003 baseline. DESIGN AND METHODS: A 22% sample of the total population in León, both urban and rural, was selected in 1993. This sample was updated in 2002 and will be followed up on a biannual basis with regard to births, deaths, in-migration, and out-migration. A group of 18 female fieldworkers perform 10 household interviews per day, 20 days per month. They use a map that is produced by a Geographical Information System. It shows all the households, and is the main means of the interviewers finding the households. An extensive data quality control system is used. RESULTS: In total, 54,647 persons lived in the area of the surveillance system, and they resided in 10,994 households. The mean age was 26 years; the sex ratio was 0.93. The infant and neonatal mortality rates were 25.4 and 20.5 per 1,000 live births, respectively. In total, 2,034 people out-migrated from the study area and 3,377 in-migrated. Of the households, 53% were classified as non-poor, 41% as poor, and 6% as extremely poor. Six per cent of the population did not have a toilet or a latrine, and only 16% in the rural area had indoor running water. The surveillance system revealed that 10% were illiterate. CONCLUSIONS: The HDSS in León has shown that it can serve as a platform for further intervention studies as well as for research training

    Using Methanol Beacons to Find Water in the Dark

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    Interstellar methanol is only formed efficiently from hydrogenation of CO molecules accreted onto grains, and icy grain mantles are observed to consist of 1-30% methanol relative to water. In regions of both low and high mass star formation gas-phase methanol abundances are consistent with partial or complete removal of the ices, either by thermal evaporation or by shock-induced sputtering in outflows. However, the widespread presence of gas-phase methanol in molecular clouds attests to some non-thermal desorption process at work. In particular, distinct peaks of methanol emission at positions significantly offset from protostellar activity implies a transient desorption process, such as clump-clump collisions, rather than a continuous one like photodesorption. Such processes are likely to disrupt a major part of the ice mantles and lead to high gas-phase water abundances clearly distinguishable from what is expected from photodesorption or steady-state gas-phase chemistry. We will report on the first detection of gas-phase water in a cold dark cloud - well offset from protostellar activity - resulting from a small scale survey with Herschel HIFI towards methanol peaks. Physical properties of the sources as well as implications for mantle desorption mechanisms and chemistry in dark clouds will be discussed and compared to those of active star formation

    Expanding shells around young clusters - S 171/Be 59

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    Context. Some HII regions that surround young stellar clusters are bordered by molecular shells that appear to expand at a rate inconsistent with our current model simulations. In this study we focus on the dynamics of Sharpless 171 (including NGC 7822), which surrounds the cluster Berkeley 59. Aims. We aim to compare the velocity pattern over the molecular shell with the mean radial velocity of the cluster for estimates of the expansion velocities of different shell structures, and to match the observed properties with model simulations. Methods. Optical spectra of 27 stars located in Berkeley 59 were collected at the Nordic Optical Telescope, and a number of molecular structures scattered over the entire region were mapped in 13CO(1- 0) at Onsala Space Observatory. Results. We obtained radial velocities and MK classes for the clustera\u27s stars. At least four of the O stars are found to be spectroscopic binaries, in addition to one triplet system. From these data we obtain the mean radial velocity of the cluster. From the 13CO spectra we identify three shell structures, expanding relative to the cluster at moderate velocity (4 km s- 1), high velocity (12 km s- 1), and in between. The high-velocity cloudlets extend over a larger radius and are less massive than the low-velocity cloudlets. We performed a model simulation to understand the evolution of this complex. Conclusions. Our simulation of the Sharpless 171 complex and Berkeley 59 cluster demonstrates that the individual components can be explained as a shell driven by stellar winds from the massive cluster members. However, our relatively simple model produces a single component. Modelling of the propagation of shell fragments through a uniform interstellar medium demonstrates that dense cloudlets detached from the shell are decelerated less efficiently than the shell itself. They can reach greater distances and retain higher velocities than the shell

    Responsiveness of a modified version of the postural assessment scale for stroke patients and longitudinal change in postural control after stroke- Postural Stroke Study in Gothenburg (POSTGOT) -

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    Abstract Background Responsiveness data certify that a change in a measurement output represents a real change, not a measurement error or biological variability. The objective was to evaluate the responsiveness of the modified version of the Postural Assessment Scale for Stroke Patients (SwePASS) in patients with a first event of stroke. An additional aim was to estimate the change in postural control during the first 12 months after stroke onset. Methods The SwePASS assessments were conducted during the first week and 3, 6 and 12 months after stroke in 90 patients. Svensson’s method, Relative Position (RP), Relative Concentration (RC) and Relative Rank Variance (RV), were used to estimate the scale’s responsiveness and the patients’ change in postural control over time. Results From the first week to 3 months after stroke, the patients improved in terms of postural control with 2 to 12 times larger systematic changes in Relative Position (RP), for which 9 items and the total score showed a significant responsiveness to change when compared to the intrarater reliability measurement error of the SwePASS reported in a previous study. When SwePASS was used to assess change in postural control between the first week and 3 months, 74% of the patients received higher scores while 10% received lower scores, RP 0.31 (95% CI 0.219-0.402). The corresponding figures between 3 and 6 and between 6 and 12 months were 37% and 16%, RP 0.09 (95% CI 0.030-0.152), and 18% and 26%, RP −0.07 (95% CI −0.134- (−0.010)), respectively. Conclusions The SwePASS is responsive to change. Postural control evaluated using the SwePASS showed an improvement during the first 6 months after stroke. The measurement property, in the form of responsiveness, shows that the SwePASS scoring method can be considered for use in rehabilitation when assessing postural control in patients after stroke, especially during the first 3 months.</p
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