| 1. |
- Decin, L., et al.
(författare)
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Silicon in the dust formation zone of IRC+10216
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518, s. L143-
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Tidskriftsartikel (refereegranskat)abstract
- The interstellar medium is enriched primarily by matter ejected from evolved low and intermediate mass stars. The outflows from these stars create a circumstellar envelope in which a rich gas-phase and dust-nucleation chemistry takes place. We observed the nearest carbon-rich evolved star, IRC + 10216, using the PACS (55-210 mu m) and SPIRE (194-672 mu m) spectrometers on board Herschel. We find several tens of lines from SiS and SiO, including lines from the v = 1 vibrational level. For SiS these transitions range up to J = 124-123, corresponding to energies around 6700 K, while the highest detectable transition is J = 90-89 for SiO, which corresponds to an energy around 8400 K. Both species trace the dust formation zone of IRC + 10216, and the broad energy ranges involved in their detected transitions permit us to derive the physical properties of the gas and the particular zone in which each species has been formed. This allows us to check the accuracy of chemical thermodynamical equilibrium models and the suggested depletion of SiS and SiO due to accretion onto dust grains.
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| 2. |
- Alef, Walter, et al.
(författare)
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BRAND - The next generation receiver for VLBI
- 2018
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Ingår i: Proceedings of Science. - Trieste, Italy : Sissa Medialab. - 1824-8039. ; 344
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Konferensbidrag (refereegranskat)abstract
- The aim of the BRAND EVN project is to build a very wide receiver prototype for primary focus with a frequency range from 1.5 GHz to 15.5 GHz In addition we will investigate solutions for secondary focus telescopes. The project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 730562 [RadioNet]. We present the status of the project which was started on January 1st, 2017 and is progressing smoothly: Feed, LNA, filters, major digital components, and some of the firmware are available now. © Copyright owned by the author(s) under the terms of the Creative Commons.
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| 3. |
- Cernicharo, J., et al.
(författare)
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Discovery of two new magnesium-bearing species in IRC+10216: MgC3N and MgC4H
- 2019
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 630
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Tidskriftsartikel (refereegranskat)abstract
- We report on the detection of two series of harmonically related doublets in IRC +10216. From the observed frequencies, the rotational constant of the first series is B = 1380.888 MHz and that of the second series is B = 1381.512 MHz. The two series correspond to two species with a (2)Sigma electronic ground state. After considering all possible candidates, and based on quantum chemical calculations, the first series is assigned to MgC3N and the second to MgC4H. For the latter species, optical spectroscopy measurements support its identification. Unlike diatomic metal-containing molecules, the line profiles of the two new molecules indicate that they are formed in the outer layers of the envelope, as occurs for MgNC and other polyatomic metal-cyanides. We also confirm the detection of MgCCH that was previously reported from the observation of two doublets. The relative abundance of MgC3N with respect to MgNC is close to one while that of MgC4H relative to MgCCH is about ten. The synthesis of these magnesium cyanides and acetylides in IRC +10216 can be explained in terms of a two-step process initiated by the radiative association of Mg+ with large cyanopolyynes and polyynes followed by the dissociative recombination of the ionic complexes.
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| 4. |
- López, A., et al.
(författare)
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Laboratory characterization and astrophysical detection of vibrationally excited states of vinyl cyanide in Orion-KL
- 2014
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 572
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Tidskriftsartikel (refereegranskat)abstract
- Context. We perform a laboratory characterization in the 18–1893 GHz range and astronomical detection between 80–280 GHz in Orion-KL with IRAM-30 m of CH2CHCN (vinyl cyanide) in its ground and vibrationally excited states. Aims. Our aim is to improve the understanding of rotational spectra of vibrationally excited vinyl cyanide with new laboratory data and analysis. The laboratory results allow searching for these excited state transitions in the Orion-KL line survey. Furthermore, rotational lines of CH2CHCN contribute to the understanding of the physical and chemical properties of the cloud. Methods. Laboratory measurements of CH2CHCN made on several different frequency-modulated spectrometers were combined into a single broadband 50–1900 GHz spectrum and its assignment was confirmed by Stark modulation spectra recorded in the 18–40 GHz region and by ab-initio anharmonic force field calculations. For analyzing the emission lines of vinyl cyanide detected in Orion-KL we used the excitation and radiative transfer code (MADEX) at LTE conditions. Results. Detailed characterization of laboratory spectra of CH2CHCN in nine different excited vibrational states: ?11 = 1, ?15 = 1, 2) ⇔ (?10 = 1,?15 = 1) ⇔ (?11 = 1,?14 = 1), and ?11 = 4 are determined, as well as the detection of transitions in the ?11 = 2and ?11 = 2, ?10 = 1 ⇔ (?11 = 1,?15 = 1), ?11 = 3/?15 = 2/?14 = 1, (?11 = 1,?10 = 1) ⇔ (?11 = 2,?15 = 1), ?9 = 1, (?11 = 1,?15 = The rotational transitions of the ground state of this molecule emerge from four cloud components of hot core nature, which trace the ?11 = 3 states for the first time in Orion-KL and of those in the ?10 = 1 ⇔ (?11 = 1,?15 = 1) dyad of states for the first time in space. physical and chemical conditions of high mass star forming regions in the Orion-KL Nebula. The lowest energy vibrationally excited states of vinyl cyanide, such as ?11 = 1 (at 328.5 K), ?15 = 1 (at 478.6 K), ?11 = 2 (at 657.8 K), the ?10 = 1 ⇔ (?11 = 1,?15 = 1) dyad (at 806.4/809.9 K), and ?11 = 3 (at 987.9 K), are populated under warm and dense conditions, so they probe the hottest parts of the Orion-KL source. The vibrational temperatures derived for the ?11 = 1, ?11 = 2, and ?15 = 1 states are 252 ± 76K, 242 ± 121K, column density of CH2CHCN in the ground state is (3.0 ± 0.9) × 1015 cm−2. We report the detection of methyl isocyanide (CH3NC) and 227 ± 68K, respectively; all of them are close to the mean kinetic temperature of the hot core component (210K). The total for the first time in Orion-KL and a tentative detection of vinyl isocyanide (CH2CHNC). We also give column density ratios between the cyanide and isocyanide isomers, obtaining a N(CH3NC)/N(CH3CN) ratio of 0.002. Conclusions. Laboratory characterization of many previously unassigned vibrationally excited states of vinyl cyanide ranging from microwave to THz frequencies allowed us to detect these molecular species in Orion-KL. Column density, rotational and vibrational temperatures for CH2CHCN in their ground and excited states, and the isotopologues have been constrained by means of a sample of more than 1000 lines in this survey.
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| 5. |
- Saporetti, M. A., et al.
(författare)
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X/Ku/Ka-band high Gain Reflector Antenna Intercomparison Campaign Results
- 2021
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Ingår i: 2021 Antenna Measurement Techniques Association Symposium (AMTA). - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- Antenna measurement Intercomparison Campaigns represent a successful activity within the working group on antenna measurement of the European Association on Antennas and Propagation [1] since the group foundation in 2005. These campaigns, constitute an important resource for participating facilities to demonstrate their measurement proficiency, useful internally but also towards obtaining or maintaining official accreditations. In this paper we present the completion of a campaign involving a high gain X/Ku/Ka-band reflector, MVG SR40 fed by an MVG SH4000 Dual Ridge Horn. Preliminary results were shown in [2]. Results from seven facilities are compared through plots of gain/directivity patterns. The data is used to generate reference patterns and establish accurate gain performance data based on the uncertainty estimates provided by each facility. Statistical analysis of the measured data such as Equivalent Noise Level and Birge ratio of each measurement with respect to the established reference will also be shown.
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| 6. |
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| 9. |
- Tercero, F, et al.
(författare)
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The epidemiology of moderate and severe injuries in a Nicaraguan community : a household-based survey
- 2006
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Ingår i: Public Health. - London : Saunders Elsevier. - 0033-3506 .- 1476-5616. ; 120:2, s. 106-114
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Tidskriftsartikel (refereegranskat)abstract
- Although injuries constitute a major public health problem worldwide, the magnitude and nature of this problem is difficult to establish in low-income settings due to the lack of valid and representative data. In Nicaragua, several parallel studies have been carried out attempting to assess levels and patterns of injury using various sources of information. The objective of this study was to describe the magnitude and profile of moderate and severe injuries in a well-defined community in Nicaragua. The study was conducted using a household-based survey design. Randomized cluster sampling provided information from 10,797 households (63,886 inhabitants). The outcomes included fatal and non-fatal injuries registered during a recall period of 6 weeks. Seven percent of all. injuries were classified as moderate or severe. The estimated annual incidence rate of moderate/severe injuries was 27.6 per 1000 [95% confidence intervals (CI): 26.4-29.2], white the mortality and impairment rates were 108.9 (95% CI: 83.5-134.4) and 95.3 (95% CI: 71.4-119.2) per 100,000 inhabitants, respectively. Home and traffic areas were the main environments associated with injury occurrence. The most affected groups were the elderly, children and mates. No differences were found between urban and rural areas. Only 9% of all cases, including minor injuries, sought hospital treatment. The main causes of non-fatal injuries were falls, traffic and cuts, whereas fatalities were largely associated with intentional injuries. For every death due to injury, there was one permanent disability, 25 moderate/severe injuries and 354 minor injuries. This study provides a broad description of injury magnitudes and patterns in a defined Nicaraguan community, and demonstrates the aggregate injury pyramid of the same community. It also identifies the issue of severity and concludes with a recommendation to apply different criteria of severity. Our results support the call for a careful evaluation of injury data sources and severity scores when planning injury prevention programmes.
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