| 1. |
- Sanchez-Vega, M., et al.
(författare)
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Studies of quadrupole collectivity in the γ -soft 106Ru
- 2008
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Ingår i: European Physical Journal A. - 1434-6001 .- 1434-601X. ; 35:2, s. 159-165
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Tidskriftsartikel (refereegranskat)abstract
- Various alternative models were used to describe the structure of 106Ru . For example, the General Collective Model (GCM) predicts shape-coexistence for 106Ru with a spherical and a triaxial minimum and strongly mixed structures, while in the IBA-2 calculations, where 106Ru was considered as transitional from vibrational U(5) to γ -soft O(6) , no need was found to include the shape-coexisting configurations. In order to provide additional constraints on the model interpretations, we have applied the Advanced Time-Delayed (ATD) βγγ(t) method to measure the level lifetimes of the excited levels in 106Ru . The new results include the half-lives of T 1/2 = 183(3) ps and 7.5(30)ps for the 2+ 1 and 2+ 2 states, respectively.
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| 2. |
- Araujo, C. M., et al.
(författare)
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Electrical resistivity, MNM transition and band-gap narrowing of cubic GaN : Si
- 2002
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Ingår i: Microelectronics Journal. - 0026-2692. ; 33:4, s. 365-369
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Tidskriftsartikel (refereegranskat)abstract
- The electrical resistivity of the Si-donor cubic GaN is investigated theoretically at low temperature. The critical impurity concentration, N-c, for the metal-nonmetal transition is estimated in three different ways: from using the generalized Drude approach (GDA) for the resistivity; from the vanishing of the chemical potential calculated using the dielectric function model with a Lorentz-Lorenz correction; from finding the crossing point between the energy in the insulating and metallic states. The bandgap narrowing (BGN) has been determined theoretically and experimentally above the MNM transition, The experimental data have been obtained with photoluminescence measurements. Theoretical and experimental results are in rough agreement in the range of impurity concentration of interest.
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| 3. |
- Fernandez, J. R. L., et al.
(författare)
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Electrical resistivity and band-gap shift of Si-doped GaN and metal-nonmetal transition in cubic GaN, InN and AlN systems
- 2001
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Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 231:3, s. 420-427
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Tidskriftsartikel (refereegranskat)abstract
- The critical impurity concentration N-c of the metal-nonmetal (MNM) transition for the cubic GaN, InN and AIN systems. is calculated using the following two different criteria: vanishing of the donor binding energy and the crossing point between the energies in the metallic and insulating phases. A dielectric function model with a Lorentz-Lorenz correction is used for the insulating phase. The InN presents an order of magnitude increase in N-c as compared to the other two systems. The electrical resistivity of the Si-donor system GaN is investigated theoretically and experimentally from room temperature down to 10K. It presents a metallic character above a certain high impurity concentration identified as N-c. The samples were grown by plasma assisted molecular beam epitaxy (MBE) on GaAs (0 0 1) substrate. The model calculation is carried out from a recently proposed generalized Drude approach (GDA) presenting a very good estimation for the metallic region. The band-gap shift (BGS) of Si-doped GaN has also been investigated above the MNM transition where this shift is observed. Theoretical and experimental results have a rough agreement in a range of impurity concentration of interest.
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| 4. |
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| 5. |
- Bird, D. M., et al.
(författare)
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Dynamics of the spin transition in the adsorption of hydrogen atoms on metals
- 2004
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028. ; 566-568:1-3 part 2, s. 761-766
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Tidskriftsartikel (refereegranskat)abstract
- The time-dependent, mean-field Newns-Anderson model is solved in the wide-band limit. Equations for the time-evolution of the occupation of the spin-dependent adsorbate levels and for the rate of non-adiabatic energy transfer from adsorbate to substrate are derived. Numerical solutions are obtained in the region of space close to the transition point between spin-polarised and non-polarised ground states, for model parameters that correspond to an H-atom incident on the Cu(111) surface. Away from the spin transition the non-adiabatic energy transfer is in close agreement with the nearly-adiabatic limit. Near the transition, non-adiabatic effects are large and the nearly-adiabatic approximation fails.
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| 6. |
- Cederwall, Bo, et al.
(författare)
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Evidence for a spin-aligned neutron-proton paired phase from the level structure of 92Pd
- 2011
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 469:7328, s. 68-71
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Tidskriftsartikel (refereegranskat)abstract
- Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work(1) that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing(2-6), in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus Pd-92. Gamma rays emitted following the Ni-58(Ar-36,2n)Pd-92 fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution c-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction(2-6). We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling(7,8)) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.
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| 7. |
- Cibula, D., et al.
(författare)
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Completion of radical hysterectomy does not improve survival of patients with cervical cancer and intraoperatively detected lymph node involvement : ABRAX international retrospective cohort study
- 2021
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Ingår i: European Journal of Cancer. - : Elsevier BV. - 0959-8049. ; 143, s. 88-100
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Tidskriftsartikel (refereegranskat)abstract
- Background: The management of cervical cancer patients with intraoperative detection of lymph node involvement remains controversial. Since all these patients are referred for (chemo)radiation after the surgery, the key decision is whether radical hysterectomy should be completed as originally planned, taking into account an additional morbidity associated with extensive surgical dissection prior to adjuvant treatment. The ABRAX study investigated whether completing a radical uterine procedure is associated with an improved oncological outcome of such patients. Patients and methods: We performed retrospective analyses of 515 cervical cancer patients (51 institutions, 19 countries) who were referred for primary curative surgery between 2005 and 2015 (stage IA–IIB, common tumour types) in whom lymph node involvement was detected intraoperatively. Patients were stratified according to whether the planned uterine surgery was completed (COMPL group, N = 361) or abandoned (ABAND group, N = 154) to compare progression-free survival. Definitive chemoradiation was given to 92.9% patients in the ABAND group and adjuvant (chemo)radiation or chemotherapy to 91.4% of patients in the COMPL group. Results: The risks of recurrence (hazard ratio [HR] 1.154, 95% confidence intervals [CI] 0.799–1.666, P = 0.45), pelvic recurrence (HR 0.836, 95% CI 0.458–1.523, P = 0.56), or death (HR 1.064, 95% CI 0.690–1.641, P = 0.78) were not significantly different between the two groups. No subgroup showed a survival benefit from completing radical hysterectomy. Disease-free survival reached 74% (381/515), with a median follow-up of 58 months. Prognostic factors were balanced between the two groups. FIGO stage and number of pelvic lymph nodes involved were significant prognostic factors in the whole study cohort. Conclusion: We showed that the completion of radical hysterectomy does not improve survival in patients with intraoperatively detected lymph node involvement, regardless of tumour size or histological type. If lymph node involvement is confirmed intraoperatively, abandoning uterine radical procedure should be considered, and the patient should be referred for definitive chemoradiation. Clinical trials identifier: NCT04037124.
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| 8. |
- deSouza, Nandita M., et al.
(författare)
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Validated imaging biomarkers as decision-making tools in clinical trials and routine practice: current status and recommendations from the EIBALL* subcommittee of the European Society of Radiology (ESR)
- 2019
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Ingår i: Insights into Imaging. - : SPRINGEROPEN. - 1869-4101. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Observer-driven pattern recognition is the standard for interpretation of medical images. To achieve global parity in interpretation, semi-quantitative scoring systems have been developed based on observer assessments; these are widely used in scoring coronary artery disease, the arthritides and neurological conditions and for indicating the likelihood of malignancy. However, in an era of machine learning and artificial intelligence, it is increasingly desirable that we extract quantitative biomarkers from medical images that inform on disease detection, characterisation, monitoring and assessment of response to treatment. Quantitation has the potential to provide objective decision-support tools in the management pathway of patients. Despite this, the quantitative potential of imaging remains under-exploited because of variability of the measurement, lack of harmonised systems for data acquisition and analysis, and crucially, a paucity of evidence on how such quantitation potentially affects clinical decision-making and patient outcome. This article reviews the current evidence for the use of semi-quantitative and quantitative biomarkers in clinical settings at various stages of the disease pathway including diagnosis, staging and prognosis, as well as predicting and detecting treatment response. It critically appraises current practice and sets out recommendations for using imaging objectively to drive patient management decisions.
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| 9. |
- Falgarone, E., et al.
(författare)
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CH+(1-0) and 13CH+(1-0) absorption lines in the direction of massive star-forming regions
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521:1
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Tidskriftsartikel (refereegranskat)abstract
- We report the detection of the ground-state rotational transition of the methylidyne cation CH+ and its isotopologue (CH+)-C-13 toward the remote massive star-forming regions W33A, W49N, and W51 with the HIFI instrument onboard the Herschel satellite. Both lines are seen only in absorption against the dust continuum emission of the star-forming regions. The CH+ absorption is saturated over almost the entire velocity ranges sampled by the lines-of-sight that include gas associated with the star-forming regions (SFR) and Galactic foreground material. The CH+ column densities are inferred from the optically thin components. A lower limit of the isotopic ratio [(CH+)-C-12]/[(CH+)-C-13]> 35.5 is derived from the absorptions of foreground material toward W49N. The column density ratio, N(CH+)/N(HCO+), is found to vary by at least a factor 10, between 4 and > 40, in the Galactic foreground material. Line-of-sight 12CH+ average abundances relative to total hydrogen are estimated. Their average value, N(CH+)/NH > 2.6 x 10(-8), is higher than that observed in the solar neighborhood and confirms the high abundances of CH+ in the Galactic interstellar medium. We compare this result to the predictions of turbulent dissipation regions (TDR) models and find that these high abundances can be reproduced for the inner Galaxy conditions. It is remarkable that the range of predicted N(CH+)/ N(HCO+) ratios, from 1 to similar to 50, is comparable to that observed.
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| 10. |
- Gerin, M., et al.
(författare)
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Hydride spectroscopy of the diffuse interstellar medium: new clues on the gas fraction in molecular form and cosmic ray ionization rate in relation to H-3(+)
- 2012
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Ingår i: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. - : The Royal Society. - 1364-503X .- 1471-2962. ; 370:1978, s. 5174-5185
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Tidskriftsartikel (refereegranskat)abstract
- The Herschel-guaranteed time key programme PRobing InterStellar Molecules with Absorption line Studies (PRISMAS)(1) is providing a survey of the interstellar hydrides containing the elements C, O, N, F and Cl. As the building blocks of interstellar molecules, hydrides provide key information on their formation pathways. They can also be used as tracers of important physical and chemical properties of the interstellar gas that are difficult to measure otherwise. This paper presents an analysis of two sight-lines investigated by the PRISMAS project, towards the star-forming regions W49N and W51. By combining the information extracted from the detected spectral lines, we present an analysis of the physical properties of the diffuse interstellar gas, including the electron abundance, the fraction of gas in molecular form, and constraints on the cosmic ray ionization rate and the gas density.
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| 11. |
- Gerin, M., et al.
(författare)
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Interstellar CH absorption in the diffuse interstellar medium along the sight-lines to G10.6-0.4 (W31C), W49N, and W51
- 2010
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521:1, s. Article Number: L16-
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Tidskriftsartikel (refereegranskat)abstract
- We report the detection of the ground state N, J = 1, 3/2 -> 1, 1/2 doublet of the methylidyne radical CH at similar to 532 GHz and similar to 536 GHz with the Herschel/ HIFI instrument along the sight-line to the massive star-forming regions G10.6-0.4 (W31C), W49N, and W51. While the molecular cores associated with these massive star-forming regions show emission lines, clouds in the diffuse interstellar medium are detected in absorption against the strong submillimeter background. The combination of hyperfine structure with emission and absorption results in complex profiles, with overlap of the different hyperfine components. The opacities of most of the CH absorption features are linearly correlated with those of CCH, CN, and HCO+ in the same velocity intervals. In specific narrow velocity intervals, the opacities of CN and HCO+ deviate from the mean trends, giving rise to more opaque absorption features. We propose that CCH can be used as another tracer of the molecular gas in the absence of better tracers, with [CCH]/[H2] similar to 3.2 +/- 1.1 x 10-8. The observed [CN]/[CH], [CCH]/[CH] abundance ratios suggest that the bulk of the diffuse matter along the lines of sight has gas densities nH = n(H) + 2n(H2) ranging between 100 and 1000 cm-3).
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| 12. |
- Gerin, M., et al.
(författare)
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Interstellar OH+, H2O+ and H3O+ along the sight-line to G10.6-0.4
- 2010
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518:4, s. 110-
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Tidskriftsartikel (refereegranskat)abstract
- We report the detection of absorption lines by the reactive ions OH+, H2O+ and H3O+ along the line of sight to the submillimeter continuum source G10.6$-$0.4 (W31C). We used the Herschel HIFI instrument in dual beam switch mode to observe the ground state rotational transitions of OH+ at 971 GHz, H2O+ at 1115 and 607 GHz, and H3O+ at 984 GHz. The resultant spectra show deep absorption over a broad velocity range that originates in the interstellar matter along the line of sight to G10.6$-$0.4 as well as in the molecular gas directly associated with that source. The OH+ spectrum reaches saturation over most velocities corresponding to the foreground gas, while the opacity of the H2O+ lines remains lower than 1 in the same velocity range, and the H3O+ line shows only weak absorption. For LSR velocities between 7 and 50 kms$^{-1}$ we estimate total column densities of $N$(OH+) $> 2.5 \times 10^{14}$ cm$^{-2}$, $N$(H2O+) $\sim 6 \times 10^{13}$ cm$^{-2}$ and $N$(H3O+) $\sim 4.0 \times 10^{13}$ cm$^{-2}$. These detections confirm the role of O$^+$ and OH$^+$ in initiating the oxygen chemistry in diffuse molecular gas and strengthen our understanding of the gas phase production of water. The high ratio of the OH+ by the H2O+ column density implies that these species predominantly trace low-density gas with a small fraction of hydrogen in molecular form.
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| 13. |
- Goicoechea, J.R., et al.
(författare)
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VELOCITY-RESOLVED [C II] EMISSION AND [C II]/FIR MAPPING ALONG ORION WITH HERSCHEL
- 2015
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Ingår i: Astrophysical Journal. - 1538-4357 .- 0004-637X. ; 812:1, s. 75-
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Tidskriftsartikel (refereegranskat)abstract
- We present the first ~7.′5 × 11.′5 velocity-resolved (~0.2 km/s) map of the [C II] 158 μm line toward the Orion molecular cloud1 (OMC1) taken with the Herschel/HIFI instrument. In combination with far-IR (FIR) photometric images and velocity-resolved maps of the H41α hydrogen recombination and CO J = 2–1 lines, this data set provides an unprecedented view of the intricate small-scale kinematics of the ionized/photodissociation region (PDR)/molecular gas interfaces and of the radiative feedback from massive stars. The main contribution to the [C II] luminosity (~85%) is from the extended, FUV-illuminated face of the cloud (G0 > 500, nH > 5 × 10^3 cm^−3) and from dense PDRs (G0>~10^4, nH>~10^5 cm^−3) at the interface between OMC 1 and the H II region surrounding the Trapezium cluster. Around ~15% of the [C II] emission arises from a different gas component without a CO counterpart. The [C II] excitation, PDR gas turbulence, line opacity (from [13C II]), and role of the geometry of the illuminating stars with respect to the cloud are investigated. We construct maps of the L[CII]/LFIR and LFIR/MGas ratios and show that L[CII]/LFIR decreases from the extended cloud component (~10^−2–10^−3) to the more opaque star-forming cores (~10^-3-10−4). The lowest values are reminiscent of the “[C II] deficit” seen in local ultraluminous IR galaxies hosting vigorous star formation. Spatial correlation analysis shows that the decreasing L[C II]/LFIR ratio correlates better with the column density of dust through the molecular cloud than with LFIR/MGas. We conclude that the [C II]-emitting column relative to the total dust column along each line of sight is responsible for the observed L[C II]/LFIR variations through the cloud.
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| 14. |
- Hoyer, S., et al.
(författare)
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TOI-220b: a warm sub-Neptune discovered by TESS
- 2021
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 505:3, s. 3361-3379
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we report the discovery of TOI-220b, a new sub-Neptune detected by the Transiting Exoplanet Survey Satellite (TESS) and confirmed by radial velocity follow-up observations with the HARPS spectrograph. Based on the combined analysis of TESS transit photometry and high precision radial velocity measurements, we estimate a planetary mass of 13.8 +/- 1.0M(circle plus) and radius of 3.03 +/- 0.15R(circle plus), implying a bulk density of 2.73 +/- 0.47. TOI-220b orbits a relative bright (V=10.4) and old (10.1 +/- 1.4Gyr) K dwarf star with a period of similar to 10.69d. Thus, TOI-220b is a new warm sub-Neptune with very precise mass and radius determinations. A Bayesian analysis of the TOI-220b internal structure indicates that due to the strong irradiation it receives, the low density of this planet could be explained with a steam atmosphere in radiative-convective equilibrium and a supercritical water layer on top of a differentiated interior made of a silicate mantle and a small iron core.
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| 15. |
- Indriolo, N., et al.
(författare)
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Herschel Survey of Galactic OH+, H2O+, and H3O+: Probing the Molecular Hydrogen Fraction and Cosmic-Ray Ionization Rate
- 2015
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Ingår i: Astrophysical Journal. - 1538-4357 .- 0004-637X. ; 800:1, s. 40-
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Tidskriftsartikel (refereegranskat)abstract
- In diffuse interstellar clouds the chemistry that leads to the formation of the oxygen-bearing ions OH+, H2O+, and H3O+ begins with the ionization of atomic hydrogen by cosmic rays, and continues through subsequent hydrogen abstraction reactions involving H2. Given these reaction pathways, the observed abundances of these molecules are useful in constraining both the total cosmic-ray ionization rate of atomic hydrogen (ζH) and molecular hydrogen fraction (f_H_2). We present observations targeting transitions of OH+, H2O+, and H3O+ made with the Herschel Space Observatory along 20 Galactic sight lines toward bright submillimeter continuum sources. Both OH+ and H2O+ are detected in absorption in multiple velocity components along every sight line, but H3O+ is only detected along 7 sight lines. From the molecular abundances we compute f_H_2 in multiple distinct components along each line of sight, and find a Gaussian distribution with mean and standard deviation 0.042 ± 0.018. This confirms previous findings that OH+ and H2O+ primarily reside in gas with low H2 fractions. We also infer ζH throughout our sample, and find a lognormal distribution with mean log (ζH) = –15.75 (ζH = 1.78 × 10–16 s–1) and standard deviation 0.29 for gas within the Galactic disk, but outside of the Galactic center. This is in good agreement with the mean and distribution of cosmic-ray ionization rates previously inferred from H_3^+ observations. Ionization rates in the Galactic center tend to be 10-100 times larger than found in the Galactic disk, also in accord with prior studies.
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| 16. |
- Katsoulis, J, et al.
(författare)
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Impact of sample storage on detection of periodontal bacteria.
- 2005
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Ingår i: Oral Microbiology and Immunology. - 0902-0055 .- 1399-302X. ; 20:2, s. 128-130
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND/AIMS: Information on the impact of sample storage prior to analysis by DNA methods is limited. The aim of this study was to investigate the effect of subgingival sample storage on bacterial detection and enumeration.MATERIAL AND METHODS: Subgingival plaque samples were studied by a) checkerboard DNA-DNA hybridization by immediate processing, b) storage at + 4 degrees C for 6 weeks, c) storage at - 20 degrees C for 6 months or d) storage at - 20 degrees C for 12 months.RESULTS: No differences in total DNA were found between protocol 1 and 2, or between protocol 3 and 4. Protocol 1 yielded 2.4 times more total bacterial DNA than did protocol 3 (P < 0.001). Actinobacillus actinomycetemcomitans and Campylobacter gracilis were detected in 21.1% of the immediately processed samples but only in 6.6% of the samples after 12 months of storage. Similar changes were noticed for Treponema denticola, which was detected in 22.3% and 9.2%, respectively. Streptococci spp., Fusobacterium nucleatum and Tannerella forsythia did not seem to be affected by storage. In contrast, the level of Campylobacter rectus detection frequency changed from 2.6% if processed immediately to 15.8% if samples were stored for 12 months.CONCLUSIONS: In longitudinal clinical studies including microbiological samples and processed with DNA-DNA hybridization methods, samples should be stored for the same period of time before processing to avoid loss of microbiological information.
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| 17. |
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| 18. |
- Lis, D. C., et al.
(författare)
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Herschel/HIFI measurements of the ortho/para ratio in water towards Sagittarius B2(M) and W31C
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521:1, s. Article Number: L26 -
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Tidskriftsartikel (refereegranskat)abstract
- We present Herschel/HIFI observations of the fundamental rotational transitions of ortho- and para-H216O and H218O in absorption towards Sagittarius B2(M) and W31C. The ortho/para ratio in water in the foreground clouds on the line of sight towards these bright continuum sources is generally consistent with the statistical high-temperature ratio of 3, within the observational uncertainties. However, somewhat unexpectedly, we derive a low ortho/para ratio of 2.35 +/- 0.35, corresponding to a spin temperature of similar to 27 K, towards Sagittarius B2(M) at velocities of the expanding molecular ring. Water molecules in this region appear to have formed with, or relaxed to, an ortho/para ratio close to the value corresponding to the local temperature of the gas and dust.
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| 19. |
- Mookerjea, B., et al.
(författare)
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Excitation and abundance of C3 in star forming cores Herschel/HIFI observations of the sight-lines to W31C and W49N
- 2010
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521:1, s. Article Number: L13 -
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Tidskriftsartikel (refereegranskat)abstract
- We present spectrally resolved observations of triatomic carbon (C-3) in several ro-vibrational transitions between the vibrational ground state and the low-energy nu(2) bending mode at frequencies between 1654-1897 GHz along the sight-lines to the submillimeter continuum sources W31C and W49N, using Herschel's HIFI instrument. We detect C-3 in absorption arising from the warm envelope surrounding the hot core, as indicated by the velocity peak position and shape of the line profile. The sensitivity does not allow to detect C-3 absorption due to diffuse foreground clouds. From the column densities of the rotational levels in the vibrational ground state probed by the absorption we derive a rotation temperature (T-rot) of similar to 50-70 K, which is a good measure of the kinetic temperature of the absorbing gas, as radiative transitions within the vibrational ground state are forbidden. It is also in good agreement with the dust temperatures for W31C and W49N. Applying the partition function correction based on the derived T-rot, we get column densities N(C-3) similar to 7-9 x 10(14) cm(-2) and abundance x(C-3) similar to 10(-8) with respect to H-2. For W31C, using a radiative transfer model including far-infrared pumping by the dust continuum and a temperature gradient within the source along the line of sight we find that a model with x(C-3) = 10(-8), T-kin = 30-50 K, N(C-3) = 1.5 x 10(15) cm(-2) fits the observations reasonably well and provides parameters in very good agreement with the simple excitation analysis.
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| 20. |
- Ness, A. R., et al.
(författare)
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Centralization of cleft care in the UK. Part 6 : a tale of two studies
- 2015
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Ingår i: Orthod Craniofac Res. - 1601-6343 (Electronic) 1601-6335 (Linking) ; 18 Suppl 2, s. 56-62
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: We summarize and critique the methodology and outcomes from a substantial study which has investigated the impact of reconfigured cleft care in the United Kingdom (UK) 15 years after the UK government started to implement the centralization of cleft care in response to an earlier survey in 1998, the Clinical Standards Advisory Group (CSAG). SETTING AND SAMPLE POPULATION: A UK multicentre cross-sectional study of 5-year-olds born with non-syndromic unilateral cleft lip and palate. Data were collected from children born in the UK with a unilateral cleft lip and palate between 1 April 2005 and 31 March 2007. MATERIALS AND METHODS: We discuss and contextualize the outcomes from speech recordings, hearing, photographs, models, oral health and psychosocial factors in the current study. We refer to the earlier survey and other relevant studies. RESULTS: We present arguments for centralization of cleft care in healthcare systems, and we evidence this with improvements seen over a period of 15 years in the UK. We also make recommendations on how future audit and research may configure. CONCLUSIONS: Outcomes for children with a unilateral cleft lip and palate have improved after the introduction of a centralized multidisciplinary service, and other countries may benefit from this model. Predictors of early outcomes are still needed, and repeated cross-sectional studies, larger longitudinal studies and adequately powered trials are required to create a research-led evidence-based (centralized) service.
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| 21. |
- Neufeld, D. A., et al.
(författare)
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Herschel/HIFI observations of interstellar OH+ and H2O+ towards W49N: a probe of diffuse clouds with a small molecular fraction
- 2010
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521:1, s. Article Number: L10-
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Tidskriftsartikel (refereegranskat)abstract
- We report the detection of absorption by interstellar hydroxyl cations and water cations, along the sight-line to the bright continuum source W49N. We have used Herschel's HIFI instrument, in dual beam switch mode, to observe the 972 GHz N = 1-0 transition of OH+ and the 1115 GHz 1(11)-0(00) transition of ortho-H2O+. The resultant spectra show absorption by ortho-H2O+, and strong absorption by OH+, in foreground material at velocities in the range 0 to 70 km s(-1) with respect to the local standard of rest. The inferred OH+/H2O+ abundance ratio ranges from similar to 3 to similar to 15, implying that the observed OH+ arises in clouds of small molecular fraction, in the 2-8% range. This conclusion is confirmed by the distribution of OH+ and H2O+ in Doppler velocity space, which is similar to that of atomic hydrogen, as observed by means of 21 cm absorption measurements, and dissimilar from that typical of other molecular tracers. The observed OH+/H abundance ratio of a few x10(-8) suggests a cosmic ray ionization rate for atomic hydrogen of 0.6-2.4 x 10(-16) s(-1), in good agreement with estimates inferred previously for diffuse clouds in the Galactic disk from observations of interstellar H-3(+) and other species.
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| 22. |
- Neufeld, D.A., et al.
(författare)
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HERSCHEL OBSERVATIONS of INTERSTELLAR CHLORONIUM. II. DETECTIONS TOWARD G29.96-0.02, W49N, W51, and W3(OH), and DETERMINATIONS of the ORTHO-TO-PARA and 35Cl/37Cl ISOTOPIC RATIOS
- 2015
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Ingår i: Astrophysical Journal. - 1538-4357 .- 0004-637X. ; 807:1
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Tidskriftsartikel (refereegranskat)abstract
- We report additional detections of the chloronium molecular ion, H2Cl+, toward four bright submillimeter continuum sources: G29.96-0.02, W49N, W51, and W3(OH). With the use of the HIFI instrument on board the Herschel Space Observatory, we observed the 212-101 transition of ortho-H235Cl+ at 781.627 GHz in absorption toward all four sources. Much of the detected absorption arises in diffuse foreground clouds that are unassociated with the background continuum sources and in which our best estimates of the N(H2Cl+)/N(H) ratio lie in the range (0.9-4.8)× 10-9. These chloronium abundances relative to atomic hydrogen can exceed the predictions of current astrochemical models by up to a factor of 5. Toward W49N, we have also detected the 212-101 transition of ortho-H237Cl+ at 780.053 GHz and the 111-000 transition of para-H235Cl+ at 485.418 GHz. These observations imply H235Cl+/H237Cl+ column density ratios that are consistent with the solar system 35Cl/37Cl isotopic ratio of 3.1, and chloronium ortho-to-para ratios consistent with 3, the ratio of spin statistical weights.
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| 23. |
- Neufeld, D.A., et al.
(författare)
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Strong absorption by interstellar hydrogen fluoride: Herschel/HIFI observations of the sight-line to G10.6-0.4 (W31C)
- 2010
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518:4, s. 108-
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Tidskriftsartikel (refereegranskat)abstract
- We report the detection of strong absorption by interstellar hydrogen fluoride along the sight-line to the submillimeter continuum source G10.6-0.4 (W31C). We have used Herschel's HIFI instrument, in dual beam switch mode, to observe the 1232.4763 GHz J=1-0 HF transition in the upper sideband of the Band 5a receiver. The resultant spectrum shows weak HF emission from G10.6-0.4 at LSR velocities in the range -10 to -3 km/s, accompanied by strong absorption by foreground material at LSR velocities in the range 15 to 50 km/s. The spectrum is similar to that of the 1113.3430 GHz 1(11)-0(00) transition of para-water, although at some frequencies the HF (hydrogen fluoride) optical depth clearly exceeds that of para-H2O. The optically-thick HF absorption that we have observed places a conservative lower limit of 1.6E+14 cm-2 on the HF column density along the sight-line to G10.6-0.4. Our lower limit on the HF abundance, 6E-9 relative to hydrogen nuclei, implies that hydrogen fluoride accounts for between ~ 30 and 100% of the fluorine nuclei in the gas phase along this sight-line. This observation corroborates theoretical predictions that - because the unique thermochemistry of fluorine permits the exothermic reaction of F atoms with molecular hydrogen - HF will be the dominant reservoir of interstellar fluorine under a wide range of conditions.
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| 24. |
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| 25. |
- Persson, Carina, 1964, et al.
(författare)
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First detection of [NII] 205 μm absorption in interstellar gas. Herschel-HIFI observations towards W31C, W49N, W51, and G34.3+0.1.
- 2014
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 568, s. 37-
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Tidskriftsartikel (refereegranskat)abstract
- We present high resolution [N II] 205 μm (3^P_1 − 3^P_0) spectra obtained with Herschel-HIFI towards a small sample of far-infrared bright star forming regions in the Galactic plane: All sources display an emission line profile associated directly with the H II regions themselves. For the first time we also detect absorption of the [N II] 205 μm line by extended low-density foreground material towards W 31C and W 49N over a wide range of velocities. We attribute this absorption to the warm ionised medium (WIM) and find N(N+) ≈ 1.5×10^17 cm^-2 towards both sources. This is in agreement with recent Herschel-HIFI observations of [C II] 158 μm, also observed in absorption in the same sight-lines, if ≈7–10% of all C + ions exist in the WIM on average. Using an abundance ratio of [N]/[H] = 6.76×10^-5 in the gas phase we find that the mean electron and proton volume densities are ∼0.1–0.3 cm^-3 assuming a WIM volume filling fraction of 0.1–0.4 with a corresponding line-of-sight filling fraction of 0.46–0.74. A low density and a high WIM filling fraction are also supported by RADEX modelling of the [N II] 205 μm absorption and emission together with visible emission lines attributed mainly to the WIM. The detection of the 205 μm line in absorption emphasises the importance of a high spectral resolution, and also offers a new tool for investigation of the WIM.
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| 26. |
- Persson, Carina, 1964, et al.
(författare)
-
Nitrogen hydrides in interstellar gas Herschel/HIFI observations towards G10.6-0.4 (W31C)
- 2010
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521:1, s. Article Number: L45 -
-
Tidskriftsartikel (refereegranskat)abstract
- The HIFI instrument on board the Herschel Space Observatory has been used to observe interstellar nitrogen hydrides along the sight-line towards G10.6-0.4 in order to improve our understanding of the interstellar chemistry of nitrogen. We report observations of absorption in NH N = 1
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| 27. |
- Persson, Carina, 1964, et al.
(författare)
-
Nitrogen hydrides in interstellar gas II. Analysis of Herschel/HIFI observations towards W49N and G10.6-0.4 (W31C)
- 2012
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 543:Article Number: A145, s. 145-179
-
Tidskriftsartikel (refereegranskat)abstract
- As a part of the Herschel key programme PRISMAS, we have used the Herschel-HIFI instrument to observe interstellar nitrogen hydrides along the sight-lines towards eight high-mass star-forming regions in order to elucidate the production pathways leading to nitrogen-bearing species in diffuse gas. Here, we report observations towards W49N of the NH N = 1 - 0, J = 2 - 1, and J = 1 - 0, ortho-NH2 N_(Ka, K_c) J = 1_(1,1) 3/2 - 0_(0,0) 1/2, ortho-NH3 J_K = 1_0 - 0_0 and 2_0 - 1_0, para-NH3 J_K = 2_1 - 1_1 transitions, and unsuccessful searches for NH+. All detections show absorption by foreground material over a wide range of velocities, as well as absorption associated directly with the hot-core source itself. As in the previously published observations towards G10.6-0.4, the NH, NH2 and NH3 spectra towards W49N show strikingly similar and non-saturated absorption features. We decompose the absorption of the foreground material towards W49N into different velocity components in order to investigate whether the relative abundances vary among the velocity components, and, in addition, we re-analyse the absorption lines towards G10.6-0.4 in the same manner. Abundances, with respect to molecular hydrogen, in each velocity component are estimated using CH, which is found to correlate with H2 in the solar neighbourhood diffuse gas. The analysis points to a co-existence of the nitrogen hydrides in diffuse or translucent interstellar gaswith a high molecular fraction. Towards both sources, we find that NH is always at least as abundant as both o-NH2 and o-NH3, in sharp contrast to previous results for dark clouds. We find relatively constant N(NH)/N(o-NH3) and N(o-NH2)/N(o-NH3) ratios with mean values of 3.2 and 1.9 towards W49N, and 5.4 and 2.2 towards G10.6-0.4, respectively. The mean abundance of o-NH4 is ~2x10^-9 towards both sources. The nitrogen hydrides also show linear correlations with CN and HNC towards both sources, and looser correlations with CH. The upper limits on the NH+ abundance indicate column densities
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| 28. |
- Persson, Martin, 1971-, et al.
(författare)
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A cross-sectional survey of 5-year-old children with non-syndromic unilateral cleft lip and palate : the Cleft Care UK study. Part 1
- 2015
-
Ingår i: Orthod Craniofac Res. - 1601-6343 (Electronic) 1601-6335 (Linking) ; 18 Suppl 2, s. 1-13
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: We describe the methodology for a major study investigating the impact of reconfigured cleft care in the United Kingdom (UK) 15 years after an initial survey, detailed in the Clinical Standards Advisory Group (CSAG) report in 1998, had informed government recommendations on centralization. SETTING AND SAMPLE POPULATION: This is a UK multicentre cross-sectional study of 5-year-olds born with non-syndromic unilateral cleft lip and palate. Children born between 1 April 2005 and 31 March 2007 were seen in cleft centre audit clinics. MATERIALS AND METHODS: Consent was obtained for the collection of routine clinical measures (speech recordings, hearing, photographs, models, oral health, psychosocial factors) and anthropometric measures (height, weight, head circumference). The methodology for each clinical measure followed those of the earlier survey as closely as possible. RESULTS: We identified 359 eligible children and recruited 268 (74.7%) to the study. Eleven separate records for each child were collected at the audit clinics. In total, 2666 (90.4%) were collected from a potential 2948 records. The response rates for the self-reported questionnaires, completed at home, were 52.6% for the Health and Lifestyle Questionnaire and 52.2% for the Satisfaction with Service Questionnaire. CONCLUSIONS: Response rates and measures were similar to those achieved in the previous survey. There are practical, administrative and methodological challenges in repeating cross-sectional surveys 15 years apart and producing comparable data.
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| 29. |
- Post, J. R., et al.
(författare)
-
Angler numerical response across landscapes and the collapse of freshwater fisheries
- 2008
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Ingår i: Ecological Applications. - : Ecological Society of America (ESA). - 1051-0761 .- 1939-5582. ; 18:4, s. 1038-1049
-
Tidskriftsartikel (refereegranskat)abstract
- Recreational angling opportunities in lakes are distributed across landscapes and attract anglers based on the combination of angling quality, travel distance, and availability of facilities. The relationship between angler density and fishing quality, as measured by catch rate, represents a numerical response that is analogous to a predator numerical response to variability in prey abundance. We quantified this numerical response of anglers to rainbow trout, Oncorhynchus mykiss, populations distributed over a large lake district in south-central British Columbia, Canada. We developed a harvest dynamics model by linking this empirical description of the spatial numerical response of anglers to a logistic population growth rate model. The model was parameterized for rainbow trout and simulated spatial patterns of angler density and catch rates over a landscape. At locations distant from urban centers, angler density is low and catch rate high, suggesting near pristine conditions; at intermediate distances angler density is higher while catch rates are lower and approximate maximum sustainable levels; and at short distances angler density is sufficiently high to harvest to local extirpation. We extrapolated the model to other lake districts varying in human population size using an empirically derived angling participation rate relationship. Extrapolation to lake districts with one-tenth the human population maintained viable fisheries close to the urban area, and districts with 10 times the human populations could not maintain viable fisheries across much of their lake district. Landscape-scale spatial patterns differed quantitatively for species varying in rates of intrinsic population growth and carrying capacity, but the qualitative spatial patterns were consistent among species, demonstrating the pervasive impacts of the angler numerical response. To achieve a management goal of sustaining fisheries across landscapes, a change in management perspective is necessary, from that of individual lakes to one of dynamic harvest processes across landscapes. This new approach makes it clear that a one-size-fits-all management approach must be replaced with a mosaic of approaches cognizant of landscape-scale processes.
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| 30. |
- Pratt, J. R., et al.
(författare)
-
Effects of methylphosphonate, a phosphate analogue, on the expression and degradation of the high-affinity phosphate transporter Pho84, in Saccharomyces cerevisiae
- 2004
-
Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 43:45, s. 14444-53
-
Tidskriftsartikel (refereegranskat)abstract
- In Saccharomyces cerevisiae, the Pho84 high-affinity transport system is the major phosphate transporter activated when the cells experience a limitation in external phosphate. In this study, we have compared the phosphate-responsive mechanism of cells expressing PHO84 with a Deltapho84 strain by use of a phosphate analogue, methylphosphonate, which was judged to be suitable for assessment of phosphate homeostasis in the cells. Intracellular levels of the analogue, which in several respects mimicks phosphate, were monitored by (31)P NMR spectroscopy. Results show that methylphosphonate is a nonhydrolyzable and nonutilizable analogue that cannot be used to replenish phosphate or polyphosphate in yeast cells grown under conditions of phosphate limitation. However, the presence of methylphosphonate under such conditions represses the Pho5 acidic phosphatase activity of PHO84 cells, a finding that implies a direct role of the analogue in the regulation of phosphate-responsive genes and/or proteins. Likewise, accumulation of the Pho84 protein at the plasma membrane of the same cells is inhibited by methylphosphonate, although the derepressive expression of the PHO84 gene is unperturbed. Thus, a post-transcriptional regulation is suggested. Supportive of this suggestion is the fact that addition of methylphosphonate to cells with abundant and active Pho84 at the plasma membrane causes enhanced internalization of the Pho84 protein. Altogether, these observations suggest that the Pho84 transporter is regulated not only at the transcriptional level but also by a direct molecule-sensing mechanism at the protein level.
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| 31. |
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| 32. |
- Sanchez-Vega, M., et al.
(författare)
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Studies of quadrupole collectivity in the γ -soft 106Ru
- 2008
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 35:2, s. 159-165
-
Tidskriftsartikel (refereegranskat)abstract
- Various alternative models were used to describe the structure of Ru-106. For example, the General Collective Model (GCM) predicts shape-coexistence for Ru-106 with a spherical and a triaxial minimum and strongly mixed structures, while in the IBA-2 calculations, where Ru-106 was considered as transitional from vibrational U(5) to gamma -soft O(6) , no need was found to include the shape-coexisting configurations. In order to provide additional constraints on the model interpretations, we have applied the Advanced Time-Delayed (ATD) beta gamma gamma(t) method to measure the level lifetimes of the excited levels in Ru-106 . The new results include the half-lives of T-1/2 = 183(3) ps and 7.5(30)ps for the 2(1)(+) and 2(1)(+) states, respectively.
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| 33. |
- Scott, J. K., et al.
(författare)
-
Centralization of services for children born with orofacial clefts in the United kingdom : a cross-sectional survey
- 2014
-
Ingår i: Cleft Palate Craniofac J. - 1545-1569 (Electronic) 1055-6656 (Linking) ; 51:5, s. e102-9
-
Tidskriftsartikel (refereegranskat)abstract
- Objective : To examine current provision of cleft lip and/or palate services in the U.K. and compliance with recommendations made by the Clinical Standards Advisory Group (CSAG) in 1998. Design : Cross-sectional questionnaire survey. Setting : All 11 services within the U.K. providing care for children born with a cleft lip and palate. Participants : Members from each healthcare specialty in each U.K. cleft team. Interventions : Self-administered postal questionnaires enquired about the provision of cleft services. Data were collected about the overall cleft service, team coordination, hearing, orthodontics, pediatric dentistry, primary cleft surgery, psychology, restorative dentistry, secondary surgery, specialist cleft nursing, and speech and language therapy. Results : Questionnaires were returned from members of 130/150 cleft teams (87%) and these showed that U.K. cleft services have been restructured to 11 centralized services with 17 primary operative sites and 61 peripheral sites. All services provide care through a multidisciplinary (MDT) model, but the composition of each team varies. Primary cleft surgery and orthodontics were the only specialties that were represented in all cleft teams. Specialties may be represented in a team but their attendance at MDT clinics is variable. Only one team met all of the CSAG recommendations. Conclusions : Our survey shows that cleft services have centralized over the last 10 years, and an MDT model of care has been adopted. Further research is needed to show how this has influenced outcomes and to see whether some models of centralized care are associated with better outcomes.
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| 34. |
- Scott, J. K., et al.
(författare)
-
Perceptions of team members working in cleft services in the United Kingdom : a pilot study
- 2015
-
Ingår i: Cleft Palate Craniofac J. - 1545-1569 (Electronic) 1055-6656 (Linking) ; 52:1, s. e1-7
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cleft care provision in the United Kingdom has been centralized over the past 15 years to improve outcomes for children born with cleft lip and palate. However, to date, there have been no investigations to examine how well these multidisciplinary teams are performing. METHODS: In this pilot study, a cross-sectional questionnaire surveyed members of all health care specialties working to provide cleft care in 11 services across the United Kingdom. Team members were asked to complete the Team Work Assessment (TWA) to investigate perceptions of team working in cleft services. The TWA comprises 55 items measuring seven constructs: team foundation, function, performance and skills, team climate and atmosphere, team leadership, and team identity; individual constructs were also aggregated to provide an overall TWA score. Items were measured using five-point Likert-type scales and were converted into percentage agreement for analysis. RESULTS: Responses were received from members of every cleft team. Ninety-nine of 138 cleft team questionnaires (71.7%) were returned and analyzed. The median (interquartile range) percentage of maximum possible score across teams was 75.5% (70.8, 88.2) for the sum of all items. Team performance and team identity were viewed most positively, with 82.0% (75.0, 88.2) and 88.4% (82.2, 91.4), respectively. Team foundation and leadership were viewed least positively with 79.0% (72.6, 84.6) and 76.6% (70.6, 85.4), respectively. CONCLUSIONS: Cleft team members perceive that their teams work well, but there are variations in response according to construct.
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| 35. |
- Scott, J. K., et al.
(författare)
-
Perceptions of team members working in cleft services in the United Kingdom : a pilot study
- 2015
-
Ingår i: Cleft Palate Craniofac J. ; 52:1, s. e1-7
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cleft care provision in the United Kingdom has been centralized over the past 15 years to improve outcomes for children born with cleft lip and palate. However, to date, there have been no investigations to examine how well these multidisciplinary teams are performing. METHODS: In this pilot study, a cross-sectional questionnaire surveyed members of all health care specialties working to provide cleft care in 11 services across the United Kingdom. Team members were asked to complete the Team Work Assessment (TWA) to investigate perceptions of team working in cleft services. The TWA comprises 55 items measuring seven constructs: team foundation, function, performance and skills, team climate and atmosphere, team leadership, and team identity; individual constructs were also aggregated to provide an overall TWA score. Items were measured using five-point Likert-type scales and were converted into percentage agreement for analysis. RESULTS: Responses were received from members of every cleft team. Ninety-nine of 138 cleft team questionnaires (71.7%) were returned and analyzed. The median (interquartile range) percentage of maximum possible score across teams was 75.5% (70.8, 88.2) for the sum of all items. Team performance and team identity were viewed most positively, with 82.0% (75.0, 88.2) and 88.4% (82.2, 91.4), respectively. Team foundation and leadership were viewed least positively with 79.0% (72.6, 84.6) and 76.6% (70.6, 85.4), respectively. CONCLUSIONS: Cleft team members perceive that their teams work well, but there are variations in response according to construct.
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| 36. |
- Smallridge, J., et al.
(författare)
-
Functional outcomes in the Cleft Care UK study--Part 3 : oral health and audiology
- 2015
-
Ingår i: Orthod Craniofac Res. - 1601-6343 (Electronic) 1601-6335 (Linking) ; 18 Suppl 2, s. 25-35
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To compare oral health and hearing outcomes from the Clinical Standards Advisory Group (CSAG, 1998) and the Cleft Care UK (CCUK, 2013) studies. SETTING AND SAMPLE POPULATION: Two UK-based cross-sectional studies of 5-year-olds born with non-syndromic unilateral cleft lip and palate undertaken 15 years apart. CSAG children were treated in a dispersed model of care with low-volume operators. CCUK children were treated in a centralized, high volume operator system. MATERIALS AND METHODS: Oral health data were collected using a standardized proforma. Hearing was assessed using pure tone audiometry and middle ear status by otoscopy and tympanometry. ENT and hearing history were collected from medical notes and parental report. RESULTS: Oral health was assessed in 264 of 268 children (98.5%). The mean dmft was 2.3, 48% were caries free, and 44.7% had untreated caries. There was no evidence this had changed since the CSAG survey. Oral hygiene was generally good, 96% were enrolled with a dentist. Audiology was assessed in 227 of 268 children (84.7%). Forty-three per cent of children received at least one set of grommets--a 17.6% reduction compared to CSAG. Abnormal middle ear status was apparent in 50.7% of children. There was no change in hearing levels, but more children with hearing loss were managed with hearing aids. CONCLUSIONS: Outcomes for dental caries and hearing were no better in CCUK than in CSAG, although there was reduced use of grommets and increased use of hearing aids. The service specifications and recommendations should be scrutinized and implemented.
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| 37. |
- Sonnentrucker, P., et al.
(författare)
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Detection of hydrogen fluoride absorption in diffuse molecular clouds with Herschel/HIFI: an ubiquitous tracer of molecular gas
- 2010
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521:1, s. Article Number: L12-
-
Tidskriftsartikel (refereegranskat)abstract
- We discuss the detection of absorption by interstellar hydrogen fluoride (HF) along the sight line to the submillimeter continuum sources W49N and W51. We have used Herschel's HIFI instrument in dual beam switch mode to observe the 1232.4762 GHz J = 1-0 HF transition in the upper sideband of the band 5a receiver. We detected foreground absorption by HF toward both sources over a wide range of velocities. Optically thin absorption components were detected on both sight lines, allowing us to measure - as opposed to obtain a lower limit on - the column density of HF for the first time. As in previous observations of HF toward the source G10.6-0.4, the derived HF column density is typically comparable to that of water vapor, even though the elemental abundance of oxygen is greater than that of fluorine by four orders of magnitude. We used the rather uncertain N(CH) - N(H-2) relationship derived previously toward diffuse molecular clouds to infer the molecular hydrogen column density in the clouds exhibiting HF absorption. Within the uncertainties, we find that the abundance of HF with respect to H-2 is consistent with the theoretical prediction that HF is the main reservoir of gas-phase fluorine for these clouds. Thus, hydrogen fluoride has the potential to become an excellent tracer of molecular hydrogen, and provides a sensitive probe of clouds of small H-2 column density. Indeed, the observations of hydrogen fluoride reported here reveal the presence of a low column density diffuse molecular cloud along the W51 sight line, at an LSR velocity of similar to 24 km s(-1), that had not been identified in molecular absorption line studies prior to the launch of Herschel.
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| 38. |
- van Dishoeck, E. F., et al.
(författare)
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Water in star-forming regions: Physics and chemistry from clouds to disks as probed by Herschel spectroscopy
- 2021
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 648
-
Tidskriftsartikel (refereegranskat)abstract
- Context. Water is a key molecule in the physics and chemistry of star and planet formation, but it is difficult to observe from Earth. The Herschel Space Observatory provided unprecedented sensitivity as well as spatial and spectral resolution to study water. The Water In Star-forming regions with Herschel (WISH) key program was designed to observe water in a wide range of environments and provide a legacy data set to address its physics and chemistry. Aims. The aim of WISH is to determine which physical components are traced by the gas-phase water lines observed with Herschel and to quantify the excitation conditions and water abundances in each of these components. This then provides insight into how and where the bulk of the water is formed in space and how it is transported from clouds to disks, and ultimately comets and planets. Methods. Data and results from WISH are summarized together with those from related open time programs. WISH targeted ∼80 sources along the two axes of luminosity and evolutionary stage: from low- to high-mass protostars (luminosities from <1 to > 10Lpdbl) and from pre-stellar cores to protoplanetary disks. Lines of H2O and its isotopologs, HDO, OH, CO, and [O I], were observed with the HIFI and PACS instruments, complemented by other chemically-related molecules that are probes of ultraviolet, X-ray, or grain chemistry. The analysis consists of coupling the physical structure of the sources with simple chemical networks and using non-LTE radiative transfer calculations to directly compare models and observations. Results. Most of the far-infrared water emission observed with Herschel in star-forming regions originates from warm outflowing and shocked gas at a high density and temperature (> 10cm-3, 300-1000 K, v ∼ 25 km s-1), heated by kinetic energy dissipation. This gas is not probed by single-dish low-J CO lines, but only by CO lines with Jup > 14. The emission is compact, with at least two different types of velocity components seen. Water is a significant, but not dominant, coolant of warm gas in the earliest protostellar stages. The warm gas water abundance is universally low: orders of magnitude below the H2O/H2 abundance of 4 × 10-4 expected if all volatile oxygen is locked in water. In cold pre-stellar cores and outer protostellar envelopes, the water abundance structure is uniquely probed on scales much smaller than the beam through velocity-resolved line profiles. The inferred gaseous water abundance decreases with depth into the cloud with an enhanced layer at the edge due to photodesorption of water ice. All of these conclusions hold irrespective of protostellar luminosity. For low-mass protostars, a constant gaseous HDO/H2O ratio of ∼0.025 with position into the cold envelope is found. This value is representative of the outermost photodesorbed ice layers and cold gas-phase chemistry, and much higher than that of bulk ice. In contrast, the gas-phase NH3 abundance stays constant as a function of position in low-mass pre- and protostellar cores. Water abundances in the inner hot cores are high, but with variations from 5 × 10-6 to a few × 10-4 for low- and high-mass sources. Water vapor emission from both young and mature disks is weak. Conclusions. The main chemical pathways of water at each of the star-formation stages have been identified and quantified. Low warm water abundances can be explained with shock models that include UV radiation to dissociate water and modify the shock structure. UV fields up to 102-10times the general interstellar radiation field are inferred in the outflow cavity walls on scales of the Herschel beam from various hydrides. Both high temperature chemistry and ice sputtering contribute to the gaseous water abundance at low velocities, with only gas-phase (re-)formation producing water at high velocities. Combined analyses of water gas and ice show that up to 50% of the oxygen budget may be missing. In cold clouds, an elegant solution is that this apparently missing oxygen is locked up in larger μm-sized grains that do not contribute to infrared ice absorption. The fact that even warm outflows and hot cores do not show H2O at full oxygen abundance points to an unidentified refractory component, which is also found in diffuse clouds. The weak water vapor emission from disks indicates that water ice is locked up in larger pebbles early on in the embedded Class I stage and that these pebbles have settled and drifted inward by the Class II stage. Water is transported from clouds to disks mostly as ice, with no evidence for strong accretion shocks. Even at abundances that are somewhat lower than expected, many oceans of water are likely present in planet-forming regions. Based on the lessons for galactic protostars, the low-J H2O line emission (Eup < 300 K) observed in extragalactic sources is inferred to be predominantly collisionally excited and to originate mostly from compact regions of current star formation activity. Recommendations for future mid- to far-infrared missions are made.
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| 39. |
- Van Eylen, Vincent, et al.
(författare)
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Masses and compositions of three small planets orbiting the nearby M dwarf L231-32 (TOI-270) and the M dwarf radius valley
- 2021
-
Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 507:2, s. 2154-2173
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Tidskriftsartikel (refereegranskat)abstract
- We report on precise Doppler measurements of L231-32 (TOI-270), a nearby M dwarf (d = 22 pc, M = 0.39 M, R = 0.38 R), which hosts three transiting planets that were recently discovered using data from the Transiting Exoplanet Survey Satellite (TESS). The three planets are 1.2, 2.4, and 2.1 times the size of Earth and have orbital periods of 3.4, 5.7, and 11.4 d. We obtained 29 high-resolution optical spectra with the newly commissioned Echelle Spectrograph for Rocky Exoplanet and Stable Spectroscopic Observations (ESPRESSO) and 58 spectra using the High Accuracy Radial velocity Planet Searcher (HARPS). From these observations, we find the masses of the planets to be 1.58 ± 0.26, 6.15 ± 0.37, and 4.78 ± 0.43 M, respectively. The combination of radius and mass measurements suggests that the innermost planet has a rocky composition similar to that of Earth, while the outer two planets have lower densities. Thus, the inner planet and the outer planets are on opposite sides of the 'radius valley'-a region in the radius-period diagram with relatively few members-which has been interpreted as a consequence of atmospheric photoevaporation. We place these findings into the context of other small close-in planets orbiting M dwarf stars, and use support vector machines to determine the location and slope of the M dwarf (Teff < 4000 K) radius valley as a function of orbital period. We compare the location of the M dwarf radius valley to the radius valley observed for FGK stars, and find that its location is a good match to photoevaporation and core-powered mass-loss models. Finally, we show that planets below the M dwarf radius valley have compositions consistent with stripped rocky cores, whereas most planets above have a lower density consistent with the presence of a H-He atmosphere.
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| 40. |
- Waylen, A., et al.
(författare)
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Cleft Care UK study. Part 5 : child psychosocial outcomes and satisfaction with cleft services
- 2015
-
Ingår i: Orthod Craniofac Res. - 1601-6343 (Electronic) 1601-6335 (Linking) ; 18 Suppl 2, s. 47-55
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To describe the impact of cleft service centralization on parental perceptions of child outcomes and satisfaction with care from the Cleft Care UK (CCUK) study and compare them to the Clinical Standards Advisory Group (CSAG) study that took place 15 years earlier. SETTING AND SAMPLE POPULATION: A subgroup of respondents from a UK multicentre cross-sectional study (CCUK) of 5-year-olds born with non-syndromic unilateral cleft lip and palate. MATERIALS AND METHODS: Data on parents' perceptions of child self-confidence and their satisfaction with treatment outcomes and service provision were collected via self-report questionnaires. Data were compared with findings from the 1998 CSAG study. RESULTS: Fewer parents in the CCUK study perceived their children as having poor self-confidence than in the 1998 CSAG study (8 and 19%, respectively). At least 81% of parents report satisfaction with the child's facial features after surgery and 98% report being satisfied with the care received. These results are similar to those reported in 1998. There is no evidence of an adverse impact on families' ability to attend appointments at the cleft clinic following centralization. Levels of reported problems (around 30%) with attendance were similar to those reported by CSAG. CONCLUSION: Centralization of cleft services appears to have improved parental perceptions of some child outcomes but has made little difference to already high levels of parental satisfaction with cleft care services. Centralization is not associated with an increase in the proportion of families who find it difficult to attend appointments.
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