300 research outputs found
The infrared spectra of very large, compact, highly symmetric, polycyclic aromatic hydrocarbons (PAHs)
The mid-infrared spectra of large PAHs ranging from C54H18 to C130H28 are
determined computationally using Density Functional Theory. Trends in the band
positions and intensities as a function of PAH size, charge and geometry are
discussed. Regarding the 3.3, 6.3 and 11.2 micron bands similar conclusions
hold as with small PAHs.
This does not hold for the other features. The larger PAH cations and anions
produce bands at 7.8 micron and, as PAH sizes increases, a band near 8.5 micron
becomes prominent and shifts slightly to the red. In addition, the average
anion peak falls slightly to the red of the average cation peak. The similarity
in behavior of the 7.8 and 8.6 micron bands with the astronomical observations
suggests that they arise from large, cationic and anionic PAHs, with the
specific peak position and profile reflecting the PAH cation to anion
concentration ratio and relative intensities of PAH size. Hence, the broad
astronomical 7.7 micron band is produced by a mixture of small and large PAH
cations and anions, with small and large PAHs contributing more to the 7.6 and
7.8 micron component respectively.
For the CH out-of-plane vibrations, the duo hydrogens couple with the solo
vibrations and produce bands that fall at wavelengths slightly different than
their counterparts in smaller PAHs. As a consequence, previously deduced PAH
structures are altered in favor of more compact and symmetric forms. In
addition, the overlap between the duo and trio bands may reproduce the
blue-shaded 12.8 micron profile.Comment: ApJ, 36 pages, 9 fig
Searching for stable fullerenes in space with computational chemistry
We report a computational study of the stability and infrared (IR)
vibrational spectra of neutral and singly ionised fullerene cages containing
between 44 and 70 carbon atoms. The stability is characterised in terms of the
standard enthalpy of formation per CC bond, the HOMO-LUMO gap, and the energy
required to eliminate a C fragment. We compare the simulated IR spectra of
these fullerene species to the observed emission spectra of several planetary
nebulae (Tc 1, SMP SMC 16, and SMP LMC 56) where strong C emission has
been detected. Although we could not conclusively identify fullerenes other
than C and C, our results point to the possible presence of
smaller (44, 50, and 56-atom) cages in those astronomical objects.
Observational confirmation of our prediction should become possible when the
James Webb Space Telescope comes online.Comment: 11 pages, 13 figures, 1 table. Accepted for publication on MNRA
Medication adherence among Turkish type-2 diabetics in Belgium: results from a qualitative study
Abstract title: Medication adherence among Turkish type-2 diabetics in Belgium: results from a qualitative study. Aim: Prevalence of diabetes in Belgium is 2 to 3 times higher among people from Turkish descent. Medication adherence, an essential element of the diabetic regimen, appears to be lower among nonwhite ethnic groups. This study identifies factors influencing medication adherence among Turkish type-2 diabetics living in Belgium. Methods: Since this topic hasn’t been studied before we conducted an explorative, qualitative study using semi-structured in-depth interviews with the aid of an interpreter. The topicslist was based on insights from the literature and conversations with Turkish diabetics and health care workers and was slightly adjusted after the first interviews. 21 Turkish type-2 diabetics living in Belgium were selected using theoretical sampling. Respondent’s most recent HbA1c-values were also collected. Interviews lasted between 2 and 5 hours, were audio-taped, fully transcribed and translated. Thematic analysis was conducted by the first two authors with different educational backgrounds (sociologist/pharmacist). The first phase was a detailed, thematic analysis of the individual cases, in the second phase an analysis across cases, distinguishing adherers from non-adherers, identified factors influencing medication adherence. NVivo 8 was used for managing, coding and analysing the qualitative data. Results: Factors influencing medication adherence among type-2 diabetics from Turkish descent include knowledge of and attitudes towards diabetes and antidiabetics, health and medication beliefs, social support from health care providers and family members, the nature of the patient-provider relationship, perceptions of health care worker’s expertise and social roles in daily life. A typology was constructed identifying different constellations of factors that distinguish adherers from non-adherers. Implications for clinical practice are discussed. Conclusion: This qualitative study identifies factors influencing medication adherence among type-2 Turkish diabetics living in Belgium and provides a typology, distinguishing adherers from non-adherers, that may guide clinical practice. Results from this qualitative study will be tested in a future, quantitative study
Medication adherence among Turkish type-2 diabetics in Belgium: results from a qualitative study
Abstract title: Medication adherence among Turkish type-2 diabetics in Belgium: results from a qualitative study. Aim: Prevalence of diabetes in Belgium is 2 to 3 times higher among people from Turkish descent. Medication adherence, an essential element of the diabetic regimen, appears to be lower among nonwhite ethnic groups. This study identifies factors influencing medication adherence among Turkish type-2 diabetics living in Belgium. Methods: Since this topic hasn’t been studied before we conducted an explorative, qualitative study using semi-structured in-depth interviews with the aid of an interpreter. The topicslist was based on insights from the literature and conversations with Turkish diabetics and health care workers and was slightly adjusted after the first interviews. 21 Turkish type-2 diabetics living in Belgium were selected using theoretical sampling. Respondent’s most recent HbA1c-values were also collected. Interviews lasted between 2 and 5 hours, were audio-taped, fully transcribed and translated. Thematic analysis was conducted by the first two authors with different educational backgrounds (sociologist/pharmacist). The first phase was a detailed, thematic analysis of the individual cases, in the second phase an analysis across cases, distinguishing adherers from non-adherers, identified factors influencing medication adherence. NVivo 8 was used for managing, coding and analysing the qualitative data. Results: Factors influencing medication adherence among type-2 diabetics from Turkish descent include knowledge of and attitudes towards diabetes and antidiabetics, health and medication beliefs, social support from health care providers and family members, the nature of the patient-provider relationship, perceptions of health care worker’s expertise and social roles in daily life. A typology was constructed identifying different constellations of factors that distinguish adherers from non-adherers. Implications for clinical practice are discussed. Conclusion: This qualitative study identifies factors influencing medication adherence among type-2 Turkish diabetics living in Belgium and provides a typology, distinguishing adherers from non-adherers, that may guide clinical practice. Results from this qualitative study will be tested in a future, quantitative study
EUROMON: The multi-country model of De Nederlandsche Bank
This Occasional Study wraps up the modelling work that has been done in recent years regarding DNB’s multi-country model EUROMON. It offers a description of the current version of the model and provides information about its simulation properties through the analysis of variety of standard scenarios. EUROMON is an estimated multi-country model. The current version includes 13 individual country models plus a trade block providing the international linkages between these countries. The 13 countries are the EMU-participants Germany, France, Italy, Spain, the Netherlands, Belgium, Austria and Finland, the EU-countries of the United Kingdom, Sweden and Denmark, plus the United States and Japan. The country models all share the same basic structure. Differences mainly relate to distinct values of model parameters and speeds of adjustment, and in some cases to slightly different specifications of equations in order to allow for specific institutional features of individual countries. EUROMON is a neo-Keynesian model in spirit, combining a vertical supply curve in the long run with an important role for demand factors in the short-run determination of output. The model incorporates a wage bargaining framework which makes the long-run supply curve dependent on real factors, such as tax policies. EUROMON is an aggregate model, with no further breakdown in sectors or categories of goods and services. The current version of the model is backward-looking. The study concludes by addressing the main shortcomings and strong features of the model that require further attention
EUROMON: The multi-country model of De Nederlandsche Bank
This Occasional Study wraps up the modelling work that has been done in recent years regarding DNB’s multi-country model EUROMON. It offers a description of the current version of the model and provides information about its simulation properties through the analysis of variety of standard scenarios. EUROMON is an estimated multi-country model. The current version includes 13 individual country models plus a trade block providing the international linkages between these countries. The 13 countries are the EMU-participants Germany, France, Italy, Spain, the Netherlands, Belgium, Austria and Finland, the EU-countries of the United Kingdom, Sweden and Denmark, plus the United States and Japan. The country models all share the same basic structure. Differences mainly relate to distinct values of model parameters and speeds of adjustment, and in some cases to slightly different specifications of equations in order to allow for specific institutional features of individual countries. EUROMON is a neo-Keynesian model in spirit, combining a vertical supply curve in the long run with an important role for demand factors in the short-run determination of output. The model incorporates a wage bargaining framework which makes the long-run supply curve dependent on real factors, such as tax policies. EUROMON is an aggregate model, with no further breakdown in sectors or categories of goods and services. The current version of the model is backward-looking. The study concludes by addressing the main shortcomings and strong features of the model that require further attention
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