Molecular properties of (U)LIRGs: CO, HCN, HNC and HCO+

The observed molecular properties of a sample of FIR-luminous and OH megamaser (OH-MM) galaxies have been investigated. The ratio of high and low-density tracer lines is found to be determined by the progression of the star formation in the system. The HCO+/HCN and HCO+/HNC line ratios are good proxies for the density of the gas, and PDR and XDR sources can be distinguished using the HNC/HCN line ratio. The properties of the OH-MM sources in the sample can be explained by PDR chemistry in gas with densities higher than 10^5.5 cm^-3, confirming the classical OH-MM model of IR pumped amplification with (variable) low gains.Comment: 5 pages, 2 figures, to appear in: IAU Symposium 242 Astrophysical Masers and their Environment

The irradiated ISM of ULIRGs

The nuclei of ULIRGs harbor massive young stars, an accreting central black hole, or both. Results are presented for molecular gas that is exposed to X-rays (1-100 keV, XDRs) and far-ultraviolet radiation (6-13.6 eV, PDRs). Attention is paid to species like HCO+, HCN, HNC, OH, H2O and CO. Line ratios of HCN/HCO+ and HNC/HCN discriminate between PDRs and XDRs. Very high J (>10) CO lines, observable with HIFI/Herschel, discriminate very well between XDRs and PDRs. In XDRs, it is easy to produce large abundances of warm (T>100 K) H2O and OH. In PDRs, only OH is produced similarly well.Comment: 5 pages, 6 figures, to appear in: IAU Symposium 242 Astrophysical Masers and their Environment

Unraveling the drivers of regional variation in healthcare spending by analyzing prevalent chronic diseases.

To indicate inefficiencies in health systems, previous studies examined regional variation in healthcare spending by analyzing the entire population. As a result, population heterogeneity is taken into account to a limited extent only. Furthermore, it clouds a detailed interpretation which could be used to inform regional budget allocation decisions to improve quality of care of one chronic disease over another. Therefore, we aimed to gain insight into the drivers of regional variation in healthcare spending by studying prevalent chronic diseases

Star Formation in Extreme Environments: The Effects of Cosmic Rays and Mechanical Heating

Context: Molecular data of extreme environments, such as Arp 220, but also NGC 253, show evidence for extremely high cosmic ray (CR) rates (10^3-10^4 * Milky Way) and mechanical heating from supernova driven turbulence. Aims: The consequences of high CR rates and mechanical heating on the chemistry in clouds are explored. Methods: PDR model predictions are made for low, n=10^3, and high, n=10^5.5 cm^-3, density clouds using well-tested chemistry and radiation transfer codes. Column densities of relevant species are discussed, and special attention is given to water related species. Fluxes are shown for fine-structure lines of O, C+, C, and N+, and molecular lines of CO, HCN, HNC, and HCO+. A comparison is made to an X-ray dominated region model. Results: Fine-structure lines of [CII], [CI], and [OI] are remarkably similar for different mechanical heating and CR rates, when already exposed to large amounts of UV. HCN and H2O abundances are boosted for very high mechanical heating rates, while ionized species are relatively unaffected. OH+ and H2O+ are enhanced for very high CR rates zeta > 5 * 10^-14 s^-1. A combination of OH+, OH, H2O+, H2O, and H3O+ trace the CR rates, and are able to distinguish between enhanced cosmic rays and X-rays.Comment: 13 pages, 8 figures, A&A accepte

Behavior change in a lifestyle intervention for type 2 diabetes prevention in Dutch primary care: opportunities for intervention content

Background Despite the favorable effects of behavior change interventions on diabetes risk, lifestyle modification is a complicated process. In this study we therefore investigated opportunities for refining a lifestyle intervention for type 2 diabetes prevention, based on participant perceptions of behavior change progress. Methods A 30 month intervention was performed in Dutch primary care among high-risk individuals (FINDRISC-score ≥ 13) and was compared to usual care. Participant perceptions of behavior change progress for losing weight, dietary modification, and increasing physical activity were assessed after18 months with questionnaires. Based on the response, participants were categorized as ‘planners’, ‘initiators’ or ‘achievers’ and frequencies were evaluated in both study groups. Furthermore, participants reported on barriers for lifestyle change. Results In both groups, around 80% of all participants (intervention: N = 370; usual care: N = 322) planned change. Except for reducing fat intake (p = 0.08), the number of initiators was significantly higher in the intervention group than in usual care. The percentage of achievers was high for the dietary and exercise objectives (intervention: 81–95%; usual care: 83–93%), but was lower for losing weight (intervention: 67%; usual care: 62%). Important motivational barriers were ‘I already meet the standards’ and ‘I’m satisfied with my current behavior’. Temptation to snack, product taste and lack of time were important volitional barriers. Conclusions The results suggest that the intervention supports participants to bridge the gap between motivation and action. Several opportunities for intervention refinement are however revealed, including more stringent criteria for participant inclusion, tools for (self)-monitoring of health, emphasis on the ‘small-step-approach’, and more attention for stimulus control

Mechanical feedback in the molecular ISM of luminous IR galaxies

Aims: Molecular emission lines originating in the nuclei of luminous infra-red galaxies are used to determine the physical properties of the nuclear ISM in these systems. Methods: A large observational database of molecular emission lines is compared with model predictions that include heating by UV and X-ray radiation, mechanical heating, and the effects of cosmic rays. Results: The observed line ratios and model predictions imply a separation of the observedsystems into three groups: XDRs, UV-dominated high-density (n>=10^5 cm-3) PDRs, and lower-density (n=10^4.5 cm-3) PDRs that are dominated by mechanical feedback. Conclusions: The division of the two types of PDRs follows naturally from the evolution of the star formation cycle of these sources, which evolves from deeply embedded young stars, resulting in high-density (n>=10^5 cm-3) PDRs, to a stage where the gas density has decreased (n=10^4.5 cm-3) and mechanical feedback from supernova shocks dominates the heating budget.Comment: 4 pages, 3 figures, published as Letter to the Editor in A&A (see http://www.aanda.org/articles/aa/abs/2008/34/aa10327-08/aa10327-08.html

Evolution of the ISM in Luminous IR Galaxies

Molecules that trace the high-density regions of the interstellar medium may be used to evaluate the changing physical and chemical environment during the ongoing nuclear activity in (Ultra-)Luminous Infrared Galaxies. The changing ratios of the HCN(1-0), HNC(1-0), HCO+(1-0), CN(1-0) and CN(2-1), and CS(3-2) transitions were compared with the HCN(1-0)/CO(1-0) ratio, which is proposed to represent the progression time scale of the starburst. These diagnostic diagrams were interpreted using the results of theoretical modeling using a large physical and chemical network to describe the state of the nuclear ISM in the evolving galaxies. Systematic changes are seen in the line ratios as the sources evolve from early stage for the nuclear starburst (ULIRGs) to later stages. These changes result from changing environmental conditions and particularly from the lowering of the average density of the medium. A temperature rise due to mechanical heating of the medium by feedback explains the lowering of the ratios at later evolutionary stages. Infrared pumping may affect the CN and HNC line ratios during early evolutionary stages. Molecular transitions display a behavior that relates to changes of the environment during an evolving nuclear starburst. Molecular properties may be used to designate the evolutionary stage of the nuclear starburst. The HCN(1-0)/CO(1-0) and HCO+(1-0)/HCN(1-0) ratios serve as indicators of the time evolution of the outburst.Comment: To be published in Astronomy and Astrophysics - 11 pages, 9 figures, 1 tabl

On the interactions between mesenchymal stem cells and regulatory T cells for immunomodulation in transplantation

Experimental studies have established the use of mesenchymal stem cells (MSC) as a candidate immunosuppressive therapy. MSC exert their immunomodulatory function through the inhibition of CD4+ and CD8+ T cell proliferation. It is unknown whether MSC impair the immunosuppressive function of regulatory T cells (Treg). In vitro and in vivo studies suggest that MSC mediate their immunomodulatory effects through the induction of Treg. In this review we will focus on the interactions between MSC and Treg, and evaluate the consequences of these cellular interplays for prospective MSC immunotherapy in organ transplantation

Vibrationally excited HC3N in NGC 4418

We investigate the molecular gas properties of the deeply obscured luminous infrared galaxy NGC 4418. We address the excitation of the complex molecule HC3N to determine whether its unusually luminous emission is related to the nature of the buried nuclear source. We use IRAM 30m and JCMT observations of rotational and vibrational lines of HC3N to model the excitation of the molecule by means of rotational diagrams. We report the first confirmed extragalactic detection of vibrational lines of HC3N. We detect 6 different rotational transitions ranging from J=10-9 to J=30-29 in the ground vibrational state and obtain a tentative detection of the J=38-37 line. We also detect 7 rotational transitions of the vibrationally excited states v6 and v7, with angular momenta ranging from J=10-9 to 28-27. The energies of the upper states of the observed transitions range from 20 to 850 K. In the optically thin regime, we find that the rotational transitions of the vibrational ground state can be fitted for two temperatures, 30 K and 260 K, while the vibrationally excited levels can be fitted for a rotational temperature of 90 K and a vibrational temperature of 500 K. In the inner 300 pc of NGC 4418, we estimate a high HC3N abundance, of the order of 10^-7. The excitation of the HC3N molecule responds strongly to the intense radiation field and the presence of warm, dense gas and dust at the center of NGC 4418. The intense HC3N line emission is a result of both high abundances and excitation. The properties of the HC3N emitting gas are similar to those found for hot cores in Sgr B2, which implies that the nucleus (< 300 pc) of NGC 4418 is reminiscent of a hot core. The potential presence of a compact, hot component (T=500 K) is also discussed