Impurity effect of Lambda hyperon on collective excitations of atomic nuclei

Taking the ground state rotational band in $^{24}$Mg as an example, we investigate the impurity effect of $\Lambda$ hyperon on collective excitations of atomic nuclei in the framework of non-relativistic energy density functional theory. To this end, we take into account correlations related to the restoration of broken symmetries and fluctuations of collective variables by solving the eigenvalue problem of a five-dimensional collective Hamiltonian for quadrupole vibrational and rotational degrees of freedom. The parameters of the collective Hamiltonian are determined with constrained mean-field calculations for triaxial shapes using the SGII Skyrme force. We compare the low-spin spectrum for $^{24}$Mg with the spectrum for the same nucleus inside $^{25}_{\Lambda}$Mg. It is found that the $\Lambda$ hyperon stretches the ground state band and reduces the $B(E2:2^+_1 \rightarrow 0^+_1)$ value by $\sim 9$, mainly by softening the potential energy surface towards the spherical shape, even though the shrinkage effect on the average proton radius is only $\sim0.5$.Comment: 16 pages, 5 figures, and 1 tabl

Evidence for episodic warm outflowing CO gas from the intermediate mass young stellar object IRAS 08470-4321

We present a R=10,000 M-band spectrum of LLN19 (IRAS 08470-4321), a heavily embedded intermediate-mass young stellar object located in the Vela Molecular Cloud, obtained with VLT-ISAAC. The data were fitted by a 2-slab cold-hot model and a wind model. The spectrum exhibits deep broad ro-vibrational absorption lines of 12CO v=1<-0 and 13CO v=1<-0. A weak CO ice feature at 4.67 micron is also detected. Differences in velocity indicate that the warm gas is distinct from the cold millimeter emitting gas, which may be associated with the absorption by cooler gas (45K). The outflowing warm gas at 300-400K and with a mass-loss rate varying between 0.48E-7 and 4.2E-7 MSun /yr can explain most of the absorption. Several absorption lines were spectrally resolved in subsequent spectra obtained with the VLT-CRIRES instrument. Multiple absorption substructures in the high-resolution (R=100,000) spectra indicate that the mass-loss is episodic with at least two major events that occurred recently (<28 years). The discrete mass-loss events together with the large turbulent width of the gas (dv=10-12 km/s) are consistent with the predictions of the Jet-Bow shock outflow and the wide-angle wind model. The CO gas/solid column density ratio of 20-100 in the line-of-sight confirms that the circumstellar environment of LLN~19 is warm. We also derive a 12C/13C ratio of 67 +/- 3, consistent with previous measurements in local molecular clouds but not with the higher ratios found in the envelope of other young stellar objects.Comment: 16 pages, 12 figures, accepted for publication in MNRA

Treatment of multidrug-resistant tuberculosis in a remote, conflict-affected area of the Democratic Republic of Congo.

The Democratic Republic of Congo is a high-burden country for multidrug-resistant tuberculosis. Médecins Sans Frontières has supported the Ministry of Health in the conflict-affected region of Shabunda since 1997. In 2006, three patients were diagnosed with drug-resistant TB (DR-TB) and had no options for further treatment. An innovative model was developed to treat these patients despite the remote setting. Key innovations were the devolving of responsibility for treatment to non-TB clinicians remotely supported by a TB specialist, use of simplified monitoring protocols, and a strong focus on addressing stigma to support adherence. Treatment was successfully completed after a median of 24 months. This pilot programme demonstrates that successful treatment for DR-TB is possible on a small scale in remote settings

FUV and X-ray irradiated protoplanetary disks: a grid of models I. The disk structure

Context. Planets are thought to eventually form from the mostly gaseous (~99% of the mass) disks around young stars. The density structure and chemical composition of protoplanetary disks are affected by the incident radiation field at optical, FUV, and X-ray wavelengths, as well as by the dust properties. Aims. The effect of FUV and X-rays on the disk structure and the gas chemical composition are investigated. This work forms the basis of a second paper, which discusses the impact on diagnostic lines of, e.g., C+, O, H2O, and Ne+ observed with facilities such as Spitzer and Herschel. Methods. A grid of 240 models is computed in which the X-ray and FUV luminosity, minimum grain size, dust size distribution, and surface density distribution are varied in a systematic way. The hydrostatic structure and the thermo-chemical structure are calculated using ProDiMo. Results. The abundance structure of neutral oxygen is stable to changes in the X-ray and FUV luminosity, and the emission lines will thus be useful tracers of the disk mass and temperature. The C+ abundance distribution is sensitive to both X-rays and FUV. The radial column density profile shows two peaks, one at the inner rim and a second one at a radius r=5-10 AU. Ne+ and other heavy elements have a very strong response to X-rays, and the column density in the inner disk increases by two orders of magnitude from the lowest (LX = 1e29 erg/s) to the highest considered X-ray flux (LX = 1e32 erg/s). FUV confines the Ne+ ionized region to areas closer to the star at low X-ray luminosities (LX = 1e29 erg/s). H2O abundances are enhanced by X-rays due to higher temperatures in the inner disk and higher ionization fractions in the outer disk. The line fluxes and profiles are affected by the effects on these species, thus providing diagnostic value in the study of FUV and X-ray irradiated disks around T Tauri stars. (abridged)Comment: 47 pages, accepted by Astronomy and Astrophysics, a high resolution version of the paper is located at http://www.astro.rug.nl/~meijerink/disk_paperI_xrays.pd

Grain size limits derived from 3.6 {\mu}m and 4.5 {\mu}m coreshine

Recently discovered scattered light from molecular cloud cores in the wavelength range 3-5 {\mu}m (called "coreshine") seems to indicate the presence of grains with sizes above 0.5 {\mu}m. We aim to analyze 3.6 and 4.5 {\mu}m coreshine from molecular cloud cores to probe the largest grains in the size distribution. We analyzed dedicated deep Cycle 9 Spitzer IRAC observations in the 3.6 and 4.5 {\mu}m bands for a sample of 10 low-mass cores. We used a new modeling approach based on a combination of ratios of the two background- and foreground-subtracted surface brightnesses and observed limits of the optical depth. The dust grains were modeled as ice-coated silicate and carbonaceous spheres. We discuss the impact of local radiation fields with a spectral slope differing from what is seen in the DIRBE allsky maps. For the cores L260, ecc806, L1262, L1517A, L1512, and L1544, the model reproduces the data with maximum grain sizes around 0.9, 0.5, 0.65, 1.5, 0.6, and > 1.5 {\mu}m, respectively. The maximum coreshine intensities of L1506C, L1439, and L1498 in the individual bands require smaller maximum grain sizes than derived from the observed distribution of band ratios. Additional isotropic local radiation fields with a spectral shape differing from the DIRBE map shape do not remove this discrepancy. In the case of Rho Oph 9, we were unable to reliably disentangle the coreshine emission from background variations and the strong local PAH emission. Considering surface brightness ratios in the 3.6 and 4.5 {\mu}m bands across a molecular cloud core is an effective method of disentangling the complex interplay of structure and opacities when used in combination with observed limits of the optical depth.Comment: 23 pages, 18 figures, accepted for publication in A&

The effects of dust evolution on disks in the mid-IR

In this paper, we couple together the dust evolution code two-pop-py with the thermochemical disk modelling code ProDiMo. We create a series of thermochemical disk models that simulate the evolution of dust over time from 0.018 Myr to 10 Myr, including the radial drift, growth, and settling of dust grains. We examine the effects of this dust evolution on the mid-infrared gas emission, focussing on the mid-infrared spectral lines of C2H2, CO2, HCN, NH3, OH, and H2O that are readily observable with Spitzer and the upcoming E-ELT and JWST. The addition of dust evolution acts to increase line fluxes by reducing the population of small dust grains. We find that the spectral lines of all species except C2H2 respond strongly to dust evolution, with line fluxes increasing by more than an order of magnitude across the model series as the density of small dust grains decreases over time. The C2H2 line fluxes are extremely low due to a lack of abundance in the infrared line-emitting regions, despite C2H2 being commonly detected with Spitzer, suggesting that warm chemistry in the inner disk may need further investigation. Finally, we find that the CO2 flux densities increase more rapidly than the other species as the dust disk evolves. This suggests that the flux ratios of CO2 to other species may be lower in disks with less-evolved dust populations.Comment: 13 pages, 9 figures, accepted in A&

Floquet stroboscopic divisibility in non-Markovian dynamics

We provide a general discussion of the Liouvillian spectrum for a system coupled to a non-Markovian bath using Floquet theory. This approach is suitable when the system is described by a time-convolutionless master equation with time-periodic rates. Surprisingly, the periodic nature of rates allow us to have a stroboscopic divisible dynamical map at discrete times, which we refer to as Floquet stroboscopic divisibility. We illustrate the general theory for a Schr\"odinger cat which is roaming inside a non-Markovian bath, and demonstrate the appearance of stroboscopic revival of the cat at later time after its death. Our theory may have profound implications in entropy production in non-equilibrium systems.Comment: We changed the title and explained in more detail the definition of non-Markovian dynamics used in the manuscrip

CO ro-vibrational lines in HD100546: A search for disc asymmetries and the role of fluorescence

We have studied the emission of CO ro-vibrational lines in the disc around the Herbig Be star HD100546 with the final goal of using these lines as a diagnostic to understand inner disc structure in the context of planet formation. High-resolution IR spectra of CO ro-vibrational emission at eight different position angles were taken with CRIRES at the VLT. From these spectra flux tables, CO ro-vibrational line profiles, and population diagrams were produced. We have investigated variations in the line profile shapes and line strengths as a function of slit position angle. We used the thermochemical disc modelling code ProDiMo based on the chemistry, radiation field, and temperature structure of a previously published model for HD100546. Comparing observations and the model, we investigated the possibility of disc asymmetries, the excitation mechanism (UV fluorescence), the geometry, and physical conditions of the inner disc. The observed CO ro-vibrational lines are largely emitted from the inner rim of the outer disc at 10-13 AU. The line shapes are similar for all v levels and line fluxes from all vibrational levels vary only within one order of magnitude. All line profile asymmetries and variations can be explained with a symmetric disc model to which a slit correction and pointing offset is applied. Because the angular size of the CO emitting region (10-13 AU) and the slit width are comparable the line profiles are very sensitive to the placing of the slit. The model reproduces the line shapes and the fluxes of the v=1-0 lines as well as the spatial extent of the CO ro-vibrational emission. It does not reproduce the observed band ratios of 0.5-0.2 with higher vibrational bands. We find that lower gas volume densities at the surface of the inner rim of the outer disc can make the fluorescence pumping more effcient and reproduce the observed band ratios.Comment: 20 pages, 21 figure