Massive Star Formation in Luminous Infrared Galaxies: Giant HII Regions and their relation to Super Star Clusters

We have used HST/NICMOS H-band narrow-band Pa-alpha (at rest 1.87micron) images to identify star clusters and HII regions respectively in a sample of 8 luminous infrared galaxies (LIRGs). These observations have revealed the presence of a large population of super star clusters (SSC) and bright HII regions. A significant fraction of the HII regions shows H-alpha luminosities above that of 30 Doradus, the prototypical giant HII region. The excess of extremely luminous HII regions in LIRGs has been confirmed by comparison with normal galaxies observed at similar spatial resolutions. Despite the large numbers of identified star clusters and HII regions in LIRGs, we only find a small fraction of coincidences, between 4% and 30%. Using synthesis models we have reproduced the relative fractions of young HII regions, intermediate and old star clusters observed in Arp299 and the central region NGC3256 using a Salpeter IMF and instantaneous star formation. HII regions with no detected near-infrared cluster counterpart (25-39%) represent the youngest sites of star formation, with ages of up to approximately 5Myr and mostly intermediate mass (~10^5Msun) ionizing clusters. For these two galaxies, and within the present detection threshold we can only detect coincidences (4-10%) between an HII region and a near-infrared star cluster for the most massive star clusters (~10^6Msun) during the first 7Myr of their evolution. The identified near-infrared SSCs with no detectable Pa-alpha emission represent the ``old'' population (53-66% of the detected sources), with ages of between 7 and 20-40Myr. Older clusters possibly created in this or previous episodes of star formation are likely to exist in these systems but cannot be identified with the present detection threshold. (Abridged)Comment: Accepted for publication in AJ (July issue). Figure 2 not included. Go to: http://nicmos2.as.arizona.edu/~aalonso/work/papers/lirghii_v2.ps for a complete version of pape

HII regions in spiral galaxies: Size distribution, luminosity function, and new isochrone diagnostics of density wave kinematics

We investigate the relationship of the HII region luminosity function (HII LF) to the HII region size distribution and density wave triggering in grand-design spiral galaxies. We suggest that the differential nebular size distribution is described by a power law of slope ~ -4, with flattening at radii below ~ 130 pc. This contrasts with the conventional exponential description, but it is physically and quantitatively consistent with the typical observed value of -2 for the HII LF slope. We have developed an interactive code that computes spatial isochrones for the evolving loci of spiral density waves in disk galaxies. This allows comparison of the nebular spatial distribution with the spatial isochrones for simple rotation curve parameters. Our comparisons for four grand-design galaxies suggest that the corotation radius r_co coincides with the outer ends of the star-forming arms. This value for r_co yields the best spatial correspondence between the HII regions and the isochrones, and also appears to yield a coincidence between the Inner Lindblad Resonance with the radial onset of star formation in the arms. Thus, we suggest that isochrones offer a new, simple, and effective technique for determining r_co, and thus the spiral pattern speed. However, application of the isochrones also demonstrates that evolution of the nebular population is difficult to spatially isolate in these galaxies.Comment: 15 pp, 8 figs, uses emulateapj. Accepted to A

Obscured star formation in the central region of the dwarf galaxy NGC5253

We present HST/NICMOS observations (1.1-2.2micron) and 1.9-4.1micron spectroscopy of the central region of the dwarf galaxy NGC5253. The HST/NICMOS observations reveal the presence of a nuclear double star cluster separated by 0.3-0.4arcsec or 6-8pc (for a distance d=4.1Mpc). The double star cluster, also a bright double source of Pa-alpha emission, appears to be coincident with the double radio nebula detected at 1.3cm. The eastern near-infrared star cluster (C1) is identified with the youngest optical cluster, whereas the western star cluster (C2), although it is almost completely obscured in the optical, becomes the brightest star cluster in the central region of NGC 5253 at wavelengths longer than 2micron. Both clusters are extremely young with ages of approximately 3.5 million years old. C2 is more massive than C1 by a factor of 6 to 20 (M(C2)= 7.7 x 10^5 - 2.6 x 10^6Msun, for a Salpeter IMF in the mass range 0.1-100Msun). Analysis of the circumnuclear spectrum excluding C1 and C2, as well as of a number of other near-infrared selected clusters with a range of (young) ages, suggests that the star formation was triggered across the central regions of the galaxy. We have also modelled the nuclear UV to mid-infrared spectral energy distribution (SED) of NGC5253 and found that the infrared part is well modelled with a highly obscured (A_V= 17mag) young starburst with a stellar mass consistent with our photometric estimates for C1 and C2. The SED model predicts a moderately bright polycyclic aromatic hydrocarbon (PAH) feature at 3.3micron that is not detected in our nuclear L-band spectrum. NGC5253's low metallicity and a top-heavy IMF likely combine to suppress the 3.3micron PAH emission that is commonly seen in more massive starburst systems.Comment: Accepted for publication in ApJ. High quality versions of Figures 1 and 2 are available upon reques

Adaptive model-driven user interface development systems

Adaptive user interfaces (UIs) were introduced to address some of the usability problems that plague many software applications. Model-driven engineering formed the basis for most of the systems targeting the development of such UIs. An overview of these systems is presented and a set of criteria is established to evaluate the strengths and shortcomings of the state-of-the-art, which is categorized under architectures, techniques, and tools. A summary of the evaluation is presented in tables that visually illustrate the fulfillment of each criterion by each system. The evaluation identified several gaps in the existing art and highlighted the areas of promising improvement

Changes in malaria morbidity and mortality in Mpumalanga Province, South Africa (2001- 2009): a retrospective study

<p>Abstract</p> <p>Background</p> <p>Malaria remains a serious epidemic threat in Mpumalanga Province. In order to appropriately target interventions to achieve substantial reduction in the burden of malaria and ultimately eliminate the disease, there is a need to track progress of malaria control efforts by assessing the time trends and evaluating the impact of current control interventions. This study aimed to assess the changes in the burden of malaria in Mpumalanga Province during the past eight malaria seasons (2001/02 to 2008/09) and whether indoor residual spraying (IRS) and climate variability had an effect on these changes.</p> <p>Methods</p> <p>This is a descriptive retrospective study based on the analysis of secondary malaria surveillance data (cases and deaths) in Mpumalanga Province. Data were extracted from the Integrated Malaria Information System. Time series model (Autoregressive Integrated Moving Average) was used to assess the association between climate and malaria.</p> <p>Results</p> <p>Within the study period, a total of 35,191 cases and 164 deaths due to malaria were notified in Mpumalanga Province. There was a significant decrease in the incidence of malaria from 385 in 2001/02 to 50 cases per 100,000 population in 2008/09 (<it>P </it>< 0.005). The incidence and case fatality (CFR) rates for the study period were 134 cases per 100,000 and 0.54%, respectively. Mortality due to malaria was lower in infants and children (CFR < 0.5%) and higher in those >65 years, with the mean CFR of 2.1% as compared to the national target of 0.5%. A distinct seasonal transmission pattern was found to be significantly related to changes in rainfall patterns (<it>P </it>= 0.007). A notable decline in malaria case notification was observed following apparent scale-up of IRS coverage from 2006/07 to 2008/09 malaria seasons.</p> <p>Conclusions</p> <p>Mpumalanga Province has achieved the goal of reducing malaria morbidity and mortality by over 70%, partly as a result of scale-up of IRS intervention in combination with other control strategies. These results highlight the need to continue with IRS together with other control strategies until interruption in local malaria transmission is completely achieved. However, the goal to eliminate malaria as a public health problem requires efforts to be directed towards the control of imported malaria cases; development of strategies to interrupt local transmission; and maintaining high quality surveillance and reporting system.</p

Swift UV/Optical Telescope Imaging of Star Forming Regions in M81 and Holmberg IX

We present Swift UV/Optical Telescope (UVOT) imaging of the galaxies M81 and Holmberg IX. We combine UVOT imaging in three near-ultraviolet (NUV) filters (uvw2: 1928 Å; uvm2: 2246 Å; uvw1: 2600 Å) with ground-based optical imaging from the Sloan Digital Sky Survey to constrain the stellar populations of both galaxies. Our analysis consists of three different methods. First, we use the NUV imaging to identify UV star-forming knots and then perform spectral energy distribution (SED) modeling on the UV/optical photometry of these sources. Second, we measure surface brightness profiles of the disk of M81 in the NUV and optical. Lastly, we use SED fitting of individual pixels to map the properties of the two galaxies. In agreement with earlier studies, we find evidence for a burst in star formation in both galaxies starting ~200 Myr ago coincident with the suggested time of an M81-M82 interaction. In line with theories of its origin as a tidal dwarf, we find that the luminosity-weighted age of Holmberg IX is a few hundred million years. Both galaxies are best fit by a Milky Way dust extinction law with a prominent 2175 Å bump. In addition, we describe a stacked median filter technique for modeling the diffuse background light within a galaxy and a Markov chain method for cleaning segment maps generated by SExtractor

Lack of effect of salt on the glucose and insulin response to mashed potatoes, white rice, and lima beans.

The effect of 4.25 g of table salt on the insulin and glucose response to three forms of carbohydrate with varying glycemic indices was studied. There was no statistical difference in the peak response or area under the glucose or insulin curves for any of these foods in the presence of salt. It is concluded that salt has no effect on the absorption of starches