The determination of the mass of a Magellanic Cloud planetary nebula by speckle interferometry

We have resolved a Magellanic Cloud planetary nebula by speckle interferometry for the first time. Our observations of SMC N2 show it to have a double-ring structure, the rings having angular radii of 0.22 and 0.38 arcsec, corresponding to absolute radii of 0.06 and 0.10 pc. Our speckle observations of the galactic planetary nebula Vy 2–2 show a ring of angular diameter 0.4 arcsec, in agreement with previous VLA radio data. The radial hydrogen density profile for SMC N2 is determined and masses of 0.09M⊙ and 0.27M⊙ for the inner and outer shells respectively are derived, so that the total mass of this optically thin nebula is 0.36M⊙⁠. The nebular expansion velocity of SMC N2 has been derived from a high-resolution spectrum of the [O III] 5007 Å line and expansion ages of between 5000 and 12 000 yr have been derived for the shells. A reanalysis of the available nebular data leads us to derive a central star effective temperature of 110 000 K and a luminosity of 4340L⊙⁠, corresponding to a stellar mass of 0.59M⊙⁠, from a comparison with published evolutionary tracks. The stellar evolutionary age since leaving the AGB is about 8000 yr, consistent with the nebublar expansion age

The 'Scourie dyke' suite of the north-west mainland Lewisian of Scotland, with particular reference to the structural geology and geochemistry

The 'Scourie Dyke' Suite of the North-West mainland Lewisian of Scotland - with particular reference to the structural geology and geochemistry. The 'Scourie Dykes' were intruded into Scourian gneisses about 1,900 million years ago and were subsequently deformed and metamorphosed about 1,750 million years ago during the Laxfordian orogeny. The intrusive relationships of the dykes and the deformation styles they show in reworked areas are described for a number of areas between Durness and Loch Torridon. An attempt is made to correlate the deformational and metamorphic episodes that have affected the dykes. The igneous and metamorphic petrology and geochemistry of the different dyke types are described and used to propose a scheme for their evolution. The density of dyke outcrop in the Lewisian has been measured and the results plotted as contour maps. These maps show that dyke material is concentrated in parallel, NW-SE trending belts perpendicular to the crustal extension. The spacing of the belts is thought to give an indication of the variationin thickness of the crust 1,900 million years ago

Providing Job Embedded Professional Learning for Mathematics Specialists

We know that if professional learning opportunities are to be meaningful and create long-lasting and systemic change, they must be ongoing and job-embedded. One of the most beneficial aspects of having mathematics specialists in schools is that they can provide job-embedded professional learning directly to teachers. Perhaps due to the strong impact mathematics specialists have on teaching and learning, we may overlook the need to provide professional learning to support the growth of mathematics specialists themselves. Just as we provide coaching to teachers to affect their professional growth, we must identify similar opportunities to affect the growth of mathematics specialists. This paper will identify the purposes of these opportunities to include supporting growth in content knowledge, pedagogical expertise, coaching skills, and professionalism and leadership. We recognize that sustained efforts must be undertaken to see significant growth in these areas. Through interviews with individuals from Virginia school divisions and professional organizations, we identify models that can be replicated to provide the recommended professional learning for mathematics specialists

Minimum Conductivity and Evidence for Phase Transitions in Ultra-clean Bilayer Graphene

Bilayer graphene (BLG) at the charge neutrality point (CNP) is strongly susceptible to electronic interactions, and expected to undergo a phase transition into a state with spontaneous broken symmetries. By systematically investigating a large number of singly- and doubly-gated bilayer graphene (BLG) devices, we show that an insulating state appears only in devices with high mobility and low extrinsic doping. This insulating state has an associated transition temperature Tc~5K and an energy gap of ~3 meV, thus strongly suggesting a gapped broken symmetry state that is destroyed by very weak disorder. The transition to the intrinsic broken symmetry state can be tuned by disorder, out-of-plane electric field, or carrier density

Integrated prevalence mapping of schistosomiasis, soil-transmitted helminthiasis and malaria in lakeside and island communities in Lake Victoria, Uganda

<p>Abstract</p> <p>Background</p> <p>It is widely advocated that integrated strategies for the control of neglected tropical diseases (NTDs) are cost-effective in comparison to vertical disease-specific programmes. A prerequisite for implementation of control interventions is the availability of baseline data of prevalence, including the population at risk and disease overlap. Despite extensive literature on the distribution of schistosomiasis on the mainland in Uganda, there has been a knowledge gap for the prevalence of co-infections with malaria, particularly for island communities in Lake Victoria. In this study, nine lakeshore and island districts were surveyed for the prevalence of NTDs and malaria, as well as educational and health infrastructure.</p> <p>Results</p> <p>A total of 203 communities were surveyed, including over 5000 school-age children. Varying levels of existing health infrastructure were observed between districts, with only Jinja District regularly treating people for NTDs. Community medicine distributors (CMD) were identified and trained in drug delivery to strengthen capacity. Prevalence levels of intestinal schistosomiasis and soil-transmitted helminthiasis were assessed via Kato-Katz thick smears of stool and malaria prevalence determined by microscopy of fingerprick blood samples. Prevalence levels were 40.8%, 26.04% and 46.4%, respectively, while the prevalence of co-infection by <it>Schistosoma mansoni </it>and <it>Plasmodium </it>spp. was 23.5%. Socio-economic status was strongly associated as a risk factor for positive infection status with one or more of these diseases.</p> <p>Conclusions</p> <p>These results emphasise the challenges of providing wide-scale coverage of health infrastructure and drug distribution in remote lakeshore communities. The data further indicate that co-infections with malaria and NTDs are common, implying that integrated interventions for NTDs and malaria are likely to maximize cost-effectiveness and sustainability of disease control efforts.</p

Sorting of EGF and transferrin at the plasma membrane and by cargo-specific signaling to EEA1-enriched endosomes

The biological function of receptors is determined by their appropriate trafficking through the endosomal pathway. Following internalization, the transferrin (Tf) receptor quantitatively recycles to the plasma membrane, whereas the epidermal growth factor (EGF) receptor undergoes degradation. To determine how Tf and EGF engage these two different pathways we imaged their binding and early endocytic pathway in live cells using total internal reflection fluorescence microscopy (TIRF-M). We find that EGF and Tf bind to distinct plasma membrane regions and are incorporated into different endocytic vesicles. After internalization, both EGF-enriched and Tf-enriched vesicles interact with endosomes containing early endosome antigen 1 (EEA1). EGF is incorporated and retained in these endosomes, while Tf-containing vesicles rapidly dissociate and move to a juxtanuclear compartment. Endocytic vesicles carrying EGF recruit more Rab5 GTPase than those carrying Tf, which, by strengthening their association with EEA1-enriched endosomes, may provide a mechanism for the observed cargo-specific sorting. These results reveal pre-endocytic sorting of Tf and EGF, a specialized role for EEA1-enriched endosomes in EGF trafficking, and a potential mechanism for cargo-specified sorting of endocytic vesicles by these endosomes

Can music move people? : The effects of musical complexity and silence on waiting time

Previous research has suggested that music might influence the amount of time for which people are prepared to wait in a given environment. In an attempt to investigate the mechanisms underlying such effects, this study employed three levels of musical complexity and also a “no-music” condition. While one of these played in the background, participants were left to wait in a laboratory for the supposed start of an experiment. The results indicated that participants waited for the least amount of time during the no-music condition, and that there were no differences between the three music conditions. Other evidence indicated that this may be attributable to the music distracting participants’ attention from an internal timing mechanism. The results are discussed in terms of their implications for consumer behavior and research on the psychology of everyday life