Charge-exchange emission in the starburst galaxies M82 and NGC3256

Charge-exchange (CE) emission produces features which are detectable with the current X-ray instrumentation in the brightest near galaxies. We describe these aspects in the observed X-ray spectra of the star forming galaxies M82 and NGC 3256, from the Suzaku and XMM-Newton telescopes. Emission from both ions (O, C) and neutrals (Mg, Si) is recognised. We also describe how microcalorimeter instrumentation on future missions will improve CE observations.Comment: 4 pages. Proc. Workshop "Charge-exchange in the Universe", Paris, Nov. 2011. To appear in Astron.Nach

Conserving the birds of Uganda's Banana-Coffee Arc: Land Sparing and Land Sharing Compared

Reconciling the aims of feeding an ever more demanding human population and conserving biodiversity is a difficult challenge. Here, we explore potential solutions by assessing whether land sparing (farming for high yield, potentially enabling the protection of non-farmland habitat), land sharing (lower yielding farming with more biodiversity within farmland) or a mixed strategy would result in better bird conservation outcomes for a specified level of agricultural production. We surveyed forest and farmland study areas in southern Uganda, measuring the population density of 256 bird species and agricultural yield: food energy and gross income. Parametric non-linear functions relating density to yield were fitted. Species were identified as "winners" (total population size always at least as great with agriculture present as without it) or "losers" (total population sometimes or always reduced with agriculture present) for a range of targets for total agricultural production. For each target we determined whether each species would be predicted to have a higher total population with land sparing, land sharing or with any intermediate level of sparing at an intermediate yield. We found that most species were expected to have their highest total populations with land sparing, particularly loser species and species with small global range sizes. Hence, more species would benefit from high-yield farming if used as part of a strategy to reduce forest loss than from low-yield farming and land sharing, as has been found in Ghana and India in a previous study. We caution against advocacy for high-yield farming alone as a means to deliver land sparing if it is done without strong protection for natural habitats, other ecosystem services and social welfare. Instead, we suggest that conservationists explore how conservation and agricultural policies can be better integrated to deliver land sparing by, for example, combining land-use planning and agronomic support for small farmers

Molecular pathogenesis and targeted therapy of sporadic pancreatic neuroendocrine tumors

Over the past few years, knowledge regarding the molecular pathology of sporadic pancreatic neuroendocrine tumors (PNETs) has increased substantially, and a number of targeted agents have been tested in clinical trials in this tumor type. For some of these agents there is a strong biological rationale. Among them, the mammalian target of rapamycin inhibitor Everolimus and the antiangiogenic agent Sunitinib have both been approved for the treatment of PNETs. However, there is lack of knowledge regarding biomarkers able to predict their efficacy, and mechanisms of resistance. Other angiogenesis inhibitors, such as Pazopanib, inhibitors of Src, Hedgehog or of PI3K might all be useful in association or sequence with approved agents. On the other hand, the clinical significance, and potential for treatment of the most common mutations occurring in sporadic PNETs, in the MEN-1 gene and in ATRX and DAXX, remains uncertain. The present paper reviews the main molecular changes occurring in PNETs and how they might be linked with treatment options

The origin of the Moon within a terrestrial synestia

The giant impact hypothesis remains the leading theory for lunar origin. However, current models struggle to explain the Moon's composition and isotopic similarity with Earth. Here we present a new lunar origin model. High-energy, high-angular momentum giant impacts can create a post-impact structure that exceeds the corotation limit (CoRoL), which defines the hottest thermal state and angular momentum possible for a corotating body. In a typical super-CoRoL body, traditional definitions of mantle, atmosphere and disk are not appropriate, and the body forms a new type of planetary structure, named a synestia. Using simulations of cooling synestias combined with dynamic, thermodynamic and geochemical calculations, we show that satellite formation from a synestia can produce the main features of our Moon. We find that cooling drives mixing of the structure, and condensation generates moonlets that orbit within the synestia, surrounded by tens of bars of bulk silicate Earth (BSE) vapor. The moonlets and growing moon are heated by the vapor until the first major element (Si) begins to vaporize and buffer the temperature. Moonlets equilibrate with BSE vapor at the temperature of silicate vaporization and the pressure of the structure, establishing the lunar isotopic composition and pattern of moderately volatile elements. Eventually, the cooling synestia recedes within the lunar orbit, terminating the main stage of lunar accretion. Our model shifts the paradigm for lunar origin from specifying a certain impact scenario to achieving a Moon-forming synestia. Giant impacts that produce potential Moon-forming synestias were common at the end of terrestrial planet formation.Comment: Accepted for publication in Journal of Geophysical Research: Planets. Main text: 44 pages, 24 figures. Supplement: 16 pages, 5 figures, 3 table

Docking of Yeast Vacuoles Is Catalyzed by the Ras-like GTPase Ypt7p after Symmetric Priming by Sec18p (NSF)

Vacuole inheritance in yeast involves the formation of tubular and vesicular “segregation structures” which migrate into the bud and fuse there to establish the daughter cell vacuole. Vacuole fusion has been reconstituted in vitro and may be used as a model for an NSF-dependent reaction of priming, docking, and fusion. We have developed biochemical and microscopic assays for the docking step of in vitro vacuole fusion and characterized its requirements. The vacuoles must be primed for docking by the action of Sec17p (α-SNAP) and Sec18p (NSF). Priming is necessary for both fusion partners. It produces a labile state which requires rapid docking in order to lead productively to fusion. In addition to Sec17p/Sec18p, docking requires the activity of the Ras-like GTPase Ypt7p. Unlike Sec17p/Sec18p, which must act before docking, Ypt7p is directly involved in the docking process itself

A Vacuolar v–t-SNARE Complex, the Predominant Form In Vivo and on Isolated Vacuoles, Is Disassembled and Activated for Docking and Fusion

Homotypic vacuole fusion in yeast requires Sec18p (N-ethylmaleimide–sensitive fusion protein [NSF]), Sec17p (soluble NSF attachment protein [α-SNAP]), and typical vesicle (v) and target membrane (t) SNAP receptors (SNAREs). We now report that vacuolar v- and t-SNAREs are mainly found with Sec17p as v–t-SNARE complexes in vivo and on purified vacuoles rather than only transiently forming such complexes during docking, and disrupting them upon fusion. In the priming reaction, Sec18p and ATP dissociate this v–t-SNARE complex, accompanied by the release of Sec17p. SNARE complex structure governs each functional aspect of priming, as the v-SNARE regulates the rate of Sec17p release and, in turn, Sec17p-dependent SNARE complex disassembly is required for independent function of the two SNAREs. Sec17p physically and functionally interacts largely with the t-SNARE. (a) Antibodies to the t-SNARE, but not the v-SNARE, block Sec17p release. (b) Sec17p is associated with the t-SNARE in the absence of v-SNARE, but is not bound to the v-SNARE without t-SNARE. (c) Vacuoles with t-SNARE but no v-SNARE still require Sec17p/Sec18p priming, whereas their fusion partners with v-SNARE but no t-SNARE do not. Sec18p thus acts, upon ATP hydrolysis, to disassemble the v–t-SNARE complex, prime the t-SNARE, and release the Sec17p to allow SNARE participation in docking and fusion. These studies suggest that the analogous ATP-dependent disassembly of the 20-S complex of NSF, α-SNAP, and v- and t-SNAREs, which has been studied in detergent extracts, corresponds to the priming of SNAREs for docking rather than to the fusion of docked membranes