Smoking, dementia and cognitive decline in the elderly, a systematic review.

Background. Nicotine may aid reaction time, learning and memory, but smoking increases cardiovascular risk. Cardiovascular risk factors have been linked to increased risk of dementia. A previous meta-analysis found that current smokers were at higher risk of subsequent dementia, Alzheimers disease, vascular dementia and cognitive decline. Methods. In order to update and examine this further a systematic review and meta-analysis was carried out using different search and inclusion criteria, database selection and more recent publications. Both reviews were restricted to those aged 65 and over. Results. The review reported here found a significantly increased risk of Alzheimers disease with current smoking and a likely but not significantly increased risk of vascular dementia, dementia unspecified and cognitive decline. Neither review found clear relationships with former smoking. Conclusion. Current smoking increases risk of Alzheimers disease and may increase risk of other dementias. This reinforces need for smoking cessation, particularly aged 65 and over. Nicotine alone needs further investigation. © 2008 Peters et al; licensee BioMed Central Ltd

Allendeite and Hexamolybdenum: Two New Ultra-Refractory Minerals in Allende and Two Missing Links

During our nano-mineralogy investigation of the Allende meteorite, we discovered two new minerals that occur as micro- to nano-crystals in refractory inclusions: Allendeite, Sc_4Zr_3O_(12), a new Scand Zr-rich oxide; and hexamolybdenum, (Mo,Ru,Fe), a Mo-dominant alloy. Allendeite, which may be an important ultra-refractory carrier linking Zr-, Sc- oxides and the more common Sc-, Zr-enriched clinopyroxenes (Cpx) in CAIs, hosts perovskite (Pv), spinel (Sp), Os-Ir-W-Mo alloys, and hexamolybdenum. The observation of two structurally and chemically distinct highly refractory, low-Pt alloy minerals not associated with Fe-Ni alloys provides the first direct physical evidence for at least two separate carriers of the highly refractory metals in CAIs. Hexamolybdenum links Osrich and Pt-rich meteoritic alloys and may be a precursor of the latter. Both new minerals have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA 2007-027, 029)

Correlations and zoning patterns of phosphorus and chromium in olivine from H chondrites and the LL chondrite Semarkona

Phosphorus zoning is observed in olivines in high-FeO (type IIA) chondrules in H chondrites over the entire range of petrologic grades: H3.1–H6. Features in P concentrations such as oscillatory and sector zoning, and high P cores are present in olivines that are otherwise unzoned in the divalent cations. Aluminum concentrations are low and not significantly associated with P zoning in chondrule olivines. In highly unequilibrated H chondrites, phosphorus zoning is generally positively correlated with Cr. Atomic Cr:P in olivine is roughly 1:1 (3:1 for one zone in one olivine in RC 075), consistent with Cr^(3+) charge-balancing P^(5+) substituting for Si^(4+). Normal igneous zonation involving the dominant chrome species Cr^(2+) was observed only in the LL3.0 chondrite Semarkona. In more equilibrated chondrites (H3.5–H3.8), Cr spatially correlated with P is occasionally observed but it is diffuse relative to the P zones. In H4–H6 chondrites, P-correlated Cr is absent. One signature of higher metamorphic grades (≥H3.8) is the presence of near matrix olivines that are devoid of P oscillatory zoning. The restriction to relatively high metamorphic grade and to grains near the chondrule–matrix interface suggests that this is a response to metasomatic processes. We also observed P-enriched halos near the chondrule–matrix interface in H3.3–H3.8 chondrites, likely reflecting the loss of P and Ca from mesostasis and precipitation of Ca phosphate near the chondrule surface. These halos are absent in equilibrated chondrites due to coarsening of the phosphate and in unequilibrated chondrites due to low degrees of metasomatism. Olivines in type IA chondrules show none of the P-zoning ubiquitous in type IIA chondrules or terrestrial igneous olivines, likely reflecting sequestration of P in reduced form within metallic alloys and sulfides during melting of type IA chondrules

Event-Driven Network Programming

Software-defined networking (SDN) programs must simultaneously describe static forwarding behavior and dynamic updates in response to events. Event-driven updates are critical to get right, but difficult to implement correctly due to the high degree of concurrency in networks. Existing SDN platforms offer weak guarantees that can break application invariants, leading to problems such as dropped packets, degraded performance, security violations, etc. This paper introduces EVENT-DRIVEN CONSISTENT UPDATES that are guaranteed to preserve well-defined behaviors when transitioning between configurations in response to events. We propose NETWORK EVENT STRUCTURES (NESs) to model constraints on updates, such as which events can be enabled simultaneously and causal dependencies between events. We define an extension of the NetKAT language with mutable state, give semantics to stateful programs using NESs, and discuss provably-correct strategies for implementing NESs in SDNs. Finally, we evaluate our approach empirically, demonstrating that it gives well-defined consistency guarantees while avoiding expensive synchronization and packet buffering

The Stability of Zirconia-Saturated Perovskite and Conditions in the Early Solar System

Perovskite and tazheranite (cubic zirconia) are among the most refractory oxides in nebular vapors [1] and important repositories for several refractory elements whose concentrations can potentially be used to constrain the environments of formation. There are numerous studies on the phase relations and thermodynamic properties of zirconias containing Al, Ca, Mg, Sc, Ti, and the REE [e.g., 2-4], but meteoritic zirconia is rare [5]. Meteoritic perovskite is much more common [e.g., 5-9], but there are few constraints on thermodynamic properties of the relevant solid solutions. Here, we describe experiments to determine the partitioning of minor elements between perovskite and zirconia of variable Zr/Ti; the results will be used to constrain thermodynamic modeling for the solid solutions represented by meteoritic perovskite

Black girls navigate the physical and emotional landscape of the neighbourhood: Normalized violence and strategic agency

This article considers how young Black women living in gang-affected neighbourhoods in an urban area in England, UK navigate their safety in public and private spaces, and how these spaces overlap and intersect. Drawing on a project with 18 participants aged 14–19, the research seeks to understand how the participants inhabit, navigate and strategize for their safety through their narratives of life and survival in an unsafe neighbourhood. Findings indicate that they experience sexual harassment in public spaces and gang-associated sexual and physical violence as common, accepted aspects of their everyday realities, from as young as 12. The narratives suggest that participants navigate complex friendship groups to protect each other and their families through tight codes of trust, secrecy, privacy and conflict-management strategies. This article seeks to bring attention to how young women utilize their agency to illuminate the coping strategies they draw on to navigate their physical environments. The article concludes with a discussion of the implications for interventions