Insights into secondary reactions occurring during atmospheric ablation of micrometeoroids

Ablation of micrometeoroids during atmospheric entry yields volatile gases such as water, carbon dioxide, and sulfur dioxide, capable of altering atmospheric chemistry and hence the climate and habitability of the planetary surface. While laboratory experiments have revealed the yields of these gases during laboratory simulations of ablation, the reactions responsible for the generation of these gases have remained unclear, with a typical assumption being that species simply undergo thermal decomposition without engaging in more complex chemistry. Here, pyrolysis–Fourier transform infrared spectroscopy reveals that mixtures of meteorite-relevant materials undergo secondary reactions during simulated ablation, with organic matter capable of taking part in carbothermic reduction of iron oxides and sulfates, resulting in yields of volatile gases that differ from those predicted by simple thermal decomposition. Sulfates are most susceptible to carbothermic reduction, producing greater yields of sulfur dioxide and carbon dioxide at lower temperatures than would be expected from simple thermal decomposition, even when mixed with meteoritically relevant abundances of low-reactivity Type IV kerogen. Iron oxides were less susceptible, with elevated yields of water, carbon dioxide, and carbon monoxide only occurring when mixed with high abundances of more reactive Type III kerogen. We use these insights to reinterpret previous ablation simulation experiments and to predict the reactions capable of occurring during ablation of carbonaceous micrometeoroids in atmospheres of different compositions

Nomina dubia and faunistic issues with New Zealand spiders(Araneae)

Attempts to clarify the identity of obscure New Zealand spider taxa have lead to the conclusion that six species are best treated as nomina dubia [Philodromus rubrofrontus Urquhart 1891 (Philodromidae); Dictyna urquhartii Roewer 1951, (Dictynidae); Linyphia albiapiata Urquhart 1891, Linyphia cruenta Urquhart 1891, Linyphia multicolor Urquhart 1891, Linyphia pellos Urquhart 1891 (Linyphiidae)]. Four species currently listed in Araneus Clerck 1757 (Araneidae) are re-affirmed as synonyms [Araneus lineaacutus (Urquhart 1887) = Zealaranea crassa (Walckenaer 1842), Araneus powelli (Urquhart 1894) = Novaranea laevigata (Urquhart 1891), Araneus sublutius (Urquhart 1892b) = Zealaranea trinotata (Urquhart 1890), Araneus ventricosellus (Roewer 1942) = Eriophora heroine (L. Koch 1871)]. An old record of Araneus brisbanae (L. Koch 1867b) (Araneidae) from New Zealand is a misidentification of Eriophora decorosa Urquhart 1894. The family Philodromidae, the genera Dictyna Sundevall 1833 (Dictynidae) and Linyphia Latreille 1804 (Linyphiidae), as well as Tharpyna munda L. Koch 1875 (Thomisidae) and Araneus brisbanae (Araneidae) are absent from New Zealand

The combustion characteristics and stable carbon isotopic compositions of irradiated organic matter: implications for terrestrial and extraterrestrial sample analysis

Exposure to ionizing radiation causes the mean combustion temperature of naturally occurring, solid, terrestrial organic matter, derived from the radiation-induced polymerization of methane, to increase

Systematic review of SGLT2 receptor inhibitors in dual or triple therapy in type 2 diabetes

Background Despite the number of medications for type 2 diabetes, many people with the condition do not achieve good glycaemic control. Some existing glucose-lowering agents have adverse effects such as weight gain or hypoglycaemia. Type 2 diabetes tends to be a progressive disease, and most patients require treatment with combinations of glucose-lowering agents. The sodium glucose co-transporter 2 (SGLT2) receptor inhibitors are a new class of glucose-lowering agents. Objective To assess the clinical effectiveness and safety of the SGLT2 receptor inhibitors in dual or triple therapy in type 2 diabetes. Data sources MEDLINE, Embase, Cochrane Library (all sections); Science Citation Index; trial registries; conference abstracts; drug regulatory authorities; bibliographies of retrieved papers. Inclusion criteria Randomised controlled trials of SGLT2 receptor inhibitors compared with placebo or active comparator in type 2 diabetes in dual or combination therapy. Methods Systematic review. Quality assessment used the Cochrane risk of bias score. Results Seven trials, published in full, assessed dapagliflozin and one assessed canagliflozin. Trial quality appeared good. Dapagliflozin 10 mg reduced HbA1c by −0.54% (weighted mean differences (WMD), 95% CI −0.67 to −0.40) compared to placebo, but there was no difference compared to glipizide. Canagliflozin reduced HbA1c slightly more than sitagliptin (up to −0.21% vs sitagliptin). Both dapagliflozin and canagliflozin led to weight loss (dapagliflozin WMD −1.81 kg (95% CI −2.04 to −1.57), canagliflozin up to −2.3 kg compared to placebo). Limitations Long-term trial extensions suggested that effects were maintained over time. Data on canagliflozin are currently available from only one paper. Costs of the drugs are not known so cost-effectiveness cannot be assessed. More data on safety are needed, with the Food and Drug Administration having concerns about breast and bladder cancers. Conclusions Dapagliflozin appears effective in reducing HbA1c and weight in type 2 diabetes, although more safety data are needed

Parasites on parasites:Coupled fluctuations in stacked contact processes

We present a model for host-parasite dynamics which incorporates both vertical and horizontal transmission as well as spatial structure. Our model consists of stacked contact processes (CP), where the dynamics of the host is a simple CP on a lattice while the dynamics of the parasite is a secondary CP which sits on top of the host-occupied sites. In the simplest case, where infection does not incur any cost, we uncover a novel effect: a non-monotonic dependence of parasite prevalence on host turnover. Inspired by natural examples of hyperparasitism, we extend our model to multiple levels of parasites and identify a transition between the maintenance of a finite and infinite number of levels, which we conjecture is connected to a roughening transition in models of surface growth

A quantitative study of quasiparticle traps using the single-Cooper-pair-transistor

We use radio-frequency reflectometry to measure quasiparticle tunneling rates in the single-Cooper-pair-transistor. Devices with and without quasiparticle traps in proximity to the island are studied. A $10^2$ to $10^3$-fold reduction in the quasiparticle tunneling rate onto the island is observed in the case of quasiparticle traps. In the quasiparticle trap samples we also measure a commensurate decrease in quasiparticle tunneling rate off the island.Comment: 4 pages, 4 fig

Microsecond resolution of quasiparticle tunneling in the single-Cooper-pair-transistor

We present radio-frequency measurements on a single-Cooper-pair-transistor in which individual quasiparticle poisoning events were observed with microsecond temporal resolution. Thermal activation of the quasiparticle dynamics is investigated, and consequently, we are able to determine energetics of the poisoning and un-poisoning processes. In particular, we are able to assign an effective quasiparticle temperature to parameterize the poisoning rate.Comment: 4 pages, 4 fig

NOVEL HORTICULTURAL ADAPTATIONS TO CLIMATE AND THEIR UNIQUE LANDSCAPES

The industrial agricultural and agribusiness global food complex is increasingly geared to standardization and uniformity in production, supply chains, and retailing. Across the globe, agricultural practices and their landscapes are homogenizing. This results in agricultural landscapes and regions that lack identifiable character with their place of production. Despite this trajectory, distinctive agricultural landscapes can be identified which defy these global trends. These are what we term novel landscapes. They have emerged from specific socio-cultural, economic, environmental, and climatic conditions resulting in landscapes readily linked to a particular region. Unique agricultural practices have modified landscapes so that they are unmistakably representative of specific location climate. Capacity to innovate in response to place-specific conditions is likely to become essential as we face increasing climatic and resource challenges. It also marks a shift in values that recognizes diversity in agricultural practice as both an environmentally practical and culturally significant good. This chapter explores this potential, presenting horticultural case examples that illustrate novel horticultural landscapes from ancient vineyards to climate-controlled and artificially lit contemporary greenhouses

Energy gap measurement of nanostructured thin aluminium films for use in single Cooper-pair devices

Within the context of superconducting gap engineering, Al-\alox-Al tunnel junctions have been used to study the variation in superconducting gap, $\Delta$, with film thickness. Films of thickness 5, 7, 10 and 30 nm were used to form the small area superconductor-insulator-superconductor (SIS) tunnel junctions. In agreement with previous measurements we have observed an increase in the superconducting energy gap of aluminium with a decrease in film thickness. In addition, we find grain size in small area films with thickness \textbf{$\geq$} 10 nm has no appreciable effect on energy gap. Finally, we utilize 7 and 30 nm films in a single Cooper-pair transistor, and observe the modification of the finite bias transport processes due to the engineered gap profile