Photoprocesses in protoplanetary disks

Circumstellar disks are exposed to intense ultraviolet radiation from the young star. In the inner disks, the UV radiation can be enhanced by more than seven orders of magnitude compared with the average interstellar field, resulting in a physical and chemical structure that resembles that of a dense photon-dominated region (PDR). This intense UV field affects the chemistry, the vertical structure of the disk, and the gas temperature, especially in the surface layers of the disk. The parameters which make disks different from traditional PDRs are discussed, including the shape of the UV radiation field, grain growth, the absence of PAHs, the gas/dust ratio and the presence of inner holes. New photorates for selected species, including simple ions, are presented. Also, a summary of available cross sections at Lyman alpha 1216 A is made. Rates are computed for radiation fields with color temperatures ranging from 4000 to 30,000 K, and can be applied to a wide variety of astrophysical regions including exo-planetary atmospheres. The importance of photoprocesses is illustrated for a number of representative disk models, including disk models with grain growth and settling.Comment: A website with the final published version and all photodissociation cross sections and rates can be found at http://www.strw.leidenuniv.nl/~ewine/phot

Breeding amphibians in captivity

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73877/1/j.1748-1090.1977.tb00864.x.pd

Great Apes' Risk-Taking Strategies in a Decision Making Task

We investigate decision-making behaviour in all four non-human great ape species. Apes chose between a safe and a risky option across trials of varying expected values. All species chose the safe option more often with decreasing probability of success. While all species were risk-seeking, orangutans and chimpanzees chose the risky option more often than gorillas and bonobos. Hence all four species' preferences were ordered in a manner consistent with normative dictates of expected value, but varied predictably in their willingness to take risks

Chemistry in Disks. IV. Benchmarking gas-grain chemical models with surface reactions

Abridged: We detail and benchmark two sophisticated chemical models developed by the Heidelberg and Bordeaux astrochemistry groups. The main goal of this study is to elaborate on a few well-described tests for state-of-the-art astrochemical codes covering a range of physical conditions and chemical processes, in particular those aimed at constraining current and future interferometric observations of protoplanetary disks. We consider three physical models: a cold molecular cloud core, a hot core, and an outer region of a T Tauri disk. Our chemical network (for both models) is based on the original gas-phase osu_03_2008 ratefile and includes gas-grain interactions and a set of surface reactions for the H-, O-, C-, S-, and N-bearing molecules. The benchmarking is performed with the increasing complexity of the considered processes: (1) the pure gas-phase chemistry, (2) the gas-phase chemistry with accretion and desorption, and (3) the full gas-grain model with surface reactions. Using atomic initial abundances with heavily depleted metals and hydrogen in its molecular form, the chemical evolution is modeled within 10^9 years. The time-dependent abundances calculated with the two chemical models are essentially the same for all considered physical cases and for all species, including the most complex polyatomic ions and organic molecules. This result however required a lot of efforts to make all necessary details consistent through the model runs, e.g. definition of the gas particle density, density of grain surface sites, the strength and shape of the UV radiation field, etc. The reference models and the benchmark setup, along with the two chemical codes and resulting time-dependent abundances are made publicly available in the Internet: http://www.mpia.de/homes/semenov/Chemistry_benchmark/home.htmlComment: 12 pages, 5 figures, 3 tables, accepted for publication in A&A. The relevant web page is: http://www.mpia.de/homes/semenov/Chemistry_benchmark/home.htm

The impact of viral mutations on recognition by SARS-CoV-2 specific T cells.

We identify amino acid variants within dominant SARS-CoV-2 T cell epitopes by interrogating global sequence data. Several variants within nucleocapsid and ORF3a epitopes have arisen independently in multiple lineages and result in loss of recognition by epitope-specific T cells assessed by IFN-γ and cytotoxic killing assays. Complete loss of T cell responsiveness was seen due to Q213K in the A∗01:01-restricted CD8+ ORF3a epitope FTSDYYQLY207-215; due to P13L, P13S, and P13T in the B∗27:05-restricted CD8+ nucleocapsid epitope QRNAPRITF9-17; and due to T362I and P365S in the A∗03:01/A∗11:01-restricted CD8+ nucleocapsid epitope KTFPPTEPK361-369. CD8+ T cell lines unable to recognize variant epitopes have diverse T cell receptor repertoires. These data demonstrate the potential for T cell evasion and highlight the need for ongoing surveillance for variants capable of escaping T cell as well as humoral immunity.This work is supported by the UK Medical Research Council (MRC); Chinese Academy of Medical Sciences(CAMS) Innovation Fund for Medical Sciences (CIFMS), China; National Institute for Health Research (NIHR)Oxford Biomedical Research Centre, and UK Researchand Innovation (UKRI)/NIHR through the UK Coro-navirus Immunology Consortium (UK-CIC). Sequencing of SARS-CoV-2 samples and collation of data wasundertaken by the COG-UK CONSORTIUM. COG-UK is supported by funding from the Medical ResearchCouncil (MRC) part of UK Research & Innovation (UKRI),the National Institute of Health Research (NIHR),and Genome Research Limited, operating as the Wellcome Sanger Institute. T.I.d.S. is supported by a Well-come Trust Intermediate Clinical Fellowship (110058/Z/15/Z). L.T. is supported by the Wellcome Trust(grant number 205228/Z/16/Z) and by theUniversity of Liverpool Centre for Excellence in Infectious DiseaseResearch (CEIDR). S.D. is funded by an NIHR GlobalResearch Professorship (NIHR300791). L.T. and S.C.M.are also supported by the U.S. Food and Drug Administration Medical Countermeasures Initiative contract75F40120C00085 and the National Institute for Health Research Health Protection Research Unit (HPRU) inEmerging and Zoonotic Infections (NIHR200907) at University of Liverpool inpartnership with Public HealthEngland (PHE), in collaboration with Liverpool School of Tropical Medicine and the University of Oxford.L.T. is based at the University of Liverpool. M.D.P. is funded by the NIHR Sheffield Biomedical ResearchCentre (BRC – IS-BRC-1215-20017). ISARIC4C is supported by the MRC (grant no MC_PC_19059). J.C.K.is a Wellcome Investigator (WT204969/Z/16/Z) and supported by NIHR Oxford Biomedical Research Centreand CIFMS. The views expressed are those of the authors and not necessarily those of the NIHR or MRC

Thermally actuated interferometric sensors based on the thermal expansion of transparent elastomeric media

In this article the fabrication and characterization of two thermally actuated optical devices for the measurement of temperature and power are described. A transparent polymer having a high coefficient of thermal expansion-poly(dimethylsiloxane) (PDMS)-was used as the temperature- sensitive medium. Changes in the dimensions of the polymer on heating caused the observed optical responses of both devices. The temperature sensor based on the Fabry-Perot cavity measures temperature differences to a precision of 0.005 degrees C within the linear working ranges of the device. The power sensor uses the architecture of a Mach-Zender interferometer; it is suitable for measurements of powers in them W/cm(2) range, delivered optically to the surface of the device in the visible wavelength region. The devices are inexpensive, easy to fabricate, and mechanically rugged. They offer alternatives to other sensors for measuring temperature and power

Environmental drivers of macroinvertebrate communities in High Arctic rivers (Svalbard)

Summary The impacts of climate-induced environmental changes on freshwater biodiversity are not well understood in Arctic regions. We quantified water source contributions (meltwater, ground water), environmental habitat conditions and benthic macroinvertebrate community dynamics in north-west Svalbard. The aim was to use contemporary findings to infer how future environmental change may affect these Arctic river ecosystems. Water source dynamics played an important role in influencing environmental habitat conditions; meltwater contributions to flow were related significantly to discharge, channel stability, electrical conductivity and pH. Low regional benthic macroinvertebrate diversity relative to other Arctic regions was attributed to harsh winter conditions and biogeographical dispersal constraints associated with the Svalbard archipelago. Generalised estimating equations and multivariate ordination models showed benthic macroinvertebrate diversity and abundance were influenced significantly by several environmental habitat variables. Rivers in non-glacierised basins typically supported more diverse and abundant communities than those in glacierised basins, most likely as a consequence of the warmer water temperature and less-disturbed habitat conditions associated with these systems. Consequently, shifts in water source contributions driven by changes in climate may alter environmental habitat conditions in Svalbard rivers and could lead to an increase in abundance and diversity among some freshwater macroinvertebrate communities

'Maenads dancing before the Martyrs' memorial': Oxford women writers and the classical tradition

For prominent Victorian women writers such as Elizabeth Barrett Browning and George Eliot some degree of classical education was closely associated with successful literary ambitions, but the schools and universities where the classics were taught remained closed to them. Women achieved full membership of Oxford university after the First World War, around the same time as the compulsory Greek element of the Oxford degree was abolished. Before this, many women students had to pursue intensive courses of Greek even when their main subject of study was English or history. Aspiring writers such as Vera Brittain and Dorothy L. Sayers rushed through classical texts like theIliad and theAeneid in the original languages, later producing imaginative and often challenging reworkings of classical texts which reflect the experiences of the modern, educated woman. The adaptation of epic themes to modern forms such as the First World War memoir and the detective story is an important similarity in Sayers’ and Brittain’s literary responses to classical literature