Hydrodynamic simulations of merging clusters of galaxies

We present the results of high-resolution AP3M+SPH simulations of merging clusters of galaxies. We find that the compression and shocking of the core gas during a merger can lead to large increases in bolometric X-ray luminosities and emission-weighted temperatures of clusters. Cooling flows are completely disrupted during equal-mass mergers, with the mass deposition rate dropping to zero as the cores of the clusters collide. The large increase in the cooling time of the core gas strongly suggests that cooling flows will not recover from such a merger within a Hubble time. Mergers with subclumps having one eighth of the mass of the main cluster are also found to disrupt a cooling flow if the merger is head-on. However, in this case the entropy injected into the core gas is rapidly radiated away and the cooling flow restarts within a few Gyr of the merger. Mergers in which the subcluster has an impact parameter of 500 kpc do not disrupt the cooling flow, although the mass deposition rate is reduced by ∼30 per cent. Finally, we find that equal mass, off-centre mergers can effectively mix gas in the cores of clusters, while head on mergers lead to very little mixing. Gas stripped from the outer layers of subclumps results in parts of the outer layers of the main cluster being well mixed, although they have little effect on the gas in the core of the cluster. None of the mergers examined here resulted in the intracluster medium being well mixed globally

Nature versus Nurture: The curved spine of the galaxy cluster X-ray luminosity -- temperature relation

The physical processes that define the spine of the galaxy cluster X-ray luminosity -- temperature (L-T) relation are investigated using a large hydrodynamical simulation of the Universe. This simulation models the same volume and phases as the Millennium Simulation and has a linear extent of 500 h^{-1} Mpc. We demonstrate that mergers typically boost a cluster along but also slightly below the L-T relation. Due to this boost we expect that all of the very brightest clusters will be near the peak of a merger. Objects from near the top of the L-T relation tend to have assembled much of their mass earlier than an average halo of similar final mass. Conversely, objects from the bottom of the relation are often experiencing an ongoing or recent merger.Comment: 8 pages, 7 figures, submitted to MNRA

Tube choledochoureterostomy: A simple method for bile diversion

A technique of bile diversion by tube choledochoureterostomy has been devised for the purpose of studying the role of bile in the intestinal absorption of drugs. This method was used in six dogs. No technical difficulties or major complications developed, as are inevitable with alternative methods, including external fistula. © 1990 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted

Synthesis of amides from acid chlorides and amines in the bio-based solvent Cyrene™

Cyrene™ as a bio-alternative dipolar aprotic solvent: a waste minimizing and molar efficient protocol for the synthesis of amides from acid chlorides and primary amines in the bio-available solvent Cyrene™ is disclosed. This protocol removed the use of toxic solvents, such as dimethylformamide and dichloromethane. A simple aqueous work-up procedure for the removal of the high boiling solvent Cyrene™ resulted in up to a 55-fold increase in molar efficiency (Mol E.%) versus standard operating procedures. In order to rapidly compare the molar efficiency of this process against other methodologies an Excel based Mol. E% calculator was developed that automates many of the calculations. An investigation into the hydration of Cyrene™ found that it readily hydrates to form a geminal diol in the presence of water and that this process is exothermic

Hydrologically driven ecosystem processes determine the distribution and persistence of ecosystem-specialist predators under climate change

Climate change has the capacity to alter physical and biological ecosystem processes, jeopardizing the survival of associated species. This is a particular concern in cool, wet northern peatlands that could experience warmer, drier conditions. Here we show that climate, ecosystem processes and food chains combine to influence the population performance of species in British blanket bogs. Our peatland process model accurately predicts water-table depth, which predicts abundance of craneflies (keystone invertebrates), which in turn predicts observed abundances and population persistence of three ecosystem-specialist bird species that feed on craneflies during the breeding season. Climate change projections suggest that falling water tables could cause 56–81% declines in cranefly abundance and, hence, 15–51% reductions in the abundances of these birds by 2051–2080. We conclude that physical (precipitation, temperature and topography), biophysical (evapotranspiration and desiccation of invertebrates) and ecological (food chains) processes combine to determine the distributions and survival of ecosystem-specialist predators

A Gauge Invariant Unitary Theory for Pion Photoproduction

A covariant, unitary and gauge invariant theory for pion photoproduction on a single nucleon is presented. To achieve gauge invariance at the operator level one needs to include both the $\pi N$ and $\gamma\pi N$ thresholds. The final amplitude can be written in terms of a distorted wave in the final $\pi N$ channel provided one includes additional diagrams to the standard Born term in which the photon is coupled to the final state pion and nucleon. These additional diagrams are required in order to satisfy gauge invariance.Comment: 4 pages, LaTeX, 1 figure as a separate uuencoded compressed tar fil

Engineering Proteinase Inihibitor Genes For Plant Defense Against Predators

Small proteinaceous inhibitors (Mr\u3c20,000) of the digestive serine proteinases of animals and microorganisms are found as moderately abundant proteins in storage organs and leaves of many plant genera. The proteins are powerful inhibitors of the digestive enzymes of plant predators and therefore are considered to be part of the array of defensive chemicals of plants. Proteinase inhibitor genes show excellent promise, using DNA technology, to manipulate plant genomes to express these biologically active proteins in order to improve natural defense systems. Members of two unrelated families of serine proteinase inhibitors found in tomato and potato plants, called Inhibitor I (monomer Mr 8000) and Inhibitor II (monomer Mr 12,300), are under both environmental and developmental regulation in different tissues of the plants. Genes coding for wound-inducible Inhibitors I and II have been isolated from both tomato and potato genomes and characterized. Tobacco plants have been transformed with the chimeric genes containing wound-inducible promoters fused with the reporter gene, chloramphenicol acetyl transferase, to assess promoter function and signal transmission. Transacting factors that regulate their expression in response to wounding are also being identified and purified. Intact genes are being employed to transform agriculturally important crop plants to determine their potential usefulness to enhance defensive capabilities of plants against herbivores and pathogens

Household and area determinants of emergency department attendance and hospitalisation in people with multimorbidity:a systematic review

OBJECTIVES: Multimorbidity is one of the greatest challenges facing healthcare internationally. Emergency department (ED) attendance and hospitalisation rates are higher in people with multimorbidity, but most research focuses on associations with individual characteristics, ignoring household or area mediators of service use. DESIGN: Systematic review reported using the synthesis without meta-analysis framework. DATA SOURCES: Twelve electronic databases (1 January 2000–21 September 2021): MEDLINE/OVID, Embase, Global Health, PsycINFO, ASSIA, CAB Abstracts, Science Citation Index Expanded/ISI Web of Science, Scopus, Cumulative Index to Nursing and Allied Health Literature, Sociological Abstracts, the Cochrane Library, and OpenGrey. ELIGIBILITY CRITERIA: Adults aged ≥16 years, with multimorbidity. Exposure(s) were household and/or area determinants of health. Outcomes were ED attendance and/or hospitalisation. The literature search was limited to publications in English. DATA EXTRACTION AND SYNTHESIS: Independent double screening of titles and abstracts to select relevant full-text studies. Methodological quality was assessed using an adaptation of the Newcastle-Ottawa Quality Assessment Scale tool. Given high study heterogeneity, narrative synthesis was performed. RESULTS: After deduplication, 10 721 titles and abstracts were screened, and 142 full-text articles were reviewed, of which 10 were eligible for inclusion. In people with multimorbidity, household food insecurity was associated with hospitalisation (OR 1.58 (95% CI 1.06 to 2.36) in concordant multimorbidity). People with multimorbidity living in the most versus least deprived areas attended ED more frequently (8.9% (95% CI 8.6 to 9.1) in most versus 6.3% (95% CI 6.1 to 6.6) in least), had higher rates of hospitalisation (26% in most versus 22% in least), and higher probability of hospitalisation (6.4% (95% CI 5.8 to 7.2) in most versus 4.2% (95% CI 3.8 to 4.7) in least). There was non-conclusive evidence that household income is associated with ED attendance and hospitalisation. No statistically significant relationships were found between marital status, living with others with multimorbidity, or rurality with ED attendance or hospitalisation. CONCLUSIONS: There is some evidence that household and area contexts mediate associations of multimorbidity with ED attendance and hospitalisation, but firm conclusions are constrained by the small number of studies published and study design heterogeneity. Further research is required on large population samples using robust analytical methods. PROSPERO REGISTRATION NUMBER: CRD42021283515