Are Cosmological Gas Accretion Streams Multiphase and Turbulent?

Simulations of cosmological filamentary accretion reveal flows ("streams") of warm gas, ~$10^4$ K, which are efficient in bringing gas into galaxies. We present a phenomenological scenario where gas in such flows -- if it is shocked as it enters the halo as we assume -- become biphasic and, as a result, turbulent. We consider a collimated stream of warm gas that flows into a halo from an over dense filament of the cosmic web. The post-shock streaming gas expands because it has a higher pressure than the ambient halo gas, and fragments as it cools. The fragmented stream forms a two phase medium: a warm cloudy phase embedded in hot post-shock gas. We argue that the hot phase sustains the accretion shock. A fraction of the initial kinetic energy of the infalling gas is converted into turbulence among and within the warm clouds. The thermodynamic evolution of the post-shock gas is largely determined by the relative timescales of several processes -- the cooling, the expansion of the post-shock gas, the amount of turbulence in the clouds, and the halo dynamics. We expect the gas to become multiphase when the cooling and dynamical times are of the same order-of-magnitude. In this framework, we show that this occurs in the important mass range of ~$10^{11}$ to $10^{13}$ M$_\odot$ , where the bulk of stars have formed in galaxies. Gas accreting along cosmic web filaments may eventually lose coherence and mix with the ambient halo gas. Through both the phase separation and "disruption" of the stream, the accretion efficiency onto a galaxy in a halo dynamical time is lowered. De-collimating flows make the direct interaction between galaxy feedback and accretion streams more likely, thereby further reducing the overall accretion efficiency. Moderating the gas accretion efficiency through these mechanisms may help to alleviate a number of significant challenges in theoretical galaxy formation.Comment: 13 pages, 8 figures, Submitted to A&A, New version includes new figure

Modelling the Common Agricultural Policy.General equilibrium effects of the 2014-2020 budget agreement

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The EU budget battle: Assessing the trade and welfare impacts of CAP budgetary reform

There is a paucity of quantitative impact assessments of the sectorial and macroeconomic impacts of CAP budget reform for EU member states. To fill this gap, the current study employs a sophisticated agricultural variant of the GTAP model to evaluate the recently agreed CAP spending limits for the financial period 2014–2020 as well as a more radical 50% cut to the CAP budget proposed by the UK government. The study incorporates methodological innovation in terms of the modelling of CAP budgetary mechanisms. Furthermore, official EU auditing statistics are employed to (i) greatly improve the existing representation of agricultural support payments in the GTAP benchmark data and (ii) implement a detailed contemporary CAP baseline for member states to capture both the decoupled/coupled split of support payments and the distribution of support across both ‘pillars’. In general, CAP expenditure cuts have muted impacts on EU and world agricultural markets; whereas changes in net transfer payments have implications for real income and macro trade balances in EU member states. This observation is particularly pertinent when assessing conciliatory reductions in the UK rebate in exchange for deeper CAP budget cuts.Publishe

2020 Common agricultural policy in Spain. General equilibrium effects of a EU28 budget deal

This paper employs a Computable General Equilibrium (CGE) model to assess the effects of the agreed 2014-2020 Common Agricultural Policy (CAP) budget cuts. It illustrates modest impacts on Spanish, European and world agricultural markets, given the non-distortive representation of the CAP.Publishe

Baculovirus display of single chain antibody (scFv) using a novel signal peptide

Background: Cells permissive to virus can become refractory to viral replication upon intracellular expression of single chain fragment variable (scFv) antibodies directed towards viral structural or regulatory proteins, or virus-coded enzymes. For example, an intrabody derived from MH-SVM33, a monoclonal antibody against a conserved C-terminal epitope of the HIV-1 matrix protein (MAp17), was found to exert an inhibitory effect on HIV-1 replication.<p></p> Results: Two versions of MH-SVM33-derived scFv were constructed in recombinant baculoviruses (BVs) and expressed in BV-infected Sf9 cells, N-myristoylation-competent scFvG2/p17 and N-myristoylation-incompetent scFvE2/p17 protein, both carrying a C-terminal HA tag. ScFvG2/p17 expression resulted in an insoluble, membrane-associated protein, whereas scFvE2/p17 was recovered in both soluble and membrane-incorporated forms. When coexpressed with the HIV-1 Pr55Gag precursor, scFvG2/p17 and scFvE2/p17 did not show any detectable negative effect on virus-like particle (VLP) assembly and egress, and both failed to be encapsidated in VLP. However, soluble scFvE2/p17 isolated from Sf9 cell lysates was capable of binding to its specific antigen, in the form of a synthetic p17 peptide or as Gag polyprotein-embedded epitope. Significant amounts of scFvE2/p17 were released in the extracellular medium of BV-infected cells in high-molecular weight, pelletable form. This particulate form corresponded to BV particles displaying scFvE2/p17 molecules, inserted into the BV envelope via the scFv N-terminal region. The BV-displayed scFvE2/p17 molecules were found to be immunologically functional, as they reacted with the C-terminal epitope of MAp17. Fusion of the N-terminal 18 amino acid residues from the scFvE2/p17 sequence (N18E2) to another scFv recognizing CD147 (scFv-M6-1B9) conferred the property of BV-display to the resulting chimeric scFv-N18E2/M6.<p></p> Conclusion: Expression of scFvE2/p17 in insect cells using a BV vector resulted in baculoviral progeny displaying scFvE2/p17. The function required for BV envelope incorporation was carried by the N-terminal octadecapeptide of scFvE2/p17, which acted as a signal peptide for BV display. Fusion of this peptide to the N-terminus of scFv molecules of interest could be applied as a general method for BV-display of scFv in a GP64- and VSV-G-independent manner.<p></p&gt

Assessing potential coupling factors of European decoupled payments with the Modular Agricultural GeNeral Equilibrium Tool (MAGNET)

In 2020, decoupled payments will represent about 42% of the CAP budget (green payments excluded). This report assesses the potential effects of European decoupled payments on farmers' production decisions, prior to a sensitivity analysis of different coupling factors using the Modular Applied GeNeral Equilibrium Tool (MAGNET). Scientific literature reveals different coupling channels such as capitalisation in land value, farmers' risk behaviour, credit accessibility, uncertainty about future policies and labour allocation through which European decoupled payments influence farm choices and thus output. For each of these channels the relevant literature introducing theoretical and empirical assessments is evaluated with the aim of deriving plausible behavioural parameters that improve the representation of decoupled payments in economic simulation models. To capture completely decoupled production behaviour, many CGE models typically represent decoupled payments as a uniform subsidy rate to the land using (agricultural) sectors. Nevertheless based on a thorough review of the literature, it appears that a more suitable modelling approach which caters for heterogeneous member state land markets, may be to split the allocation of decoupled payments. On the one hand, a proportion is committed to land as a function of the capitalisation rate into the rental value, whilst a second tranche is distributed uniformly across all factors, reflecting a balance of different coupling channels. A sensitivity analysis concludes that if one assumes differing degrees of coupling, it does have some implication for output and price results when conducting policy analysis.JRC.D.4-Economics of Agricultur

The impacts of a CAP budget reform on the world economy: A CGE assessment

European agricultural market support and direct payments amount to 44 billion Euros in 2012 – of which farm subsidies represent 40 billion euros. Rural development measures add 13 billion Euros to the European Union (EU) budget devoted to the Common Agricultural Policy (CAP). As a total, roughly 40 per cent of the EU budget aims at funding this sector-based policy. Whereas a CAP reform is expected for the period post-2013, an agreement on the 2014-2020 EU financial framework shall be reached before then. This paper attempts to capture the implications for the EU and third countries of resource reallocations in the CAP budget provision for the period 2014-2020. It employs a sophisticated dynamic variant of the GTAP model, known as the Modular Applied General Equilibrium Tool (MAGNET) model. Given the focus on agri-food markets, a number of additional modelling features are incorporated to capture the peculiarities of agricultural factor markets (e.g. endogenous land supply, heterogeneous land usage; agricultural/non-agricultural factor split) and agricultural policy (e.g. decoupled payments, rural development support). Of particular importance to this study is the comparatively detailed treatment of the CAP budget, with coverage of first and second pillar, where the latter explicitly characterises between five distinct rural development measures (i.e. physical investment, human capacity, agri-environmental, less favoured areas, and wider rural development). Finally, the 'own resources' component of the European budget is also modelled, with associated rebate mechanisms, in order to consider the political economy of European budgetary reform.CGEcommon agricultural policyEuropean budgettradePublishe