Why do old flies die?

International audienc

Reimagining the milk supply chain: Reusable vessels for bulk delivery

Milk packaging has been analysed multiple times in pursuit of finding the most appropriate vessel from an environmental point of view. Research has concentrated on commercially available containers of 0.5 – 2.5 litres, usually made from High-Density Polyethylene (HDPE), Polyethylene Terephtalate (PET), paper-based cartons, or glass, with some studies considering a reuse scheme for glass bottles. Whilst applicable for household delivery, such a reuse scheme is not practical for delivery to cafés where large volumes of milk are used every day; little information is known about transportation of bulk volumes of milk in bigger vessels such as steel churns. This study compares a proposed milk supply chain using a mix of reusable stainless steel churns and reusable glass bottles with the current supply chain that uses single-use HDPE bottles, for transportation of milk to 10 cafés belonging to The University of Sheffield. A cradle-to-grave life cycle assessment (LCA) is conducted using data obtained from the university and Our Cow Molly, a local dairy farm which delivers milk to the university. Sensitivity analysis was performed around the recycling rate of plastic bottles, water consumption for churn cleaning, the reuse rate of glass bottles and churns and the source of the on-farm electricity. The study suggests that the greenhouse gas emission can be lowered by approx. 6.5 tons of CO2 equivalent annually if the reuse scheme is applied (this equates to a 65% reduction for the processes analysed). Considerable savings are also reported in categories such as water consumption, fossil resources depletion and cumulative energy demand. The reuse scheme is, however, likely to induce a similar or higher mineral resource use and higher environmental damage in the marine eutrophication category due to water treatment. Production of plastic bottles in the plastic scenario and maintenance and transport on the reusable side are the main contributors to the environmental impact. Further improvements in the reuse scenario could be achieved by reducing the amount of water used for cleaning and hence the electricity demand for water heating. The reuse scheme could also benefit environmentally from using an electric refrigerated van instead of a diesel vehicle

MEF2 is an in vivo immune-metabolic switch

Infections disturb metabolic homeostasis in many contexts, but the underlying connections are not completely understood. To address this, we use paired genetic and computational screens in Drosophila to identify transcriptional regulators of immunity and pathology and their associated target genes and physiologies. We show that Mef2 is required in the fat body for anabolic function and the immune response. Using genetic and biochemical approaches, we find that MEF2 is phosphorylated at a conserved site in healthy flies and promotes expression of lipogenic and glycogenic enzymes. Upon infection, this phosphorylation is lost, and the activity of MEF2 changes—MEF2 now associates with the TATA binding protein to bind a distinct TATA box sequence and promote antimicrobial peptide expression. The loss of phosphorylated MEF2 contributes to loss of anabolic enzyme expression in Gram-negative bacterial infection. MEF2 is thus a critical transcriptional switch in the adult fat body between metabolism and immunity

Statistical Theory of Spin Relaxation and Diffusion in Solids

A comprehensive theoretical description is given for the spin relaxation and diffusion in solids. The formulation is made in a general statistical-mechanical way. The method of the nonequilibrium statistical operator (NSO) developed by D. N. Zubarev is employed to analyze a relaxation dynamics of a spin subsystem. Perturbation of this subsystem in solids may produce a nonequilibrium state which is then relaxed to an equilibrium state due to the interaction between the particles or with a thermal bath (lattice). The generalized kinetic equations were derived previously for a system weakly coupled to a thermal bath to elucidate the nature of transport and relaxation processes. In this paper, these results are used to describe the relaxation and diffusion of nuclear spins in solids. The aim is to formulate a successive and coherent microscopic description of the nuclear magnetic relaxation and diffusion in solids. The nuclear spin-lattice relaxation is considered and the Gorter relation is derived. As an example, a theory of spin diffusion of the nuclear magnetic moment in dilute alloys (like Cu-Mn) is developed. It is shown that due to the dipolar interaction between host nuclear spins and impurity spins, a nonuniform distribution in the host nuclear spin system will occur and consequently the macroscopic relaxation time will be strongly determined by the spin diffusion. The explicit expressions for the relaxation time in certain physically relevant cases are given.Comment: 41 pages, 119 Refs. Corrected typos, added reference

Assessing Big-Bang Nucleosynthesis

Systematic uncertainties in the light-element abundances and their evolution make a rigorous statistical assessment difficult. However, using Bayesian methods we show that the following statement is robust: the predicted and measured abundances are consistent with 95\% credibility only if the baryon-to-photon ratio is between $2\times 10^{-10}$ and $6.5\times 10^{-10}$ and the number of light neutrino species is less than 3.9. Our analysis suggests that the $^4$He abundance may have been systematically underestimated.Comment: 7 pages, LaTeX(2.09), 6 postscript figures (attached). A postscript version with figures can be found at ftp://astro.uchicago.edu/pub/astro/copi/assessing_BBN . (See the README file for details

The PHENIX Experiment at RHIC

The physics emphases of the PHENIX collaboration and the design and current status of the PHENIX detector are discussed. The plan of the collaboration for making the most effective use of the available luminosity in the first years of RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program available at http://www.rhic.bnl.gov/phenix

Primordial Nucleosynthesis for the New Cosmology: Determining Uncertainties and Examining Concordance

Big bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) have a long history together in the standard cosmology. The general concordance between the predicted and observed light element abundances provides a direct probe of the universal baryon density. Recent CMB anisotropy measurements, particularly the observations performed by the WMAP satellite, examine this concordance by independently measuring the cosmic baryon density. Key to this test of concordance is a quantitative understanding of the uncertainties in the BBN light element abundance predictions. These uncertainties are dominated by systematic errors in nuclear cross sections. We critically analyze the cross section data, producing representations that describe this data and its uncertainties, taking into account the correlations among data, and explicitly treating the systematic errors between data sets. Using these updated nuclear inputs, we compute the new BBN abundance predictions, and quantitatively examine their concordance with observations. Depending on what deuterium observations are adopted, one gets the following constraints on the baryon density: OmegaBh^2=0.0229\pm0.0013 or OmegaBh^2 = 0.0216^{+0.0020}_{-0.0021} at 68% confidence, fixing N_{\nu,eff}=3.0. Concerns over systematics in helium and lithium observations limit the confidence constraints based on this data provide. With new nuclear cross section data, light element abundance observations and the ever increasing resolution of the CMB anisotropy, tighter constraints can be placed on nuclear and particle astrophysics. ABRIDGEDComment: 54 pages, 20 figures, 5 tables v2: reflects PRD version minor changes to text and reference