Nutrient provision capacity of alternative livestock farming systems per area of arable farmland required

Although climate impacts of ruminant agriculture are a major concern worldwide, using policy instruments to force grazing farms out of the livestock industry may diminish opportunities to produce nutritious food without exacerbating the food-feed competition for fertile and accessible land resources. Here, we present a new set of quantitative evidence to demonstrate that, per unit of overall nutrient value supplied by a given commodity, the demand for land suitable for human-edible crop production is considerably smaller under ruminant systems than monogastric systems, and consistently so at both farm and regional scales. We also demonstrate that imposition of a naïvely designed “red meat tax” has the potential to invite socioeconomic losses far greater than its environmental benefits, due largely to the induced misallocation of resources at the national scale. Our results reiterate the risk inherent in an excessively climate-focused debate on the role of livestock in human society and call for more multidimensional approaches of sustainability assessment to draw better-balanced policy packages

An improved version of the Shadow Position Sensor readout electronics on-board the ESA PROBA-3 Mission

PROBA-3 [1] [2] is a Mission of the European Space Agency (ESA) composed by two satellites flying in formation and aimed at achieving unprecedented performance in terms of relative positioning. The mission purpose is, in first place, technological: the repeated formation break and acquisition during each orbit (every about twenty hours) will be useful to demonstrate the efficacy of the closed-loop control system in keeping the formation-flying (FF) and attitude (i.e. the alignment with respect to the Sun) of the system. From the scientific side, instead, the two spacecraft will create a giant instrument about 150 m long: an externally occulted coronagraph named ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun) dedicated to the study of the inner part of the visible solar corona. The two satellites composing the mission are: the Coronagraph Spacecraft (CSC), hosting the Coronagraph Instrument (CI), and the disk-shaped (1.4 m diameter) Occulter Spacecraft (OSC). The PROBA-3 GNC (Guidance, Navigation and Control) system will employ several metrological subsystems to keep and retain the desired relative position and the absolute attitude (i.e. with respect to the Sun) of the aligned spacecraft, when in observational mode. The SPS subsystem [5] is one of these metrological instruments. It is composed of eight silicon photomultipliers (SiPMs), sensors operated in photovoltaic mode [6] that will sense the penumbra light around the Instrument's pupil so to detect any FF displacement from the nominal position. In proximity of the CDR (Critical Design Review) phase, we describe in the present paper the changes occurred to design in the last year in consequence of the tests performed on the SPS Breadboard (Evaluation Board, EB) and the SPS Development Model (DM) and that will finally lead to the realization of the flight version of the SPS system

Time course of collagen peak in bile duct-ligated rats

<p>Abstract</p> <p>Background</p> <p>One of the most useful experimental fibrogenesis models is the "bile duct-ligated rats". Our aim was to investigate the quantitative hepatic collagen content by two different methods during the different stages of hepatic fibrosis in bile duct-ligated rats on a weekly basis. We questioned whether the 1-wk or 4-wk bile duct-ligated model is suitable in animal fibrogenesis trials.</p> <p>Methods</p> <p>Of the 53 male Wistar rats, 8 (Group 0) were used as a healthy control group. Bile duct ligation (BDL) had been performed in the rest. Bile duct-ligated rates were sacrificed 7 days later in group 1 (10 rats), 14 days later in group 2 (9 rats), 21 days later in group 3(9 rats) and 28 days later in group 4 (9 rats). Eight rats underwent sham-operation (Sham). Hepatic collagen measurements as well as serum levels of liver enzymes and function tests were all analysed.</p> <p>Results</p> <p>The peak level of collagen was observed biochemically and histomorphometricly at the end of third week (P < 0.001 and P < 0.05). Suprisingly, collagen levels had decreased with the course of time such as at the end of fourth week (P < 0.01 and P < 0.05).</p> <p>Conclusion</p> <p>We have shown that fibrosis in bile duct-ligated rats is transient, i.e. reverses spontaneously after 3 weeks. This contrasts any situation in patients where hepatic fibrosis is progressive and irreversible as countless studies performed by many investigators in the same animal model.</p

The shadow position sensors (SPS) formation flying metrology subsystem for the ESA PROBA-3 mission: present status and future developments

PROBA-3 [1] [2] is a Mission of the European Space Agency (ESA) composed of two formation-flying satellites, planned for their joint launch by the end of 2018. Its main purposes have a dual nature: scientific and technological. In particular, it is designed to observe and study the inner part of the visible solar corona, thanks to a dedicated coronagraph called ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), and to demonstrate the in-orbit formation flying (FF) and attitude control capability of its two satellites. The Coronagraph payload on-board PROBA-3 consists of the following parts: the Coronagraph Instrument (CI) with the Shadow Position Sensor (SPS) on the Coronagraph Spacecraft (CSC), the Occulter Position Sensor (OPSE) [3] [4] and the External Occulting (EO) disk on the Occulter Spacecraft (OSC). The SPS subsystem [5] is one of the main metrological devices of the Mission, adopted to control and to maintain the relative (i.e. between the two satellites) and absolute (i.e. with respect to the Sun) FF attitude. It is composed of eight micro arrays of silicon photomultipliers (SiPMs) [6] that shall be able to measure, with the required sensitivity and dynamic range as asked by ESA, the penumbral light intensity on the Coronagraph entrance pupil. With the present paper we describe the testing activities on the SPS breadboard (BB) and Development Model (DM) as well as the present status and future developments of this PROBA-3 metrological subsystem

Humid savanna-forest dynamics: A matrix model with vegetation-fire interactions and seasonality

Rainfall seasonality and vegetation-fire feedbacks characterize humid savannas and tropical forests dynamics. In these ecosystems fire occurrence is influenced by the amount of grass, and trees respond to fire differently according to their height. Here we present a spatially implicit matrix model of humid savanna-forest dynamics. The state variables are the fraction of space occupied by trees and the grass biomass density. Rainfall seasonality is included using a discrete seasonal time step, distinguishing between wet and dry seasons. The demography of trees is taken into account considering different size classes and describing their dynamics with transition matrices, which depend on the season and presence/absence of fire. The occurrence of fire is represented by a Bernoulli variable, whose probability of occurrence is function of grass density. We explore different fire probabilities at the savanna-forest boundary and show different behaviors of the ecosystems. We investigate also the model's behavior with matrices of three Acacia species taken from literature

Identification and characterization of a bile acid receptor in isolated liver surface membranes.

It is generally assumed that hepatic transport of bile acids is a carrier-mediated process. However, the basic mechanisms by which these organic anions are translocated across the liver cell surface membrane are not well understood. Since carrier-mediated transport involved binding of the transported molecule to specific receptor sites, we have investigated the possibility that bile acid receptors are present in liver surface membranes. Isolated liver surface membranes were incubated at 4 degrees C with [14C]cholic acid and [14C]taurocholic acid, and membrane-boudn bile acid was separated from free by a rapid ultrafiltration technique through glass-fiber filters. Specific bile acid binding is rapid and reversible and represents approximately 80% of the total bile acid bound to liver surface membranes. Taurocholic acid binding is independent of the medium pH, while cholic acid binding demonstrates an optimum at pH 6.0. Analysis of equilibrium data for both cholic and taurocholic acid binding indicates that specific binding is saturable and consistent with Michaelis-Menten kinetics, while nonspecific binding is nonsaturable. Apparent maximal binding capacity and dissociation constant values indicate a large capacity system of receptors that have an affinity for bile acids comparable to that of the hepatic transport mechanism. Scatchard analysis of the saturation kinetics as well as inhibition studies suggest that bile acids bind to a single and noninteracting class of anion that competes with bile acids for hepatic uptake, also inhibits cholic acid binding. In contrast, no inhibition was demonstrated with indocyanine green and probenecid. Specific bile acid binding is enriched and primarily located in liver surface membranes and found only in tissues involved in bile acid transport. Specific bile acid binding is independnet of Na+, Ca2+, and Mg2+ and does not require metabolic energy. In addition, thiol groups and disulfide are not required for activity at the binding site. However, specific bile acid binding is markedly decreased by low concentrations of proteolytic enzymes and is also decreased by the action of neuraminidase and phospholipases A and C. These results are consistent with the existence of a homogeneous bile acid receptor protein in liver surface membranes. The primary surface membrane location of this receptor, its binding properties, and its ligand specificity suggest that bile acid binding to this receptor may represent the initial interaction in bile acid transport across liver surface membranes