Failures of homogeneous and isotropic cosmologies in extended quasidilaton massive gravity

We analyze the extended quasidilaton massive gravity model around a Friedmann-Lemaître-Robertson- Walker cosmological background. We present a careful stability analysis of asymptotic fixed points. We find that the traditional fixed point cannot be approached dynamically, except from a perfectly fine-tuned initial condition involving both the quasidilaton and the Hubble parameter. A less-well examined fixed- point solution, where the time derivative of the zeroth Stückelberg field vanishes φ_ 0 1⁄4 0, encounters no such difficulty, and the fixed point is an attractor in some finite region of initial conditions. We examine the question of the presence of a Boulware-Deser ghost in the theory. We show that the additional constraint that generically allows for the elimination of the Boulware-Deser mode is only present under special initial conditions. We find that the only possibility corresponds to the traditional fixed point and the initial conditions are the same fine-tuned conditions that allow the fixed point to be approached dynamically.Fil: Anselmi, Stefano. Université Paris Diderot - Paris 7; Francia. Institut d’Astrophysique de Paris; Francia. Case Western Reserve University; Estados UnidosFil: Kumar, Saurabh. Case Western Reserve University; Estados UnidosFil: Lopez Nacir, Diana Laura. Cern - European Organization For Nuclear Research; Suiza. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Starkman, Glenn D.. Case Western Reserve University; Estados Unido

Extracting deflation probability forecasts from Treasury yields

We construct probability forecasts for episodes of price deflation (i.e., a falling price level) using yields on nominal and real U.S. Treasury bonds. The deflation probability forecasts identify two "deflation scares" during the past decade: a mild one following the 2001 recession, and a more serious one starting in late 2008 with the deepening of the financial crisis. The estimated deflation probabilities are generally consistent with those from macroeconomic models and surveys of professional forecasters, but they also provide highfrequency insight into the views of financial market participants. The probabilities can also be used to price the deflation option embedded in real Treasury bonds.Deflation (Finance)

Inflation expectations and risk premiums in an arbitrage-free model of nominal and real bond yields

Differences between yields on comparable-maturity U.S. Treasury nominal and real debt, the so-called breakeven inflation (BEI) rates, are widely used indicators of inflation expectations. However, better measures of inflation expectations could be obtained by subtracting inflation risk premiums from the BEI rates. We provide such decompositions using an estimated affine arbitrage-free model of the term structure that captures the pricing of both nominal and real Treasury securities. Our empirical results suggest that long-term inflation expectations have been well anchored over the past few years, and inflation risk premiums, although volatile, have been close to zero on average.Inflation (Finance) ; Treasury bonds

Potential carbon sources for the head-down deposit-feeding polychaete Heteromastus filiformis

In this study we investigated potential carbon sources for the capitellid polychaete, Heteromastus filiformis. It is a head-down deposit feeder ingesting sediment from at least 15 cm below the sediment-water interface. This orientation appears to minimize the worm\u27s ability to acquire food and oxygen and maximize its exposure to sulfide. The food sources we examined were metabolically active bacteria, benthic algae, detritus and chemoautotrophic bacteria. Carbon retention efficiencies from metabolically active bacteria, benthic algae and detritus by H. filiformis were 26%, 8% and 4% respectively. These values are relatively low compared to other deposit feeding species suggesting that H. filiformis does not possess unique digestive capabilities. Rubisco (Ribulose bisphosphate carboxylase) assays were negative, which indicates an absence of symbiotic chemoautotrophic bacteria in tissue or absorbed carbon. Average δ 13C were −12.83 for worms and −20.70 for 15 cm sediment, which indicates that external gardening of chemoautotrophs is not a major carbon source for H. filiformis. Nevertheless, several experiments showed that this capitellid worm had an unusually high gross heterotrophic CO2 uptake. We suggest that H. filiformis utilizes both dissolved and particulate carbon sources stored within anoxic and sulfidic sediments that are not utilized by other deposit feeding organisms

Epipsammic browsing and deposit-feeding in mud snails (Hydrobiidae)

A study of feeding behavior of Hydrobia ulvae Pennant, H. ventrosa Montagu, H. neglecta Muus, and Potamopyrgus jenkinsi Smith (Hydrobiidae, Gastropoda) on a wide size range of sediment fractions showed that these snails are capable of feeding on material adhering to sediment particles by swallowing small particles (deposit-feeding), and by browsing upon particle surfaces, which we call epipsammic browsing ...

Rapid physical and biological particle mixing on an intertidal sandflat

Sediment mixing processes were investigated using inert tracer experiments, benthic macrofaunal community analysis, and surveys of ray feeding pits to quantify the relative rates and controls of physical and biological reworking on Debidue Flat, an intertidal sandflat in South Carolina. Sediment reworking on Debidue Flat was rapid, with both advective and biodiffusive mixing operating over different vertical spatial scales. Physical reworking by tidal currents dominated initial transport of the tracer in the top 5-10 cm on timescales of ~30 days. Although the exact mechanism of tracer transport is unclear, it is most likely due to active fluidization of surface sediments during stages of the tide followed by a density-driven settling of tracer resulting in a steady downward transport to the depth of bedform reworking. Biodiffusive mixing was evident throughout the sampled interval (~30 cm) and dominated reworking at depths greater than 10 cm. Estimated biodiffusive mixing coefficients (Db) were high all year (0.15-0.28 cm2d-1), and were comparable to values reported for coastal bioturbated muds. The haustoriid amphipod Pseudohaustorius caroliniensis was most likely responsible for tracer dispersal in the 10 -30 cm interval based on its distribution, abundance, size, and observed burrow structures. Ray pit excavation and infilling were seasonal disturbances that contributed ~12-22% to spatially averaged advective transport rates but were locally intense and capable alone of turning over the entire upper ~15 cm of the flat in ~100 -1000 d. We propose that the mixing processes on Debidue Flat promote an unconstricted, open sediment matrix that maintains the high permeability required for the rapid porewater exchange to 25 cm noted for this system. Thus, in addition to redistributing organic substrates, physical and biological particle mixing play important roles in controlling permeability of flat deposits and quantification of these processes is important to understand controls on permeability and biogeochemical cycling of solutes in sandy systems

Thermal Energy Storage for Load Shifting

The following document accounts for the progress made in the prototype development of our design solution since the Critical Design Review, and our group’s response to recent world events which greatly impacted planned activities. Our design challenge is to develop a thermal energy storage system which will sequester the energy from a photovoltaic (PV) array during the day and allow for its dispersal at night in the form of near boiling water. Looking at our user’s needs, we broke our design solution into four components: water heating, storage, distribution, and controls. Research of all components was conducted to ascertain which systems should be developed and which system components could be purchased. Engineering specifications were developed to directly address customer needs and to create performance goals which our final solution can be measured against. During this phase, our group was tasked with procuring all required materials, manufacturing our prototype, and conducting verification testing. The system configuration was selected in the previous phase, and lists of components were compiled, along with manufacturing steps. We have constructed our prototype, and we have completed some preliminary testing, however there is more work to be completed by our sponsor. The selected system composition is outlined, including supporting documentation for testing procedures. Our Final Design Review outlines all final development activities which have taken place and next steps required for further iteration of our prototype