Trading Horizons and the Value of Money

This paper shows that flat money can be feasible and essential even if the trading horizon is finite and deterministic. The result hinges on two features of our model. First, individual actions can affect the future availability of productive resources. So, agents may be willing to sell for money, even if on that date they have no reason to accept it. This makes monetary trade feasible in all preceding dates. Second, agents are anonymous and direct their search for partners. So, gift-giving arrangements may be prevented because agents can misrepresent their consumption needs. This makes money essential in exploiting any gains from specialization and trade

On Market Activity and the Value of Money

In a random-matching monetary economy, efficient and inefficient sellers choose between home or market production. Since inefficient sellers bargain up their prices, two equilibria may exist– with high or low market participation–depending on extent of heterogeneity and frictions. In equilibrium, the presence of inefficient sellers on the market has two opposing effects. It raises trading frequencies, so it lowers consumption risk, but it lowers the value of money, raising prices. This may reduce trading efficiency. Equilibria with full and limited participation can coexist; when average efficiency is high and agents are patient, limited participation is socially preferable

Trading Horizons and the Value of Money

We develop an anonymous trading framework where specialization and trade are beneficial to society and trading arrangements are endogenous. Its key features are that individual actions can have long-lasting aggregate consequences and the current allocation of consumption can affect the future availability of productive resources. We study equilibrium patterns of exchange when the trading sequences are finite and deterministic, demonstrating that fiat money does not necessarily loose its beneficial allocative role. The reason is that individual actions that reduce the agent’s current payoff–such as selling for money on its final trading date–can be incentive-compatible when this prevents others from making choices carrying adverse long-lasting aggregate consequences

Dynamic Data Structures for Timed Automata Acceptance

We study a variant of the classical membership problem in automata theory, which consists of deciding whether a given input word is accepted by a given automaton. We do so through the lenses of parameterized dynamic data structures: we assume that the automaton is fixed and its size is the parameter, while the input word is revealed as in a stream, one symbol at a time following the natural order on positions. The goal is to design a dynamic data structure that can be efficiently updated upon revealing the next symbol, while maintaining the answer to the query on whether the word consisting of symbols revealed so far is accepted by the automaton. We provide complexity bounds for this dynamic acceptance problem for timed automata that process symbols interleaved with time spans. The main contribution is a dynamic data structure that maintains acceptance of a fixed one-clock timed automaton ? with amortized update time 2^{?(|?|)} per input symbol

Effects of pre-farrowing sow vaccination against Mycoplasma hyopneumoniae on offspring colonisation and lung lesions

This study investigated Mycoplasma hyopneumoniae colonisation and lung lesions at slaughter in pigs from vaccinated (V) and non-vaccinated (NV) sows, in two herds (A and B). In each herd, two sow batches were V against M. hyopneumoniae with a commercial bacterin at six and three weeks before farrowing and two sow batches remained NV. From each sow batch, laryngeal swabs were collected from the litters of five primiparous sows at weaning and seven days post-weaning. All samples were tested for M. hyopneumoniae by nested PCR. In total, 488 piglets were sampled. At slaughter, the extent of Mycoplasma-like pneumonia lesions (lung lesion score (LLS)) was assessed. The colonisation rates with M. hyopneumoniae at weaning and seven days post-weaning were (V-A=14.2, NV-A=20.0 (P=0.225); V-B=0.9, NV-B=0.8 (P=0.948)) and (V-A=0.8, NV-A=7.0 (P=0.039); V-B=1.8, NV-B=2.5 (P=0.738)), respectively. The average LLS (in per cent) was V-A=15.5, NV-A=26.4 (P=0.021); V-B=9.7, NV-B=8.4 (P=0.541). In conclusion, in herd A, with a substantially higher level of piglet colonisation at weaning than herd B, offspring from V sows had a significantly lower colonisation rate seven days post-weaning and a significantly lower LLS at slaughter compared with the offspring of the NV sows. This implies that sow vaccination might be useful for control of M. hyopneumoniae infections, although significant results may not be achieved at all times (such as in herd B)

Coverability in VASS Revisited: Improving Rackoff’s Bound to Obtain Conditional Optimality

Seminal results establish that the coverability problem for Vector Addition Systems with States (VASS) is in EXPSPACE (Rackoff, \u2778) and is EXPSPACE-hard already under unary encodings (Lipton, \u2776). More precisely, Rosier and Yen later utilise Rackoff’s bounding technique to show that if coverability holds then there is a run of length at most $n^{2^(d log d)}$, where d is the dimension and n is the size of the given unary VASS. Earlier, Lipton showed that there exist instances of coverability in d-dimensional unary VASS that are only witnessed by runs of length at least $n^{2^Ω(d)}$. Our first result closes this gap. We improve the upper bound by removing the twice-exponentiated log(d) factor, thus matching Lipton’s lower bound. This closes the corresponding gap for the exact space required to decide coverability. This also yields a deterministic $n^{2^(d)}$-time algorithm for coverability. Our second result is a matching lower bound, that there does not exist a deterministic $n^{2^o(d)}$-time algorithm, conditioned upon the Exponential Time Hypothesis. When analysing coverability, a standard proof technique is to consider VASS with bounded counters. Bounded VASS make for an interesting and popular model due to strong connections with timed automata. Withal, we study a natural setting where the counter bound is linear in the size of the VASS. Here the trivial exhaustive search algorithm runs in $(n^{d+1})$-time. We give evidence to this being near-optimal. We prove that in dimension one this trivial algorithm is conditionally optimal, by showing that $n^{2-o(1)}$-time is required under the k-cycle hypothesis. In general fixed dimension d, we show that $n^{d-2-o(1)}$-time is required under the 3-uniform hyperclique hypothesis

QuantumATK: An integrated platform of electronic and atomic-scale modelling tools

QuantumATK is an integrated set of atomic-scale modelling tools developed since 2003 by professional software engineers in collaboration with academic researchers. While different aspects and individual modules of the platform have been previously presented, the purpose of this paper is to give a general overview of the platform. The QuantumATK simulation engines enable electronic-structure calculations using density functional theory or tight-binding model Hamiltonians, and also offers bonded or reactive empirical force fields in many different parametrizations. Density functional theory is implemented using either a plane-wave basis or expansion of electronic states in a linear combination of atomic orbitals. The platform includes a long list of advanced modules, including Green's-function methods for electron transport simulations and surface calculations, first-principles electron-phonon and electron-photon couplings, simulation of atomic-scale heat transport, ion dynamics, spintronics, optical properties of materials, static polarization, and more. Seamless integration of the different simulation engines into a common platform allows for easy combination of different simulation methods into complex workflows. Besides giving a general overview and presenting a number of implementation details not previously published, we also present four different application examples. These are calculations of the phonon-limited mobility of Cu, Ag and Au, electron transport in a gated 2D device, multi-model simulation of lithium ion drift through a battery cathode in an external electric field, and electronic-structure calculations of the composition-dependent band gap of SiGe alloys.Comment: Submitted to Journal of Physics: Condensed Matte

Abundance and Distribution of Enteric Bacteria and Viruses in Coastal and Estuarine Sediments—a Review

The long term survival of fecal indicator organisms (FIOs) and human pathogenic microorganisms in sediments is important from a water quality, human health and ecological perspective. Typically, both bacteria and viruses strongly associate with particulate matter present in freshwater, estuarine and marine environments. This association tends to be stronger in finer textured sediments and is strongly influenced by the type and quantity of clay minerals and organic matter present. Binding to particle surfaces promotes the persistence of bacteria in the environment by offering physical and chemical protection from biotic and abiotic stresses. How bacterial and viral viability and pathogenicity is influenced by surface attachment requires further study. Typically, long-term association with surfaces including sediments induces bacteria to enter a viable-but-non-culturable (VBNC) state. Inherent methodological challenges of quantifying VBNC bacteria may lead to the frequent under-reporting of their abundance in sediments. The implications of this in a quantitative risk assessment context remain unclear. Similarly, sediments can harbor significant amounts of enteric viruses, however, the factors regulating their persistence remains poorly understood. Quantification of viruses in sediment remains problematic due to our poor ability to recover intact viral particles from sediment surfaces (typically <10%), our inability to distinguish between infective and damaged (non-infective) viral particles, aggregation of viral particles, and inhibition during qPCR. This suggests that the true viral titre in sediments may be being vastly underestimated. In turn, this is limiting our ability to understand the fate and transport of viruses in sediments. Model systems (e.g., human cell culture) are also lacking for some key viruses, preventing our ability to evaluate the infectivity of viruses recovered from sediments (e.g., norovirus). The release of particle-bound bacteria and viruses into the water column during sediment resuspension also represents a risk to water quality. In conclusion, our poor process level understanding of viral/bacterial-sediment interactions combined with methodological challenges is limiting the accurate source apportionment and quantitative microbial risk assessment for pathogenic organisms associated with sediments in aquatic environments

Contributi per una flora vascolare di Toscana. XII (739-812)

Vengono presentate nuove località e/o conferme relative a 74 taxa specifici e sottospecifici di piante vascolari della flora vascolare to- scana, appartenenti a 69 generi e 28 famiglie: Bunium, Trinia (Apia- ceae), Nerium (Apocynaceae), Lemna (Araceae), Artemisia, Bidens, Centaurea, Crupina, Gazania, Hieracium, Rhagadiolus, Symphyotri- chum, Tagetes, Tripleurospermum (Asteraceae), Impatiens (Balsami- naceae), Anredera (Basellaceae), Cynoglottis, Phacelia (Boraginaceae), Cardamine, Diplotaxis, Hornungia (Brassicaceae), Campanula, Lobe- lia (Campanulaceae), Cerastium, Dianthus, Polycarpon, Spergularia, Stellaria (Caryophyllaceae), Commelina (Commelinaceae), Fallopia (Convolvulaceae), Sempervivum (Crassulaceae), Dryopteris (Dryopte- ridaceae), Euphorbia (Euphorbiaceae), Lathyrus, Medicago, Ononis, Trigonella (Fabaceae), Geranium (Geraniaceae), Lycopus, Stachys (Lamiaceae), Malva (Malvaceae), Anacamptis, Cephalanthera, Epi- pactis, Orchis (Orchidaceae), Linaria (Plantaginaceae), Ceratochloa, Eragrostis, Festuca, Gastridium, Hyparrhenia, Molineriella, Phalaris, Phyllostachys, Setaria, Sporobolus, Stipellula (Poaceae), Anogramma (Pteridaceae), Anemonoides, Ranunculus (Ranunculaceae), Reseda (Resedaceae), Alchemilla, Kerria, Pyracantha, Rosa, Rubus (Rosa- ceae), Galium, Valantia (Rubiaceae), Thesium (Santalaceae). Infine, viene discusso lo status di conservazione delle entità e gli eventuali vincoli di protezione dei biotopi segnalati