Learning, uncertainty and central bank activism in an economy with strategic interactions

In this paper we examine the optimal level of central bank activism in a standard model of monetary policy with uncertainty, learning and strategic interactions. We calibrate the model using G7 data and find that the presence of strategic interactions between the central bank and private agents creates an additional motivation for caution in optimal monetary policy. An active policy designed to help learning and reduce future uncertainty creates extra volatility in inflation expectations, which is detrimental to welfare

Regime-dependent impulse response functions in a Markov-switching vector autoregression model

In this paper we introduce identifying restrictions into a Markov-switching vector autoregression model. We define a separate set of impulse responses for each Markov regime to show how fundamental disturbances affect the variables in the model dependent on the regime. We go to illustrate the use of these regime-dependent impulse response functions in a model of the U.S. economy. The regimes we identify come close to the “old” and “new economy” regimes found in recent research. We provide evidence that oil price shocks are much less contractionary and inflationary than they used to be. We show furthermore that the decoupling of the US economic performance from oil price shocks cannot be explained by “good luck” alone, but that structural changes within the US economy have taken place.vector autoregression; regime switching; shocks; new economy

Portrait des activités délinquantes et de l’usage de substances psychoactives chez des jeunes consultant un centre de réadaptation pour personnes alcooliques et toxicomanes

Près de 900 jeunes présentant une problématique sévère de toxicomanie ont été évalués lors de leur demande de service en centre spécialisé. Un portrait de leur consommation de substances psychoactives est dressé et comparé en fonction des types d’encadrement judiciaire auquel est soumis l’individu, mais aussi en fonction du sexe. On constate des variations importantes de consommation de drogues entre les groupes (jeunes contrevenants par rapport aux jeunes en situation de protection ou encore, sous aucun encadrement légal) permettant d’appuyer l’hypothèse de liens entre, d’une part, l’intensité et le type de consommation de substances psychoactives et, d’autre part, la gravité des activités délictueuses. On tente d’identifier la portion de délits commis pour des fins de consommation de substances psychoactives et, donc, d’évaluer la proportion de jeunes qui cesseraient probablement les activités délictueuses si on pouvait les aider à cesser cette consommation de drogues. Les différences entre les sexes sont également mises en évidence.Nearly 900 heavy alcohol or drug adolescent users were evaluated at their admission into a substance abuse center. Description of their alcohol and drug use is done in interaction with the legal status in which they are embedded but also by sex. Differences are observed between groups (offenders versus the child welfare or without legal restrictions). Those differences give support to the presumed link between severity of substances abuse and importance of criminality. Efforts are made to calculate proportions of subjects for which criminal activities would presumably reduce or stopped by the instauration of abstinence. Differences between sexes are also analyzed

Synchrotron Emission from Dark Matter in Galactic Subhalos. A Look into the Smith Cloud

One of the key predictions of the WIMP paradigm for Dark Matter (DM) is that DM particles can annihilate into charged particles. These annihilations will proceed in e.g. Galactic subhalos such as dwarf Galaxies or, as recently pointed out, high velocity clouds such as the "Smith Cloud". In this note, we focus on the radio emission associated with DM annihilations into electrons and positrons occurring in the Smith Cloud. The phenomenology of this emission is discussed in quite some detail. We argue that the uncertainties in the propagation can be captured by the typical diffusion-loss length parameter (Syrovatskii variable) but that the angle-integrated radio fluxes are independent of the propagation. We conclude that if the Smith Cloud is indeed dominated by DM, radio signals from DM annihilation stand out amongst other messengers. Furthermore, low frequencies such as the ones observed by e.g. the Low Frequency Array (LOFAR) and the next-generation Square Kilometre Array (SKA) are optimal for searches for DM in the Smith Cloud. As a practical application, we set conservative constraints on dark matter annihilation cross section using data of continuum radio emission from the Galaxy at 22 MHz and at 1.4 GHz. Stronger constraints could be reached by background subtraction, exploiting the profile and frequency dependence of the putative DM signal. We set stronger but tentative limits using the median noise in brightness temperature from the Green Bank Telescope and the LOFAR sensitivities.Comment: 23 pages, 17 figures. Extended discussion on how the limits/forecasts are obtained. Matches published versio

Gait switches in deep-diving beaked whales : biomechanical strategies for long-duration dives

Work in the Canary Islands was funded by the Office of Naval Research and the National Oceanographic Partnership Program (NOPP), by a consortium consisting of the Canary Islands Government, the Spanish Ministry of Environment and the Spanish Ministry of Defense and by the European environmental funding LIFE-INDEMARES program for the inventory and designation of the Natura 2000 network in marine areas of the Spanish territory, headed by Fundacion Biodiversidad, with additional support from the Cabildo Insular of El Hierro. Fieldwork in the Ligurian Sea was funded by NOPP. Research in the Gully was funded by the Strategic Environmental Research and Development Program (SERDP) programs RC-2113 and RC-2337. L.M.M.L. was funded by a ‘la Caixa’ Fellowship within the 2010 UK Framework Programme. N.A.d.S. was funded for this study by ONR and by the EU FP7 Marie Curie project SOUNDMAR. M.J. was funded by a Marie Curie Career Integration Grant, and from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland) and their support is gratefully acknowledged. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions.Diving animals modulate their swimming gaits to promote locomotor efficiency and so enable longer, more productive dives. Beaked whales perform extremely long and deep foraging dives that probably exceed aerobic capacities for some species. Here, we use biomechanical data from suction-cup tags attached to three species of beaked whales (Mesoplodon densirostris, N = 10; Ziphius cavirostris, N = 9; and Hyperoodon ampullatus, N = 2) to characterize their swimming gaits. In addition to continuous stroking and stroke and-glide gaits described for other diving mammals, all whales produced occasional fluke-strokes with distinctly larger dorsoventral acceleration, which we termed 'type-B' strokes. These high-power strokes occurred almost exclusively during deep dive ascents as part of a novel mixed gait. To quantify body rotations and specific acceleration generated during strokes we adapted a kinematic method combining data from two sensors in the tag. Body rotations estimated with high-rate magnetometer data were subtracted from accelerometer data to estimate the resulting surge and heave accelerations. Using this method, we show that stroke duration, rotation angle and acceleration were bi-modal for these species, with B-strokes having 76% of the duration, 52% larger body rotation and four times more surge than normal strokes. The additional acceleration of B-strokes did not lead to faster ascents, but rather enabled brief glides, which may improve the overall efficiency of this gait. Their occurrence towards the end of long dives leads us to propose that B-strokes may recruit fast-twitch fibres that comprise similar to 80% of swimming muscles in Blainville's beaked whales, thus prolonging foraging time at depth.PostprintPeer reviewe

Tracking the kinematics of caudal-oscillatory swimming : a comparison of two on-animal sensing methods

Funding: Marie Sklodowska Curie Career Integration Grant and by The Marine Alliance for Science and Technology for Scotland (MASTS).Studies of locomotion kinematics require high-resolution information about body movements and the specific acceleration (SA) that these generate. On-animal accelerometers measure both orientation and SA but an additional orientation sensor is needed to accurately separate these. Although gyroscopes can perform this function, their power consumption, drift and complex data processing make them unattractive for biologging. Lower power magnetometers can also be used with some limitations. Here, we present an integrated and simplified method for estimating body rotations and SA applicable to both gyroscopes and magnetometers, enabling a direct comparison of these two sensors. We use a tag with both sensors to demonstrate how caudal-oscillation rate and SA are adjusted by a diving whale in response to rapidly changing buoyancy forces as the lungs compress while descending. Both sensors gave similar estimates of the dynamic forces demonstrating that magnetometers may offer a simpler low-power alternative for miniature tags in some applications.PostprintPeer reviewe

Abrupt onset of carbonate deposition in Lake Kivu during the 1960s: response to recent environmental changes

This study interprets the recent history of Lake Kivu, a tropical lake in the East African Rift Valley. The current gross sedimentation was characterized from a moored sediment trap array deployed over 2years. The past net sedimentation was investigated with three short cores from two different basins. Diatom assemblages from cores were interpreted as reflecting changes in mixing depth, surface salinity and nutrient availability. The contemporary sediment trap data indicate seasonal variability, governed by diatom blooms during the annual mixing in the dry season, similar to Lakes Malawi and Tanganyika. The ratio of settling fluxes to net sediment accumulation rates implies mineralization rates of 80-90% at the sediment-water interface. The sediment cores revealed an abrupt change ~40years ago, when carbonate precipitation started. Since the 1960s, deep-water methane concentrations, nutrient fluxes and soil mineral inputs have increased considerably and diatom assemblages have altered. These modifications probably resulted from a combination of three factors, commonly altering lake systems: the introduction of a non-native fish species, eutrophication, and hydrological changes inducing greater upwelling. Both the fish introduction and increased rainfall occurred at the time when the onset of carbonate precipitation was observed, whereas catchment population growth accompanied by intensified land use increased the flux of soil minerals already since the early twentieth century due to more intense erosio

Combined Computational-Experimental Analyses of CFTR Exon Strength Uncover Predictability of Exon-Skipping Level.

International audienceWith the increased number of identified nucleotide sequence variations in genes, the current challenge is to classify them as disease causing or neutral. These variants of unknown clinical significance can alter multiple processes, from gene transcription to RNA splicing or protein function. Using an approach combining several in silico tools, we identified some exons presenting weaker splicing motifs than other exons in the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene. These exons exhibit higher rates of basal skipping than exons harboring no identifiable weak splicing signals using minigene assays. We then screened 19 described mutations in three different exons, and identified exon-skipping substitutions. These substitutions induced higher skipping levels in exons having one or more weak splicing motifs. Indeed, this level remained under 2% for exons with strong splicing motifs and could reach 40% for exons having at least one weak motif. Further analysis revealed a functional exon splicing enhancer within exon 3 that was associated with the SR protein SF2/ASF and whose disruption induced exon skipping. Exon skipping was confirmed in vivo in two nasal epithelial cell brushing samples. Our approach, which point out exons with some splicing signals weaknesses, will help spot splicing mutations of clinical relevance

Data Capture Project at the Royal Botanic Garden Edinburgh

Botanic gardens, with their large holdings of living plants collected from around the world, are important guardians of plant biodiversity, but acquiring and curating these genetic resources is enormously expensive. For these reasons it is crucial that botanic gardens document and curate their collections in order to gain the greatest benefit from the plants in their care. Great priority is given to making detailed field notes and the process of documentation is often continued during the plants formative years when being propagated. However, for the large majority of plants this process often stops once the material is planted in its final garden location. The Data Capture Project at the Royal Botanic Garden Edinburgh is an attempt to document specific aspects of the plant collections so that the information captured can be of use to the research community even after the plants have died

TGF-b2 induction regulates invasiveness of theileria-transformed leukocytes and disease susceptibility

Theileria parasites invade and transform bovine leukocytes causing either East Coast fever (T. parva), or tropical theileriosis (T. annulata). Susceptible animals usually die within weeks of infection, but indigenous infected cattle show markedly reduced pathology, suggesting that host genetic factors may cause disease susceptibility. Attenuated live vaccines are widely used to control tropical theileriosis and attenuation is associated with reduced invasiveness of infected macrophages in vitro. Disease pathogenesis is therefore linked to aggressive invasiveness, rather than uncontrolled proliferation of Theileria-infected leukocytes. We show that the invasive potential of Theileria-transformed leukocytes involves TGF-b signalling. Attenuated live vaccine lines express reduced TGF-b2 and their invasiveness can be rescued with exogenous TGF-b. Importantly, infected macrophages from disease susceptible Holstein-Friesian (HF) cows express more TGF-b2 and traverse Matrigel with great efficiency compared to those from disease-resistant Sahiwal cattle. Thus, TGF-b2 levels correlate with disease susceptibility. Using fluorescence and time-lapse video microscopy we show that Theileria-infected, disease-susceptible HF macrophages exhibit increased actin dynamics in their lamellipodia and podosomal adhesion structures and develop more membrane blebs. TGF-b2-associated invasiveness in HF macrophages has a transcription-independent element that relies on cytoskeleton remodelling via activation of Rho kinase (ROCK). We propose that a TGF-b autocrine loop confers an amoeboid-like motility on Theileria-infected leukocytes, which combines with MMP-dependent motility to drive invasiveness and virulence