2,874 research outputs found
MTS Time Series: Market and Data Description for the European Bond and Repo Database
MTS Time Series: Market and Data Description for the European Bond and Repo Database Alfonso Dufour and Frank Skinner MTS Time Series is a new source of high frequency and daily data for European fixed income markets. For the first time academic researchers and market practitioners have available a wealth of trading data for a large number of European sovereign bond markets. The database includes data on daily cash and repo trading activity and comprehensive high frequency trade and quote data. This paper discusses specific aspects of the structure of the MTS markets and illustrates the characteristics of the database. In particular, the coverage and the structure of the database are provided.
Review: Vascular effects of PPARs in the context of NASH.
BACKGROUND
Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors known to regulate glucose and fatty acid metabolism, inflammation, endothelial function and fibrosis. PPAR isoforms have been extensively studied in metabolic diseases, including type 2 diabetes and cardiovascular diseases. Recent data extend the key role of PPARs to liver diseases coursing with vascular dysfunction, including nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH).
AIM
This review summarises and discusses the pathobiological role of PPARs in cardiovascular diseases with a special focus on their impact and therapeutic potential in NAFLD and NASH.
RESULTS AND CONCLUSIONS
PPARs may be attractive for the treatment of NASH due to their liver-specific effects but also because of their efficacy in improving cardiovascular outcomes, which may later impact liver disease. Assessment of cardiovascular disease in the context of NASH trials is, therefore, of the utmost importance, both from a safety and efficacy perspective
Transient outburst events from tidally disrupted asteroids near white dwarfs
We discuss the possibility of observing the transient formation event of an
accretion disk from the tidal destruction process of an asteroid near a white
dwarf (WD). This scenario is commonly proposed as the explanation for dusty
disks around WDs. We find that the initial formation phase lasts for about a
month and material that ends in a close orbit near the WD forms a gaseous disk
rather than a dusty disk. The mass and size of this gaseous accretion disk is
very similar to that of Dwarf Novae (DNe) in quiescence. The bolometric
luminosity of the event at maximum is estimated to be 0.001-0.1Lsun. Based on
the similarity with DNe we expect that transient outburst events such as
discussed here will be observed at wavelengths ranging from visible to the
X-ray, and be detected by present and future surveys.Comment: Accepted by New Astronom
A study of randomness, correlations and collectivity in the nuclear shell model
A variable combination of realistic and random two-body interactions allows
the study of collective properties, such as the energy spectra and B(E2)
transition strengths in 44Ti, 48Cr and 24Mg. It is found that the average
energies of the yrast band states maintain the ordering for any degree of
randomness, but the B(E2) values lose their quadrupole collectivity when
randomness dominates the Hamiltonian. The high probability of the yrast band to
be ordered in the presence of pure random forces exhibits the strong
correlations between the different members of the band.Comment: 8 pages, 10 figures, 8 tables, submitted to Physical Review
Global Models of Runaway Accretion in White Dwarf Debris Disks
A growing sample of white dwarfs (WDs) with metal-enriched atmospheres are
accompanied by excess infrared emission, indicating that they are encircled by
a compact dusty disk of solid debris. Such `WD debris disks' are thought to
originate from the tidal disruption of asteroids or other minor bodies, but the
precise mechanism(s) responsible for transporting matter to the WD surface
remains unclear, especially in those systems with the highest inferred metal
accretion rates dM_Z/dt ~ 1e8-1e10 g/s. Here we present global time-dependent
calculations of the coupled evolution of the gaseous and solid components of WD
debris disks. Solids transported inwards (initially due to PR drag) sublimate
at tens of WD radii, producing a source of gas that accretes onto the WD
surface and viscously spreads outwards in radius, where it overlaps with the
solid disk. If the aerodynamic coupling between the solids and gaseous disks is
sufficiently strong (and/or the gas viscosity sufficiently weak), then gas
builds up near the sublimation radius faster than it can viscously spread away.
Since the rate of drag-induced solid accretion increases with gas density, this
results in a runaway accretion process, during which the WD accretion rate
reaches values orders of magnitude higher than can be achieved by PR drag
alone. We explore the evolution of WD debris disks across a wide range of
physical conditions and calculate the predicted distribution of observed
accretion rates dM_Z/dt, finding reasonable agreement with the current sample.
Although the conditions necessary for runaway accretion are at best marginally
satisfied given the minimal level of aerodynamic drag between circular gaseous
and solid disks, the presence of other stronger forms of solid-gas
coupling---such as would result if the gaseous disk is only mildly
eccentric---substantially increase the likelihood of runaway accretion.Comment: 23 pages, 20 figures, submitted to MNRA
Spitzer Mid-Infrared Observations of Seven Bipolar Planetary Nebulae
We have investigated the mid-infrared (MIR) and visual structures of seven
bipolar planetary nebulae (BPNe), using imaging and spectroscopy acquired using
the Spitzer Space Telescope (SST), and the Observatorio Astronomico Nacional in
Mexico. The results show that the sources are more extended towards longer MIR
wavelengths, as well as having higher levels of surface brightness in the 5.8
and 8.0 microns bands. It is also noted that the 5.8/4.5 and 8.0/4.5 microns
flux ratios increase with increasing distance from the nuclei of the sources.
All of these latter trends may be attributable to emission by polycyclic
aromatic hydrocarbons (PAHs) and/or warm dust continua within circum-nebular
photo-dissociation regions (PDRs). A corresponding decrease in the flux ratios
8.0/5.8 microns may, by contrast, arise due to changes in the properties of the
PAH emitting grains. We note evidence for possible 8.0 microns ring-like
structures in the envelope of NGC 2346, located in a region beyond the minor
axis limits of the ionized envelope. An analysis of the inner two rings shows
that whilst they have higher surface brightnesses at longer MIR wavelengths,
they are relatively stronger (compared to underlying emission) at 3.6 and 4.5
microns. There is also evidence for point reflection symmetry along the major
axis of the outflow.Comment: 27 pages, 22 figures, Accepted for publication in MNRAS. 69 pages in
arXi
Periodic vacuum and particles in two dimensions
Different dynamical symmetry breaking patterns are explored for the two
dimensional phi4 model with higher order derivative terms. The one-loop saddle
point expansion predicts a rather involved phase structure and a new Gaussian
critical line. This vacuum structure is corroborated by the Monte Carlo method,
as well. Analogies with the structure of solids, the density wave phases and
the effects of the quenched impurities are mentioned. The unitarity of the time
evolution operator in real time is established by means of the reflection
positivity.Comment: Final version, additional references and the proof of reflection
positivity added, 41 pages, 16 figure
Broad AOX expression in a genetically tractable mouse model does not disturb normal physiology
Plants and many lower organisms, but not mammals, express alternative oxidases (AOXs) that branch the mitochondrial respiratory chain, transferring electrons directly from ubiquinol to oxygen without proton pumping. Thus, they maintain electron flow under conditions when the classical respiratory chain is impaired, limiting excess production of oxygen radicals and supporting redox and metabolic homeostasis. AOX from Ciona intestinalis has been used to study and mitigate mitochondrial impairments in mammalian cell lines, Drosophila disease models and, most recently, in the mouse, where multiple lentivector-AOX transgenes conferred substantial expression in specific tissues. Here, we describe a genetically tractable mouse model in which Ciona AOX has been targeted to the Rosa26 locus for ubiquitous expression. The AOX(Rosa26) mouse exhibited only subtle phenotypic effects on respiratory complex formation, oxygen consumption or the global metabolome, and showed an essentially normal physiology. AOX conferred robust resistance to inhibitors of the respiratory chain in organello; moreover, animals exposed to a systemically applied LD50 dose of cyanide did not succumb. The AOX(Rosa26) mouse is a useful tool to investigate respiratory control mechanisms and to decipher mitochondrial disease aetiology in vivo.Peer reviewe
Respiratory chain signalling is essential for adaptive remodelling following cardiac ischaemia
Abstract Cardiac ischaemia-reperfusion (I/R) injury has been attributed to stress signals arising from an impaired mitochondrial electron transport chain (ETC), which include redox imbalance, metabolic stalling and excessive production of reactive oxygen species (ROS). The alternative oxidase (AOX) is a respiratory enzyme, absent in mammals, that accepts electrons from a reduced quinone pool to reduce oxygen to water, thereby restoring electron flux when impaired and, in the process, blunting ROS production. Hence, AOX represents a natural rescue mechanism from respiratory stress. This study aimed to determine how respiratory restoration through xenotopically expressed AOX affects the re-perfused post-ischaemic mouse heart. As expected, AOX supports ETC function and attenuates the ROS load in post-anoxic heart mitochondria. However, post-ischaemic cardiac remodelling over 3 and 9Â weeks was not improved. AOX blunted transcript levels of factors known to be up-regulated upon I/R such as the atrial natriuretic peptide (Anp) whilst expression of pro-fibrotic and pro-apoptotic transcripts were increased. Ex vivo analysis revealed contractile failure at nine but not 3Â weeks after ischaemia whilst label-free quantitative proteomics identified an increase in proteins promoting adverse extracellular matrix remodelling. Together, this indicates an essential role for ETC-derived signals during cardiac adaptive remodelling and identified ROS as a possible effector.Peer reviewe
Respiratory chain signalling is essential for adaptive remodelling following cardiac ischaemia
Abstract Cardiac ischaemia-reperfusion (I/R) injury has been attributed to stress signals arising from an impaired mitochondrial electron transport chain (ETC), which include redox imbalance, metabolic stalling and excessive production of reactive oxygen species (ROS). The alternative oxidase (AOX) is a respiratory enzyme, absent in mammals, that accepts electrons from a reduced quinone pool to reduce oxygen to water, thereby restoring electron flux when impaired and, in the process, blunting ROS production. Hence, AOX represents a natural rescue mechanism from respiratory stress. This study aimed to determine how respiratory restoration through xenotopically expressed AOX affects the re-perfused post-ischaemic mouse heart. As expected, AOX supports ETC function and attenuates the ROS load in post-anoxic heart mitochondria. However, post-ischaemic cardiac remodelling over 3 and 9Â weeks was not improved. AOX blunted transcript levels of factors known to be up-regulated upon I/R such as the atrial natriuretic peptide (Anp) whilst expression of pro-fibrotic and pro-apoptotic transcripts were increased. Ex vivo analysis revealed contractile failure at nine but not 3Â weeks after ischaemia whilst label-free quantitative proteomics identified an increase in proteins promoting adverse extracellular matrix remodelling. Together, this indicates an essential role for ETC-derived signals during cardiac adaptive remodelling and identified ROS as a possible effector.Peer reviewe
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