10,698 research outputs found
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Seasonal persistence of circulation anomalies in the Southern Hemisphere stratosphere, and its implications for the troposphere
Previous studies have highlighted an important organising influence of the seasonal Southern Hemisphere stratospheric vortex breakdown on the large-scale stratospheric and tropospheric circulation. The present study extends this work by considering the statistical predictability of the stratospheric vortex breakdown event, using re-analysis data. Perturbations to the winter stratospheric vortex are shown to persist into austral spring, and to lead to a shift in the statistics of the breakdown event during austral summer. This is interpreted as evidence for the potential for seasonal predictability of the vortex breakdown event in the stratosphere. Coupled variability between the stratosphere and troposphere is then considered. The semi-annual oscillation of the tropospheric mid-latitude jet is discussed and evidence for a connection between this behaviour and variations in the stratosphere is presented. Based on this connection, an argument is made for the concomitant potential for seasonal predictability in the troposphere, assuming knowledge of the stratospheric initial state. Combining these various results, a non-stationary, regime-based perspective of large-scale extra-tropical Southern Hemisphere circulation variability between late winter and summer is proposed. The implications of this perspective for some previous studies involving Annular Modes of the circulation are discussed. In particular, the long Annular Mode timescales during austral spring and summer should not be interpreted as an increased persistence of perturbations to some slowly varying seasonal cycle, but instead reflect a phase shift of the seasonal cycle induced by stratospheric variability
Interest rate co-movements, global factors and the long end of the term spread
The disconnect between rising short and low long interest rates has been a distinctive
feature of the 2000s. Both research and policy circles have argued that international
forces, such as global monetary policy (e.g. Rogoff, 2006); international business cycles
(e.g. Borio and Filardo, 2007); or a global savings glut (e.g Bernanke, 2005) may be
responsible. In this paper, we employ recent advances in panel data econometrics to
document the disconnect and link it explicitly to the existence of a global latent factor that dominates the long end of the term spread for the recent period; the saving glut story emerges as the most likely contender for the global factor
The FHD/ppsilon Epoch of Reionization Power Spectrum Pipeline
Epoch of Reionization data analysis requires unprecedented levels of accuracy
in radio interferometer pipelines. We have developed an imaging power spectrum
analysis to meet these requirements and generate robust 21 cm EoR measurements.
In this work, we build a signal path framework to mathematically describe each
step in the analysis, from data reduction in the FHD package to power spectrum
generation in the ppsilon package. In particular, we focus on the
distinguishing characteristics of FHD/ppsilon: highly accurate
spectral calibration, extensive data verification products, and end-to-end
error propagation. We present our key data analysis products in detail to
facilitate understanding of the prominent systematics in image-based power
spectrum analyses. As a verification to our analysis, we also highlight a
full-pipeline analysis simulation to demonstrate signal preservation and lack
of signal loss. This careful treatment ensures that the
FHD/ppsilon power spectrum pipeline can reduce radio
interferometric data to produce credible 21 cm EoR measurements.Comment: 21 pages, 10 figures, accepted by PAS
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Subseasonal-to-seasonal predictability of the Southern Hemisphere eddy-driven jet during austral spring and early summer
Several recent studies have suggested that the stratosphere can be a source of subseasonal-to-seasonal predictability of Southern Hemisphere circulation during the austral spring and early summer seasons, through its influence on the eddy-driven jet. We exploit the large sample size afforded by the hindcasts from the European Centre for Medium-Range Weather Forecasts Integrated Forecast System to address a number of unanswered questions. It is shown that the picture of coherent seasonal variability of the coupled stratosphere-troposphere system apparent from the reanalysis record during the spring/early summer period is robust to sampling uncertainty, and that there is evidence of nonlinearity in the case of the most extreme variations. The effect of El Nino-Southern Oscillation on the eddy-driven jet during this time of year is found to occur via the stratosphere, with no evidence of a direct tropospheric pathway. A simple two-state statistical model of the stratospheric vortex is introduced to estimate the subseasonal-to-seasonal predictability associated with shifts of the seasonal cycle in the SH extratropical atmosphere. This simple model, along with a more general model, are subsequently used to interpret skill scores associated with hindcasts made using the full seasonal forecast model. Together the results provide evidence of tropospheric predictability on subseasonal-to-seasonal timescales from at least as early as August 1, and show no evidence of a `signal-to-noise paradox' between the full seasonal forecast model and the reanalysis
A Progressive Approach to Content Generation
Abstract. PCG approaches are commonly categorised as constructive, generate-and-test or search-based. Each of these approaches has its distinctive advantages and drawbacks. In this paper, we propose an approach to Content Generation (CG) â in particular level generation â that combines the advantages of construc-tive and search-based approaches thus providing a fast, flexible and reliable way of generating diverse content of high quality. In our framework, CG is seen from a new perspective which differentiates between two main aspects of the game-play experience, namely the order of the in-game interactions and the associated level design. The framework first generates timelines following the search-based paradigm. Timelines are game-independent and they reflect the rhythmic feel of the levels. A progressive, constructive-based approach is then implemented to evaluate timelines by mapping them into level designs. The framework is applied for the generation of puzzles for the Cut the Rope game and the results in terms of performance, expressivity and controllability are characterised and discussed.
Loss of constitutive activity is correlated with increased thermostability of the human adenosine A2A receptor
BACKGROUND AND PURPOSE: Thermostabilization by mutagenesis is one method which has facilitated the determination of high-resolution structures of the adenosine A(2A) receptor (A(2A)R). Sets of mutations were identified, which both thermostabilized the receptor and resulted in preferential agonist (Rag23 mutant) or antagonist (Rant5 and Rant21) binding forms as assessed by radioligand binding analysis. While the ligand-binding profiles of these mutants are known, the effects these mutations have on receptor activation and downstream signalling are less well characterized. EXPERIMENTAL APPROACH: Here we have investigated the effects of the thermostabilizing mutations on receptor activation using a yeast cell growth assay. The assay employs an engineered Saccharomyces cerevisiae, MMY24, which couples receptor activation to cell growth. KEY RESULTS: Analysis of the receptor activation profile revealed that the wild-type (WT) A(2A)R had considerable constitutive activity. In contrast, the Rag23, Rant5 and Rant21 thermostabilized mutants all exhibited no constitutive activity. While the preferentially antagonist-binding mutants Rant5 and Rant21 showed a complete lack of agonist-induced activity, the Rag23 mutant showed high levels of agonist-induced receptor activity. Further analysis using a mutant intermediate between Rag23 and WT indicated that the loss of constitutive activity observed in the agonist responsive mutants was not due to reduced G-protein coupling. CONCLUSIONS AND IMPLICATIONS: The loss of constitutive activity may be an important feature of these thermostabilized GPCRs. In addition, the constitutively active and agonist-induced active conformations of the A(2A)R are distinct
Loss of constitutive activity is correlated with increased thermostability of the human adenosine A2A receptor
In this note we present an explicit realization of the affine vertex algebra V^cri(gl(1|1)) inside of the tensor product F â M where F is a fermionic verex algebra and M is a commutative vertex algebra. This immediately gives an alternative description of the center of V^cri(gl(1|1)) as a subalgebra M_0 of M. We reconstruct the Molev-Mukhin formula for the Hilbert-Poincare series of the center of V^cri(gl(1|1)). Moreover, we construct a family of irreducible Vcri(gl(1|1))-modules realized on F and parameterized by Ï+, Ï- â C((z)). We propose a generalization of V^cri(gl(1|1)) as a critical level version of the super W_{1+â} vertex algebra
Introduction to Mentalization-Based Approaches for Parents, Children, Youths, and Families
Family members mentalize when they try to understand each other's behavior on the basis of intentional mental states. This article aims to introduce and briefly describe how the concept of mentalization can provide a useful framework for clinicians to understand psychopathology of children, youths, and families. The authors further outline how mentalization-based techniques and interventions can be applied to build epistemic trust and to reestablish mentalizing in families by presenting clinical vignettes of initial sessions from various clinical settings in the United Kingdom and Germany. The article concludes with a brief summary about the current evidence for mentalization-based interventions with children, adolescents, and families and provides an outlook for future clinical and research work
The Chromospheric Activity and Ages of M Dwarf Stars in Wide Binary Systems
We investigate the relationship between age and chromospheric activity for
139 M dwarf stars in wide binary systems with white dwarf companions. The age
of each system is determined from the cooling age of its white dwarf component.
The current limit for activity-age relations found for M dwarfs in open
clusters is 4 Gyr. Our unique approach to finding ages for M stars allows for
the exploration of this relationship at ages older than 4 Gyr. The general
trend of stars remaining active for a longer time at later spectral type is
confirmed. However, our larger sample and greater age range reveals additional
complexity in assigning age based on activity alone. We find that M dwarfs in
wide binaries older than 4 Gyr depart from the log-linear relation for clusters
and are found to have activity at magnitudes, colors and masses which are
brighter, bluer and more massive than predicted by the cluster relation. In
addition to our activity-age results, we present the measured radial velocities
and complete space motions for 161 white dwarf stars in wide binaries.Comment: 22 pages including 9 figures and 5 tables. Accepted for publication
in The Astronomical Journa
Bouncing Neutrons and the Neutron Centrifuge
The recent observation of the quantum state of the neutron bouncing freely
under gravity allows some novel experiments. A method of purifying the ground
state is given, and possible applications to the measurement of the electric
dipole moment of the neutron and the short distance behaviour of gravity are
discussed.Comment: 7 pages, 7 figure
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