5,428 research outputs found
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A Rank Approach to Equity Forecast Construction
The purpose of this paper is to present a rank based approach to cross-sectionallinear factor modelling. The emphasis is on approximating factor exposures in aconsistent manner in order to facilitate the merging of subjective information(from professional investors) with objective information (from accounting dataand/or state of the art quantitative models) in a statistically rigorous way withoutneeding to impose the unrealistic simplifying assumptions typical of more standardtime series models. We deal with the problems of identifying country and sectorreturns by an innovative hierarchical factor structure. This is all discussed fromthe perspective that investment models are not immutable but rather need to bedesigned with characteristics that are fit for their purpose; for example, returningaggregate county and sector forecasts that are consistent by construction
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Monetary Policy, Nominal Interest Rates, and Long-horizon Inflation Uncertainty
Empirical evidence presented in this paper shows that the predictability of inflation at long horizons varies considerably across countries. Both simple theory and empirical evidence suggest that the crucial factor is the extent to which systematic monetary policy succeeds in stabilising the incipient unit root in inflation. The mechanism by which it does this appears, however, to be complicated by strong empirical evidence that nominal interest rates have real effects, which implies that monetary policy need not be so vigorous in reaction to inflation. This helps explain why inflation rates in the US and (especially) Germany have been relatively predictable, despite monetary policy rules which appear to have been barely stabilising. The paper also presents tentative evidence that the power of nominal interest rate effects is inversely related to long-horizon inflation uncertainty, and hence ultimately uncertainty about monetary policy
Aboriginal Languages in Quebec: Fighting Linguicide with Bilingual Education
Aboriginal peoples in Quebec are fighting for the survival of their language and culture. An essential component of Aboriginal decolonization and empowerment is the protection and enhancement of the Aboriginal heritage language. In this article, we review twenty years of research in Arctic Quebec (Nunavik) involving Inuit students educated in Inuktitut as well as in French and English. Our research reveals that children not only learn better in their own heritage language as opposed to one of the societally dominant languages, but also develop a more positive view of themselves, and a healthier view of Inuit as a group. Bilingual Education is shown to be of crucial importance for the vitality of Inuit language and culture.Les peuples autochtones du Québec luttent afin de préserver la survie de leur langue et de leur culture. Un élément essentiel de la décolonisation et de l’autonomisation autochtone est la protection et l’enrichissement de la langue ancestrale autochtone. Dans cet article, nous effectuons une analyse de vingt années de recherche dans le Nord du Québec (Nunavik) impliquant des élèves inuits scolarisés en français et en anglais. Nos recherches ont révélé que ces enfants non seulement apprennent mieux dans leur propre langue ancestrale plutôt que dans une des langues dominantes de la société, mais aussi qu’ils développent une image d’eux-mêmes plus positive, et une représentation plus saine des Inuits en tant que groupe. Il est démontré que l’enseignement bilingue est d’une importance cruciale, contribuant à la vitalité de la langue et de la culture inuites
Limitations for change detection in multiple Gabor targets
We investigate the limitations on the ability to detect when a target has changed, using Gabor targets as simple quantifiable stimuli. Using a partial report technique to equalise response variables, we show that the log of the Weber fraction for detecting a spatial frequency change is proportional to the log of the number of targets, with a set-size effect that is greater than that reported for visual search. This is not a simple perceptual limitation, because pre-cueing a single target out of four restores performance to the level found when only one target is present. It is argued that the primary limitation on performance is the division of attention across multiple targets, rather than decay within visual memory. However in a simplified change detection experiment without cueing, where only one target of the set changed, not only was the set size effect still larger, but it was greater at 2000 msec ISI than at 250 msec ISI, indicating a possible memory component. The steepness of the set size effects obtained suggests that even moderate complexity of a stimulus in terms of number of component objects can overload attentional processes, suggesting a possible low-level mechanism for change blindness
IL-10 permits transient activation of dendritic cells to tolerize T cells and protect from central nervous system autoimmune disease
Dendritic cells (DCs) are key players in the development of immunity. They can direct both the size and the quality of an immune response and thus are attractive tools to mediate immunotherapy. DC function has been thought to reflect the cells' maturation, with immunosuppressive agents such as IL-10 understood to retain DCs in an immature and tolerogenic state. Here we report that DC activated in the presence of IL-10 do show functional and phenotypic maturation. Their activation is transient and occurs earlier and more briefly than in cells matured with LPS alone. Despite initially equivalent up-regulation of surface MHC and co-stimulation, the IL-10-treated DCs expressed little IL-12 and failed to stimulate T cell proliferation both in vitro and in vivo. Interaction with IL-10-treated DCs rendered antigen-specific T cells unresponsive to subsequent challenge and their injection reduced the severity of experimental autoimmune disease. Our data suggest that IL-10 acts not by inhibiting maturation but instead by controlling the kinetics and the quality of DC activation. This alternative pathway of DC differentiation offers significant therapeutic promise
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Generalised Mean-Variance Analysis and Robust Portfolio Diversification
This paper presents a new approach to portfolio optimisation that we call generalised mean-variance (GMV) analysis. One important case of this approach is based on the stocks m-tile (or quantile): if m = n, where n is the number of stocks, m-tile membership becomes rank. Our analysis is the rank equivalent of conventional Markowitz Mean Variance analysis. The first stage to generate rank probability statistics using, historic data, Monte Carlo analysis or direct user input. The second stage is optimisation based on those rank statistics to calculate recommended portfolio weights. Our optimisation uses state preference theory to derive an objective function that can be minimised using standard quadratic programming techniques. We deal with some advantages of this method including a more intuitive fully diversified (or minimum risk) position on the efficient frontier with all the portfolio holdings equally weighted
Structural brain changes in First Episode Schizophrenia compared with Fronto-Temporal Lobar Degeneration: a meta-analysis.
BACKGROUND: The authors sought to compare gray matter changes in First Episode Schizophrenia (FES) compared with Fronto-Temporal Lobar Degeneration (FTLD) using meta-analytic methods applied to neuro-imaging studies. METHODS: A systematic search was conducted for published, structural voxel-based morphometric MRI studies in patients with FES or FTLD. Data were combined using anatomical likelihood estimation (ALE) to determine the extent of gray matter decreases and analysed to ascertain the degree of overlap in the spatial distribution of brain changes in both diseases. RESULTS: Data were extracted from 18 FES studies (including a total of 555 patients and 621 comparison subjects) and 20 studies of FTLD or related disorders (including a total of 311 patients and 431 comparison subjects). The similarity in spatial overlap of brain changes in the two disorders was significant (p = 0.001). Gray matter deficits common to both disorders included bilateral caudate, left insula and bilateral uncus regions. CONCLUSIONS: There is a significant overlap in the distribution of structural brain changes in First Episode Schizophrenia and Fronto-Temporal Lobar Degeneration. This may reflect overlapping aetiologies, or a common vulnerability of these regions to the distinct aetio-pathological processes in the two disorders.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are
Microflare Heating of a Solar Active Region Observed with NuSTAR, Hinode/XRT, and SDO/AIA
NuSTAR is a highly sensitive focusing hard X-ray (HXR) telescope and has
observed several small microflares in its initial solar pointings. In this
paper, we present the first joint observation of a microflare with NuSTAR and
Hinode/XRT on 2015 April 29 at ~11:29 UT. This microflare shows heating of
material to several million Kelvin, observed in Soft X-rays (SXRs) with
Hinode/XRT, and was faintly visible in Extreme Ultraviolet (EUV) with SDO/AIA.
For three of the four NuSTAR observations of this region (pre-, decay, and post
phases) the spectrum is well fitted by a single thermal model of 3.2-3.5 MK,
but the spectrum during the impulsive phase shows additional emission up to 10
MK, emission equivalent to A0.1 GOES class. We recover the differential
emission measure (DEM) using SDO/AIA, Hinode/XRT, and NuSTAR, giving
unprecedented coverage in temperature. We find the pre-flare DEM peaks at ~3 MK
and falls off sharply by 5 MK; but during the microflare's impulsive phase the
emission above 3 MK is brighter and extends to 10 MK, giving a heating rate of
about erg s. As the NuSTAR spectrum is purely
thermal we determined upper-limits on the possible non-thermal bremsstrahlung
emission. We find that for the accelerated electrons to be the source of the
heating requires a power-law spectrum of with a low energy
cut-off keV. In summary, this first NuSTAR microflare
strongly resembles much more powerful flares.Comment: Accepted for publication in ApJ. 14 pages with 12 figures and 1 tabl
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