4,085 research outputs found
Modeling and forecasting exchange rate volatility in time-frequency domain
This paper proposes an enhanced approach to modeling and forecasting
volatility using high frequency data. Using a forecasting model based on
Realized GARCH with multiple time-frequency decomposed realized volatility
measures, we study the influence of different timescales on volatility
forecasts. The decomposition of volatility into several timescales approximates
the behaviour of traders at corresponding investment horizons. The proposed
methodology is moreover able to account for impact of jumps due to a recently
proposed jump wavelet two scale realized volatility estimator. We propose a
realized Jump-GARCH models estimated in two versions using maximum likelihood
as well as observation-driven estimation framework of generalized
autoregressive score. We compare forecasts using several popular realized
volatility measures on foreign exchange rate futures data covering the recent
financial crisis. Our results indicate that disentangling jump variation from
the integrated variation is important for forecasting performance. An
interesting insight into the volatility process is also provided by its
multiscale decomposition. We find that most of the information for future
volatility comes from high frequency part of the spectra representing very
short investment horizons. Our newly proposed models outperform statistically
the popular as well conventional models in both one-day and multi-period-ahead
forecasting
Surveying the SO(10) Model Landscape: The Left-Right Symmetric Case
Grand Unified Theories (GUTs) are a very well motivated extensions of the
Standard Model (SM), but the landscape of models and possibilities is
overwhelming, and different patterns can lead to rather distinct
phenomenologies. In this work we present a way to automatise the model building
process, by considering a top to bottom approach that constructs viable and
sensible theories from a small and controllable set of inputs at the high
scale. By providing a GUT scale symmetry group and the field content, possible
symmetry breaking paths are generated and checked for consistency, ensuring
anomaly cancellation, SM embedding and gauge coupling unification. We emphasise
the usefulness of this approach for the particular case of a non-supersymmetric
SO(10) model with an intermediate left-right symmetry and we analyse how
low-energy observables such as proton decay and lepton flavour violation might
affect the generated model landscape.Comment: 36 pages, 6 figure
MACHINE LEARNING FOR THING DETECTION, BEHAVIOR ANALYTICS, AND THREAT DETECTION: AN EFFICIENT ELIMINATION METHOD OF REDUNDANT FEATURE-SUBSETS
Techniques are described herein to efficiently detect redundant features in a machine learning process. The techniques are able to compute feature redundancy not only for a single feature at a time, but for any subset of features without the need to naively train and evaluate a classifier for each combination of features
Trafficking of Mononuclear Phagocytes in Healthy Arteries and Atherosclerosis
Monocytes and macrophages play essential roles in all stages of atherosclerosis – from early precursor lesions to advanced stages of the disease. Intima-resident macrophages are among the first cells to be confronted with the influx and retention of apolipoprotein B-containing lipoproteins at the onset of hypercholesterolemia and atherosclerosis development. In this review, we outline the trafficking of monocytes and macrophages in and out of the healthy aorta, as well as the adaptation of their migratory behaviour during hypercholesterolemia. Furthermore, we discuss the functional and ontogenetic composition of the aortic pool of mononuclear phagocytes and its link to the atherosclerotic disease process. The development of mouse models of atherosclerosis regression in recent years, has enabled scientists to investigate the behaviour of monocytes and macrophages during the resolution of atherosclerosis. Herein, we describe the dynamics of these mononuclear phagocytes upon cessation of hypercholesterolemia and how they contribute to the restoration of tissue homeostasis. The aim of this review is to provide an insight into the trafficking, fate and disease-relevant dynamics of monocytes and macrophages during atherosclerosis, and to highlight remaining questions. We focus on the results of rodent studies, as analysis of cellular fates requires experimental manipulations that cannot be performed in humans but point out findings that could be replicated in human tissues. Understanding of the biology of macrophages in atherosclerosis provides an important basis for the development of therapeutic strategies to limit lesion formation and promote plaque regression
Absorption of Hydrogen in the HBond©9000 Metal Hydride Tank
The present article describes the measurements of hydrogen absorbed into an intermetallic alloy. The process of hydrogen absorption into a metal hydride tank is accompanied with generating heat that must be removed during the process. If the tank is not cooled, the gas pressure rapidly increases and even with a small amount of the stored hydrogen the pressure exceeds the permissible value. By contrast, during hydrogen desorption it is required to supply the same amount of specific heat to avoid a significant decrease in pressure which would result in a decrease in hydrogen release kinetics.  
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