Forecasting volatility in the presence of Leverage Effect

We define a simple and tractable method for adding the Leverage effect in general volatility predictions. As an application, we compare volatility predictions with and without Leverage on the SP500 Index during the period 2002-2010.

Celebrating Our Evolving, Interdisciplinary, Contextually-Embedded Field

What use is a theory if it cannot describe, explain, specify, and predict phenomena of interest? Applying this metric, Jason, Stevens, Ram, Miller, Beasley, and Gleason (2016) demonstrate the limits of three of the foundational theories of community psychology. The challenge for these and other theories stems from the field’s complexity and multiple levels of analysis. Consequently, many of the defining constructs (e.g., neighborhood, social ecology, empowerment) are insufficiently specified and tested. Yet, in light of the inherently interdisciplinary nature of community psychology, its attunement to evolving societal issues, and its broad, multi-level foci, one could argue that community psychology may never yield to the rigors and conventions of traditional psychological inquiry in ways that produce a distinct unifying theory.&nbsp

Celebrating Our Evolving, Interdisciplinary, Contextually-Embedded Field

What use is a theory if it cannot describe, explain, specify, and predict phenomena of interest? Applying this metric, Jason, Stevens, Ram, Miller, Beasley, and Gleason (2016) demonstrate the limits of three of the foundational theories of community psychology. The challenge for these and other theories stems from the field’s complexity and multiple levels of analysis. Consequently, many of the defining constructs (e.g., neighborhood, social ecology, empowerment) are insufficiently specified and tested. Yet, in light of the inherently interdisciplinary nature of community psychology, its attunement to evolving societal issues, and its broad, multi-level foci, one could argue that community psychology may never yield to the rigors and conventions of traditional psychological inquiry in ways that produce a distinct unifying theory.&nbsp

Group theory via global semigroup theory

AbstractGroups are shown to be special homomorphic images of inverse semigroups that are residually finite (actually: every element has only finitely many elements ⩾j-above). This also leads to a new approach to the Burnside problem. These results extend an earlier paper (J. C. Birget and J. Rhodes, J. Pure Appl. Algebra 32 (1984), 249–287), but can be read independently. Our goal here is not so much to prove theorems about inverse semigroups as to demonstrate the usefulness of the constructions of J. C. Birget and J. Rhodes, J. Pure Appl. Algebra 32 (1984), 249–287

Postpartum Transitions in Adolescent Mothers\u27 Romantic and Maternal Relationships

Minority adolescent mothers (N = 375) were interviewed during the prepartum (or early postpartum) period and approximately 1 year later (N = 186) regarding their maternal and romantic relationships, depressive symptomatology, and negative life events. Over time, adolescents reported that male partners provided more support than did mothers and that partners\u27 support was equally important to mothers\u27 support. Further, while support from mothers decreased over time, strain increased. Results highlight the importance of considering relationship stability, At Time 2, partner support was negatively associated with depression only among adolescents who retained the same partner (17%). In addition, adolescents who sustained a romantic relationship disruption (38%) reported more negative life events than did those who had not. Implications for research, intervention, and policy are discussed

Influential Article Review - The Rise of Communities from Economic Hubs

This paper examines economics. We present insights from a highly influential paper. Here are the highlights from this paper: This paper analyzes the Greenlandic business community and the recently established cluster relevant to extractive industries in Greenland, Arctic Cluster of Raw Materials (ACRM), to enhance local business development in mining projects in Greenland. The analysis directs toward a transition from an economic cluster to a collaborative community in order to increase business potential and to overcome limitations of smallness and inadequate competencies of the Greenlandic business community in the mining industry. Transitioning into a collaborative community creates more value by enabling member firms to realize business development that each single firm could not achieve with its own efforts by being a part of a cluster. Managing the transition process emphasizes the facilitating role for the reason that a shared service provider is required in every collaborative community. I develop a conceptual model for the transition from an economic cluster to a collaborative community based on the architectural elements of the collaborative community design. The conceptual model considers the five proximity dimensions that influence inter-firm linkages both as enablers and barriers to the transition process and collaboration. Collaboration represents a new approach to business and industrial development in remote regions of the Arctic, as challenges evident for Greenland can be found throughout the entire Arctic. For our overseas readers, we then present the insights from this paper in Spanish, French, Portuguese, and German

The WFIRST Galaxy Survey Exposure Time Calculator

This document describes the exposure time calculator for the Wide-Field Infrared Survey Telescope (WFIRST) high-latitude survey. The calculator works in both imaging and spectroscopic modes. In addition to the standard ETC functions (e.g. background and S/N determination), the calculator integrates over the galaxy population and forecasts the density and redshift distribution of galaxy shapes usable for weak lensing (in imaging mode) and the detected emission lines (in spectroscopic mode). The source code is made available for public use.Comment: 44 pages. The current C source code and version history can be found at http://www.tapir.caltech.edu/~chirata/web/software/space-etc/ ; IPAC maintains a web interface at http://wfirst-web.ipac.caltech.edu/wfDepc/wfDepc.js

SuperNova Acceleration Probe (SNAP): Investigating Photometric Redshift Optimization

The aim of this paper is to investigate ways to optimize the accuracy of photometric redshifts for a SNAP like mission. We focus on how the accuracy of the photometric redshifts depends on the magnitude limit and signal-to-noise ratio, wave-length coverage, number of filters and their shapes and observed galaxy type. We use simulated galaxy catalogs constructed to reproduce observed galaxy luminosity functions from GOODS, and derive photometric redshifts using a template fitting method. By using a catalog that resembles real data, we can estimate the expected number density of galaxies for which photometric redshifts can be derived. We find that the accuracy of photometric redshifts is strongly dependent on the signal-to-noise (S/N) (i.e., S/N>10 is needed for accurate photometric redshifts). The accuracy of the photometric redshifts is also dependent on galaxy type, with smaller scatter for earlier type galaxies. Comparing results using different filter sets, we find that including the U-band is important for decreasing the fraction of outliers, i.e., ``catastrophic failures''. Using broad overlapping filters with resolution ~4gives better photometric redshifts compared to narrower filters (resolution >~5) with the same integration time. We find that filters with square response curves result in a slightly higher scatter, mainly due to a higher fraction of outliers at faint magnitudes. We also compare a 9-filter set to a 17-filter set, where we assume that the available exposure time per filter in the latter set is half that of the first set. We find that the 9-filter set gives more accurate redshifts for a larger number of objects and reaches higher redshift, while the 17-filter set is gives better results at bright magnitudes.Comment: 30 pages, 10 figures. Submitted to A

Ash's type II theorem, profinite topology and Malcev products

This paper is concerned with the many deep and far reaching consequences of Ash's positive solution of the type II conjecture for finite monoids. After rewieving the statement and history of the problem, we show how it can be used to decide if a finite monoid is in the variety generated by the Malcev product of a given variety and the variety of groups. Many interesting varieties of finite monoids have such a description including the variety generated by inverse monoids, orthodox monoids and solid monoids. A fascinating case is that of block groups. A block group is a monoid such that every element has at most one semigroup inverse. As a consequence of the cover conjecture - also verified by Ash - it follows that block groups are precisely the divisors of power monoids of finite groups. The proof of this last fact uses earlier results of the authors and the deepest tools and results from global semigroup theory. We next give connections with the profinite group topologies on finitely generated free monoids and free groups. In particular, we show that the type II conjecture is equivalent with two other conjectures on the structure of closed sets (one conjecture for the free monoid and another one for the free group). Now Ash's theorem implies that the two topological conjectures are true and independently, a direct proof of the topological conjecture for the free group has been recently obtained by Ribes and Zalesskii. An important consequence is that a rational subset of a finitely generated free group G is closed in the profinite topology if and only if it is a finite union of sets of the form gH1H2... Hn, where each Hi is a finitely generated subgroup of G. This significantly extends classical results by M. Hall. Finally we return to the roots of this problem and give connections with the complexity theory of finite semigroups. We show that the largest local complexity function in the sense of Rhodes and Tilson is computable