On an easy transition from operator dynamics to generating functionals by Clifford algebras

Clifford geometric algebras of multivectors are treated in detail. These algebras are build over a graded space and exhibit a grading or multivector structure. The careful study of the endomorphisms of this space makes it clear, that opposite Clifford algebras have to be used also. Based on this mathematics, we give a fully Clifford algebraic account on generating functionals, which is thereby geometric. The field operators are shown to be Clifford and opposite Clifford maps. This picture relying on geometry does not need positivity in principle. Furthermore, we propose a transition from operator dynamics to corresponding generating functionals, which is based on the algebraic techniques. As a calculational benefit, this transition is considerable short compared to standard ones. The transition is not injective (unique) and depends additionally on the choice of an ordering. We obtain a direct and constructive connection between orderings and the explicit form of the functional Hamiltonian. These orderings depend on the propagator of the theory and thus on the ground state. This is invisible in path integral formulations. The method is demonstrated within two examples, a non-linear spinor field theory and spinor QED. Antisymmetrized and normal-ordered functional equations are derived in both cases.Comment: 23p., 76kB, plain LaTeX, [email protected]

The search for planetary mass companions to field brown dwarfs with HST/NICMOS

We present the results of a high-resolution spectral differential imaging survey of 12 nearby, relatively young field L dwarfs (<1 Gyr) carried out with HST/NICMOS to search for planetary mass companions at small physical separations from their host. The survey resolved two brown dwarf binaries: the L dwarf system Kelu-1AB and the newly discovered L/T transition system 2MASS J031059+164815AB. For both systems common proper motion has already been confirmed in follow-up observations which have been published elsewhere. The derived separations of the binaries are smaller than 6 AU and consistent with previous brown dwarf binary statistics. Their mass ratios of q > 0.8 confirm the preference for equal mass systems similar to a large number of other surveys. Furthermore, we found tentative evidence for a companion to the L4 dwarf 2MASS W033703-175807, straddling the brown dwarf/planetary mass boundary and revealing an uncommonly low mass ratio system (q ~ 0.2) compared to the vast majority of previously found brown dwarf binaries. With a derived minimum mass of 10 - 15 Mjup, a planetary nature of the secondary cannot be ruled out yet. However, it seems more likely to be a very low mass brown dwarf secondary at the border of the spectral T/Y transition regime, primarily due to its similarities to recently found very cool T dwarfs. This would make it one of the closest resolved brown dwarf binaries (0.087" $/pm$ 0.015", corresponding to 2.52 $\pm$ 0.44 AU at a distance of 29 pc) with the coolest (Teff ~ 600-630 K) and least massive companion to any L or T dwarf.Comment: 33 pages, 8 figures, 2 tables, accepted for publication by Ap

ExSS 2018: Workshop on explainable smart systems

Smart systems that apply complex reasoning to make decisions and plan behavior are often difficult for users to understand. While research to make systems more explainable and therefore more intelligible and transparent is gaining pace, there are numerous issues and problems regarding these systems that demand further attention. The goal of this workshop is to bring academia and industry together to address these issues. The workshop includes a keynote, poster panels, and group activities, towards developing concrete approaches to handling challenges related to the design, development, and evaluation of explainable smart systems

Resilience in Nicaragua: Preliminary Factor Analysis and Validation of the CYRM-28

Objectives: The current study used factor analytic techniques to examine the performance of the Child and Youth Resilience Measure (CYRM-28) in Nicaragua. Methods: Nicaraguan youth from Managua, León, Chinandega, and Granada (n = 2,764) completed the CYRM-28 and the Personal Wellbeing Index (PWI-A). The CYRM-28 and PWI-A are self-report measures that were translated into Spanish in previous studies. Results: A confirmatory factor analysis on the CYRM-28 did not support the eight-factor model from previous research. An exploratory factor analysis yielded a six-factor model: Social Belonging, Cultural Context, Caregiver Context, Social Skills, Spiritual Context, and Responsibility. Seven items were removed to improve model fit, reducing the CYRM-28 to only 21 items. We named the reduced measure the CYRM-21-N (Nicaragua). Implications: From our analyses, we constructed the CYRM-21-N, a briefer version of the CYRM-28 with a revised factor structure. The CYRM-21-N may be useful in studying resilience in youth populations or assessing intervention outcomes in Nicaragua

Resolving the L/T transition binary SDSS J2052-1609 AB

Binaries provide empirical key constraints for star formation theories, like the overall binary fraction, mass ratio distribution and the separation distribution. They play a crucial role to calibrate the output of theoretical models, like absolute magnitudes, colors and effective temperature depending on mass, metallicity and age. We present first results of our on-going high-resolution imaging survey of late type brown dwarfs. The survey aims at resolving tight brown dwarf binary systems to better constrain the T dwarf binary fraction. We intent to follow-up the individual binaries to determine orbital parameters. Using NACO at the VLT we performed AO-assisted near-infrared observations of SDSS J2052-1609. High-spatial resolution images of the T1 dwarf were obtained in H and Ks filters. We resolved SDSS J2052-1609 into a binary system with a separation of 0.101" \pm 0.001". Archival data from HST/NICMOS taken one year previous to our observations proves the components to be co-moving. Using the flux ratio between the components we infer J, H and Ks magnitudes for the resolved system. From the near-IR colors we estimate spectral types of T1 +1 -4 and T2.5 \pm 1 for component A and B, respectively. A first estimate of the total system mass yields Mtot > 78 Mjup, assuming a circular orbit.Comment: 5 pages, 3 figures, 3 tables, accepted for publication by A&

Towards the right assistance at the right time for using complex interfaces

Many users struggle when they have to use complex interfaces to complete everyday computing tasks. Offering intelligent, proactive assistance is becoming commonplace yet determining the right time to provide help is still difficult. We conducted an empirical study that aimed to uncover what user factors influenced following advice. Our results describe a user's background and expectations that appear to play a role in heeding assistance. Our work is a step towards understanding how to provide the right assistance at the right time and build proactive assistance systems that are personalized for individual users

Virtues, Resilience, and Well-Being of Indigenous Youth in Peru

Objectives: The objective of this study was to observe the relation of Values In Action (VIA) virtues, well-being, and resilience within a unique, non-Western population of Indigenous youth in the Peruvian Amazon. Methods: Data were collected from students (n = 172, age range: 11-16 years) attending a rural village school via self-report surveys to assess relationships using the VIA Youth-96 (VIA-Y-96) Assessment, Personal Wellbeing Index (PWI-A), and the Child and Youth Resilience Measure (CYRM-28). Results: The factor analysis of the CYRM-28 yielded a 3-factor breakdown (Social Engagement, Cultural Citizenship, and Guidance) instead of eight. Different VIA virtues predicted each of the three factors of the revised 3-factor CYRM-21-Peru model (CYRM-21-P); Transcendence, Humanity, and Wisdom were predictors of well-being; and higher reported resilience leads to higher well-being. Most participants scored very high on the PWI-A. Implications: Research presented in this paper involved a unique population of Indigenous youth residing in the Peruvian Amazon, and found that (a) VIA virtues were differentially associated with well-being, (b) Humanity was a significant predictor across Cultural Citizenship and Social Engagement in the revised CYRM-21-P, and (c) higher resilience was correlated with higher well-being. Implications of this research can be used to inspire future research of Indigenous populations in a Latin American context to develop youth development programs that teach students from a strength-based perspective to improve vocational, academic, psychological, and social well-being

Sampling properties of random graphs: the degree distribution

We discuss two sampling schemes for selecting random subnets from a network: Random sampling and connectivity dependent sampling, and investigate how the degree distribution of a node in the network is affected by the two types of sampling. Here we derive a necessary and sufficient condition that guarantees that the degree distribution of the subnet and the true network belong to the same family of probability distributions. For completely random sampling of nodes we find that this condition is fulfilled by classical random graphs; for the vast majority of networks this condition will, however, not be met. We furthermore discuss the case where the probability of sampling a node depends on the degree of a node and we find that even classical random graphs are no longer closed under this sampling regime. We conclude by relating the results to real {\it E.coli} protein interaction network data.Comment: accepted for publication in Phys.Rev.

Probability Models for Degree Distributions of Protein Interaction Networks

The degree distribution of many biological and technological networks has been described as a power-law distribution. While the degree distribution does not capture all aspects of a network, it has often been suggested that its functional form contains important clues as to underlying evolutionary processes that have shaped the network. Generally, the functional form for the degree distribution has been determined in an ad-hoc fashion, with clear power-law like behaviour often only extending over a limited range of connectivities. Here we apply formal model selection techniques to decide which probability distribution best describes the degree distributions of protein interaction networks. Contrary to previous studies this well defined approach suggests that the degree distribution of many molecular networks is often better described by distributions other than the popular power-law distribution. This, in turn, suggests that simple, if elegant, models may not necessarily help in the quantitative understanding of complex biological processes.