Information geometric complexity of a trivariate Gaussian statistical model

We evaluate the information geometric complexity of entropic motion on low-dimensional Gaussian statistical manifolds in order to quantify how difficult is making macroscopic predictions about a systems in the presence of limited information. Specifically, we observe that the complexity of such entropic inferences not only depends on the amount of available pieces of information but also on the manner in which such pieces are correlated. Finally, we uncover that for certain correlational structures, the impossibility of reaching the most favorable configuration from an entropic inference viewpoint, seems to lead to an information geometric analog of the well-known frustration effect that occurs in statistical physics.Comment: 16 pages, 1 figur

Information geometric methods for complexity

Research on the use of information geometry (IG) in modern physics has witnessed significant advances recently. In this review article, we report on the utilization of IG methods to define measures of complexity in both classical and, whenever available, quantum physical settings. A paradigmatic example of a dramatic change in complexity is given by phase transitions (PTs). Hence we review both global and local aspects of PTs described in terms of the scalar curvature of the parameter manifold and the components of the metric tensor, respectively. We also report on the behavior of geodesic paths on the parameter manifold used to gain insight into the dynamics of PTs. Going further, we survey measures of complexity arising in the geometric framework. In particular, we quantify complexity of networks in terms of the Riemannian volume of the parameter space of a statistical manifold associated with a given network. We are also concerned with complexity measures that account for the interactions of a given number of parts of a system that cannot be described in terms of a smaller number of parts of the system. Finally, we investigate complexity measures of entropic motion on curved statistical manifolds that arise from a probabilistic description of physical systems in the presence of limited information. The Kullback-Leibler divergence, the distance to an exponential family and volumes of curved parameter manifolds, are examples of essential IG notions exploited in our discussion of complexity. We conclude by discussing strengths, limits, and possible future applications of IG methods to the physics of complexity.Comment: review article, 60 pages, no figure

Catching homologies by geometric entropy

A geometric entropy is defined as the Riemannian volume of the parameter space of a statistical manifold associated with a given network. As such it can be a good candidate for measuring networks complexity. Here we investigate its ability to single out topological features of networks proceeding in a bottom-up manner: first we consider small size networks by analytical methods and then large size networks by numerical techniques. Two different classes of networks, the random graphs and the scale--free networks, are investigated computing their Betti numbers and then showing the capability of geometric entropy of detecting homologies.Comment: 12 pages, 2 Figure

Relativistic Charged Spheres II: Regularity and Stability

We present new results concerning the existence of static, electrically charged, perfect fluid spheres that have a regular interior and are arbitrarily close to a maximally charged black-hole state. These configurations are described by exact solutions of Einstein's field equations. A family of these solutions had already be found (de Felice et al., 1995) but here we generalize that result to cases with different charge distribution within the spheres and show, in an appropriate parameter space, that the set of such physically reasonable solutions has a non zero measure. We also perform a perturbation analysis and identify the solutions which are stable against adiabatic radial perturbations. We then suggest that the stable configurations can be considered as classic models of charged particles. Finally our results are used to show that a conjecture of Kristiansson et al. (1998) is incorrect.Comment: revtex, 13 pages. five EPS figures. Accepted by CQ

Strains and Jets in Black Hole Fields

We study the behaviour of an initially spherical bunch of particles emitted along trajectories parallel to the symmetry axis of a Kerr black hole. We show that, under suitable conditions, curvature and inertial strains compete to generate jet-like structures.Comment: To appear in the Proceedings of the Spanish Relativity Meeting 2007 held in Tenerife (Spain) 3 Figure

Tracing a relativistic Milky Way within the RAMOD measurement protocol

Advancement in astronomical observations and technical instrumentation implies taking into account the general relativistic effects due the gravitational fields encountered by the light while propagating from the star to the observer. Therefore, data exploitation for Gaia-like space astrometric mission (ESA, launch 2013) requires a fully relativistic interpretation of the inverse ray-tracing problem, namely the development of a highly accurate astrometric models in accordance with the geometrical environment affecting light propagation itself and the precepts of the theory of measurement. This could open a new rendition of the stellar distances and proper motions, or even an alternative detection perspective of many subtle relativistic effects suffered by light while it is propagating and subsequently recorded in the physical measurements.Comment: Proceeding for "Relativity and Gravitation, 100 Years after Einstein in Prague" to be published by Edition Open Access, revised versio

The Privilege and the Challenge: Storytelling and the Doctoral Experience

Paper presented at the 45th annual meeting of the New England Educational Research Organization (NEERO), April 17-19, 2013, Portsmouth, NH

A TDDFT study of the excited states of DNA bases and their assemblies

We present a detailed study of the optical absorption spectra of DNA bases and base pairs, carried out by means of time dependent density functional theory. The spectra for the isolated bases are compared to available theoretical and experimental data and used to assess the accuracy of the method and the quality of the exchange-correlation functional: Our approach turns out to be a reliable tool to describe the response of the nucleobases. Furthermore, we analyze in detail the impact of hydrogen bonding and $\pi$-stacking in the calculated spectra for both Watson-Crick base pairs and Watson-Crick stacked assemblies. We show that the reduction of the UV absorption intensity (hypochromicity) for light polarized along the base-pair plane depends strongly on the type of interaction. For light polarized perpendicular to the basal plane, the hypochromicity effect is reduced, but another characteristic is found, namely a blue shift of the optical spectrum of the base-assembly compared to that of the isolated bases. The use of optical tools as fingerprints for the characterization of the structure (and type of interaction) is extensively discussed.Comment: 31 pages, 8 figure

Conducting Focus Groups with College Students: Strategies to Ensure Success

Institutional researchers are often asked to conduct focus groups as an efficient way to address an institutional concern or problem. Typically, IR professionals depend on external consultants and specialists to conduct these group interviews for them; however, due to recent resource constraints (staffing, budgets), they are increasingly assuming responsibility for conducting the focus group sessions themselves. Institutional researchers require specialized skills in order to engage college students in this type of group interviewing; college students present specific characteristics and preferences that require careful consideration. Numerous research studies have used focus groups to support or augment research on college students (Breen, 2006; Diambra, McClam, Fuss, Burton, & Fudge, 2009; Kicklighter, Koonce, Rosenbloom, & Commander, 2010; Naylor, Stoffel, & Van Der Laan, 2008; Ouimet, Bunnage, Carini, Kuh, & Kennedy, 2004; Raby, 2007, 2010; Wellington, 2010; Williams, Bonnell, & Stoffel, 2009), spanning the areas of student satisfaction, assessment of student learning and support services, and program evaluation (Astin, 1993). As student research programs continue to expand and support campus decision-making, it is important that practitioners develop the necessary skills to effectively plan and conduct focus groups with college students. While some researchers have discussed the challenges of conducting focus groups with children and teens (Morgan, Gibbs, Maxwell, & Britten, 2002; Raby, 2010), few studies highlight the methods required to work effectively with college students. This paper is intended to assist practitioners by recommending practical interviewing strategies, with particular emphasis on the opportunities and challenges encountered when working with this unique population

Measuring College Student Satisfaction: A Multi-Year Study of the Factors Leading to Persistence

Using Tinto\u27s (1987) social integration theory as a framework, this study measured student satisfaction in six transformative areas: educational experience, skills development, faculty interaction, personal growth, sense of community, and overall expectations. Emerging as a strategic planning process priority, this project sought to identify those areas where students succeeded or were at risk. Employing a three-phase mixed methods approach, this descriptive, longitudinal study was conducted from 1990-2004 at a highly selective specialized college and assisted college administrators in developing or modifying programs that would enhance student satisfaction to ensure degree completion