\u27Let Me See What I Could Do\u27: Students\u27 Epistemic Affect When Solving Open-Ended, Real-World Problems

This full research paper examines students’ epistemic affect, or their feelings about and within the doing of engineering, when encountering ill-defined problems in two of their first engineering science courses. Ill-defined problems are what students will encounter as professional engineers, but engineering students typically get little practice in their coursework at solving these types of problems. As students explained how they worked their way through the ill-defined and open-ended problems, we found evidence of both positive and negative feelings that arose, as well as descriptions of affective transitions, or shifts from one affect to another. Some of these transitions show evidence that students begin to regulate or anticipate these feelings as a result of repeated exposure to ill-defined problems. This work has implications for including the development of epistemic regulation as part of engineering students\u27 preparation for professional practice

Consideration for Scaffolding Open-Ended Engineering Problems: Instructor Reflections After Three Years

This full research-to-practice paper is a collaboration between researchers and instructors to examine the scaffolding of open-ended problems. Most assigned homework problems are closed-ended with one correct answer and are unlike the ill-defined problems practicing engineers solve in the workplace. To begin bridging this gap, our research team of engineering education researchers and instructors have been designing and implementing ill-defined, open-ended homework problems for the past three years. This study presents instructor reflections on considerations for scaffolding open-ended problems, made after examining survey data from their own students. We present the results in six practices of scaffolding that better support students in their solving of the problems

A Reinvestigation by Circular Dichroism and NMR: Ruthenium(II) and Rhodium(III) Metallointercalators Do Not Bind Cooperatively to DNA

Fast, long-range electron transfer mediated by the DNA helix has been questioned by some researchers citing the possible clustering, or cooperative association, of noncovalently bound donors and acceptors on DNA. A systematic investigation of binding to DNA by the metallointercalators Δ-bis(1,10-phenanthroline)(dipyridophenazine)ruthenium(II) (Ru), Δ-bis(9,10-phenanthrenequinone diimine)(2,2‘-bipyridine)rhodium(III) (Rh), and Δ-bis(9, 10-phenanthrenequinone diimine)(5-(amidoglutaryl)-1,10-phenanthroline)rhodium(III) (Rh‘) using circular dichroism and NMR has shown no evidence for their cooperative clustering on a DNA helix. Circular dichroism (CD) studies of Ru and Rh in [poly(dA-dT)]_2, mixed-sequence calf thymus DNA, and [poly(dG-dC)]_2 as a function of loading indicate that the largest perturbations to the CD signal occur upon initial addition of DNA, with no subsequent systematic variation. Difference spectra of the two metallointercalators bound together versus separately are virtually indistinguishable at high and low loadings. Two-dimensional 1H NMR studies of Ru and Rh‘ binding to a DNA decamer duplex in 90:10 H_2O/D_2O have also been conducted. A more direct structural picture of the site occupancies of these complexes on a DNA helix emerges through examination of the dramatic upfield shifts of the imino protons of the DNA bases that occur upon intercalation. These studies reveal that with both complexes present, each intercalates specifically toward either end of the duplex, with a 4 base pair separation between them. In contrast, the complexes individually bound to the duplex showed low site-selectivity, and preferred more central sites. If anything, these data indicate anti-cooperative binding to the helix, which might be expected based upon electrostatic considerations. Time-resolved measurements of the Ru(II) luminescence reveal substantial subnanosecond quenching (approximately 60%) in the presence of Rh(III). Based upon the NMR results, this quenching must proceed over a distance >14 Å via electron transfer through the DNA π-stack. These experiments with noncovalently bound intercalators are fully consistent with earlier studies of electron transfer through DNA utilizing covalently bound donors and acceptors and definitively prove clustering cannot be responsible for the fast photoinduced electron transfer between metallointercalators mediated by the DNA double helix

A Reinvestigation by Circular Dichroism and NMR: Ruthenium(II) and Rhodium(III) Metallointercalators Do Not Bind Cooperatively to DNA

Fast, long-range electron transfer mediated by the DNA helix has been questioned by some researchers citing the possible clustering, or cooperative association, of noncovalently bound donors and acceptors on DNA. A systematic investigation of binding to DNA by the metallointercalators Δ-bis(1,10-phenanthroline)(dipyridophenazine)ruthenium(II) (Ru), Δ-bis(9,10-phenanthrenequinone diimine)(2,2‘-bipyridine)rhodium(III) (Rh), and Δ-bis(9, 10-phenanthrenequinone diimine)(5-(amidoglutaryl)-1,10-phenanthroline)rhodium(III) (Rh‘) using circular dichroism and NMR has shown no evidence for their cooperative clustering on a DNA helix. Circular dichroism (CD) studies of Ru and Rh in [poly(dA-dT)]_2, mixed-sequence calf thymus DNA, and [poly(dG-dC)]_2 as a function of loading indicate that the largest perturbations to the CD signal occur upon initial addition of DNA, with no subsequent systematic variation. Difference spectra of the two metallointercalators bound together versus separately are virtually indistinguishable at high and low loadings. Two-dimensional 1H NMR studies of Ru and Rh‘ binding to a DNA decamer duplex in 90:10 H_2O/D_2O have also been conducted. A more direct structural picture of the site occupancies of these complexes on a DNA helix emerges through examination of the dramatic upfield shifts of the imino protons of the DNA bases that occur upon intercalation. These studies reveal that with both complexes present, each intercalates specifically toward either end of the duplex, with a 4 base pair separation between them. In contrast, the complexes individually bound to the duplex showed low site-selectivity, and preferred more central sites. If anything, these data indicate anti-cooperative binding to the helix, which might be expected based upon electrostatic considerations. Time-resolved measurements of the Ru(II) luminescence reveal substantial subnanosecond quenching (approximately 60%) in the presence of Rh(III). Based upon the NMR results, this quenching must proceed over a distance >14 Å via electron transfer through the DNA π-stack. These experiments with noncovalently bound intercalators are fully consistent with earlier studies of electron transfer through DNA utilizing covalently bound donors and acceptors and definitively prove clustering cannot be responsible for the fast photoinduced electron transfer between metallointercalators mediated by the DNA double helix

Quantum transport through a DNA wire in a dissipative environment

Electronic transport through DNA wires in the presence of a strong dissipative environment is investigated. We show that new bath-induced electronic states are formed within the bandgap. These states show up in the linear conductance spectrum as a temperature dependent background and lead to a crossover from tunneling to thermal activated behavior with increasing temperature. Depending on the strength of the electron-bath coupling, the conductance at the Fermi level can show a weak exponential or even an algebraic length dependence. Our results suggest a new environmental-induced transport mechanism. This might be relevant for the understanding of molecular conduction experiments in liquid solution, like those recently performed on poly(GC) oligomers in a water buffer (B. Xu et al., Nano Lett 4, 1105 (2004)).Comment: 5 pages, 3 figure

The Role of <i>Roles</i> in Risk Management Change:The Case of an Italian Bank

This paper explores the role of roles (i.e. groups of actors characterised by the same functional tasks within an organisation), and of their interactions, within processes of change in risk management (RM). By combining insights from the literature on RM and from institutional studies, this paper suggests that change in RM can be interpreted as a process that involves both enabling and precipitating dynamics [Greenwood, R., &amp; Hinings, C. R. (1996). Understanding radical organizational change: Bringing together the old and the new institutionalism. The Academy of Management Review, 21, 1022\ue2\u80\u931054. doi:10.5465/AMR.1996.9704071862] between different roles. Aiming to address these dynamics empirically, we rely on a longitudinal case study of an Italian bank. The study shows that the interactions between roles were dependent on their respective specific interests, the different institutional templates they supported, and the shifts in power for control over relevant information. These dynamics both affected and were affected by the change in the template-in-use within the bank and allowed a sort of RM ideal (i.e. the search for more RM) to persist over evolving templates

Vibrational Enhancement of the Effective Donor - Acceptor Coupling

The paper deals with a simple three sites model for charge transfer phenomena in an one-dimensional donor (D) - bridge (B) - acceptor (A) system coupled with vibrational dynamics of the B site. It is found that in a certain range of parameters the vibrational coupling leads to an enhancement of the effective donor - acceptor electronic coupling as a result of the formation of the polaron on the B site. This enhancement of the charge transfer efficiency is maximum at the resonance, where the effective energy of the fluctuating B site coincides with the donor (acceptor) energy.Comment: 5 pages, 3 figure

Vicarious Effort-Based Decision-Making in Autism Spectrum Disorders

This study investigated vicarious effort-based decision-making in 50 adolescents with autism spectrum disorders (ASD) compared to 32 controls using the Effort Expenditure for Rewards Task. Participants made choices to win money for themselves or for another person. When choosing for themselves, the ASD group exhibited relatively similar patterns of effort-based decision-making across reward parameters. However, when choosing for another person, the ASD group demonstrated relatively decreased sensitivity to reward magnitude, particularly in the high magnitude condition. Finally, patterns of responding in the ASD group were related to individual differences in consummatory pleasure capacity. These findings indicate atypical vicarious effort-based decision-making in ASD and more broadly add to the growing body of literature addressing social reward processing deficits in ASD

Green function techniques in the treatment of quantum transport at the molecular scale

The theoretical investigation of charge (and spin) transport at nanometer length scales requires the use of advanced and powerful techniques able to deal with the dynamical properties of the relevant physical systems, to explicitly include out-of-equilibrium situations typical for electrical/heat transport as well as to take into account interaction effects in a systematic way. Equilibrium Green function techniques and their extension to non-equilibrium situations via the Keldysh formalism build one of the pillars of current state-of-the-art approaches to quantum transport which have been implemented in both model Hamiltonian formulations and first-principle methodologies. We offer a tutorial overview of the applications of Green functions to deal with some fundamental aspects of charge transport at the nanoscale, mainly focusing on applications to model Hamiltonian formulations.Comment: Tutorial review, LaTeX, 129 pages, 41 figures, 300 references, submitted to Springer series "Lecture Notes in Physics