Modulation of Majorana-Induced Current Cross-Correlations by Quantum Dots

We study charge transport through a topological superconductor with a pair of Majorana end states, coupled to leads via quantum dots with resonant levels. The non-locality of the Majorana bound states opens the possibility of crossed Andreev reflection with nonlocal shot noise, due to the injection of an electron into one end of the superconductor followed by the emission of a hole at the other end. In the space of energies of the two resonant quantum dot levels, we find a four peaked clover-like pattern for the strength of noise due to crossed Andreev reflection, distinct from the single ellipsoidal peak found in the absence of Majorana bound states.Comment: 4.2 pages, 4 figures + 4.5 pages, 6 figures supplemental materia

Effect of intraband Coulomb repulsion on the excitonic spin-density wave

We present a study of the magnetic ground state of a two-band model with nested electron and hole Fermi surfaces and both interband and intraband Coulomb interactions. Our aim is to understand how the excitonic spin-density-wave (ESDW) state induced by the interband Coulomb repulsion is affected by the intraband interactions. We first determine the magnetic instabilities of our model in an unbiased way by employing the random-phase approximation (RPA) to calculate the static spin susceptibility in the paramagnetic state. From this, we construct the mean-field phase diagram, demonstrating the robustness of the ESDW against the intraband interaction. We then calculate the RPA transverse spin susceptibility in the ESDW state and show that the intraband Coulomb repulsion significantly renormalizes the paramagnon line shape and suppresses the spin-wave velocity. We conclude with a discussion of the relevance of this suppression for the commensurate ESDW state of Mn-doped Cr alloys.Comment: 8 pages, 6 figure

How Does Youth Participatory Eco-Justice Action Research (YPEAR) Affect the Development of Environmental Literacy in Urban High School Students?

The field of environmental education (EE) has the aim of producing an environmentally literate citizenry that is not only aware of environmental problems, but motivated to work towards their solution (Stapp, 1969). However, much of the U.S. EE curricular focus has been on understanding the biophysical environment with rural populations, with little discussion about the environmental problems created by the dominant Western cultural norms (Kenis, & Mathijs, 2012; Malone, 2006; Prakash,1995). This study suggests in order to truly develop environmentally literate citizens who will work to change the oppressive habits of our dominant culture, people must be willing to enter into discourse to understand and be empowered to work towards a solution. As the birthplace of critical pedagogical movements, urban educators have much to offer the field of EE as they have been working to empower marginalized populations in meaningful ways for decades (Anyon, 1980; Freire, 1970; Ladson-Billings, 1994; Ye, Valrelas & Guajardo, 2011). This research study drew from the critical pedagogical movement and examined how the notions of ecopedagogy, empowerment and transformation overlapped to develop environmentally literacy. Specifically, this qualitative exploratory case study provides insight on the impact one urban high school’s three-credit Youth Participatory Eco-justice Action Research (YPEAR) project had on the development of urban students’ environmental literacy. A diverse mix of nineteen urban high school seniors shared their experiences with the YPEAR process through interviews and discussions. After reviewing the curriculum documents and the transcribed student mid-year interviews, alumni exit interviews and student and staff discussions, the data was coded into categories. Through critical reflection on the initial codes and larger blocks of texts, ten themes were discovered. These themes were then used as a foil from which to understand how the notions of ecopedagogy, empowerment and transformation became manifest in the school’s curriculum, students’ YPEAR project, and ultimately supported students’ development of environmental literacy

Importance of ubiquitin-mediated degradation on diacetyl chemosensation in c. elegans

Ubiquitin is a small regulatory protein that can be attached to other proteins in a cell, tagging them for destruction. Ubiquitin plays a critical role in regulating the abundance and activity of many proteins. We examined the role of ubiquitin and the cellular pathway it follows in olfactory neurons in the model organism C. elegans. C. elegans senses and moves towards sources of diacetyl, a volatile compound generated by the bacteria it consumes. This behavior is dependent on the diacetyl receptor, ODR-10. We hypothesized that the ubiquitin-mediated degradation system is involved in the regulation of this sensory receptor. Using transgenic strains with dysfunctional ubquitin-mediated degredation systems in their olfactory neurons, we studied how mutant strains of C. elegans react to diacetyl, and visualized their ODR-10 levels through fluorescence imaging. Our preliminary results suggest that overexpression of ubiquitin is detrimental to the olfactory sensation of diacetyl in C. elegans

Roles of ubiquitin and stress in diacetyl chemosensation of C. elegans

Ubiquitin is a small protein that can be attached to other proteins in a cell, tagging them for destruction. The process of adding ubiquitin to a protein substrate (ubiquitination), and the subsequent trafficking and degradation of this substrate, is a principle regulator of the abundance and activity of many proteins across all forms of life. We are examining the role and dynamics of this regulatory system in the olfactory neurons of the model organism Caenorhabditis elegans, specifically the olfactory receptor protein ODR-10, which allows the worm to detect diacetyl, a volatile compound that is produced by the bacteria the worm eats. Without ODR-10, worms cannot properly perform “chemotaxis”—detection and movement towards food (Bargmann et al., 1996). Bargmann et al., 1996). Methodology: To further characterize how the ubiquitin degradation pathway functions to regulate the worm’s sense of smell and the trafficking of ODR-10, we put worms with ubiquitin pathway mutations under conditions of food stress and compared both their food-seeking behavior and ODR-10 abundance/localization within the AWA neuron to the wild-type strain. The ubiquitin-mediated degradation pathway is known to regulate other cell-surface receptors in neurons (Kowalski et al., 2011), and by testing the diacetyl-sensing ability of worms with mutations in this pathway, we found that abnormal ubiquitination in the ODR-10 expressing neuron (“AWA”) leads to reduced diacetyl detection in the worm (Fig. 1) , suggesting that the ubiquitin pathway is indeed involved in regulating ODR-10 (Fig. 2). To further characterize how the ubiquitin degradation pathway functions to regulate the worm’s sense of smell and the trafficking of ODR-10, we put worms with ubiquitin pathway mutations under conditions of food stress and compared both their food-seeking behavior and ODR-10 abundance/localization within the AWA neuron to the wild-type strain. We found that while little difference in chemotaxis ability is observed between the mutant strains, the fraction of worms with visible ODR-10 fluorescence varies significantly, suggesting that mechanisms besides ubiquitination to regulate olfaction may be at play

Shift in Perspective: Case Study of Motivational Factors in an Online Innovation Community

New product innovations are necessary to attract consumers for companies to survive in the market in the long term in our fast-moving world. One way to gain access to such new creative solutions is through online communities whose members exchange ideas on virtual platforms (Antikainen & Väätäjä, 2010). This explorative research paper investigates the motivational reasons of users who engage themselves on innovation platforms. The aim is to provide practice-oriented design recommendations to support community managers in establishing or improving innovation communities in companies. The improved conditions have a positive influence on the creativity of individual users and thus contribute to the increased innovative power of the entire online community. The study focuses on LEGO Ideas as an example of an online innovation community with members from all over the world. Within the community LEGO models are designed, discussed, re-designed and finally rated by enthusiasts. The best-rated models are then produced as innovative products. The designers of the models receive a share of the sales revenues. The article specifically addresses the following research question: What key factors motivate online community innovators’ engagement? [Aus: Introduction

RUNNING APPROACH VELOCITY AND ENERGY TRANSFORMATION IN DIFFICULT VAULTS IN GYMNASTICS

Introduction: Running approach velocity is the most important phase of energy production in gymnastic vaults. The take-off from a springboard and the push-off from a vaulting horse are phases of energy transformation. Difficult vaults in gymnastics can be characterized by a high and wide second flight phase. In this phase rapid airborne rotations are performed. These difficult saltos demand an appropriate level of translational impulse and angular momentum. Methods: A special measuring system wasused with two 50 Hz video cameras connected by genlock. Running approach velocity was measured with a laser velocity system. Additionally, the vault was recorded with a high speed video system (500 Hz). This setup was applied at the 1997 World Gymnastics Championships in Lausanne. Results: About 300 running approach velocities for different vaults were analyzed. The highest speed was 8.9 m/s in the men’s competition and 7.9 m/s in the women’s competition. The male gymnasts reached approximately 1 m/s higher running approach velocity than female gymnasts. The highest flight was 3 m over the mat. These parameters were measured in handspring vaults. With round off entry vaults (Yurchenko) the running approach velocity and the heights of the second flight phase were slightly lower. Conclusions: The investigations during the 1997 World Gymnastics Championships prove that the greatest difficulties also demand the highest levels of running approach velocity. Concerning the take-off it is interesting to note that after contact with the springboard the knee and hip joints were fixed. Therefore, the take-off from the elastic springboard is more a tension-shortening cycle than a stretchshortening cycle. The first flight phase is very low but with a high level of angular momentum. The transformation index of the energy and angular momentum from the first flight phase to the second flight phase proves that both parameters have decreased. The extensive databases make it possible to recommend training programs for the FIG. In addition to that, recommendations were made for the new point code. This point code will be valid after the 2000 Olympic Games. References: Brueggemann, G.-P. (1994). Biomechanics of Gymnastic Techniques. Sport Science Review, Champaign, 3, 2, 79-120. Komi, P.V. (1992). Stretch-shortening cycle. In Komi, P.V. (Ed.). The encyclopaedia of sports medicine. Vol. III: Strength and power in sport. Oxford, UK: Blackwall Scientific, 169-179. Krug, J. & Noble, L. (1997). Application for Participation in the 1997-98 ISBS Gymnastics Project. Fig. 1: Measuring Syste