Optimizing the performance of thermionic devices using energy filtering

Conventional thermionic power generators and refrigerators utilize a barrier in the direction of transport to selectively transmit high-energy electrons. Here we show that the energy spectrum of electrons transmitted in this way is not optimal, and we derive the ideal energy spectrum for operation in the maximum power regime. By using suitable energy filters, such as resonances in quantum dots, the power of thermionic devices can, in principle, be improved by an order of magnitude.Comment: 3 pages, 2 figure

Deoxyribonucleic Acid Synthesis in Ultraviolet-Light-Irradiated Chinese Hamster Cells

Two mammalian cell lines, Chinese hamster ovary (CHO) which can recover colony-forming ability between fractionated doses of ultraviolet light (UV), and Chinese hamster B-14FAF28 which cannot recover, were tested for the ability to bypass UV-induced photoproducts in DNA during postirradiation DNA synthesis. The molecular weight distributions of newly synthesized DNA in UV-irradiated populations of both cell lines showed evidence for photoproduct bypass. Hence, the bypass mechanism does not correlate with recovery after UV

VLT and GTC observations of SDSS J0123+00: a type 2 quasar triggered in a galaxy encounter?

We present long-slit spectroscopy, continuum and [OIII]5007 imaging data obtained with the Very Large Telescope and the Gran Telescopio Canarias of the type 2 quasar SDSS J0123+00 at z=0.399. The quasar lies in a complex, gas-rich environment. It appears to be physically connected by a tidal bridge to another galaxy at a projected distance of ~100 kpc, which suggests this is an interacting system. Ionized gas is detected to a distance of at least ~133 kpc from the nucleus. The nebula has a total extension of ~180 kpc. This is one of the largest ionized nebulae ever detected associated with an active galaxy. Based on the environmental properties, we propose that the origin of the nebula is tidal debris from a galactic encounter, which could as well be the triggering mechanism of the nuclear activity. SDSS J0123+00 demonstrates that giant, luminous ionized nebulae can exist associated with type 2 quasars of low radio luminosities, contrary to expectations based on type 1 quasar studies.Comment: 6 pages, 5 figures. Accepted for publication in MNRAS Letter

Concept study for a high-efficiency nanowire-based thermoelectric

Materials capable of highly efficient, direct thermal-to-electric energy conversion would have substantial economic potential. Theory predicts that thermoelectric efficiencies approaching the Carnot limit can be achieved at low temperatures in one-dimensional conductors that contain an energy filter such as a double-barrier resonant tunneling structure. The recent advances in growth techniques suggest that such devices can now be realized in heterostructured, semiconductor nanowires. Here we propose specific structural parameters for InAs/InP nanowires that may allow the experimental observation of near-Carnot efficient thermoelectric energy conversion in a single nanowire at low temperature

Perceptions of the Impact of Non-contact Boxing on Social and Community Engagement for Individuals with Parkinson’s Disease: A qualitative study

Purpose: To explore the perceptions of individuals with Parkinson’s disease (PD) on their experiences within a community based, non-contact boxing program. Specifically, this study considered how these individuals perceived non-contact boxing to influence their social and community engagement and factors influencing ongoing participation in this program. Method: This was a phenomenological case study that utilized qualitative methods for data collection including semi-structured interviews and observation. Colaizzi’s method was used for data analysis. A convenience sample obtained from a boxing club that offered PD specific boxing classes was used. The sample included 10 participants (3 female, 7 male) ranging in age from 52 to 84 years. Participants typically attended a 75 minute boxing class two to three times per week. Results: The exhaustive description of the phenomenon was that individuals with PD have a strong desire to maintain the life they had prior to their diagnosis and chose activities, such as non-contact boxing, which supported their ability to sustain that lifestyle. Two themes were identified which included 1) “The people I’ve met here and spent time with will be friends forever” and 2) “I don’t have to be Muhammed Ali. It’s not about that.” Conclusions: This study provided a basic understanding of the subjective experiences of individuals with PD who participated in non-contact boxing. Findings demonstrated that non-contact boxing facilitates the growth of supportive relationship for individuals with PD. The study also found that individuals with PD believe non-contact boxing provided a variety of physical, cognitive, and emotional benefits which facilitated their ability to maintain participation in valued activities

The Dopaminergic System in the Aging Brain of Drosophila

Drosophila models of Parkinson's disease are characterized by two principal phenotypes: the specific loss of dopaminergic (DA) neurons in the aging brain and defects in motor behavior. However, an age-related analysis of these baseline parameters in wildtype Drosophila is lacking. Here we analyzed the DA system and motor behavior in aging Drosophila. DA neurons in the adult brain can be grouped into bilateral symmetric clusters, each comprising a stereotypical number of cells. Analysis of TH > mCD8::GFP and cell type-specific MARCM clones revealed that DA neurons show cluster-specific, stereotypical projection patterns with terminal arborization in target regions that represent distinct functional areas of the adult brain. Target areas include the mushroom bodies, involved in memory formation and motivation, and the central complex, involved in the control of motor behavior, indicating that similar to the mammalian brain, DA neurons in the fly brain are involved in the regulation of specific behaviors. Behavioral analysis revealed that Drosophila show an age-related decline in startle-induced locomotion and negative geotaxis. Motion tracking however, revealed that walking activity, and exploration behavior, but not centrophobism increase at late stages of life. Analysis of TH > Dcr2, mCD8::GFP revealed a specific effect of Dcr2 expression on walking activity but not on exploratory or centrophobic behavior, indicating that the siRNA pathway may modulate distinct DA behaviors in Drosophila. Moreover, DA neurons were maintained between early- and late life, as quantified by TH > mCD8::GFP and anti-TH labeling, indicating that adult onset, age-related degeneration of DA neurons does not occur in the aging brain of Drosophila. Taken together, our data establish baseline parameters in Drosophila for the study of Parkinson's disease as well as other disorders affecting DA neurons and movement control

Online, interactive user guidance for high-dimensional, constrained motion planning

We consider the problem of planning a collision-free path for a high-dimensional robot. Specifically, we suggest a planning framework where a motion-planning algorithm can obtain guidance from a user. In contrast to existing approaches that try to speed up planning by incorporating experiences or demonstrations ahead of planning, we suggest to seek user guidance only when the planner identifies that it ceases to make significant progress towards the goal. Guidance is provided in the form of an intermediate configuration $\hat{q}$, which is used to bias the planner to go through $\hat{q}$. We demonstrate our approach for the case where the planning algorithm is Multi-Heuristic A* (MHA*) and the robot is a 34-DOF humanoid. We show that our approach allows to compute highly-constrained paths with little domain knowledge. Without our approach, solving such problems requires carefully-crafting domain-dependent heuristics