A self-contained quantum harmonic engine

We propose a system made of three quantum harmonic oscillators as a compact quantum engine for producing mechanical work. The three oscillators play respectively the role of the hot bath, the working medium and the cold bath. The working medium performs an Otto cycle during which its frequency is changed and it is sequentially coupled to each of the two other oscillators. As the two environments are finite, the lifetime of the machine is finite and after a number of cycles it stops working and needs to be reset. We analyse the entanglement and quantum discord generated during the strokes and show that high work generation is always accompanied by large quantum correlations.Comment: Updated, published version. See also related but independent work from Pozas-Kerstjens et al. arXiv:1708.0636

New insights into the protective power of platelets in malaria infection

Platelets, as well as regulating blood hemostasis, are an important component of thebody's defense against invading microbial pathogens. We previously reported that platelets protect during malaria infection by binding Plasmodiuminfected erythrocytes (IE) and killing the parasite within. More recent studies have now revealed the platelet plasmocidalfactor, platelet factor 4 (PF4) and the red cell-expressed Duffyantigen molecule as the central players in the parasite killing activity of platelets

Surgeon Involvement in Pre-Clinical Medical Education: Attitudes of Directors of Education

Background: Application rates to surgical residencies have shown a downward trend recently. Introducing students to surgeons early in medical school can increase interest in surgery as a career and enhance the instruction of important surgical topics. Directors of undergraduate medical education have unique insight and influence regarding the participation of surgeons in pre-clinical education. Methods: To understand the attitudes of these educators towards surgeons as teachers in pre-clinical programs, a survey was administered to the directors of undergraduate medical education at each of the English-language medical schools in Canada. Results: Educators estimate the participation of surgeons in all categories of pre-clinical education to be low, despite being valuable, and think that it should be increased. The most significant barrier to participation identified was a lack of surgeons’ time. Conclusions: Despite the value of surgeons participating in pre-clinical education, their rate of participation is low. Steps should be taken to facilitate the involvement of surgeons in this phase of education, which may lead to improved education for students and increased student interest in surgery residencies.

Consumer-Ready Insulated Solar Electric Cooker

An insulated solar electric cooker, or ISEC, converts solar energy into electricity to cook food, boil water, provide heat or even help charge batteries. In this project, the focus is an ISEC with a phase change material (PCM) that helps store heat when the solar energy input is minimal, such as after the sun has set. Although a successful ISEC already exists that utilizes PCM, this product can be improved in many ways. The specific revisions investigated in this report are the improvement of the thermal efficiency with the implementation of a vacuum-sealed outer pot, the reduction of the overall manufacturing costs, and a more user-friendly consumer experience. These revisions can help millions worldwide by providing a safe and inexpensive alternative to biomass fuel cooking which is inefficient and unsafe without proper ventilation. The ISEC can alleviate this problem with an environmentally conscious and easy-to-use solar-powered cooker. The final product is thermally efficient, intuitive to use, and low-cost so that it can be easily manufactured and deployed in its final iteration. There are several areas in which the former ISEC was improved, and the group focused on bolstering these functions to create a highly functional and efficient operating system. This Final Design Report documents the team’s efforts towards designing, manufacturing, and testing a new and improved iteration of the Insulated Solar Electric Cooker

Adaptive sampling strategies for risk-averse stochastic optimization with constraints

We introduce adaptive sampling methods for risk-neutral and risk-averse stochastic programs with deterministic constraints. In particular, we propose a variant of the stochastic projected gradient method where the sample size used to approximate the reduced gradient is determined a posteriori and updated adaptively. We also propose an SQP-type method based on similar adaptive sampling principles. Both methods lead to a significant reduction in cost. Numerical experiments from finance and engineering illustrate the performance and efficacy of the presented algorithms. The methods here are applicable to a broad class of expectation-based risk measures, however, we focus mainly on expected risk and conditional value-at-risk minimization problems

Predicting the locations of possible long-lived low-mass first stars: Importance of satellite dwarf galaxies

The search for metal-free stars has so far been unsuccessful, proving that if there are surviving stars from the first generation, they are rare, they have been polluted, or we have been looking in the wrong place. To predict the likely location of Population~III (Pop~III) survivors, we semi-analytically model early star formation in progenitors of Milky Way-like galaxies and their environments. We base our model on merger trees from the high-resolution dark matter only simulation suite \textit{Caterpillar}. Radiative and chemical feedback are taken into account self-consistently, based on the spatial distribution of the haloes. Our results are consistent with the non-detection of Pop III survivors in the Milky Way today. We find that possible surviving Population III stars are more common in Milky Way satellites than in the main Galaxy. In particular, low mass Milky Way satellites contain a much larger fraction of Pop~III stars than the Milky Way. Such nearby, low mass Milky Way satellites are promising targets for future attempts to find Pop~III survivors, especially for high-resolution, high signal-to-noise spectroscopic observations. We provide the probabilities for finding a Pop~III survivor in the red giant branch phase for all known Milky Way satellites to guide future observations.Comment: 17 pages, 12 figures, 1 table, submitted to MNRA

Einstein's steady-state theory: an abandoned model of the cosmos

We present a translation and analysis of an unpublished manuscript by Albert Einstein in which he attempted to construct a 'steady-state' model of the universe. The manuscript, which appears to have been written in early 1931, demonstrates that Einstein once explored a cosmic model in which the mean density of matter in an expanding universe is maintained constant by the continuous formation of matter from empty space. This model is very different to previously known Einsteinian models of the cosmos (both static and dynamic) but anticipates the later steady-state cosmology of Hoyle, Bondi and Gold in some ways. We find that Einstein's steady-state model contains a fundamental flaw and suggest that it was abandoned for this reason. We also suggest that he declined to explore a more sophisticated version because he found such theories rather contrived. The manuscript is of historical interest because it reveals that Einstein debated between steady-state and evolving models of the cosmos decades before a similar debate took place in the cosmological community.Comment: 22 pages, 2 figures. Includes first English translation of unpublished Einstein manuscript. Accepted for publication in Eur.Phys.J.(H