A Search for Binary Stars at Low Metallicity

We present initial results measuring the companion fraction of metal-poor stars ([Fe/H]$<-$2.0). We are employing the Lick Observatory planet-finding system to make high-precision Doppler observations of these objects. The binary fraction of metal-poor stars provides important constraints on star formation in the early Galaxy (Carney et al. 2003). Although it has been shown that a majority of solar metallicity stars are in binaries, it is not clear if this is the case for metal-poor stars. Is there a metallicity floor below which binary systems do not form or become rare? To test this we are determining binary fractions at metallicities below [Fe/H]$=-2.0$. Our measurments are not as precise as the planet finders', but we are still finding errors of only 50 to 300 m/s, depending on the signal-to-noise of a spectrum and stellar atmosphere of the star. At this precision we can be much more complete than previous studies in our search for stellar companions.Comment: To appear in conference proceedings,"First Stars III", eds. B. O'Shea, A. Heger & T. Abel. 3 pages, 5 figure

O(N) symmetry-breaking quantum quench: Topological defects versus quasiparticles

We present an analytical derivation of the winding number counting topological defects created by an O(N) symmetry-breaking quantum quench in N spatial dimensions. Our approach is universal in the sense that we do not employ any approximations apart from the large-$N$ limit. The final result is nonperturbative in N, i.e., it cannot be obtained by %the usual an expansion in 1/N, and we obtain far less topological defects than quasiparticle excitations, in sharp distinction to previous, low-dimensional investigations.Comment: 6 pages of RevTex4-1, 1 figure; to be published in Physical Review

Effect of fluctuations on the superfluid-supersolid phase transition on the lattice

We derive a controlled expansion into mean field plus fluctuations for the extended Bose-Hubbard model, involving interactions with many neighbors on an arbitrary periodic lattice, and study the superfluid-supersolid phase transition. Near the critical point, the impact of (thermal and quantum) fluctuations on top of the mean field grows, which entails striking effects, such as negative superfluid densities and thermodynamical instability of the superfluid phase -- earlier as expected from mean-field dynamics. We also predict the existence of long-lived "supercooled" states with anomalously large quantum fluctuations.Comment: 5 pages of RevTex4; as published in Physical Review

Teaching responsible conduct responsibly.

The advancement of science requires trust – trust in the literature, in our collaborators, in the data we are handed, and most of all in ourselves. Policies issued by U.S. federal funding agencies (e.g., the National Institutes of Health and National Science Foundation) have been valuable in prompting institutions to initiate formal mechanisms for providing instruction in the responsible conduct of research (RCR). However, the guidelines vary greatly in scope, detail, and the types of individuals to which they apply. Unfortunately, at many institutions, the provision of RCR instruction has become a bureaucratic exercise aimed at fulfilling a regulatory requirement, instead of an activity optimized for promoting a climate of integrity. We argue that for RCR instruction to be effective it should (1) be provided to everyone involved in the research enterprise, be they students, trainees, faculty, or staff, (2) be infused throughout one’s time at an institution. For graduate students, that would include from orientation to thesis completion, including integration into all “core classes” within their discipline, as well as into discussions at research group meetings. (3) We also advocate that the bulk of the instruction should be provided primarily by active researchers who know the issues and have relevance to, and credibly with, those being taught, and (4) that the instruction actively engages the learners. Not only will we be providing RCR instruction in a much more optimized manner, such an approach also emphasizes through our actions, not just in words, that behaving responsibly is an essential skill for researchers

Exploring Cooperation with Social Machines

As humans become more and more immersed in a networked world of connected and mobile devices, cooperation and sociability to achieve valued outcomes within geographic locales appears to be waning in favour of extended personal networks and interaction using semi-automated agents to support communications, transportation and other services. From a messaging structure that is complex, multiplexed and much of the time asynchronous, conditions emerge that disrupt symmetry of information exchange. People thus encounter circumstances that seem unpredictable given the information available to them, resulting in limited or failed cooperation and consequent quality of outcomes. We explore the role of Social Machines to support, change, and enhance human cooperation within a blended reality context

New Technologies and Mixed-Use Convergence How Humans and Algorithms are Adapting to Each Other

Human experience with technology has shifted from technological contexts requiring occasional intervention by a fraction of people mostly in command of technologies, to technological contexts that require constant ongoing participation from most people to complete tasks. We examine the current state of `mixed-use' new technologies integration with legacy systems, and whether the human assistance required to complete tasks and processes could function as a training ground for future smart systems, or whether increasing `co-dependence with' or `training of' algorithmic systems, enhancing task completion and inadvertently educating systems in human behaviour and intelligence, will simply subsume people into the algorithmic landscape. As the Internet of Things (IoT) arises in conjunction with advancing robotics and drone technology, semi and fully automated algorithmic systems are being developed that intersect with human experience in new and heterogeneous ways. Many new technologies are not yet flexible enough to support the choices people require in their daily lives, due to limitations in the algorithmic `logics' used that restrict options to predetermined pathways conceived of by programmers. This greatly limits human agency, and presently the potential to overcome problems that arise in processes. In this mixed-use period, we have the opportunity to develop new ways to address ethical guidance as knowledge that machines can learn. We explore promoting embedding of ethically-based principles into automated contexts through: (1) developing mutually agreed automated external ethical review systems (human or otherwise) that evaluate conformance across multiple ethical codes and provide feedback to designers, agents, and users on the distribution of conformance; (2) focusing on review systems to drive distributed development of embedded ethical principles in individual services by responding to this feedback to develop ongoing correction through dynamic adaption or incremental releases; and (3) using multi-agent simulation tools to forecast scenarios in real time

Bogoliubov theory of quantum correlations in the time-dependent Bose-Hubbard model

By means of an adapted mean-field expansion for large fillings $n\gg1$, we study the evolution of quantum fluctuations in the time-dependent Bose-Hubbard model, starting in the superfluid state and approaching the Mott phase by decreasing the tunneling rate or increasing the interaction strength in time. For experimentally relevant cases, we derive analytical results for the temporal behavior of the number and phase fluctuations, respectively. This allows us to calculate the growth of the quantum depletion and the decay of off-diagonal long-range order. We estimate the conditions for the observability of the time dependence in the correlation functions in the experimental setups with external trapping present. Finally, we discuss the analogy to quantum effects in the early universe during the inflationary epoch.Comment: 11 pages of RevTex4, 2 figures; significantly extended, with several analytically solvable cases added, to appear in Physical Review

Thing Theory: Connecting Humans to Smart Healthcare

Healthcare providers will enter location-aware smart environments with the expectation that their devices will integrate, their location will be incorporated, and the environment that they are within will specifically respond to their needs, as well as to the needs of their patients. Cooperation and coordination in complex environments requires people to have access to appropriate contextually sensitive information, some of which must be shared between them. To plan and design effective location-aware smart environments for healthcare, tools are required for integrating and responding to human needs and anticipating human intents and desires. A location-aware healthcare smart environment is another layer within this already highly heterogeneous system of communication. Each component in a location-aware smart environment network can generate data and send messages that must be processed, understood and responded to in some manner. In a healthcare environment, well placed software agents can help manage critical messages shared between sensors, low level software agents and the people who act on this information, improving care for patients and outcomes for providers. The authors’ propose a framework based on the agency of both humans and environmental components: Thing Theory, a logic-based agent framework that evolves discussion on how to connect humans to a healthcare environment designed to function for their benefit

Toward a Climate of Scientific Integrity

A review of the new edition of Macrina's "Scientific integrity: Text and cases in responsible conduct of research" highlights the continuing need for teaching ethical guidelines to young researchers