Bio-inspired swing leg control for spring-mass robots running on ground with unexpected height disturbance

We proposed three swing leg control policies for spring-mass running robots, inspired by experimental data from our recent collaborative work on ground running birds. Previous investigations suggest that animals may prioritize injury avoidance and/or efficiency as their objective function during running rather than maintaining limit-cycle stability. Therefore, in this study we targeted structural capacity (maximum leg force to avoid damage) and efficiency as the main goals for our control policies, since these objective functions are crucial to reduce motor size and structure weight. Each proposed policy controls the leg angle as a function of time during flight phase such that its objective function during the subsequent stance phase is regulated. The three objective functions that are regulated in the control policies are (i) the leg peak force, (ii) the axial impulse, and (iii) the leg actuator work. It should be noted that each control policy regulates one single objective function. Surprisingly, all three swing leg control policies result in nearly identical subsequent stance phase dynamics. This implies that the implementation of any of the proposed control policies would satisfy both goals (damage avoidance and efficiency) at once. Furthermore, all three control policies require a surprisingly simple leg angle adjustment: leg retraction with constant angular acceleration

Experiences in porting mini-applications to OpenACC and OpenMP on heterogeneous systems

This article studies mini-applications—Minisweep, GenASiS, GPP, and FF—that use computational methods commonly encountered in HPC. We have ported these applications to develop OpenACC and OpenMP versions, and evaluated their performance on Titan (Cray XK7 with K20x GPUs), Cori (Cray XC40 with Intel KNL), Summit (IBM AC922 with Volta GPUs), and Cori-GPU (Cray CS-Storm 500NX with Intel Skylake and Volta GPUs). Our goals are for these new ports to be useful to both application and compiler developers, to document and describe the lessons learned and the methodology to create optimized OpenMP and OpenACC versions, and to provide a description of possible migration paths between the two specifications. Cases where specific directives or code patterns result in improved performance for a given architecture are highlighted. We also include discussions of the functionality and maturity of the latest compilers available on the above platforms with respect to OpenACC or OpenMP implementations

Large Area Crop Inventory Experiment (LACIE). Intensive test site assessment report

There are no author-identified significant results in this report

Spectral Function for the S=1 Heisenberg Antiferromagetic Chain

We study the spectral function, $S(k,\omega)$ for the spin-1, one dimensional antiferromagnetic chain using a time-dependent density matrix renormalizaton group (DMRG) numerical method. We develop methods for extrapolating the time dependent correlation functions to larger times in order to enhance the frequency resolution. The resulting spectral functions are impressively precise and accurate. Our results confirm many qualitative expectations from non-linear $\sigma$ model methods and test them quantitatively. The critical wave-vector at which the single particle excitation emerges from the 2-particle continuum is estimated to be $0.23\pi-0.24\pi$.Comment: 12 pages, 19 fig

State-dependent, addressable subwavelength lattices with cold atoms

We discuss how adiabatic potentials can be used to create addressable lattices on a subwavelength scale, which can be used as a tool for local operations and readout within a lattice substructure, while taking advantage of the faster timescales and higher energy and temperature scales determined by the shorter lattice spacing. For alkaline-earth-like atoms with non-zero nuclear spin, these potentials can be made state dependent, for which we give specific examples with $^{171}$Yb atoms. We discuss in detail the limitations in generating the lattice potentials, in particular non-adiabatic losses, and show that the loss rates can always be made exponentially small by increasing the laser power.Comment: replaced with the published version. 23 pages, 11 figure

A new stall-onset criterion for low speed dynamic-stall

The Beddoes/Leishman dynamic-stall model has become one of the most popular for the provision of unsteady aerofoil data embedded in much larger codes. The underlying modeling philosophy was that it should be based on the best understanding, or description, of the associated physical phenomena. Even though the model was guided by the flow physics, it requires significant empirical inputs in the form of measured coefficients and constants. Beddoes provided these for a Mach number range of 0.3–0.8. This paper considers one such input for a Mach number of 0.12, where, from the Glasgow data, it is shown that the current stall-onset criterion, and subsequent adjustments, yield problematic results. A new stall criterion is proposed and developed in the best traditions of the model. It is shown to be very capable of reconstructing the Glasgow's data for stall onset both the ramp-up and oscillatory tests

Nonequilibrium Current in the One Dimensional Hubbard Model at Half-Filling

Nonlinear transport in the one dimensional Hubbard model at half-filling under a finite bias voltage is investigated by the adaptive time-dependent density matrix renormalization group method. For repulsive on-site interaction, dielectric breakdown of the Mott insulating ground state to a current-carrying nonequilibrium steady state is clearly observed when the voltage exceeds the charge gap. It is found that by increasing the voltage further the current-voltage characteristics are scaled only by the charge gap and the scaling curve exhibits almost linear dependence on the voltage whose slope is suppressed by the electron correlation. In the case of attractive interaction the linear conductance is the perfect one $2e^2/h$ which agrees with the prediction by the Luttinger liquid theory.Comment: 4 pages, 7 figure

What advice are oncologists and surgeons in the United Kingdom giving to breast cancer patients about physical activity?

Evidence has shown that physical activity may attenuate the negative physical, psychological and functional effects of treatment in women diagnosed with breast cancer. Physical activity levels also decline substantially during and after completion of treatment for cancer, highlighting the importance of strategies to promote participation in regular physical activity in this population. Oncologists and surgeons may serve as an influential source of motivation to be physically activity in cancer patients, by conveying the importance of a healthy lifestyle. The primary purpose of the present study was to investigate whether oncologists and surgeons routinely discuss physical activity with their breast cancer patients and to investigate the nature of any information/advice provided during consultations. A secondary aim was to examine whether physically active oncologists and surgeons were more likely to provide advice about physical activity to patients, than inactive oncologists and surgeons. A brief postal questionnaire was sent to 710 consultant breast cancer oncologists and surgeons throughout the UK and 102 responded (response rate = 14.4%). Of responders, most (55.9%) did not routinely discuss physical activity with their patients. Amongst oncologists/surgeons (clinicians) who did offer advice, most focussed on discussing the benefits of physical activity for physical and functional health gains and for facilitating weight control and maintenance. A number of clinicians indicated they advised patients that physical activity may decrease risk of recurrence and improve survival, despite the lack of evidence from RCTs to support this suggestion. There was no significant association between the physical activity status of oncologists/surgeons and the likelihood that they discussed physical activity with patients. Educational strategies aimed at encouraging clinicians to promote physical activity in consultations need to be targeted widely amongst the cancer clinician community

Internet All Nation Breath of life (I-ANBL) a Tribal College Student Engaged Development of an Internet-based Smoking Cessation Intervention

Background: Compared to non-Hispanic white college students, American Indian (AI) tribal college students have the highest smoking prevalence in the U.S. (~34%). Culturally-tailored smoking cessation programs have proven to be successful in reducing smoking rates but may require new methods to reach college students. Currently, there is little documentation on the development and success of Internet-based smoking interventions for AI tribal college students. Objectives: To develop an Internet-based smoking cessation program (Internet-All Nations Breath of Life or I-ANBL) with tribal college students. Methods: We conducted six focus groups (n=41) at a tribal college. Focus groups included tribal college students who smoked and groups were stratified by sex. Transcripts were analyzed using insider and outsider perspectives. After analysis, an Internet-based smoking cessation program was developed, based on insight gained. Results: Numerous suggestions for creating the program were offered. There was consensus on the need for a variety of visuals including cultural images, videos, and interactive content. The students also suggested the integration of familiar platforms such as FacebookTM. Conclusion: When culturally tailoring a web-based smoking cessation program for tribal college students, it is important to incorporate cultural aspects and recognize gender differences. One important aspect is to recognize that for many AI, tobacco is a sacred plant and images of tobacco should be respectful. Now that this intervention has been developed, next we will test it for efficacy in a randomized controlled trial. Keywords: American Indians, tribal college, tobacco, program development, smoking cessation, community-based participatory researc

Transport of interface states in the Heisenberg chain

We demonstrate the transport of interface states in the one-dimensional ferromagnetic Heisenberg model by a time dependent magnetic field. Our analysis is based on the standard Adiabatic Theorem. This is supplemented by a numerical analysis via the recently developed time dependent DMRG method, where we calculate the adiabatic constant as a function of the strength of the magnetic field and the anisotropy of the interaction.Comment: minor revision, final version; 13 pages, 4 figure