Configuration Recognition, Communication Fault Tolerance and Self-reassembly for the CKBot

We present and experimentally verify novel methods for increasing the generality of control, autonomy and reliability for modular robotic systems. In particular, we demonstrate configuration recognition, distributed communication fault tolerance, and the organization and control of self-reassembly with the Connector Kinetic roBot (CKBot). The primary contribution of this work is the presentation and experimental verification of these innovative methods that are general and applicable to other modular robotic systems. We describe our CKBot system and compare it to other similar, state-of-the-art modular robotic systems. Our description and comparison highlights various design developments, features, and notable achievements of these systems. We present work on isomorphic configuration recognition with CKBot. Here, we utilize basic principles from graph theory to create and implement an algorithm on CKBot that automatically recognizes modular robot configurations. In particular, we describe how comparing graph spectra of configuration matrices can be used to find a permutation matrix that maps a given configuration to a known one. If a configuration is matched to one in a library of stored gaits, a permutation mapping is applied and the corresponding coordinated control for locomotion is executed. An implementation of the matching algorithm with small configurations of CKBot configurations that can be rearranged during runtime is presented. We also present work on a distributed fault-tolerance algorithm used to control CKBot configurations. Here, we use a triple modular redundancy approach for CKBot units to collectively vote on observations and execute commands in the presence of infrared (IR) communication failures. In our implementation, we broadcast infrared signals to modules which collaboratively vote on a majority course of action. Various gait selections for a seven module caterpillar and sixteen module quadruped with faulty subsets of IR receivers have been verified to demonstrate the algorithm\u27s robustness. Lastly, we present work on the communication hierarchy and control state machine for the Self-reassembly After Explosion (SAE) robot. Here, we discuss the interaction and integration of the various sensory inputs and control outputs implemented for camera-guided self-reassembly with CKBot. This section describes the overall communication system and reassembly sequence planning after a group of CKBot clusters is kicked apart

Associations of TNFR1 with kidney function outcomes by age, gender, and baseline kidney function status: Data from the Heart and Soul Study.

Tumor necrosis factor receptor type 1 (TNFR1) is associated with kidney disease and mortality risk in various populations [1], [2]. We evaluated associations of TNFR1 with mortality and mediators of this relationship in doi: 10.1016/j.atherosclerosis.2017.05.021. Whether or not these associations are influenced by age, gender, or baseline kidney function are not known. We evaluated associations of TNFR1 levels with measures of kidney function stratifying by these variables. Our outcomes included estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2, albumin to creatinine ratio (ACR) >30 mg/g, and rapid kidney function loss, defined as a change in eGFR of greater than 3% per year

Chandra Observations of SNR 1987A

We report on the results of our monitoring program of the X-ray remnant of supernova 1987A with the {\it Chandra X-Ray Observatory}. We have performed two new observations during the {\it Chandra} Cycle 3 period, bringing the total to six monitoring observations over the past three years. These six observations provide a detailed time history of the birth of a new supernova remnant in X-rays. The high angular resolution images indicate that soft X-ray bright knots are associated with the optical spots, while hard X-ray features are better correlated with radio images. We interpret this in terms of a model in which fast shocks propagating through the circumstellar HII region produce the hard X-ray and radio emission, while the soft X-ray and optical emission arise in slower shocks entering into dense knots in the circumstellar inner ring. New observations begin to show changes in the morphology that may herald a new stage in the development of this incipient supernova remnant. The observed X-ray fluxes increase by nearly a factor of three over the last 30 months. The X-ray remnant is expanding at a velocity of $\sim$5000 km s$^{-1}$.Comment: 8 pages, 6 figures, 2 color figures, To appear in AdSpR (Proceedings 34th COSPAR Synposium E1.4 "High Energy Studies of Supernova Remnants and Neutron stars" For high resolution color figures contact [email protected]

High Resolution X-Ray Spectroscopy of SN 1987A: Monitoring with XMM-Newton

We report the results of our XMM-Newton monitoring of SN 1987A. The ongoing propagation of the supernova blast wave through the inner circumstellar ring caused a drastic increase in X-ray luminosity during the last years, enabling detailed high resolution X-ray spectroscopy with the Reflection Grating Spectrometer. The observations can be used to follow the detailed evolution of the arising supernova remnant. The fluxes and broadening of the numerous emission lines seen in the dispersed spectra provide information on the evolution of the X-ray emitting plasma and its dynamics. These were analyzed in combination with the EPIC-pn spectra, which allow a precise determination of the higher temperature plasma. We modeled individual emission lines and fitted plasma emission models. Especially from the observations between 2003 and 2007 we can see a significant evolution of the plasma parameters and a deceleration of the radial velocity of the lower temperature plasma regions. We found an indication (3-sigma-level) of an iron K feature in the co-added EPIC-pn spectra. The comparison with Chandra grating observations in 2004 yields a clear temporal coherence of the spectral evolution and the sudden deceleration of the expansion velocity seen in X-ray images ~6100 days after the explosion.Comment: 10 pages, 8 Figures; accepted by A&

An Optical and Infrared Photometric Study of the Young Open Cluster IC 1805 in the Giant H II Region W4

We present deep wide-field optical CCD photometry and mid-infrared Spitzer/IRAC and MIPS 24micron data for about 100,000 stars in the young open cluster IC 1805. The members of IC 1805 were selected from their location in the various color-color and color-magnitude diagrams, and the presence of Halpha emission, mid-infrared excess emission, and X-ray emission. The reddening law toward IC 1805 is nearly normal (R_V = 3.05+/-0.06). However, the distance modulus of the cluster is estimated to be 11.9+/-0.2 mag (d = 2.4+/-0.2 kpc) from the reddening-free color-magnitude diagrams, which is larger than the distance to the nearby massive star-forming region W3(OH) measured from the radio VLBA astrometry. We also determined the age of IC 1805 (tau_MSTO = 3.5 Myr). In addition, we critically compared the age and mass scale from two pre-main-sequence evolution models. The initial mass function with a Salpeter-type slope of Gamma = -1.3+/-0.2 was obtained and the total mass of IC 1805 was estimated to be about 2700+/-200 M_sun. Finally, we found our distance determination to be statistically consistent with the Tycho-Gaia Astrometric Solution Data Release 1, within the errors. The proper motion of the B-type stars shows an elongated distribution along the Galactic plane, which could be explained by some of the B-type stars being formed in small clouds dispersed by previous episodes of star formation or supernova explosions.Comment: 45 pages, 32 figures, 9 tables, accepted for publication in ApJ

Inelastic effects in molecular junctions in the Coulomb and Kondo regimes: Nonequilibrium equation-of-motion approach

Inelastic effects in the Coulomb blockade and Kondo regimes of electron transport through molecular junctions are considered within a simple nonequilibrium equation-of-motion (EOM) approach. The scheme is self-consistent, and can qualitatively reproduce the main experimental observations of vibrational features in Coulomb blockade [H.Park et al., Nature 407, 57 (2000)] and Kondo [L.H.Yu et al., Phys. Rev. Lett. 93, 266802 (2004)] regimes. Considerations similar to the equilibrium EOM approach by Meir et al. [Phys. Rev. Lett. 66, 3048 (1991); ibid. 70, 2601 (1993)] are used on the Keldysh contour to account for the nonequilibrium nature of the junction, and dressing by appropriate Franck-Condon (FC) factors is used to account for vibrational features. Results of the equilibrium EOM scheme by Meir et al. are reproduced in the appropriate limit.Comment: 12 pages, 5 figure

Does Positive Psychology Coaching Improve Trainee Well-Being? Evidence from a Longitudinal Professional Development Coaching Program in a Cohort of Pediatric Trainees

Introduction: Trainee burnout is common and evidence supporting the effectiveness of well-being interventions for this population is limited. We studied the effect of a longitudinal coaching program grounded in positive psychology on measures of pediatric trainee well-being. Methods: Pediatric interns and fellows (n = 67) were enrolled in a positive psychology coaching program in 2017-2019. Pediatric faculty (n = 23) underwent training and were paired with trainees outside their field of interest. Trainees were surveyed at the beginning and end of the program to assess burnout and well-being, and key skills necessary to achieve well-being. Results: Thirty-one trainees completed the baseline survey and 30 completed the end of program survey. Professional fulfillment, as measured by the Professional Fulfillment Index, improved after participating in the coaching program (Cohen’s d = 0.33, p = 0.03). On bivariate analysis, ability to cope was positively correlated with gratitude (r = 0.49, p = 0.01), PERMA (r = 0.61, p = 0.001), and self-valuation (r = 0.46, p = 0.01), and negatively correlated with intolerance of uncertainty (r = -0.46, p = 0.01). Burnout was negatively correlated with professional fulfillment (r = -0.65, p \u3c 0.001) and self-valuation (r = -0.75, p \u3c 0.001). There was no deterioration in scores for trainees who participated in the coaching program. Conclusion: Our longitudinal coaching program was associated with improvement in pediatric trainees’ professional fulfillment, identified possible drivers of well-being on bivariate analysis, and may serve as a roadmap for development of well-being curricula. Our findings suggest that well-being is not merely the absence of burnout, and maintenance of well-being during training may be just as critical as improvement

A Map of the Universe

We have produced a new conformal map of the universe illustrating recent discoveries, ranging from Kuiper belt objects in the Solar system, to the galaxies and quasars from the Sloan Digital Sky Survey. This map projection, based on the logarithm map of the complex plane, preserves shapes locally, and yet is able to display the entire range of astronomical scales from the Earth's neighborhood to the cosmic microwave background. The conformal nature of the projection, preserving shapes locally, may be of particular use for analyzing large scale structure. Prominent in the map is a Sloan Great Wall of galaxies 1.37 billion light years long, 80% longer than the Great Wall discovered by Geller and Huchra and therefore the largest observed structure in the universe.Comment: Figure 8, and additional material accessible on the web at: http://www.astro.princeton.edu/~mjuric/universe

Characteristics of Diffuse X-Ray Line Emission within 20 pc of the Galactic Center

Over the last 3 yrs, the Galactic center (GC) region has been monitored with the Chandra X-Ray Observatory. With 11 Chandra observations through 2002 June, the total effective exposure reaches ~590 ks, providing significant photon statistics on the faint, filamentary, diffuse X-ray emission. The true-color X-ray image and the equivalent width (EW) images for the detected elemental species demonstrate that the diffuse X-ray features have a broad range of spatio-spectral properties. Enhancements of the low-ionization-state, or ``neutral'' Fe line emission (E~6.4 keV) to the northeast of Sgr A* can be interpreted as fluorescence within the dense ISM resulting from irradiation by hard, external X-ray sources. They may also be explained by emission induced by the bombardments by high energy particles on the ISM, such as unresolved supernova (SN) ejecta intruding into dense ISM. The detection of molecular cloud counterparts to the 6.4 keV Fe line features indicates that these Fe line features are associated with dense GC clouds and/or active star-forming regions, which supports the X-ray reflection and/or SN ejecta origins for the Fe line emission. We detect highly ionized S and Si lines which are generally coincident with the neutral Fe line emission and the dense molecular clouds in the northeast of Sgr A*. These hot plasmas are likely produced by massive star-forming activities and/or SNRs. In contrast, we find that highly ionized He-like Fe line emission (E~6.7 keV) is primarily distributed along the plane instead of being concentrated in the northeast of Sgr A*. The implied high temperature and the alignment along the plane are consistent with the magnetic confinement model.Comment: 13 pages (ApJ emulator style) including 4 figures (2 color figs). Accepted by ApJ. For full-quality figures, contact [email protected]