Achieving mouse-level strategic evasion performance using real-time computational planning

Planning is an extraordinary ability in which the brain imagines and then enacts evaluated possible futures. Using traditional planning models, computer scientists have attempted to replicate this capacity with some level of success but ultimately face a reoccurring limitation: as the plan grows in steps, the number of different possible futures makes it intractable to determine the right sequence of actions to reach a goal state. Based on prior theoretical work on how the ecology of an animal governs the value of spatial planning, we developed a more efficient biologically-inspired planning algorithm, TLPPO. This algorithm allows us to achieve mouselevel predator evasion performance with orders of magnitude less computation than a widespread algorithm for planning in the situations of partial observability that typify predator-prey interactions. We compared the performance of a real-time agent using TLPPO against the performance of live mice, all tasked with evading a robot predator. We anticipate these results will be helpful to planning algorithm users and developers, as well as to areas of neuroscience where robot-animal interaction can provide a useful approach to studying the basis of complex behaviors.Comment: 6 pages, 4 figures, ICRA 202

Direct measurement of a proton beam passing through a water target by the induced change in the water conductivity

A water target for use in a neutrino experiment at the Los Alamos Meson Physics Facility was constructed with monitors to measure the transient change in water conductivity induced by the passage of the proton beam. This novel monitoring technique permitted a direct measure of the 800-MeV incident proton beam inside the target and gave a measure of the beam alignment. The conductivity persisted over many milliseconds and exhibited an exponential time decay after the beam pulse ended with a characteristic time constant consistent with the production and recombination of OH/sup -/ and H/sub 3/O/sup +/ ions in the water. Though the concentration of these ions was observed to increase linearly with the incident proton current, when compared to the formation of ion-pairs by direct energy loss of the incident protons, the process producing the more stable conduction ions observed in this experiment was found to be many orders of magnitude less efficient. The cause of this inefficiency is not understood, but suggests one or more intermediate processes are involved in their production

A CW-pion focusing horn for low-energy muon neutrino beams

Low-energy muon neutrino beams can be produced from pion decays in-flight at high-intensity accelerators, such as the Los Alamos Meson Physics Facility (LAMPF), providing a new tool to study the role of the weak interaction in nuclear and particle physics. Employing a pion focusing device can enhance the neutrino flux by large factors, and reduce backgrounds by sign-selection of the parent pions. However, LAMPF's long beam pulse and high repetition rate makes it impractical to use pulsed horns like those found at high-energy accelerators. In this paper we discuss a CW-pion focusing device that uses coils wound inside vanes mounted radially around the beam axis to provide an azimuthal field. From our studies with a prototype magnet, we have found the optimum field configuration needed to focus pions at LAMPF energies can be obtained by adjusting the radial density of turns in the coils. This optimum yields an eight-fold increase in neutrino flux above the muon threshold over the bare-target case. Our calculations also indicate a correlation between the arrival time of the neutrinos in the detector and their energy

Periodicities in an active region correlated with Type III radio bursts observed by Parker Solar Probe

Context. Periodicities have frequently been reported across many wavelengths in the solar corona. Correlated periods of ~5 minutes, comparable to solar p-modes, are suggestive of coupling between the photosphere and the corona. Aims. Our study investigates whether there are correlations in the periodic behavior of Type III radio bursts, indicative of non-thermal electron acceleration processes, and coronal EUV emission, assessing heating and cooling, in an active region when there are no large flares. Methods. We use coordinated observations of Type III radio bursts from the FIELDS instrument on Parker Solar Probe (PSP), of extreme ultraviolet emissions by the Solar Dynamics Observatory (SDO)/AIA and white light observations by SDO/HMI, and of solar flare x-rays by Nuclear Spectroscopic Telescope Array (NuSTAR) on April 12, 2019. Several methods for assessing periodicities are utilized and compared to validate periods obtained. Results. Periodicities of about 5 minutes in the EUV in several areas of an active region are well correlated with the repetition rate of the Type III radio bursts observed on both PSP and Wind. Detrended 211A and 171A light curves show periodic profiles in multiple locations, with 171A peaks lagging those seen in 211A. This is suggestive of impulsive events that result in heating and then cooling in the lower corona. NuSTAR x-rays provide evidence for at least one microflare during the interval of Type III bursts, but there is not a one-to-one correspondence between the x-rays and the Type-III bursts. Our study provides evidence for periodic acceleration of non-thermal electrons (required to generate Type III radio bursts) when there were no observable flares either in the x-ray data or the EUV. The acceleration process, therefore, must be associated with small impulsive events, perhaps nanoflares

Dayside response of the magnetosphere to a small shock compression: Van Allen Probes, Magnetospheric MultiScale, and GOES-13.

Observations from Magnetospheric MultiScale (~8 Re) and Van Allen Probes (~5 and 4 Re) show that the initial dayside response to a small interplanetary shock is a double-peaked dawnward electric field, which is distinctly different from the usual bipolar (dawnward and then duskward) signature reported for large shocks. The associated E × B flow is radially inward. The shock compressed the magnetopause to inside 8 Re, as observed by Magnetospheric MultiScale (MMS), with a speed that is comparable to the E × B flow. The magnetopause speed and the E × B speeds were significantly less than the propagation speed of the pulse from MMS to the Van Allen Probes and GOES-13, which is consistent with the MHD fast mode. There were increased fluxes of energetic electrons up to several MeV. Signatures of drift echoes and response to ULF waves also were seen. These observations demonstrate that even very weak shocks can have significant impact on the radiation belts

SN 2009kf : a UV bright type IIP supernova discovered with Pan-STARRS 1 and GALEX

We present photometric and spectroscopic observations of a luminous type IIP Supernova 2009kf discovered by the Pan-STARRS 1 (PS1) survey and detected also by GALEX. The SN shows a plateau in its optical and bolometric light curves, lasting approximately 70 days in the rest frame, with absolute magnitude of M_V = -18.4 mag. The P-Cygni profiles of hydrogen indicate expansion velocities of 9000km/s at 61 days after discovery which is extremely high for a type IIP SN. SN 2009kf is also remarkably bright in the near-ultraviolet (NUV) and shows a slow evolution 10-20 days after optical discovery. The NUV and optical luminosity at these epochs can be modelled with a black-body with a hot effective temperature (T ~16,000 K) and a large radius (R ~1x10^{15} cm). The bright bolometric and NUV luminosity, the lightcurve peak and plateau duration, the high velocities and temperatures suggest that 2009kf is a type IIP SN powered by a larger than normal explosion energy. Recently discovered high-z SNe (0.7 < z < 2.3) have been assumed to be IIn SNe, with the bright UV luminosities due to the interaction of SN ejecta with a dense circumstellar medium (CSM). UV bright SNe similar to SN 2009kf could also account for these high-z events, and its absolute magnitude M_NUV = -21.5 +/- 0.5 mag suggests such SNe could be discovered out to z ~2.5 in the PS1 survey.Comment: Accepted for publication in APJ

Image informatics strategies for deciphering neuronal network connectivity

Brain function relies on an intricate network of highly dynamic neuronal connections that rewires dramatically under the impulse of various external cues and pathological conditions. Among the neuronal structures that show morphologi- cal plasticity are neurites, synapses, dendritic spines and even nuclei. This structural remodelling is directly connected with functional changes such as intercellular com- munication and the associated calcium-bursting behaviour. In vitro cultured neu- ronal networks are valuable models for studying these morpho-functional changes. Owing to the automation and standardisation of both image acquisition and image analysis, it has become possible to extract statistically relevant readout from such networks. Here, we focus on the current state-of-the-art in image informatics that enables quantitative microscopic interrogation of neuronal networks. We describe the major correlates of neuronal connectivity and present workflows for analysing them. Finally, we provide an outlook on the challenges that remain to be addressed, and discuss how imaging algorithms can be extended beyond in vitro imaging studies