Discovery of transient high-energy gamma-ray emission from the BL Lacertae object 5C 3.178

We report the serendipitous discovery of transient, point-like high energy gamma-ray emission coincident with the position of the suspected BL Lac object 5C 3.178. The source was detected using the Fermi Large Area Telescope (LAT) at a significance level of ~8 sigma during a 200 day period which began on MJD 55882. The observed gamma-ray emission is characterised by a moderate 0.2-300 GeV flux F(0.2-300 GeV)=$(8.22\pm2.04)\times10^{-9}$ ph cm$^{-2}$s$^{-1}$ and a hard power law spectrum with spectral index $\Gamma=1.76\pm0.09$. These properties appear consistent with the known sub-population of TeV gamma-ray-emitting BL Lac objects, implying that the source may be detectable using atmospheric Cherenkov telescope arrays. Moreover, the temporal variability of the source suggests that real-time searches of the Fermi-LAT all-sky dataset for weak emission on ~200 day timescales may represent a rewarding strategy.Comment: 5 pages, 4 figures. Accepted for publication in Astronomy & Astrophysic

On the timing between terrestrial gamma ray flashes, radio atmospherics, and optical lightning emission

On 25 October 2012 the Reuven Ramaty High Energy Solar Spectroscope Imager (RHESSI) and the Tropical Rainfall Measuring Mission (TRMM) satellites passed over a thunderstorm on the coast of Sri Lanka. RHESSI observed a terrestrial gamma ray flash (TGF) originating from this thunderstorm. Optical measurements of the causative lightning stroke were made by the lightning imaging sensor (LIS) on board TRMM. The World Wide Lightning Location Network (WWLLN) detected the very low frequency (VLF) radio emissions from the lightning stroke. The geolocation from WWLLN, which we also assume is the TGF source location, was in the convective core of the cloud. By using new information about both RHESSI and LIS timing accuracy, we find that the peak in the TGF light curve occurs 230 $\mu$s before the WWLLN time. Analysis of the optical signal from LIS shows that within the uncertainties, we cannot conclude which comes first: the gamma emission or the optical emission. We have also applied the new information about the LIS timing on a previously published event by {\O}stgaard et al. (2012). Also for this event we are not able to conclude which signal comes first. More accurate instruments are needed in order to get the exact timing between the TGF and the optical signal

OLS data system/global survey of lightning

A global lightning climatology is being assembled from the nighttime imagery of the DMSP Optical Linescan Sensor (OLS). Lightning saturates the visible channel of the OLS at nighttime and can be identified as a horizontal streak on the order of 50-100 km in horizontal extent. Lightning streaks apparent in the film strips located at the National Snow and Ice Data Center (NSIDC) prior to 1991 are being digitized. An initial survey was completed for the F7 satellite observation period January 1986 - October 1987 and for the Q satellite for the period June-July 1973. Comparisons between the OLS lightning climatology with the Arkin GPI data set during the 1986-87 El Nino event shows similar regional variations in convective activity. The digital archive of global DMSP data began at the end of February. Software is being developed at both MSFC and NSIDC to extract, navigate, and view the OLS fine and smooth imagery

Lightning Imaging Sensor (LIS) for the Earth Observing System

Not only are scientific objectives and instrument characteristics given of a calibrated optical LIS for the EOS but also for the Tropical Rainfall Measuring Mission (TRMM) which was designed to acquire and study the distribution and variability of total lightning on a global basis. The LIS can be traced to a lightning mapper sensor planned for flight on the GOES meteorological satellites. The LIS consists of a staring imager optimized to detect and locate lightning. The LIS will detect and locate lightning with storm scale resolution (i.e., 5 to 10 km) over a large region of the Earth's surface along the orbital track of the satellite, mark the time of occurrence of the lightning, and measure the radiant energy. The LIS will have a nearly uniform 90 pct. detection efficiency within the area viewed by the sensor, and will detect intracloud and cloud-to-ground discharges during day and night conditions. Also, the LIS will monitor individual storms and storm systems long enough to obtain a measure of the lightning flashing rate when they are within the field of view of the LIS. The LIS attributes include low cost, low weight and power, low data rate, and important science. The LIS will study the hydrological cycle, general circulation and sea surface temperature variations, along with examinations of the electrical coupling of thunderstorms with the ionosphere and magnetosphere, and observations and modeling of the global electric circuit

The off-line programming of a PC based industrial robot with sensory feedback (volume I of II)

The need for sensor-based automatic motion planning and control of industrial robots in an unstructured environment is extensive. For example in-factory transportation, household chores, military applications, chemical, radioactive, and other applications dangerous to humans. Researchers are attempting to build systems capable of generating purposeful motion in highly uncertain co-nplex environments, using on-line information from robot sensors. An example of such a task would be moving a mobile robot or a manipulator arm from its starting position to a goal position in a scene with unknown arbitrarily shaped obstacles. Carrying out such tasks requires, first, sensors and relatedGR201

Facing the next public health emergency: How do we know how (un)prepared we are?

In the realm of political preparedness, numerous benchmarks, metrics, and best practice models have emerged as integral sites in the ongoing debate. Taking the Global Health Security Index as a specific example, this paper delves into the advantages and disadvantages of such global security rankings. This analysis aims to explore the potential uses and drawbacks of employing metrics to evaluate and modify (inter-)national preparedness plans. Situating this discussion within the broader context of the escalating significance of crisis preparedness and management, particularly in the face of acute disruptions to vital infrastructures and the immense costs they entail, as well as their adverse impact on public health and societal safety. However, the findings of this analysis reveal a notable political and strategic risk associated with an excessive reliance on these metrics. It is important to recognize that these metrics not only rely on robust scientific methodologies but also rest upon selective assumptions about the world and the definition of threats. The case of the Global Health Security Index serves as an example, as the assumptions underpinning these metrics have proven inaccurate in the face of an actual pandemic. Consequently, overconfidence and misguided approaches to crisis preparedness have ensued. Additionally, this work offers a concise historical overview of preparedness thinking, outlines the field of Global Health Security, presents the existing metrics employed, and critically reflects on these tools. While metrics provide valuable insights, they should be approached with caution and an awareness of their limitations. By adopting a critical lens and recognizing the political dimensions inherent in these metrics, policymakers can make more informed decisions and develop more effective preparedness plans in an ever-evolving world of crises

A uniform bijection between nonnesting and noncrossing partitions

In 2007, D.I. Panyushev defined a remarkable map on the set of nonnesting partitions (antichains in the root poset of a finite Weyl group). In this paper we use Panyushev's map, together with the well-known Kreweras complement, to construct a bijection between nonnesting and noncrossing partitions. Our map is defined uniformly for all root systems, using a recursion in which the map is assumed to be defined already for all parabolic subsystems. Unfortunately, the proof that our map is well defined, and is a bijection, is case-by-case, using a computer in the exceptional types. Fortunately, the proof involves new and interesting combinatorics in the classical types. As consequences, we prove several conjectural properties of the Panyushev map, and we prove two cyclic sieving phenomena conjectured by D. Bessis and V. Reiner