Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Observation of the Gamma-Ray Binary HESS J0632+057 with the HESS, MAGIC, and VERITAS Telescopes

The results of gamma-ray observations of the binary system HESS J0632 + 057 collected during 450 hr over 15 yr, between 2004 and 2019, are presented. Data taken with the atmospheric Cherenkov telescopes H.E.S.S., MAGIC, and VERITAS at energies above 350 GeV were used together with observations at X-ray energies obtained with Swift-XRT, Chandra, XMM-Newton, NuSTAR, and Suzaku. Some of these observations were accompanied by measurements of the H alpha emission line. A significant detection of the modulation of the very high-energy gamma-ray fluxes with a period of 316.7 +/- 4.4 days is reported, consistent with the period of 317.3 +/- 0.7 days obtained with a refined analysis of X-ray data. The analysis of data from four orbital cycles with dense observational coverage reveals short-timescale variability, with flux-decay timescales of less than 20 days at very high energies. Flux variations observed over a timescale of several years indicate orbit-to-orbit variability. The analysis confirms the previously reported correlation of X-ray and gamma-ray emission from the system at very high significance, but cannot find any correlation of optical H alpha parameters with fluxes at X-ray or gamma-ray energies in simultaneous observations. The key finding is that the emission of HESS J0632 + 057 in the X-ray and gamma-ray energy bands is highly variable on different timescales. The ratio of gamma-ray to X-ray flux shows the equality or even dominance of the gamma-ray energy range. This wealth of new data is interpreted taking into account the insufficient knowledge of the ephemeris of the system, and discussed in the context of results reported on other gamma-ray binary systems

95 GHz ESEEM of radical pairs: a source of radical separations and relative orientations

W-band (95 GHz) electron spin echo envelope modulation (ESEEM) is proposed as a method for simultaneously determining the relative orientation and separation of the constituents of spin-correlated radical pairs in the solid state. The discussion focuses on the transient secondary radical pair in bacterial photosynthetic energy conversion. © 2001 Elsevier Science B.V

To Three or Not to Three?

Empirically estimating managerial performance is often quite challenging. Without accurate measurement of managerial output or value added, it is difficult to usefully analyze the labor market for managers. This paper uses shot selection between two-point and three-point shots to develop a measure of managerial productivity in the National Basketball Association (NBA). We test whether our measure significantly impacts firm (team) output (wins) and whether this managerial productivity measure is significant in explaining labor market outcomes. We show that managerial performance does, in fact, positively impact team performance and also helps explain differences in managerial compensation

Translocations involving 8q24 in Burkitt lymphoma and other malignant lymphomas: a historical review of cytogenetics in the light of todays knowledge

Burkitt lymphoma (BL) has a characteristic clinical presentation, morphology, immunophenotype and primary chromosomal aberration, that is, the translocation t(8;14)(q24;q32) or its variants. However, diagnostic dilemmas may arise in daily practice due to overlap of BL with subsets of other aggressive, mature B-cell lymphomas such as diffuse large B-cell lymphomas (DLBCL). Recently, two gene expression studies have described a distinct molecular profile for BL, but also showed the persistence of some cases intermediate between BL and DLBCL. An alternative approach to define BL is to consider (cyto)genetic data, in particular chromosomal abnormalities other than the t(8;14) or its variants. In this review the 'Mitelman Database of Chromosome Aberrations in Cancer,' harboring the majority of all published neoplasia-related karyotypes, was explored to define a cytogenetic profile of 'true' BL. This core subset of BL showed a very low complexity of chromosomal abnormalities with 40% of the cases having the IG-MYC fusion as the sole abnormality. In the remaining cases, additional recurrent but partially exclusive abnormalities included gains at chromosomes 1q, 7 and 12, and losses of 6q, 13q32-34 and 17p. Within the core subset, no differences were found between pediatric and adult patients. In addition, the genetic profile of the core subset was significantly different from BL with an 8q24 breakpoint not affecting one of the three immunoglobulin loci, BL with a translocation involving 18q21/BCL2, 3q27/BCL6 or 11q13/BCL1, additionally to a breakpoint at 8q24/MYC, and from other morphological types of lymphomas with an 8q24/MYC breakpoint. These groups showed a higher cytogenetic complexity than the core subset of BL. BL without a detectable 8q24/MYC breakpoint might be heterogeneous and deserves further studies. We suggest that, concordant with the WHO classification to be published in 2008, the diagnosis of BL should be restricted to cases with expression of CD10 and BCL6, absence or very weak expression of BCL2 protein, a homogeneously very high proliferation index and a proven IG-MYC translocation without evidence of a chromosomal translocation typical for other lymphoma entities. In addition, a high number of nonspecific cytogenetic abnormalities should suggest need for a critical review of the diagnosis of BL