KMT-2018-BLG-0748Lb: sub-Saturn microlensing planet orbiting an ultracool host

Aims. We announce the discovery of a microlensing planetary system, in which a sub-Saturn planet is orbiting an ultracool dwarf host. Methods. We detected the planetary system by analyzing the short-timescale (tE ~ 4.4 days) lensing event KMT-2018-BLG-0748. The central part of the light curve exhibits asymmetry due to negative deviations in the rising side and positive deviations in the falling side. Results. We find that the deviations are explained by a binary-lens model with a mass ratio between the lens components of q ~ 2 × 10−3. The short event timescale, together with the small angular Einstein radius, θE ~ 0.11 mas, indicate that the mass of the planet host is very small. The Bayesian analysis conducted under the assumption that the planet frequency is independent of the host mass indicates that the mass of the planet is Mp = 0.18−0.10+0.29 MJ, and the mass of the host, Mh = 0.087−0.047+0.138 M⊙, is near the star–brown dwarf boundary, but the estimated host mass is sensitive to this assumption about the planet hosting probability. High-resolution follow-up observations would lead to revealing the nature of the planet host.

Links between remagnetizations and superchrons. New experiments and new results.

<p>Chemical widespread remagnetizations are especially frequents during superchrons. An interesting issue is whether this relationship is due to especial requirements of the mechanism of acquisition of the remagnetizations and their timing. One example of this type of remagnetizations during a superchron is the one recorded by the Jurassic carbonates from the Central High Atlas (CHA) in Morocco. This normal polarity overprint has been dated ca 100 Ma, comparing the remagnetization direction with the African APWP, i.e. during the Cretaceous Normal Superchron (CNS) and also during the extensional stage of these inverted basins.</p><p>After several paleomagnetic studies performed in this area in the framework of a big research project, paleomagnetic and rock magnetic data from a set of more than 600 paleomagnetic sites distributed over an area of 10000 km2 are available. The CHA cretaceous remagnetization has been observed in all these sites with the same magnetic properties: a viscous paleomagnetic component with maximum unblocking temperatures of 200-250ºC and the remagnetization normal polarity component up to 450–500ºC. Both are carried by authigenic uniaxial SSD magnetite. The paleomagnetic direction calculated by small circle intersection method (SCI) is also similar in the different locations of this wide area.</p><p>The mechanism proposed for this type of widespread remagnetization is the generation of magnetite grains due to the heating related with burial. The homogeneous direction of the remagnetization seems to suggest an acquisition for a short event at 100 Ma. However, the extensional stage of these basins lasts tens of millions years keeping the necessary burial conditions for growth of magnetite grains covering several polarity chrons including the CNS.</p><p>In this work we address the question of timing under with these processes happened, i.e. short vs. long remagnetization periods. We propose the hypothesis that the ca. 100 Ma paleomagnetic direction shows by the remagnetization is just the average of magnetic moments of the entire SSD magnetite population that grow from the Middle Jurassic up to the Cenozoic. Grains block the magnetic moments when they grow above their critical volume, keeping the magnetic polarity generating over time a distribution of grains in normal and reverse polarity groups. To test this hypothesis we develop 1) simulations for the calculation of magnetization directions assuming a homogeneous and constant growth of magnetite crystals and 2) rock magnetic experiments to demonstrate the presence of SSD magnetite grains with opposed magnetic moments. These experiments intend to assess the effectiveness of the SSD grains carrying the remagnetization by comparing the NRM and the ARM signal through the pseudo-Thellier approach.</p>

FPGA Implementation of Weighted Online Sequential Extreme Learning Machine for Data Classification

To design an efficient embedded module field-programmable gate array (FPGA) plays significant role. FPGA, a high speed reconfigurable hardware platform has been used in various field of research to produce the throughput efficiently. A now-a-days artificial neural network (ANN) is the most prevalent classifier for many analytical applications. In this paper, weighted online sequential extreme learning machine (WOS-ELM) classifier is presented and implemented in hardware environment to classify the different real-world bench-mark datasets. The faster learning speed, remarkable classification accuracy, lesser hardware resources, and short-event detection time, aid the hardware implementation of WOS-ELM classifier to design an embedded module. Finally, the developed hardware architecture of the WOS-ELM classifier is implemented on a high speed reconfigurable Xilinx Virtex (ML506) FPGA board to demonstrate the feasibility, effectiveness, and robustness of WOS-ELM classifier to classify the data in real-time environment.

Abnormal Returns or Mismeasured Risk? Network Effects and Risk Spillover in Stock Returns

Recent event study literature has highlighted abnormal stock returns, particularly in short event windows. A common explanation is the cross-correlation of stock returns that are often enhanced during periods of sharp market movements. This suggests the misspecification of the underlying factor model, typically the Fama-French model. By drawing upon recent panel data literature with cross-section dependence, we argue that the Fame-French factor model can be enriched by allowing explicitly for network effects between stock returns. We show that recent empirical work is consistent with the above interpretation, and we advance some hypotheses along which new structural models for stock returns may be developed. Applied to data on stock returns for the 30 Dow Jones Industrial Average (DJIA) stocks, our framework provides exciting new insights.

Actions as a Basis for Online Embodied Concepts

In co-speech gesture research, embodied cognition implies that concepts are associated with haptic and motor information that provides a framework for a gestural plan. When speakers access concepts, embodied action images are automatically activated. This study considers situations in which speakers need to create online concepts of events to investigate the aspect of the event that forms the basis of a new concept. Speakers watched short event video clips with familiar or unfamiliar attributes. They described those clips to partners who had to perform a matching task. Experimental results show that speakers gestured less and produced shorter gestures when relaying longer event descriptions. Speakers were more likely to produce gesture when some aspect of the event was unfamiliar, and they were most sensitive to the familiarity of the event’s main action. Further, when speakers did gesture, they were most likely to gesture to represent the action of the event over the physical attributes of it (the instrument used to enact or the object acted upon). These findings suggest that in creating an embodied concept for something unfamiliar, the motion of the event acts as a basis for their online embodied representation of the concept.

Bulk Lorentz factors of gamma-ray bursts

Knowledge of the bulk Lorentz factor Γ0 of gamma-ray bursts (GRBs) allows us to compute their comoving frame properties shedding light on their physics. Upon collisions with the circumburst matter, the fireball of a GRB starts to decelerate, producing a peak or a break (depending on the circumburst density profile) in the light curve of the afterglow. Considering all bursts with known redshift and with an early coverage of their emission, we find 67 GRBs (including one short event) with a peak in their optical or GeV light curves at a time tp. For another 106 GRBs we set an upper limit tpUL. The measure of tp provides the bulk Lorentz factor Γ0 of the fireball before deceleration. We show that tp is due to the dynamics of the fireball deceleration and not to the passage of a characteristic frequency of the synchrotron spectrum across the optical band. Considering the tp of 66 long GRBs and the 85 most constraining upper limits, we estimate Γ0 or a lower limit Γ0LL. Using censored data analysis methods, we reconstruct the most likely distribution of tp. All tp are larger than the time Tp,γ when the prompt γ-ray emission peaks, and are much larger than the time Tph when the fireball becomes transparent, that is, tp>Tp,γ>Tph. The reconstructed distribution of Γ0 has median value ~300 (150) for a uniform (wind) circumburst density profile. In the comoving frame, long GRBs have typical isotropic energy, luminosity, and peak energy ⟨ Eiso ⟩ = 3(8) × 1050 erg, ⟨ Liso ⟩ = 3(15) × 1047 erg s-1, and ⟨ Epeak ⟩ = 1(2) keV in the homogeneous (wind) case. We confirm that the significant correlations between Γ0 and the rest frame isotropic energy (Eiso), luminosity (Liso), and peak energy (Ep) are not due to selection effects. When combined, they lead to the observed Ep−Eiso and Ep−Liso correlations. Finally, assuming a typical opening angle of 5 degrees, we derive the distribution of the jet baryon loading which is centered around a few 10-6M⊙.

Paleoenvironmental evolution of the Guadiana Estuary, Portugal, during the Holocene: A modern foraminifera analog approach

In this paper, we reconstruct the Holocene paleoenvironmental evolution of the Guadiana Estuary, southwestern Iberian Peninsula. Two previously studied boreholes (CM3 and CM5) were revisited and analyzed in the light of a foraminifera modern analog approach. Cluster analyses define four assemblages with different biocenotic, taphonomic, elevation and distance-to-sea settings, which serve as a baseline for paleoassemblages interpretation. Faunal changes along the sedimentary sequences, together with previous sedimentological and chronological data, redefine the different phases of environmental evolution in the Guadiana Estuary since ca. 13 kyr cal. BP, with special emphasis on the Holocene marine highstand. Estuarine flooding began synchronously in both locations (ca. 9 kyr cal. BP) but manifested differently in each sedimentary sequence. The most seaward borehole records a more evident and longer highstand (ca. 8.8–3.8 kyr cal. BP), characterized by the occurrence of subtidal environments and by the presence of open marine species ( Pararotalia cf. spinigera, planktic forms and a significant number of exotic/allochthonous tests), indicating warmer and more marine conditions than today. In the most landward borehole, the highstand is shorter (ca. 8–7.6 kyr cal. BP) and less intense, characterized by the presence of a diverse, mainly autochthonous, open estuary assemblage, dominated by Ammonia aberdoveyensis and Haynesina germanica. At 4.4 kyr cal. BP, during a long deceleration phase of regional sea-level rise, a short but well-defined pulse of marine influence is recorded in CM5, when open estuarine assemblages reappear and replace marsh agglutinated assemblages, suggesting a new submergence phase. This short event is not identified in the previous works carried out in the same area, thus further data are needed to understand whether it is consequent from a global, warming period or whether it resulted only from local and ephemeral forcing effects.

Stock Market Reactions to Environmental News in the Food Industry

Few studies to date have addressed the relationship between the food industry's environmental and financial performances although the industry is one of the biggest contributors of greenhouse gas emissions. We analyze the impact of environmental news about selected food companies on their stock prices. Results show that positive (negative) events that are the result of direct internal company actions lead to higher (lower) predicted returns, whereas events related to third-party opinions lead to smaller changes in predicted returns in short event windows. This study highlights the importance of conducting the analysis on a disaggregated basis by incorporating firm-level variables.