Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run

Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo's third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours-months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets. © 2022. The Author(s). Published by the American Astronomical Society

Element Distribution in the Silicomanganese Production Process

A pilot scale, silicomanganese alloy production campaign was performed in a 440 kVA, single phase electric furnace in order to establish an overview of the minor- and trace element contents in process input raw materials and their distribution in the resulting primary and secondary products. Samples of the in-going raw materials (manganese ore, coke, quartzite, and high carbon ferromanganese slag) and the out-going products (silicomanganese alloy, silicomanganese slag, and dust) were analyzed by inductively coupled plasma mass spectrometry. The distribution of 51 elements between the product phases was discussed in terms of their boiling temperatures, Gibbs energies of oxidation and activity coefficients of elements in the metal. A thermochemical simulation using the thermochemical software FactSage 7.1 was also carried out in order to model element phase distribution between the alloy, slag, and dust/gas. The correlation between the model and experimental element concentrations in the silicomanganese slag and dust is fair for most elements. However, in the metal phase, fewer elements show good correlation between modeled results and measured experimental concentrations. The discrepancy could be explained by a lack of accurate thermodynamic descriptions for several minor species in the database

The coordination of heart and gill rhythms in \u3cem\u3eLimulus\u3c/em\u3e

WhenLimulus is exposed to hypoxia both heart rate and ventilation rate decrease together (Fig. 1, Fig. 2A). Hypoxia ultimately leads to cessation of ventilation and concomitant bradycardia. When oxygen is reintroduced into an oxygen free aquarium ventilation resumes rapidly, with a parallel increase in heart rate (Fig. 1, Fig. 2B). Covariation of heart and gill activity similar to that in hypoxia experiments also occurs during the normal respiratory behavior patterns ofLimulus, such as intermittent ventilation, swimming, hyperventilation and gill cleaning. The covariation of heart and ventilation rates is especially evident during transitions of intermittent ventilation (alternating periods of apnea and ventilation, Fig. 3). Covariation is also evident during the large increases in ventilation frequency which occur during hyperventilation and swimming (Fig. 4). Gill cleaning is a centrally determined motor sequence which consists of rhythmic flicking of the inner lobes of a gill plate between the book gill lamellae of the plate on the opposite side. During this behavior there is a marked slowing of the heart rate which is at least as great as the decrease in rate seen during periods of apnea (Figs. 5 and 6). Changes in heart rate associated with ventilatory activity do not appear to be caused by the metabolic demand resulting from such activity (Fig. 7). In addition to frequency covariation of the heart and ventilation rates, there can also be phase coordination of the two rhythms. When the two are close to the same frequency or to harmonic frequencies, the heart often maintains a phase preference with respect to the concurrent gill interval over a considerable period of time (Fig. 8). These results suggest that there are common tonic inputs to both the cardiac ganglion and the central pattern generators for the various ventilatory behaviors, which modulate the frequencies of both simultaneously. Both the frequency covariation and phase communication between the two systems may serve to increase the efficiency of the respiratory-circulatory interactions