The rotation-magnetic field relation

Today, the generation of magnetic fields in solar-type stars and its relation to activity and rotation can coherently be explained, although it is certainly not understood in its entirety. Rotation facilitates the generation of magnetic flux that couples to the stellar wind, slowing down the star. There are still many open questions, particularly at early phases (young age), and at very low mass. It is vexing that rotational braking becomes inefficient at the threshold to fully convective interiors, although no threshold in magnetic activity is seen, and the generation of large scale magnetic fields is still possible for fully convective stars. This article briefly outlines our current understanding of the rotation-magnetic field relation.Comment: 8 pages, splinter summary of the session "The rotation-magnetic field relation" at Cool Stars 15 in St Andrew

pyprop8: A lightweight code to simulate seismic observables in a layered half-space

The package pyprop8 enables calculation of the response of a 1-D layered halfspace to a seismic source, and also derivatives (‘sensitivity kernels’) of the wavefield with respect to source parameters. Seismograms, seismic spectra, and measures of static displacement (e.g. GPS, InSAR and field observations) may all be simulated. The method is based on a ThompsonHaskell propagator matrix algorithm, described in O’Toole & Woodhouse (2011) and O’Toole et al. (2012). The package is entirely written in Python, dependent only on the mainstream libraries numpy (Harris et al., 2020) and scipy (Virtanen et al., 2020). As such, it is lightweight and easy to deploy across a variety of platforms, making it particularly suited to use for teaching and outreach purposes

Automated Seismic Source Characterisation Using Deep Graph Neural Networks

Most seismological analysis methods require knowledge of the geographic location of the stations comprising a seismic network. However, common machine learning tools used in seismology do not account for this spatial information, and so there is an underutilised potential for improving the performance of machine learning models. In this work, we propose a Graph Neural Network (GNN) approach that explicitly incorporates and leverages spatial information for the task of seismic source characterisation (specifically, location and magnitude estimation), based on multi-station waveform recordings. Even using a modestly-sized GNN, we achieve model prediction accuracy that outperforms methods that are agnostic to station locations. Moreover, the proposed method is flexible to the number of seismic stations included in the analysis, and is invariant to the order in which the stations are arranged, which opens up new applications in the automation of seismological tasks and in earthquake early warning systems

We Drink Good 4.5-Billion-Year-Old Water

Water is crucial for the emergence and evolution of life on Earth. Recent studies of the water content in early forming planetary systems similar to our own show that water is an abundant and ubiquitous molecule, initially synthesized on the surfaces of tiny interstellar dust grains by the hydrogenation of frozen oxygen. Water then enters a cycle of sublimation/freezing throughout the successive phases of planetary system formation, namely, hot corinos and protoplanetary disks, eventually to be incorporated into planets, asteroids, and comets. The amount of heavy water measured on Earth and in early forming planetary systems suggests that a substantial fraction of terrestrial water was inherited from the very first phases of the Solar System formation and is 4.5 billion years old

Entwicklung eines impedimetrischen Biosensors für den Nachweis von Antigliadin Autoantikörpern

In der vorliegenden Arbeit wurde ein Biosensor für den Nachweis von Antikörpern gegen Gliadin entwickelt. Gliadine sind Bestandteile der Getreideglutene und verantwortlich für die Manifestation der Zöliakie (Gluten-Unverträglichkeit). Der Biosensor basiert auf der Immobilisierung von Gliadin auf Goldelektroden, die zuvor mit Polystyrensulfonsäure beschichtet worden waren. Die erfolgreiche Immobilisierung wurde mit Hilfe der Quarzmikrowaage dokumentiert. Die Antigen-Antikörper-Bindung konnte durch die Inkubation mit einem Peroxidase-markierten Zweitantikörper und der enzymatischen Oxidation von 3-Amino-9- Ethylcarbazol (AEC) verstärkt werden. Die Zunahme in der Elektrodenisolierung durch die Bindungs- und Ablagerungsreaktion konnte durch elektrochemische Impedanzspektroskopie (EIS) in Anwesenheit des Hexacyanoferrat- Redoxsystems gemessen werden. Die Spektren wurden mit Hilfe eines Randles-Ersatzschaltbildes ausgewertet. Hierbei konnte eine Zunahme im Ladungstransferwiderstand festgestellt werden, die pro portional zur Antigliadin-Antikörperkonzentration, im Bereich von 10-8 M bis 10-6 M, war. Mit Hilfe dieses Sensors wurden schließlich humane Seren hinsichtlich ihrer Konzentration an Gliadinantikörpern, sowohl für Immunglobuline vom Typ IgG als auch IgA, untersucht.In this study an immunosensor was developed for the analysis of anti-gliadin antibodies. These antibodies can serve as an early diagnostic marker for celiac disease. The sensor is based on polystyrenesulfonic acid modifi ed gold electrodes on which gliadin was immobilized. The anti-gliadin antibody recognition was amplifi ed by a second binding step with a peroxidase- labeled antibody and subsequent peroxidase-catalyzed oxidation of 3-amino-9-ethylcarbazole (AEC) resulting in a precipitate formation on the electrode. The change of the electrode surface properties was followed by impedance spectroscopy in the presence of ferri-/ferrocyanide. By evaluating the impedance spectra the charge transfer resistance was found to be a suitable sensor parameter. A calibration curve for the detection of anti-gliadin antibodies was established for antibody concentrations between 10-8 M and 10-6 M and the sensor was also applied for the analysis of serum samples

Planetary Spectrum Generator: an accurate online radiative transfer suite for atmospheres, comets, small bodies and exoplanets

We have developed an online radiative-transfer suite (https://psg.gsfc.nasa.gov) applicable to a broad range of planetary objects (e.g., planets, moons, comets, asteroids, TNOs, KBOs, exoplanets). The Planetary Spectrum Generator (PSG) can synthesize planetary spectra (atmospheres and surfaces) for a broad range of wavelengths (UV/Vis/near-IR/IR/far-IR/THz/sub-mm/Radio) from any observatory (e.g., JWST, ALMA, Keck, SOFIA), any orbiter (e.g., ExoMars, Juno), or any lander (e.g., MSL). This is achieved by combining several state-of-the-art radiative transfer models, spectroscopic databases and planetary databases (i.e., climatological and orbital). PSG has a 3D (three-dimensional) orbital calculator for most bodies in the solar system, and all confirmed exoplanets, while the radiative-transfer models can ingest billions of spectral signatures for hundreds of species from several spectroscopic repositories. It integrates the latest radiative-transfer and scattering methods in order to compute high resolution spectra via line-by-line calculations, and utilizes the efficient correlated-k method at moderate resolutions, while for computing cometary spectra, PSG handles non-LTE and LTE excitation processes. PSG includes a realistic noise calculator that integrates several telescope / instrument configurations (e.g., interferometry, coronagraphs) and detector technologies (e.g., CCD, heterodyne detectors, bolometers). Such an integration of advanced spectroscopic methods into an online tool can greatly serve the planetary community, ultimately enabling the retrieval of planetary parameters from remote sensing data, efficient mission planning strategies, interpretation of current and future planetary data, calibration of spectroscopic data, and development of new instrument/spacecraft concepts.Comment: Journal of Quantitative Spectroscopy and Radiative Transfer, submitte

ОЦЕНКИ ХОЛЛОВСКОЙ ПРОВОДИМОСТИ ПО ДАННЫМ МАГНИТОТЕЛЛУРИЧЕСКОГО ЗОНДИРОВАНИЯ

Many minerals have semiconductor properties. It is known that petroleum reservoir rocks permeated with hydrocarbon fluids can sometimes behave as semiconductors. In the Earth’s magnetic field, the electrical conductivity of such materials becomes anisotropic, and the Hall effect is quite possible in rocks in natural conditions and detectable by magnetotelluric sounding. In the anisotropic medium, the field is subject to normal mode splitting, and its components show different attenuation coefficients and phase velocities. The modes differ due to polarization and rotation of the field vectors (clockwise in one mode, and counterclockwise in another). With account of the Hall effect, responses of the medium can be different when the medium is excited by a single normal wave. To detect the Hall effect in MTS surveys, we use the polarization analysis method and select the spectra of modes with right and left circular polarization. Special experiments were carried out to detect the contribution of the Hall effect during the MTS surveys. This article presents the first estimates of the Hall conductivity for the studied rocks.Многие минералы по своим свойствам являются полупроводниками. Замечено также, что вмещающие породы над залежами нефти и газа, пронизываемые углеводородными флюидами, иногда проявляют себя как полупроводники. Но так как электропроводность таких сред в магнитном поле Земли становится анизотропной, вполне возможны проявления эффекта Холла в горных породах в естественных условиях, например при магнитотеллурическом зондировании. В анизотропной среде поле расщепляется на составляющие, отличающиеся коэффициентами затухания и фазовой скоростью, – нормальные моды. Отличие мод связано с их поляризацией и направлением вращения вектора поля: в одной моде поле вращается по часовой стрелке, во второй – против. За счет эффекта Холла отклик среды может быть неодинаковым в случаях возбуждения среды лишь одной из нормальных волн. Для обнаружения влияния эффекта Холла при магнитотеллурическом зондировании мы используем метод поляризационного анализа с выделением спектров мод с правой и левой круговой поляризацией. Проведены специальные эксперименты для обнаружения вклада эффекта Холла при магнитотеллурическом зондировании, получены первые оценки холловской проводимости пород