Upper limit to magnetism in LaAlO3/SrTiO3 heterostructures

Using polarized neutron reflectometry (PNR) we measured the neutron spin dependent reflectivity from four LaAlO3/SrTiO3 superlattices. This experiment implies that the upper limit for the magnetization induced by an 11 T magnetic field at 1.7 K is 2 emu/cm3. SQUID magnetometry of the superlattices sporadically finds an enhanced moment, possibly due to experimental artifacts. These observations set important restrictions on theories which imply a strongly enhanced magnetism at the interface between LaAlO3 and SrTiO3

Epistemologie der Erziehungswissenschaft: Dilemmas, Fragen, mögliche Lösungen

U radu se polazi od tvrdnje da su epistemološke karakteristike temeljne odrednice znanstvenog digniteta znanosti. Na osnovi kritičke analize epistemoloških karakteristika pedagogije upozorava se na upitnost njezina znanstvenog digniteta. Navedena se tvrdnja obrazlaže odgovorima na nekoliko pitanja: Je li razina razvijenosti suvremenog društva nametnula potrebu redefiniranja semantičkog određenja osnovnih pojmova i pedagogije same? Može li se pedagogija koja desetljećima nije promijenila svoj osnovni teorijski, epistemološko-metodologijski koncept, smatrati suvremenom? Ima li Hrvatska suvremenu pedagogiju ili je riječ o tradicionalnoj (zastarjeloj) pedagogiji? Što je osnovna funkcija pedagogije? Je li pedagogija znanost o odgoju, znanost o odgoju i obrazovanju ili znanost o osposobljavanju ljudi? Jesu li cilj i zadaci pedagogijske znanosti jednoznačno određeni? Na kraju se navode moguća rješenja. Predlažu se nova suvremena jednoznačna semantička određenja temeljnih pojmova i s tog se aspekta utvrđuje osnovna funkcija pedagogije i kao znanstvene i kao praktične discipline, kao teorije osposobljavanja.The argumentation presented in the paper starts from the premise that epistemological characteristics are the elements that science builds its scientific dignity on. A critical analysis of the epistemological characteristics of pedagogy has led the author to question its scientific dignity. The doubts stated in the paper are raised by several questions. Is the level of development of the modern society forcing us to redefine the semantic components of basic pedagogical terms and pedagogy itself? Can pedagogy, which has not changed its basic theoretical, epistemological and methodological concept for decades, really be termed contemporary? Is pedagogy in Croatia contemporary or do we still practice the traditional (and outdated) form of pedagogy? What is the main function of pedagogy? Is pedagogy the science of education, the science of education and development, or the science of human resources development? Are the goals and tasks of pedagogy as a science unambiguously set? Finally, the author suggests possible answers, advocating new, modern and unambiguous semantic definitions of the basic terms, thus determining the primary function of pedagogy as both scientific and practical discipline – a human resources development theory.Den Ausgangspunkt dieser Arbeit bildet die These, dass epistemologische Charakteristiken die wissenschaftliche Dignität jeder Wissenschaft begründen. Anhand einer kritischen Analyse von epistemologischen Charakteristiken der Erziehungswissenschaft wird auf die Fragwürdigkeit ihrer wissenschaftlichen Dignität hingewiesen, Die angeführte Behauptung wird durch Antworten auf einige Fragen erklärt: Macht die Entwicklungsebene der modernen Gesellschaft eine Redefinition der semantischen Bestimmungen pädagogischer Grundbegriffe und der Pädagogik selbst erforderlichß Kann die Erziehungswissenschaft, die seit Jahrzehnten ihr theoretisches, epistemologisch – methodologisches Grundkonzept nicht geändert hat, als modern gelten? Hat Kroatien eine moderne Erziehungswissenschaft oder ob es um eine traditionelle (veraltete) Pädagogik handelt? Was ist die Grundaufgabe der Pädagogik? Ist die Pädagogik eine Wissenschaft über die Erziehung, Wissenschaft über die Erziehung und Bildung oder Wissenschaft über die Befähigung der Menschen? Lassen sich das Ziel und die Aufgaben der Erziehungswissenschaft eindeutig bestimmen? Am Ende werden mögliche Lösungen angeführt. Vorgeschlagen werden neue moderne eindeutige semantische Bestimmungen der pädagogischen Grundbegriffe und von diesem Standpunkt aus Grundaufgaben der Pädagogik sowohl als wissenschaftlicher als auch praktischer Disziplin sowie einer Befähigungstheorie festgelegt

Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3b

We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC-2020 March 27 17:00 UTC). We conduct two independent searches: A generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence for subthreshold gravitational-wave signals associated with this GRB ensemble either. We use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each GRB. Finally, we constrain the population of low-luminosity short GRBs using results from the first to the third observing runs of Advanced LIGO and Advanced Virgo. The resulting population is in accordance with the local binary neutron star merger rate. © 2022. The Author(s). Published by the American Astronomical Society

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

GW190814: gravitational waves from the coalescence of a 23 solar mass black hole with a 2.6 solar mass compact object

We report the observation of a compact binary coalescence involving a 22.2–24.3 Me black hole and a compact object with a mass of 2.50–2.67 Me (all measurements quoted at the 90% credible level). The gravitational-wave signal, GW190814, was observed during LIGO’s and Virgo’s third observing run on 2019 August 14 at 21:10:39 UTC and has a signal-to-noise ratio of 25 in the three-detector network. The source was localized to 18.5 deg2 at a distance of - + 241 45 41 Mpc; no electromagnetic counterpart has been confirmed to date. The source has the most unequal mass ratio yet measured with gravitational waves, - + 0.112 0.009 0.008, and its secondary component is either the lightest black hole or the heaviest neutron star ever discovered in a double compact-object system. The dimensionless spin of the primary black hole is tightly constrained to �0.07. Tests of general relativity reveal no measurable deviations from the theory, and its prediction of higher-multipole emission is confirmed at high confidence. We estimate a merger rate density of 1–23 Gpc−3 yr−1 for the new class of binary coalescence sources that GW190814 represents. Astrophysical models predict that binaries with mass ratios similar to this event can form through several channels, but are unlikely to have formed in globular clusters. However, the combination of mass ratio, component masses, and the inferred merger rate for this event challenges all current models of the formation and mass distribution of compact-object binaries

Search for gravitational-wave transients associated with magnetar bursts in advanced LIGO and advanced Virgo data from the third observing run

Gravitational waves are expected to be produced from neutron star oscillations associated with magnetar giant f lares and short bursts. We present the results of a search for short-duration (milliseconds to seconds) and longduration (∼100 s) transient gravitational waves from 13 magnetar short bursts observed during Advanced LIGO, Advanced Virgo, and KAGRA’s third observation run. These 13 bursts come from two magnetars, SGR1935 +2154 and SwiftJ1818.0−1607. We also include three other electromagnetic burst events detected by FermiGBM which were identified as likely coming from one or more magnetars, but they have no association with a known magnetar. No magnetar giant flares were detected during the analysis period. We find no evidence of gravitational waves associated with any of these 16 bursts. We place upper limits on the rms of the integrated incident gravitational-wave strain that reach 3.6 × 10−²³ Hz at 100 Hz for the short-duration search and 1.1 ×10−²² Hz at 450 Hz for the long-duration search. For a ringdown signal at 1590 Hz targeted by the short-duration search the limit is set to 2.3 × 10−²² Hz. Using the estimated distance to each magnetar, we derive upper limits upper limits on the emitted gravitational-wave energy of 1.5 × 1044 erg (1.0 × 1044 erg) for SGR 1935+2154 and 9.4 × 10^43 erg (1.3 × 1044 erg) for Swift J1818.0−1607, for the short-duration (long-duration) search. Assuming isotropic emission of electromagnetic radiation of the burst fluences, we constrain the ratio of gravitational-wave energy to electromagnetic energy for bursts from SGR 1935+2154 with the available fluence information. The lowest of these ratios is 4.5 × 103