Terahertz hot electron bolometer waveguide mixers for GREAT

Supplementing the publications based on the first-light observations with the German Receiver for Astronomy at Terahertz frequencies (GREAT) on SOFIA, we present background information on the underlying heterodyne detector technology. We describe the superconducting hot electron bolometer (HEB) detectors that are used as frequency mixers in the L1 (1400 GHz), L2 (1900 GHz), and M (2500 GHz) channels of GREAT. Measured performance of the detectors is presented and background information on their operation in GREAT is given. Our mixer units are waveguide-based and couple to free-space radiation via a feedhorn antenna. The HEB mixers are designed, fabricated, characterized, and flight-qualified in-house. We are able to use the full intermediate frequency bandwidth of the mixers using silicon-germanium multi-octave cryogenic low-noise amplifiers with very low input return loss. Superconducting HEB mixers have proven to be practical and sensitive detectors for high-resolution THz frequency spectroscopy on SOFIA. We show that our niobium-titanium-nitride (NbTiN) material HEBs on silicon nitride (SiN) membrane substrates have an intermediate frequency (IF) noise roll-off frequency above 2.8 GHz, which does not limit the current receiver IF bandwidth. Our mixer technology development efforts culminate in the first successful operation of a waveguide-based HEB mixer at 2.5 THz and deployment for radioastronomy. A significant contribution to the success of GREAT is made by technological development, thorough characterization and performance optimization of the mixer and its IF interface for receiver operation on SOFIA. In particular, the development of an optimized mixer IF interface contributes to the low passband ripple and excellent stability, which GREAT demonstrated during its initial successful astronomical observation runs.Comment: Accepted for publication in A&A (SOFIA/GREAT special issue

Book of Hours: Number 28

Vellum is in poor condition, this is most likely because of the ageing of metal alloys used in the original production of the book.; Decorated initials with circular filigree. Floral, stem-like imagery. Separating the verses is a bar of red and blue with white filigree.; Angular Gothic Script; Brown, blue, red, silver, and gold inkshttps://digital.kenyon.edu/mdvlmanuscripts/1014/thumbnail.jp

First observations with CONDOR, a 1.5 THz heterodyne receiver

The THz atmospheric windows centered at roughly 1.3 and 1.5~THz, contain numerous spectral lines of astronomical importance, including three high-J CO lines, the N+ line at 205 microns, and the ground transition of para-H2D+. The CO lines are tracers of hot (several 100K), dense gas; N+ is a cooling line of diffuse, ionized gas; the H2D+ line is a non-depleting tracer of cold (~20K), dense gas. As the THz lines benefit the study of diverse phenomena (from high-mass star-forming regions to the WIM to cold prestellar cores), we have built the CO N+ Deuterium Observations Receiver (CONDOR) to further explore the THz windows by ground-based observations. CONDOR was designed to be used at the Atacama Pathfinder EXperiment (APEX) and Stratospheric Observatory For Infrared Astronomy (SOFIA). CONDOR was installed at the APEX telescope and test observations were made to characterize the instrument. The combination of CONDOR on APEX successfully detected THz radiation from astronomical sources. CONDOR operated with typical Trec=1600K and spectral Allan variance times of 30s. CONDOR's first light observations of CO 13-12 emission from the hot core Orion FIR4 (= OMC1 South) revealed a narrow line with T(MB) = 210K and delta(V)=5.4km/s. A search for N+ emission from the ionization front of the Orion Bar resulted in a non-detection. The successful deployment of CONDOR at APEX demonstrates the potential for making observations at THz frequencies from ground-based facilities.Comment: 4 pages + list of objects, 3 figures, to be published in A&A special APEX issu

Four Facets of Forecast Felicity: Calibration, Predictiveness, Randomness and Regret

Machine learning is about forecasting. Forecasts, however, obtain their usefulness only through their evaluation. Machine learning has traditionally focused on types of losses and their corresponding regret. Currently, the machine learning community regained interest in calibration. In this work, we show the conceptual equivalence of calibration and regret in evaluating forecasts. We frame the evaluation problem as a game between a forecaster, a gambler and nature. Putting intuitive restrictions on gambler and forecaster, calibration and regret naturally fall out of the framework. In addition, this game links evaluation of forecasts to randomness of outcomes. Random outcomes with respect to forecasts are equivalent to good forecasts with respect to outcomes. We call those dual aspects, calibration and regret, predictiveness and randomness, the four facets of forecast felicity

The Set Structure of Precision: Coherent Probabilities on Pre-Dynkin-Systems

In literature on imprecise probability little attention is paid to the fact that imprecise probabilities are precise on some events. We call these sets system of precision. We show that, under mild assumptions, the system of precision of a lower and upper probability form a so-called (pre-)Dynkin-system. Interestingly, there are several settings, ranging from machine learning on partial data over frequential probability theory to quantum probability theory and decision making under uncertainty, in which a priori the probabilities are only desired to be precise on a specific underlying set system. At the core of all of these settings lies the observation that precise beliefs, probabilities or frequencies on two events do not necessarily imply this precision to hold for the intersection of those events. Here, (pre-)Dynkin-systems have been adopted as systems of precision, too. We show that, under extendability conditions, those pre-Dynkin-systems equipped with probabilities can be embedded into algebras of sets. Surprisingly, the extendability conditions elaborated in a strand of work in quantum physics are equivalent to coherence in the sense of Walley (1991, Statistical reasoning with imprecise probabilities, p. 84). Thus, literature on probabilities on pre-Dynkin-systems gets linked to the literature on imprecise probability. Finally, we spell out a lattice duality which rigorously relates the system of precision to credal sets of probabilities. In particular, we provide a hitherto undescribed, parametrized family of coherent imprecise probabilities

An der Schnittstelle von Morphologie und Syntax. Einheitsformen der Personalpronomen der 1. und 2. Person Plural im Nordbairischen

In German, pronominal inflection is more distinctive than noun inflection. Despite all tendencies towards syncretism, the specific exponents of the nominative case in the first and second person pronouns have been generally retained both in the standard language and in the dialects. However, in several areas, this distinction has ceased to exist and has given way to a single form for the first and second-person plural in which case is no longer marked. The present article examines forms of this kind in the transitional area between East Franconian and Northern Bavarian. We find that these forms occur when the loss of case marking in pronominal inflection is compensated for by an unambiguous indication of person in verbal inflection. The generalized form ENK(S) in the second-person plural occurs in dialects with -TS as the verbal suffix of the second-personal plural. Distinction of case in the second-person plural is retained in dialects with the verbal suffix -T, because -T is also the verbal suffix of the third-person singular and hence there are several cases in which syncretism prevails in the verbal paradigm (as in the word form m\ue4ht from the verb m\ue4hen \u2018to mow\u2019). Since -N is the verbal suffix of the first and third-person plural (as in m\ue4hen), there is no development of a generalized first person plural form in the region under investigation. These results illustrate the fundamental link between morphology and syntax

Rappresentazione cartografica del multilinguismo: dalle valli ladine all’Ucraina orientale

La rappresentazione cartografica del multilinguismo rimane una sfida, nonostante gli sviluppi enormi della cartografia linguistica anche grazie alle potenzialità offerte dai nuovi strumenti digitali, con ripercussioni politiche importanti che e utile tenere in considerazione nell’analizzare la guerra russo-ucraina attualmente in corso. Nella sezione 1 di questo contributo mettiamo in evidenza le caratteristiche specifiche delle carte linguistiche rispetto alle altre carte tematiche e discutiamo le criticità esibite da molte carte di territori multilingui, prendendo come esempio il Trentino. Nella sezione 2 presentiamo la Survey Ladins di Dell’Aquila & Iannàccaro (2006) che offre ottimi modelli di rappresentazione cartografica del multilinguismo. La sezione 3 indaga il ruolo che rivestono le rappresentazioni della situazione linguistica nella narrativa russa della guerra contro l’Ucraina. Proponiamo una carta del multilinguismo in Ucraina che non fornisce elementi utili alla suddivisione del paese in una parte nord-occidentale ucraina e una parte sud-orientale russa. Nella sezione 4 concludiamo che il multilinguismo continuerà a caratterizzare l’Ucraina a prescindere dall’esito della guerra

Active phase-nulling of the self-mixing phase in a terahertz frequency quantum cascade laser

We demonstrate an active phase-nulling scheme for terahertz (THz) frequency quantum cascade lasers (QCLs) under optical feedback, by active electronic feedback control of the emission frequency. Using this scheme the frequency tuning rate of a THz QCL is characterised, with significantly reduced experimental complexity compared to alternative approaches. Furthermore, we demonstrate real-time displacement sensing of targets, overcoming the resolution limits imposed by quantisation in previously-implemented fringe counting methods. Our approach is readily applicable to high-frequency vibrometry and surface profiling of targets, as well as frequency-stabilisation schemes for THz QCLs

Sandra Bosco, Marcella Costa, Ludwig M. Eichinger: Deutsch – Italienisch: Sprachvergleiche/Te­desco – Italiano: confronti linguistici

Im rezensierten Band sind die Beiträge einer dem Sprachvergleich Deutsch-Italienisch 2009 in Turin gewidmeten Tagung publiziert

Intonation and Syllable Structure. A Cross-linguistic Study of German and Italian Conversations

German and Italian have quite different rhythmic and/or melodic characteristics. This paper investigates the correlates of that impression, focussing on intonation and syllable structure. The data are made up of different types of repair activity in German and Italian conversations: problems of expectation, problems of understanding, and contradictions. It turns out that speakers of German and Italian use the same intonational procedures to constitute and contextualise activity types in conversations. For the two languages it is therefore possible to devise a uniform model of intonation contour assignment according to function. A comparison of the syllabic structures of the two languages reveals that the main source of the different impressions made by German and Italian prosodic structure is not intonation, but syllable structure. This accords with recent speech perception studies