Matching LOFAR sources across radio bands

Aims. With the recent preliminary release of the LOFAR LBA Sky Survey (LoLSS), the first wide-area, ultra-low frequency observations from LOFAR were published. Our aim is to combine this data set with other surveys at higher frequencies to study the spectral properties of a large sample of radio sources. Methods. We present a new cross-matching algorithm taking into account the sizes of the radio sources and apply it to the LoLSS-PR, LoTSS-DR1, LoTSS-DR2 (all LOFAR), TGSS-ADR1 (GMRT), WENSS (WSRT) and NVSS (VLA) catalogues. We then study the number of matched counterparts for LoLSS radio sources and their spectral properties. Results. We find counterparts for 22 607 (89.5%) LoLSS sources. The remaining 2 640 sources (10.5%) are identified either as an artefact in the LoLSS survey (3.6%) or flagged due to their closeness to bright sources (6.9%). We find an average spectral index of $\alpha = -0.77 \pm 0.18$ between LoLSS and NVSS. Between LoLSS and LoTSS-DR2 we find $\alpha = -0.71 \pm 0.31$. The average spectral index is flux density independent above $S_{54} = 181$ mJy. Comparison of the spectral slopes from LoLSS--LoTSS-DR2 with LoTSS-DR2--NVSS indicates that the probed population of radio sources exhibits evidence for a negative spectral curvature.Comment: 13 pages, 22 figures and 2 tables. Accepted for publication in A&

Unterrichtstextauswahl und schülerseitige Leseinteressen in der Sekundarstufe I: Ergebnisse aus der binationalen Studie TAMOLI

Anhand der Angaben von Schweizer und deutschen Lehrpersonen (N=116) und Schüler/-innen (N=2173) der Sekundarstufe I wurde untersucht, welche Texte Lehrpersonen im Unterricht einsetzen und wie sich die Auswahl zu freizeitlichen bzw. schulbezogenen Leseinteressen der Schüler/innen verhält: Es zeigt sich, dass diese je nach Leseumgebung bei den Leseinteressen unterscheiden. Für die Freizeit rücken sie Unterhaltungsgenres ins Zentrum. Fürs schulische Lesen behalten sie diese Vorliebe teilweise bei, geben aber Themen den Vorrang, die freizeitlich wenig Zuspruch erhalten (bspw. politisch-gesellschaftskritische Texte). Letztere sind in der lehrerseitigen Textauswahl stark vertreten, Freizeitgenres dagegen wenig. Für die Unterrichtstextauswahl besteht also ein größerer Schnittbereich mit schulischen Leseinteressen der Schüler/-innen als mit freizeitlichen. Das Aufgreifen von Freizeitleseinteressen im Literaturunterricht bedarf demnach kritischer Diskussion. Es sollte berücksichtigt werden, dass Schüler/-innen diese Interessen offenbar nicht durchweg im Literaturunterricht vertreten sehen möchten. Für das schulische Lesen erhalten auch Texte hohen Zuspruch, die zur kritischen Reflexion anregen. (DIPF/Orig.)Using classroom media protocols in Swiss and German secondary schools, we analysed which text genres teachers (N=116) preferred in their teaching of German-L1 literature classes. We compared the findings with information on student (N=2173) reading interests obtained through questionnaires. The results show that teachers preferred texts about political or social topics; their selection featured only a small share of entertainment genres. Student reading interests differed between contexts: For their private reading, students preferred entertainment genres, with only a minor interest in socio-political topics. For reading at school, students retained their preference for entertainment genres, but also reported a strong interest in sociopolitical topics. Hence, teachers’ text selection had a greater overlap with students’ school reading preferences. In the discussion, we argue that teaching approaches promoting the inclusion of student interests for text selection need to consider that teenage students may not simply wish to extend their private reading to the classroom. Instead, they may expect that school provides them with texts that engage them in critical thinking and group discussion

X-ray Thomson scattering absolute intensity from the f-sum rule in the imaginary-time domain

We evaluate the f-sum rule on the dynamic structure factor in the imaginary-time domain as a formally exact and simulation-free means of normalizing X-Ray Thomson Scattering (XRTS) spectra. This circumvents error-prone real-time deconvolution of the source function and facilitates calculating the static structure factor from the properly normalized imaginary-time correlation function. We apply our technique to two distinct sets of experimental data, finding that it is effective for both narrow and broad x-ray sources. This approach could be readily adapted to other scattering spectroscopies

Electronic Density Response of Warm Dense Matter

Matter at extreme temperatures and pressures -- commonly known as warm dense matter (WDM) in the literature -- is ubiquitous throughout our Universe and occurs in a number of astrophysical objects such as giant planet interiors and brown dwarfs. Moreover, WDM is very important for technological applications such as inertial confinement fusion, and is realized in the laboratory using different techniques. A particularly important property for the understanding of WDM is given by its electronic density response to an external perturbation. Such response properties are routinely probed in x-ray Thomson scattering (XRTS) experiments, and, in addition, are central for the theoretical description of WDM. In this work, we give an overview of a number of recent developments in this field. To this end, we summarize the relevant theoretical background, covering the regime of linear-response theory as well as nonlinear effects, the fully dynamic response and its static, time-independent limit, and the connection between density response properties and imaginary-time correlation functions (ITCF). In addition, we introduce the most important numerical simulation techniques including ab initio path integral Monte Carlo (PIMC) simulations and different thermal density functional theory (DFT) approaches. From a practical perspective, we present a variety of simulation results for different density response properties, covering the archetypal model of the uniform electron gas and realistic WDM systems such as hydrogen. Moreover, we show how the concept of ITCFs can be used to infer the temperature from XRTS measurements of arbitrarily complex systems without the need for any models or approximations. Finally, we outline a strategy for future developments based on the close interplay between simulations and experiments

Matching LOFAR sources across radio bands

Böhme L, Schwarz D, de Gasperin F, Röttgering HJA, Williams WL. Matching LOFAR sources across radio bands. Astronomy and Astrophysics . 2023;674: A189.Aims. The recent preliminary release of the LOFAR LBA Sky Survey (LoLSS) is the first wide-area, ultra-low frequency observation published from the Low Frequency Array (LOFAR). Our aim is to combine this data set with other surveys at higher frequencies to study the spectral properties of a large sample of radio sources. Methods. We present a new cross-matching algorithm that takes into account the sizes of the radio sources. We applied it to the LoLSS-PR, LoTSS-DR1, LoTSS-DR2 (all LOFAR), TGSS-ADR1 (GMRT), WENSS (WSRT), and NVSS (VLA) catalogues. We then studied the number of matched counterparts for LoLSS radio sources and their spectral properties. Results. We found counterparts for 22 607 (89.5%) LoLSS sources. The remaining 2640 sources (10.5%) were identified either as an artefact in the LoLSS survey (3.6%) or flagged due to their closeness to bright sources (6.9%). We found an average spectral index of alpha = -0.77 +/- 0.18 between LoLSS and NVSS. Between LoLSS and LoTSS-DR2, we found alpha = -0.71 +/- 0.31. The average spectral index is independent of the flux density above S-54 = 181 mJy. A comparison of the spectral slopes from LoLSS-LoTSS-DR2 with LoTSS-DR2-NVSS indicates that the probed population of radio sources shows evidence of a negative spectral curvature

Data publication: Revealing Non-equilibrium and Relaxation in Warm Dense Matter

All data as needed to generate the figures in the manuscript

Movement ecology of coastal fishes in a marine protected area: implications for management and conservation

Animal movement is a key biological process for the maintenance of ecosystem services, and a major concern for the conservation of biodiversity. The aim of movement ecology is to understand the causes and consequences of these movements, including the effect of internal and external factors and its ecological implications. This research field has rapidly grown in the last decades fostered by recent technological and analytical developments, and is making substantial contributions to conservation biology, such as allowing the incorporation of the spatial and temporal scales of movements into management policies to enhance their scope and efficiency. Marine protected areas (MPAs) are the most used tools to face the effects of anthropogenic impacts on marine ecosystems. They play a major role in restoring and conserving overfished fish populations, and also potentially enhancing fisheries yield in adjacent areas through the direct spillover of juvenile and adult individuals. However, in order to be effective and generate such benefits, MPAs must be designed according to the movement attributes of targeted species, but this information is still rarely available, specially in temperate regions. In the last decades, passive acoustic telemetry techniques have demonstrated to be a valuable tool to study the movements and behavior of fishes covering large spatial and temporal scales, but the acoustic nature of the signals and the large amounts of data that they provide entail a series of challenges for their analysis and interpretation. The main objective of this thesis is to characterize the movement ecology of coastal fishes in relation to MPAs. This constitutes a basic information on the biology of species, which is required to understand changes in populations and ecosystems driven by natural or human induced impacts, as well as to correctly evaluate the outcomes of management actions. Specifically, the movements of two species, the white seabream (Diplodus sargus) and the common dentex (Dentex dentex), were monitored using acoustic telemetry in the Medes Islands MPA (Catalonia, NW Mediterranean Sea). Both species play important ecological and economical roles, shaping the structure and functioning of biological communities through top-down controls, and being an important resource for local artisanal and recreational fisheries. Nevertheless, they present a contrasting biology (omnivorous vs. predator), and therefore, different conservation needs. Firstly, we characterized the general movement attributes of the two species, including their habitat requirements and space use and activity patterns, within zones with different protection levels of the MPA. Secondly, we studied the behavioral responses of the two species to environmental fluctuations, by adding environmental information (seawater temperature and wave height) to movement analysis. These behavioral responses provide essential information on the ecology of the species such as their resistance to perturbations. Thirdly, we characterized their movement behavior during the spawning season, describing, for the first time, the formation of spawning aggregations for both species. Finally, this thesis also has an important computational and numerical component. A special effort has been done to adapt and develop new methods to visualize and analyze acoustic telemetry data, specially to improve the space use estimations by incorporating the vertical dimension, in order to provide a more comprehensive view of complex movement patterns. By studying the movement ecology of these species, we provide general mechanistic insights to understand the effects of protection on coastal fish species, as well as to predict future changes in their populations derived from climate change. We specially highlight the importance of studying the movement ecology of diverse species in order to propose integrative and more efficient management actions.Las áreas marinas protegidas (AMPs), son las herramientas de gestión más utilizadas para contrarrestar los impactos antropogénicos sobre los ecosistemas marinos y juegan un papel fundamental en la protección y restauración de las poblaciones de peces afectadas por la sobrepesca. Sin embargo, para ser efectivas y generar los beneficios que se esperan de ellas, las AMPs deben ser diseñadas en concordancia con los atributos de los movimientos de las especies de peces que se pretenden proteger, pero esta información no suele estar disponible. El principal objetivo de esta tesis es caracterizar, mediante técnicas de telemetría acústica, la ecología del movimiento de especies de peces costeros en relación a AMPs, mediante el estudio del movimiento de dos especies: el sargo común (Diplodus sargus) y el dentón (Dentex dentex), en la reserva marina de las islas Medas (Catalunya, Mediterráneo NO). Específicamente, se han caracterizado los patrones de movimiento y actividad generales de las dos especies, la presencia de respuestas comportamentales a fluctuaciones ambientales (temperatura y oleaje), y su comportamiento reproductor. Además, se ha hecho un esfuerzo especial en adaptar y desarrollar nuevas técnicas de análisis y visualización para datos de telemetría acústica, con el objetivo de mejorar las estimaciones del uso del espacio, incorporando la dimensión vertical, y de proporcionar una visión más exhaustiva de los complejos patrones de movimiento. Toda esta información es de gran aplicabilidad para la gestión de estas y otras especies costeras, así como para entender los cambios en las poblaciones y en los ecosistemas derivados del cambio global

Solution structure of a DNA double helix with consecutive metal-mediated base pairs

Metal-mediated base pairs represent a powerful tool for the site-specific functionlization of nucleic acids with metal ions. The development of applications of the metal-modified nucleic acids will depend on the availability of structural information on these double helices. We present here the NMR solution structure of a self-complementary DNA oligonucleotide with three consecutive imidazole nucleotides in its centre. In the absence of transition-metal ions, a hairpin structure is adopted with the artifical nucleotides forming the loop. In the presence of Ag(I) ions, a duplex comprising three imidazole-Ag+-imidazole base pairs is formed. Direct proof for the formation of metal-mediated base pairs was obtained from (1)J(N-15,Ag-107/109) couplings upon incorporation of N-15-labelled imidazole. The duplex adopts a B-type conformation with only minor deviations in the region of the artifical bases. This work represents the first structural characterization of a metal-modified nucleic acid with a continuous stretch of metal-mediated base pairs

Two examples of FVH in the distal branches of the anterior cerebral artery (ACA, arrows) on FLAIR images in acute ischemic stroke due to ACA occlusion.

<p>Two examples of FVH in the distal branches of the anterior cerebral artery (ACA, arrows) on FLAIR images in acute ischemic stroke due to ACA occlusion.</p