Tracing the Evolution of Agglomeration Economies: Spain, 1860-1991

This article attempts to quantify how the effect of agglomeration economies on population growth has evolved over time. Using district population in Spain between 1860 and 1991, recorded approximately every decade, this article examines whether initial population affects subsequent population growth. Our results show that, while the relationship between these two variables hardly existed during the second half of the 19th century, this link increased significantly between 1910 and 1970, although this trend was abruptly interrupted by the Civil War and the autarkic period that followed. The intensity of this relationship debilitated in the 1970s, a process that continued during the 1980s as rural out-migration diminished and de-industrialisation hit traditional manufacturing sectors. Our findings also stress that agglomeration economies were stronger in medium-size districts, especially from 1960 onwards, thus suggesting that congestion costs began to mitigate the benefits arising from agglomeration economies in the largest locations

The Shadow of Cities: Size, Location and the Spatial Distribution of Population in Spain

Using a large data set on the population of Spanish municipalities between 1877 and 2001, this paper analyses how their initial size and the presence of neighbouring urban locations influence subsequent population growth and how these links have evolved over time. Our results show that initial size is negatively related to population growth, except in the 1960s and 1970s when this relationship becomes positive. Likewise, the presence of neighbouring urban locations limited local population growth in the late 19th century, a negative effect that persisted, but at a diminishing rate, until the second half of the 20th century. The influence of nearby cities became increasingly positive from then onwards, and especially so during the 1970s

Star and jet multiplicity in the high-mass star forming region IRAS 05137+3919

Context. We present a study of the complex high-mass star forming region IRAS 05137+3919 (also known as Mol8), where multiple jets and a rich stellar cluster have been described in previous works. Aims. Our goal is to determine the number of jets and shed light on their origin, and thus determine the nature of the young stars powering these jets. We also wish to analyse the stellar clusters by resolving the brightest group of stars. Methods. The star forming region was observed in various tracers and the results were complemented with ancillary archival data. The new data represent a substantial improvement over previous studies both in resolution and frequency coverage. In particular, adaptive optics provides us with an angular resolution of 80 mas in the near IR, while new mid- and far-IR data allow us to sample the peak of the spectral energy distribution and thus reliably estimate the bolometric luminosity. Results. Thanks to the near-IR continuum and millimetre line data we can determine the structure and velocity field of the bipolar jets and outflows in this star forming region. We also find that the stars are grouped into three clusters and the jets originate in the richest of these, whose luminosity is ~ 2.4 × 104L⊙. Interestingly, our high-resolution near-IR images allow us to resolve one of the two brightest stars (A and B) of the cluster into a double source (A1+A2). Conclusions. We confirm that there are two jets and establish that they are powered by B-type stars belonging to cluster C1. On this basis and on morphological and kinematical arguments, we conclude that the less extended jet is almost perpendicular to the line of sight and that it originates in the brightest star of the cluster, while the more extended one appears to be associated with the more extincted, double source A1+A2. We propose that this is not a binary system, but a small bipolar reflection nebula at the root of the large-scale jet, outlining a still undetected circumstellar disk. The gas kinematics on a scale of ~0.2 pc seems to support our hypothesis, because it appears to trace rotation about the axis of the associated jet

Wideband 67−116 GHz receiver development for ALMA Band 2

Context. The Atacama Large Millimeter/submillimeter Array (ALMA) has been in operation since 2011, but it has not yet been populated with the full suite of its planned frequency bands. In particular, ALMA Band 2 (67−90 GHz) is the final band in the original ALMA band definition to be approved for production. Aims. We aim to produce a wideband, tuneable, sideband-separating receiver with 28 GHz of instantaneous bandwidth per polarisation operating in the sky frequency range of 67−116 GHz. Our design anticipates new ALMA requirements following the recommendations of the 2030 ALMA Development Roadmap. Methods. The cryogenic cartridge is designed to be compatible with the ALMA Band 2 cartridge slot, where the coldest components – the feedhorns, orthomode transducers, and cryogenic low noise amplifiers – operate at a temperature of 15 K. We use multiple simulation methods and tools to optimise our designs for both the passive optics and the active components. The cryogenic cartridge is interfaced with a room-temperature (warm) cartridge hosting the local oscillator and the downconverter module. This warm cartridge is largely based on GaAs semiconductor technology and is optimised to match the cryogenic receiver bandwidth with the required instantaneous local oscillator frequency tuning range. Results. Our collaboration has resulted in the design, fabrication, and testing of multiple technical solutions for each of the receiver components, producing a state-of-the-art receiver covering the full ALMA Band 2 and 3 atmospheric window. The receiver is suitable for deployment on ALMA in the coming years and it is capable of dual-polarisation, sideband-separating observations in intermediate frequency bands spanning 4−18 GHz for a total of 28 GHz on-sky bandwidth per polarisation channel. Conclusions. We conclude that the 67−116 GHz wideband implementation for ALMA Band 2 is now feasible and that this receiver provides a compelling instrumental upgrade for ALMA that will enhance observational capabilities and scientific reach