We present JWST images of NGC 6720 (the Ring Nebula), covering wavelengths from 1.6 μm to 25 μm. The bright shell is strongly fragmented with some 20 000 dense globules, bright in H2, with a characteristic diameter of 0.2 arcsec and density nH∼105–106cm−3. The shell contains a narrow ring of polycyclic aromatic hydrocarbon (PAH) emission. H2 is found throughout the shell and also in the halo. The central cavity is filled with high ionization gas and shows two linear structures seen in projection against the cavity. The central star is located 2 arcsec from the emission centroid of the cavity and shell. Linear features (‘spikes’) extend outward from the ring, pointing away from the central star. Around ten low-contrast, regularly spaced concentric arc-like features are present; they suggest orbital modulation by a low-mass companion with a period of about 280 yr. A previously known much wider companion is located at a projected separation of about 15 000 au; we show that it is an M2–M4 dwarf. NGC 6720 is therefore a triple star system. These features, including the multiplicity, are similar to those seen in the Southern Ring Nebula (NGC 3132) and may be a common aspect of such nebulae.

This note identifies a new acrostic in Christodorus’ sixth century c.e. Ekphrasis of the Baths of Zeuxippus (Anth. Pal. 2) and explains its significance.

We study ordered groups in the context of both algebra and computability. Ordered groups are groups that admit a linear order that is compatible with the group operation. We explore some properties of ordered groups and discuss some related topics. We prove results about the semidirect product in relation to orderability and computability. In particular, we give a criteria for when a semidirect product of orderable groups is orderable and for when a semidirect product is computably categorical. We also give an example of a semidirect product that has the halting set coded into its multiplication structure but it is possible to construct a computable presentation of this semidirect product.

We examine a family of orderable groups that admit exactly countably many orders and show that their space of orders has arbitrary finite Cantor–Bendixson rank. Furthermore, this family of groups is also shown to be computably categorical, which in particular will allow us to conclude that any computable presentation of the groups does not admit any noncomputable orders. Lastly, we construct an example of an orderable computable group with no computable Archimedean orders but at least one computable non-Archimedean order.

Abstract prepared by Waseet Kazmi.

E-mail: waseet.kazmi@uconn.edu

URL: http://hdl.handle.net/11134/20002:860745910

As a relatively active region, ephemeral region (ER) exhibits highly complex pattern of magnetic flux emergence. We aim to study detailed secondary flux emergences (SFEs) which we define as bipoles that their locations close to ERs and finally coalesce with ERs after a period. We study the SFEs during the whole process from emergence to decay of 5 ERs observed by the Helioseismic and Magnetic Imager (HMI) aboard Solar Dynamics Observatory (SDO). We find that the maximum unsigned magnetic flux for each of the ERs is around 1020 Mx. All ERs have tens of SFEs with an average emerging magnetic flux of approximately 5×1018 Mx. The frequency of normalized magnetic flux for all the SFEs follows a power law distribution with an index of -2.08. The majority of SFEs occur between the positive and negative polarities of ER, and their growth time is concentrated within one hour. The magnetic axis of SFEs also exhibits a random characteristic. We suggest that the relationship between SFEs and ERs can be understood by regarding the photospheric magnetic field observations as cross-sections of an emerging magnetic structure. Tracking the ERs’ evolution, we propose that the flux emergences are partially emerged Ω-loops, and that the SFEs in ERs may be sequent emergences from the bundle of flux tube of ERs.

Flux emergence at different spatial scales and with different amounts of flux has been studied using radiative magnetohydrodynamics (rMHD) simulations. We use the radiative MHD code MURaM to simulate the emergence of an untwisted magnetic flux tube of ephemeral region scale with a density nonuniformity into a background atmosphere with a small unipolar open field. We find that the tube rises to the photosphere, forming complex loop structures seen in synthetic Atmospheric Imaging Assembly(AIA) 171 Å images. The atmosphere reaches 105 K at 3Mm above the surface. Our simulation provides a reference example of a less twisted ephemeral region emergence and the atmospheric response.

This paper builds on a body of multi-disciplinary literature to analyze and compare the emergence of the prêt-à-porter industry in France and the ready-to-wear industry in Italy from their founding to their growth stages in the mid-twentieth century. The comparison demonstrates the significant impact that the French Chambre Syndicale de la Couture, des Confectionneurs et des Tailleurs pour Dame, and the National Chamber of Italian Fashion had on the trajectories of the fashion industry for each country. The article focuses on foundational entrepreneurs within the industry such as Giovanni Battista Giorgini, Jean Patou, Coco Chanel, Christian Dior, and others. It analyzes how these chambers supported the emergence of differentiated firms within the fashion industry, and how the industry responded to the business conditions in the international economy of the post-World War II period through the global recession of the 1970s.

During the Late Classic period (a.d. 550–900), ancient Maya settlement spread throughout western Belize, including the Vaca Plateau, a rugged karstic region with high densities of ritually utilized cave systems. Within the past decade, archaeologists have increasingly drawn on LiDAR technology to document the extent of such settlement at local and regional scales. Combined with traditional pedestrian survey, we have begun to amass substantial data on variation within household groups, disparities which may indicate inequality within these communities. Here, we use settlement data generated from the Las Cuevas region to quantify residential variation through Gini coefficients and Lorenz curves. Special attention is given to areal and volumetric deviation of identified households within three samples: (1) the complete 95.25 km2 study area; (2) a 12.25 km2 zone of higher population between the primary centers of Las Cuevas and Monkey Tail; and (3) households situated within 500 m of ritually utilized caves within the study area. Results indicate some degree of variation within household area and volume for all samples, suggestive of unequal access to labor within the region. This research adds to the growing database of Gini-based analyses to improve our understanding of wealth differentials within pre-modern populations throughout the Lowlands.

In Born losers: a history of failure in America (2005), historian Scott A. Sandage traces how, through the course of the nineteenth century, business failures gradually morphed into personal failures. Where losing money initially meant just that by the later nineteenth century, as the narrative of the ‘self-made man’ took hold, it came to be seen by society as a personal shortcoming and framed as a moral judgement. Fast-forward to the big-tech era of the twenty-first century and failure has become a trophy rather than a scar. Silicon Valley's credo of ‘fail fast and fail forward’ entrenches failure not only as a standard element of business practice—start-ups are expected to fail, their founders slated to move forward on their path to success—but also as a commendable addition to a CV or resumé thought to reflect ambition, innovativeness and resilience (see critique in Myers 2019). This admittedly truncated narrative of failure in America, closely intertwined with capitalist profit-seeking, serves to illustrate that failure is not a neutral concept but rather a social phenomenon, the reality and valence of which are context dependent. Moreover, like all social phenomena, failure has a history.

We have all heard horror stories of ChatGPT making information professionals redundant and taking over the world, but just how proficient is it at good old legal research? Greg Bennett, a law librarian at BPP, invested in the premium version of the package to put it to the test.

The inherent stochastic and nonlinear nature of the solar dynamo makes the strength of the solar cycles vary in a wide range, making it difficult to predict the strength of an upcoming solar cycle. Recently, our work has shown that by using the observed correlation of the polar field rise rate with the peak of polar field at cycle minimum and amplitude of following cycle, an early prediction can be made. In a follow-up study, we perform SFT simulations to explore the robustness of this correlation against variation of meridional flow speed, and against stochastic fluctuations of BMR tilt properties that give rise to anti-Joy and anti-Hale type anomalous BMRs. The results suggest that the observed correlation is a robust feature of the solar cycle and can be utilized for a reliable prediction of peak strength of a cycle at least 2 to 3 years earlier than the minimum.