The further embedding of immigration checks into UK public sector institutions have made them key sites of bordering. Information systems for datafication, established to enable the reporting and sharing data between these institutions and the UK Home Office, have become emerging sites for opposition to the UK’s border and immigration regime. In this paper, I will highlight the ways in which ‘everyday borderworkers’ in hospitals and higher education have practiced forms of refusal that have undermined these information systems and made care and education accessible to patients and students. However, such ‘data activism’ and the ‘un/bordering’ it enables is under threat from the expansion of machine learning into state bordering practices and processes or what Louise Amoore has called ‘the deep border’. Just as for some states almost every mundane space is becoming a potential site of bordering, so too computer science appears to be rendering all spaces as ‘feature spaces’. A feature is a set of attributes associated to an example and is generated by the examples the algorithm is exposed to. The algorithm still generates the feature, whether data is withheld or not. It uses the examples that are there. Clustering algorithms, Amoore argues, not only becomes a way for imagining and grouping people, places and even countries but also for inferring the behaviours and attributes of this group. I will argue that the expansion of the deep border into bordering public sector institutions will render current forms of data activism to deborder these institutions obsolete.
This article introduces the notion of kinship surveillance as the unilateral production of knowledge about familial relationships of migrants, undertaken and weaponised by the state to enact border regimes. I ask why and how knowledge about migrants’ kinship relations has been rendered a relevant scale of border control, and how it has historically been enacted through different media technologies. The article’s aim is to expose the historical cultural work that legitimises a technopolitics of weaponisation around kinship: rendering an enunciation of “family” as biological and genetic into a means of enacting border regimes. In particular, the article unpicks how fears of fraud and deception, and fears of being “too slow” and “overwhelmed”, structure the ways kinship gets technologically reduced to information points that can be extracted, stored, surveilled, and used in complicity with border regimes. In doing so, the paper draws on archival material around the introduction of “DNA fingerprinting” by the UK Home Office during the 1980s, as well as on the case of blood group testing of Chinese immigrants employed by the USA in the 1950s. At a moment of rampant digitalisation and automation of evermore clamped-down border regimes, I argue that historicizing the technopolitics of kinship surveillance decentres innovationist hypes around “smart” border technologies and challenges the naturalised epistemic authority and weaponisation of knowing and surveilling migrants’ familial relations.
Image-based sexual abuse (IBSA), including the non-consensual distribution of intimate images (NCII), is an exponentially growing issue. Private online reporting and removal tools, such as the Take It Down service run by the NCMEC, can empower victim-survivors, especially young people, who experience threats of the sharing of their intimate images. By pre-emptively reporting images, users could ideally block them from ever being posted on multiple major online platforms with one report, taking power away from perpetrators of sextortion and protecting against the reuploading of known IBSA content.
These services rely on sharing “perceptual hash values” (like digital fingerprints) of images with online platforms in order to match IBSA content without sharing the images/videos themselves. However, our research shows that generative AI attacks using consumer-grade hardware can be used to approximately reconstruct images from their hash value, known as “hash inversion”. This indicates that the hash values should be treated as carefully as the original images, otherwise vulnerable users’ privacy may be put at risk, for example if perceptual hash values of reported intimate images became public as the result of a data breach.
To mitigate this attack, we propose implementing Private Set Intersection (PSI) as an additional layer of protection, to enhance the security and privacy for users whilst maintaining the functionality required to detect and remove IBSA. We highlight the future potential for private pre-emptive reporting to combat sextortion threats, and the need for user-focused design and greater transparency in IBSA reporting and removal tools.
The Protection of Children Act, 1978 (PCA) is widely considered the definitive piece of legislation with regards to youth sexual image sharing. It states that it is an offence to make, possess or distribute indecent images of anyone under 18 and was designed to respond to cases where adults sexually abused children and filmed or photographed that abuse. As youth sexual image sharing has become increasingly normalised, many have called for the legislation to be changed or updated to prevent the over-criminalisation of young people. Another issue with the PCA is its influence on education policy, promoting the prevention / prohibition approach. I will explore how this prohibition message does not in fact prevent young people being victimised by adults but instead serves to reinforce the threats and control tactics used by groomers who coerce young people to take and share sexual images, therefore the PCA is no longer compatible with children’s rights. I will discuss how the Online Safety Act’s (2023) development of non-consensual image sharing offences may offer an alternative approach. This approach could be used to foreground young people’s consent, whilst also providing opportunities to share details of support services and how to remove images that have been shared to social media and pornography sites (such as takeitdown.ncmec.org), which a straightforward prevention message cannot easily achieve. I will conclude by showing how this approach is more compatible with children’s rights and can challenge rather than reinforce the tactics used by groomers.
There is notably growth in the use of deepfake technology to create fake, yet indistinguishable from real life, sexual images and videos of others without their consent. Though there is an emerging understanding of the impact to which this has on it’s targets, the individuals from which this information comes from is almost entirely those whose facial likeness has been used within the media, with little attention paid to those whose bodies have been used as the canvas. Across 321 participants (Mage = 45.70 years, SD = 15.88; 48.9% female), we explored societal judgements of survivors whose face and/or body likeness had been used to create sexualized videos via a vignette design, which also took into account whether said survivors where sex workers or not. Though perceived criminality did not differ across our conditions, participants allocated more blame and less anticipated impact to the body target, relative to the face target, especially if they were noted in the vignette to be a sex worker. Moreover, when accounting for personality traits, beliefs, and demographics, being male and viewing sex work as ‘a choice’ and/or ‘deviant’ predicted greater victim-blame, lower perceived criminality of deepfaking, and lower anticipated harm, with increased empathy being the only predictor of higher anticipated harm. Results suggest a need to understand the broader impacts of sexualized deepfake abuse for both facial and body targets, and continue to generate public awareness of the impact this form of image-based sexual abuse can have on its survivors.
With a strategy of obtaining deep JWST imaging and following up interesting candidates with NIRSpec spectroscopy, the JADES survey has: broken the highest redshift spectroscopically confirmed record (twice); found possible evidence for the earliest black hole at z~10.6, though other explanations exist; found direct evidence for the stochasticity of star formation in early galaxies with the highest redshift ‘mini-quenched’ galaxy, and much more besides. I will summarise key results from JADES survey focusing on Chemical evolution and abundances of the earliest galaxies.
The astrophysical origins of the heaviest elements via rapid neutron capture remain unresolved, even with exciting recent progress in gravitational wave and astronomical observations. One key barrier to elucidating r-process origins using these new observables are the uncertainties that arise from the unknown properties of the thousands of nuclear species that participate in the r process. Here we consider the role played by nuclear physics uncertainties in our interpretations of r-process observables such as light curves, abundance patterns, and isotopic ratios. We will discuss the prospects for reducing these uncertainties via advances in nuclear theory and experiment and point out potential observables that may rise above current uncertainties.
The merging of two neutron stars can provide the conditions necessary for the production of the heaviest elements in the universe via the rapid neutron capture process (r-process). When this occurs, an abundance of material is produced lying far from nuclear stability, and the decays of these nuclei produce the electromagnetic signal: the kilonova. Modeling these kilonova signals, and indeed the entire merger system, remains subject to uncertainties stemming from both nuclear properties far from stability as well as from incomplete information regarding the evolution of the extreme astrophysical environment in which this occurs.
I will discuss current work aimed at approaching this problem from both an astrophysical perspective with magnetohydrodynamic simulations of the post-merger disk with neutrino transport, as well as from a nuclear perspective with detailed nucleosynthesis studies.
We measure stellar age for APOGEE giants using our Bayesian Machine Learning framework BINGO (Bayesian INference for Galactic archaeOlogy, Ciuca et al. 2024). After de-noising the data, we found a drop in metallicity with an increase in [Mg/Fe] at an early epoch, followed by a rapid chemical enrichment with increasing [Fe/H] and decreasing [Mg/Fe]. Comparing with the Milky Way-like zoom-in cosmological simulation Auriga, we discuss that this could be due to the early epoch of gas-rich merger. We further argue that this could be associated with the last massive merger of our Galaxy, the Gaia-Sausage-Enceladus merger, and discuss how it impacted the formation of the Galactic thick and thin disks and also the Galactic bar. We will also briefly introduce Japan Astrometry Satellite Mission for INfrared Exploration (JASMINE), which will reveal the Milky Way’s central core structure and its formation history with Gaia-level (~25 uas) astrometry in the NIR Hw-band, (1.0-1.6 um), Galactic centre archaeology survey.
The spectra currently emerging from ground- and space-based facilities are of exceptional resolution and cover a broad range of wavelengths. To meaningfully analyse these spectra, astronomers utilise complex modelling codes to simulate the astrophysical observations. The main inputs to these codes are radiative and collisional atomic data to include energy levels, transition probabilities, collision rates for electron-impact excitation/ionisation, photoionisation and recombination. While some of the data can be obtained experimentally, they are usually of insufficient accuracy or limited to a small number of transitions. The R-Matrix approach is credited as one of the most powerful and reliable tools in calculating these atomic data. Recent and ongoing developments of the relativistic parallel DARC codes have enabled an order of magnitude advance in the accuracy of the atomic structure and subsequent collision calculations that are now feasible for lowly ionised high Z ions.
In 2017 the first gravitational wave from a binary neutron star merger (NSM) was detected and the ejected matter created a bright glow called a Kilonova via r-process nucleosynthesis. Disentangling r-process abundances from the broad spectra of NSM is a challenging task that demands a high degree of rigour in calculations of the ejecta opacity and the atomic calculations that underpin them. Recent publications by the group at QUB report on extensive relativistic atomic structure and electron-impact excitation collision calculations for the species Au I-III, Pt I-III, Sr II, Y II and Te I-III, which were subsequently used in collisional-radiative models to investigate line ratio diagnostics in NSM environments.
Currently, the explanation behind the explosion mechanism of core collapse supernovae is yet to be fully understood. New insight to this phenomena may come through observations of 44Ti cosmic gamma rays; this technique compares the observed flux of cosmic 44Ti gamma rays to that predicted by state-of-the-art models of supernova explosions. In doing so, the mass cut point of the star can be found. However, a road block in this procedure comes from a lack of precision in the nuclear reactions that destroy 44Ti in supernovae, most notably the reactions 44T(alpha,p)47V and 45V(p,gamma)46Cr. Therefore, this study aims to better understand the 45V(p,gamma)46Cr reaction by performing gamma-ray spectroscopy of 46Cr with the aim of identifying proton-unbound resonant states.
The experiment was conducted at the ATLAS facility at Argonne National Laboratory, using the GRETINA+FMA setup, where 46Cr was produced via the fusion-evaporation reaction 12C(36Ar,2n). The cross section for producing 46Cr, in this reaction, is estimated to be in the mu b range. Nevertheless, with the power of the GRETINA+FMA setup, we show that it is possible to cleanly identify gamma rays in 46Cr. These include decays from previously unidentified states above the proton-emission threshold, corresponding to resonances in the 45V + p system.
Type-I X-ray bursts are interpreted as thermonuclear explosions in the atmospheres of accreting neutron stars in close binary systems. During these bursts, sufficiently high temperatures are achieved such that “breakout” from the hot CNO cycle occurs. This results in a whole new set of thermonuclear reactions known as the rp process. This process involves a series of rapid proton captures resulting in the synthesis of very proton-rich nuclei up to the Sn – Te (A ∼ 100) mass region. Various sensitivity studies have highlighted the 59Cu(p,γ)60Zn reaction as significant in its impact on energy generation along the rp -process path within X-ray bursts, and hence, the resultant light curve and final isotopic burnt ashes composition. In particular, competition between the 59Cu(p,α)56Ni and 59Cu(p,γ)60Zn reactions within the NiCu cycle directly determines whether the pathway of nucleosynthesis flows towards higher mass regions. At present, stellar reaction rates for both of these astrophysical processes are based entirely on statistical-model calculations. Recently, however, an indirect study of the nucleus 60Zn has surprisingly shown a plateau in the level-density of states in the region of interest, contrary to the usual expectation of exponential growth with increasing excitation energy. As a result, a statistical-model approach of the 59Cu(p,γ) reaction rate may be insufficient, and it is therefore now essential to explore the properties of excited states in 60Zn that influence the astrophysical 59Cu(p,γ)60Zn reaction. Specifically, the 59Cu(p,γ) reaction is expected to be dominated by resonant capture to excited states above the proton-emission threshold in 60Zn, Sp = 5105.0(4) keV, that lie within the Gamow energy window, Ecm ∼ 0.7 – 1.5 MeV. In this work, we aim to utilise the 59Cu(d,n) reaction in inverse kinematics at the Facility for Rare Isotope Beams (FRIB) to obtain the first measurement of single-particle properties of resonances in the 59Cu(p,γ) reaction. Specifically, 60Zn ions separated within the S800 spectrometer and identified prompt with respect to γ-rays detected by the GRETINA array will be used to determine the energy and angle-integrated cross sections of key resonance states, while neutrons detected by the LENDA array will be used to constrain the distribution of spin-parity assignments across the relevant excitation energy region of Type-I X-ray burst nucleosynthesis.
The AT2017gfo has added to the growing interest in r-process elements, which are expected to be particularly abundant in the nucleosynthesis trajectories of neutron star mergers. With the choice of elements guided by nuclear physics at particular values of Y_e, our group calculates atomic data catered for modelling of the astrophysical objects without the use of local-thermodynamic-equilbirum using collisional radiative modelling. By enforcing observed luminosities, we are then able to make mass estimates of the candidate ions. This serves particularly as a test of the calculated atomic data and, based on the feasibility of the mass estimate, also the underlying nucleosynthesis theory. This event, as well as the GRB230307A last year sport features consistent with the fine structure lines of Te and W, which are particularly interesting to atomic and nuclear physicists likes – as these species lie at the second and third peaks respectively of the r-process abundance. These features also occur at the late stage collisionally dominated regime of the events, making an optically thin model suitable for their analysis. Collisional radiative modelling, and particularly mass estimation of these species in and out of LTE will be discussed.
Carbon burning is a key step in the evolution of massive stars, Type 1a supernovae and superbursts in x-ray binary systems. Nevertheless, our understanding of this critical fusion reaction is not as complete as might be desirable to fully constrain astrophysical models. This limitation centres of the difficulty in determining the $^{12}$C+$^{12}$C fusion cross section at energies corresponding to the Gamow window for these different scenarios as it relies on extrapolation of direct measurements made at higher energies. Such direct fusion measurements are complicated by the presence of resonances at and below the Coulomb barrier. These resonances have traditionally been associated with the formation of short-lived molecular states based on $^{12}$C+$^{12}$C or similar alpha-conjugate systems. Despite study of these resonances over many years, a comprehensive theoretical model accounting for their existence and structure is presently lacking.
Given the difficulties associated with direct fusion studies of the $^{12}$C+$^{12}$C reaction, indirect studies which can identify potential resonances within the respective Gamow windows are of high value. In this respect, a study of the $^{24}$Mg($alpha$,$alpha$’)$^{24}$Mg reaction has identified several 0$^{+}$ states in $^{24}$Mg, close to the $^{12}$C+$^{12}$C threshold, which predominantly decay to $^{20}$Ne(ground state) + $alpha$ [1]. Not only were these states newly identified but surprisingly they were not observed in previously well-studied $^{20}$Ne($alpha$,$alpha_0$)$^{20}$Ne resonance scattering, potentially suggesting that they have a dominant $^{12}$C+$^{12}$C cluster structure. Given the very low angular momentum associated with sub-barrier fusion, these states, which sit in the Gamow window for massive stars, may play a decisive role in $^{12}$C+$^{12}$C fusion. We present estimates of updated $^{12}$C+$^{12}$C fusion reaction rates based on likely parameters for such resonances [1].
A fascinating aspect of the identification of these potential 0$^+$ cluster states in $^{24}$Mg close to the break-up threshold for $^{12}$C+$^{12}$C and similar channels such as $^{16}$O+$^8$Be is the circumstantial similarity to the situation in $^{12}$C with the Hoyle state at the break-up threshold and the critical role that it plays in in helium burning.
Nucleosynthesis yields from sub-Chandrasekhar (sub M-ch) and Chandrasekhar (M-ch) SN Ia progenitors have been discussed and debated for decades on their contributions to iron peak elements in the cosmos. Investigating SNe Ia in ultra-faint dwarf galaxies (UFDs) and dwarf spheroidal galaxies (dSphs) with different star formation and chemical enrichment histories may shed light on the progenitors in different environments. To this end, we incorporate metallicity dependent SN Ia yields from different progenitors within our novel inhomogeneous chemical evolution model, i-GEtool, and compare the predicted chemical abundances to observations in different UFD and dSph galaxies. While the observed [Mn/Mg] ratios increase towards higher metallicities both within single galaxies and when considering galaxies with different metallicity distributions, the observed [Ni/Mg] ratios show a weaker correlation. In my talk, I will show that our models for UFD and dSph can reproduce the observed trends along with their scatter without invoking any contribution from sub M-ch SN Ia progenitors, at variance with previous studies in the literature. I will discuss the implications of our findings for the observed iron peak elemental abundances in the Milky Way halo and disks, outlining our future plan.
The population of isomeric (metastable) excited states in nuclei within astrophysical environments associated with R-process freezeout can affect the final abundance of stable isotopes; these astrophysically relevant isomers are known as `astromers’ [1][2]. Astromers can be populated/depopulated via various electromagnetic mechanisms, generally via low excitation energy, short-lived states above the isomer. The population of these `astromers’ has been studied theoretically using the Planckian photon bath [1] in which a network of photo-nuclear excited states and subsequent relaxations is considered during the population of an astromer from its associated nuclear ground state.
Similarly, an isomer can be depopulated [2] with a much lower, yet albeit comparable electron flux via inelastic electron-scattering processes, which will necessarily also deplete the astrophysical isomer [3]. One such electromagnetic process is `nuclear excitation by electron capture’ (NEEC), which is the inverse of internal conversion, recently reported to deplete isomers terrestrially with a high [4], yet still refuted [5], excitation probability in a radioactive ion-beam scenario.
This presentation focuses around encouraging the development hot-dense-plasma experiments using the photon and electron flux available at current or in-development peta-Watt (PW) laser facilities, which allow experimentation into separating the electromagnetic mechanisms at play in depleting isomers. This will allow us to readily challenge the relevance of astromers in calculating the final abundance of isotopes in the cosmos.
References
[1] G. Wendell Misch et al. “Astromers: Nuclear Isomers in Astrophysics”. In: The Astrophysical Journal Supplement Series 252.1 (Dec. 2020), p. 2. doi: 10.3847/ 1538-4365/abc41d
[2] G. Wendell Misch, T. M. Sprouse, and M. R. Mumpower. “Astromers in the Radioactive Decay of r-process Nuclei”. In: The Astrophysical Journal Letters 913.1 (May 2021), p. L2. doi: 10.3847/2041- 8213/abfb74
[3] J. Carroll and C. Chiara. “Isomer depletion”. In: The European Physical Journal Special Topics (Apr. 2024). doi: 10.1140/epjs/s11734-024-01149-8
[4] C. Chiara et al. “Isomer depletion as experimental evidence of nuclear excitation by electron capture”. In: Nature Publishing Group 554.7691 (2018), pp. 216–218. doi: 10.1038/nature25483.
[5] Y. Wu, C. H. Keitel, and A. P´alffy. “93mMo isomer depletion via beam-based nuclear excitation by electron capture”.
From the chemodynamical properties of tidal debris in the Milky Way (MW), it has been inferred that disrupted dwarf satellites had different chemical abundances at their time of accretion compared with similar-mass dwarf satellites which survive at present day. Specifically, disrupted satellites appear to have had lower [Fe/H] and higher [Mg/Fe] at fixed stellar mass than the surviving ones. In a recent study (Grimozzi, Font & De Rossi 2024), we have used the ARTEMIS simulations to investigate this problem, and determine the evolution of chemical abundances (e.g., the stellar mass-metallicity relation, MZR) with redshift. We have found a strong correlation between the scatter in the MZR of the disrupted dwarfs and their accretion redshift (zacc), as well as with their cold gas fractions at accretion. The slopes of the MZRs of disrupted dwarf satellites are fairly similar at different accretion redshifts, and are comparable with the MZR slope of surviving satellites in the MW today (≈ 0.32). This findings constrain some of the physical processes that regulate the chemical enrichment of dwarf galaxies (for example, the stellar feedback). The simulations also predict strong correlations between averaged properties of the disrupted dwarf populations, such as between «zacc», «[Fe/H]» and «[Mg/Fe]»), which suggests that the chemical abundances of the entire disrupted dwarf population can be used to constrain the merger history of its host. More specifically for the MW, the ARTEMIS simulations predict that the bulk of the disrupted population was accreted at «zacc» ≈ 2, to match the averaged «[Fe/H]» and «[Mg/Fe]». More broadly, our results suggest that one can gain an insight into the formation histories of other MW ‘analogues’, such as M31 or other massive galaxies nearby, provided that chemical abundances ([Fe/H] and [alpha/Fe]) of their debris from disrupted satellites become available.
The workhorse of understanding stellar evolution has been in 1D stellar evolution modelling, where simplified prescriptions of physical processes are implemented to evolve a star over its entire lifetime. While stellar evolution modelling has improved over the decades, their results are still limited by uncertainties in the physics due to complex multi-dimensional processes in stellar interiors. To better understand, and hopefully improve some of these uncertainties, we have run 3D hydrodynamic simulations of the final hour of silicon shell convection of a 14M_solar star prior to core-collapse. I will present these results, and compare them to what was found in 1D stellar evolution calculations. I will discuss how the presence of realistic turbulent mixing affects nuclear burning and how choices of convective overshooting in 1D can affect the final structure of the massive star.
Massive stars are not understood well enough given the important role their evolution and fates play in Galactic Chemical Evolution (GCE). One key uncertainty is convective boundary mixing (CBM), which encompasses the processes by which materials mix across the edge of convective turbulent regions inside stars. As a result of its effects on stellar structure during evolution, CBM also affects nucleosynthesis and consequently stellar yields. To investigate the importance of CBM we have computed two grids of stellar models at Z={10}^{-3} and two different strengths of CBM using the MESA code. The first being the typical CBM value used in literature and the second is based on the results of 3D convection simulations. In this talk, we will present a comparison of the structure of massive stars both during their evolution and at the end of their lives for these two different strengths of CBM to assess the impact of CBM on stellar evolution, SN progenitors and nucleosynthesis with a particular emphasis on the mergers of different burning shells.
Thorne-Żytkow Objects are a class of hybrid stars (Thorne & Żytkow 1977), consisting of a neutron star, surrounded by a diffuse convective envelope.
The formation rates of TŻOs are not well constrained but the presence of a modest population of such objects in the Galaxy could have a significant effect on Galactic Chemical Evolution. Optimistically, a large fraction of X-ray binaries end up as TŻOs, contributing to the abundance of p-process elements.
Farmer et al. (2023) placed a central boundary condition at ~600km above the centre of the star whereas we instead opt to place this at the surface of the neutron star and make use of an accretion prescription set by the opacity at the base of the envelope to model the release of gravitational energy.
We construct a series of models that show differences from those of Cannon and Farmer. Our models’ structures show an analogue of the supergiant-like solutions from TŻ and Cannon et al., these solutions being found across a wide range of masses, including where TŻ found a different, giant-like structure.
We find that the deviation from the Cannon et al. series can be explained by our prescriptions for neutrino generation, while the more significant differences to Farmer et al. are likely a function of the differences in boundary conditions.
We discuss the implications of the possible existence of differing series of structures for TŻOs. We also discuss the implications of our structures for nucleosynthetic pathways, and the further effects on GCE.