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A white-box false positive adversarial attack method on contrastive loss based offline handwritten signature verification models
Get PDFFunding: The first author Zhongliang Guo acknowledges the financial support through the China Scholarship Council – University of St Andrews Scholarship (Grant No.202208060113).In this paper, we tackle the challenge of white-box false positive adversarial attacks on contrastive loss based offline handwritten signature verification models. We propose a novel attack method that treats the attack as a style transfer between closely related but distinct writing styles. To guide the generation of deceptive images, we introduce two new loss functions that enhance the attack success rate by perturbing the Euclidean distance between the embedding vectors of the original and synthesized samples, while ensuring minimal perturbations by reducing the difference between the generated image and the original image. Our method demonstrates state-of-the-art performance in white-box attacks on contrastive loss based offline handwritten signature verification models, as evidenced by our experiments. The key contributions of this paper include a novel false positive attack method, two new loss functions, effective style transfer in handwriting styles, and superior performance in white-box false positive attacks compared to other white-box attack methods
Visible fluid motion on manipulation as the new threshold for intraoperatively determined knee arthroplasty component loosening : a Delphi study
Get PDFFunding: An Internal TKI-PPP grant from the Amsterdam University Medical Center.Purpose: There is a lack of a clear, uniform definition for intraoperatively assessed component loosening of a knee arthroplasty component, complicating the interpretation and interchangeability of results of diagnostic studies using an intraoperative observation as the reference test. The purpose of this study was to establish a consensus among specialised knee revision surgeons regarding the definition of intraoperatively determined loosening of total or unicondylar knee arthroplasty components. Methods: Utilising the Delphi consensus method, an international panel of highly specialised knee revision surgeons was invited to participate in a three-round process. The initiation of the first round involved the exploration of possible criteria for intraoperatively determined loosening with open questions. The second round focused on rating these criteria importance on a five-point Likert scale. For the third round, criteria that reached consensus were summarised in consecutive definitions for intraoperatively determined loosening and proposed to the panel. Consensus was established when over 70% of participants agreed with a definition for intraoperatively determined loosening. Results: The 34 responding panel members described in total 60 different criteria in the first round of which 34 criteria received consensus in the second round. Summarising these criteria resulted in four different definitions as minimal requirements for intraoperatively determined loosening. Eighty-eight percent of the panel members agreed on defining a component as loose if there is visible fluid motion at the interface observed during specific movements or when gently applying direct force. Conclusion: This study successfully established a consensus using a Delphi method among knee revision surgeons on the definition of intraoperatively determined component loosening. By agreeing on the visibility of fluid motion as new definition, this study provides a standardised reference for future diagnostic research. This definition will enhance the interpretability and interchangeability of future diagnostic studies evaluating knee arthroplasty component loosening. Level of evidence: Level V.Peer reviewe
Alfvén wave propagation, reflection and trapping in the solar wind
No full textFunding: AK received funding from the Leverhulme Trust (RPG-2021-114). TAH received funding from the Carnegie Trust grant number RIG013386. PP acknowledges support by the Italian PRIN 2022, project 2022294WNB entitled “Heliospheric shocks and space weather: from multispacecraft observations to numerical modeling”, funded by Next Generation EU, within Piano Nazionale di Ripresa e Resilienza (PNRR), Missione 4 “Istruzione e Ricerca” - Componente C2 Investimento 1.1, ‘Fondo per il Programma Nazionale di Ricerca e Progetti di Rilevante Interesse Nazionale (PRIN)’. IDM received funding from the Research Council of Norway through its Centres of Excellence scheme, project number 262622.Alfvén waves are known to be important carriers of magnetic energy that could play a role in coronal heating and/or solar wind acceleration. As these waves are efficient energy carriers, how they are dissipated still remains one of the key challenges. Using a series of 1.5D magnetohydrodynamic (MHD) simulations, we explore wave energy trapping associated with field-aligned density enhancements. We examine the parameters that govern the wave reflection and trapping. The goal of our simulations is to find optimal conditions for wave trapping, which would ultimately promote the energization of the solar atmosphere. In agreement with previous studies, we find that maximum wave reflections happen only for a narrow range of density enhancement widths, namely when it is comparable to the Alfvén wave wavelength. In our paper, we explain this scale-selectivity using a semi-analytical model that demonstrates the importance of wave interference effects. As expected, we find that spatially extended regions of density inhomogeneities favour enhanced wave reflection and trapping. However, wave interference causes saturation of the reflected energy for very extended regions of varying density.Peer reviewe
Additional JWST/NIRSpec transits of the rocky M dwarf exoplanet GJ 1132 b reveal a featureless spectrum
Get PDFFunding: S.P. acknowledges support from NASA under award No. 80GSFC24M0006. H.R.W was funded by UK Research and Innovation (UKRI) framework under the UK government’s Horizon Europe funding guarantee for an ERC Starter grant (grant No. EP/Y006313/1). S.E.M. is supported by NASA through the NASA Hubble Fellowship grant HST-HF2-51563 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. L.A. acknowledges funding from UKRI STFC Consolidated grant ST/V000454/1 and is supported by the Klarman Fellowship. J.K. acknowledges financial support from Imperial College London through an Imperial College Research Fellowship grant.As an archetypal M-dwarf rocky exoplanet, GJ 1132 b has a varied history of atmospheric measurements. At 1.13 R⊕, 1.66 M⊕, and 580 K, it orbits a bright, slowly rotating M dwarf in a 1.6 day period, making it a prime target for characterization. In this study, we combine two JWST NIRSpec/G395H transits previously reported by E. M. May et al. (2023) with two new NIRSpec/G395M transits to constrain the presence of an atmosphere. This marks the first time the G395H and G395M modes have been combined for a single target, and we report no difference in the quality of data between the two modes. For rocky M-dwarf studies, G395H may still be preferred if stacking transits to utilize the high-resolution flux-calibrated stellar spectra and assess evolving stellar heterogeneity. GJ 1132 b’s coadded transmission spectrum is best fit with a flat line. A thin steam atmosphere is also consistent with the data, but this interpretation is driven almost entirely by the first transit, which suggests an increase in cool spot coverage-fraction derived from the flux-calibrated stellar spectra. This demonstrates the importance of always considering stellar heterogeneity evolution in multivisit transits, and also the importance of a “leave-one-transit-out” approach in modeling efforts of coadded transits. We combine these results with MIRI/LRS emission data to show that together, transmission and emission are consistent with only the thinnest of atmospheres. Given GJ 1132 b’s age and distance from the star, a thin atmosphere is not likely stable. Therefore, the simplest explanation is that GJ 1132 b is indeed a bare rock.Peer reviewe
Transformer-based feature learning for algorithm selection in combinatorial optimisation
Get PDFFunding: This work was supported by the European Union's Justice programme, under GA No 101087342, POLINE (Principles Of Law In National and European VAT), by a scholarship from the Department of Computer Science and Engineering of the University of Bologna, and by UK EPSRC grant EP/V027182/1.Given a combinatorial optimisation problem, there are typically multiple ways of modelling it for presentation to an automated solver. Choosing the right combination of model and target solver can have a significant impact on the effectiveness of the solving process. The best combination of model and solver can also be instance-dependent: there may not exist a single combination that works best for all instances of the same problem. We consider the task of building machine learning models to automatically select the best combination for a problem instance. Critical to the learning process is to define instance features, which serve as input to the selection model. Our contribution is the automatic learning of instance features directly from the high-level representation of a problem instance using a transformer encoder. We evaluate the performance of our approach using the Essence modelling language via a case study of three problem classes
Problematising grand challenges through accounting inscriptions : the case of poverty
Get PDFPurpose The purpose of this study is to investigate the role of accounting inscriptions in the process of identifying a grand challenge, i.e. defining, re-presenting and constructing a grand challenge as a problem to be addressed. More specifically, we consider the case of a poverty alleviation network and the role of accounting in mediating the dynamics between multiple actors with different perspectives and interests. Design/methodology/approach To attend to the research aims, this study employs a multi-method qualitative approach based on semi-structured interviews and participant observation. Informed by Callon’s (1980) socio-logic of translation, and in particular, by the notion of problematisation, this study unpacks the process through which the identification of a problem unfolds. Findings By drawing on Callon (1980, 1984), we conceptualize the construction of a problem as a relational process where different actors, motivated by different perspectives and interests, interact around the nature of the problem. By defining areas of “certainty”, “unanalysed” and “suspicion” (Callon, 1980), the territory of analysis of the poverty problem is carved out and an understanding of poverty and how it could be mitigated is constructed. Within this process, we reveal that accounting inscriptions played a key role in supporting different actors’ problematisations within the network and ultimately in legitimizing some interests over others. Originality/value Analysing the process of problematising poverty in the context of poverty alleviation, through the theoretical construct of problematisation, enables us to contribute to the accounting literature on grand challenges by shedding light on the dynamics of how these complex problems are constructed and addressed. Further, the insights provided by our analysis contribute to the understanding of the role of accounting inscriptions in identifying the nature of a grand challenge within a network of actors; the identification of a grand challenge represents a pre-condition for deciding about any mitigation policies, strategies and/or initiatives to be undertaken.Peer reviewe
Reliable reconstruction of cricket song from biophysical models and preserved specimens
Get PDFFunding: We would like to thank the following funding sources for their support of this research: Canada Foundation for Innovation (CFI4748) and the Ontario Research Fund, NSERC Discovery (Grant no. 687216), early career supplement (675248) and an NSERC Canada research chair (Grant no. 693206) to N.M.; the Western SEED grant to N.M.; Western Undergraduate Work Study to S.D.; Western Undergrad Summer Research Internship to R.W.; and UK Natural Environment Research Council funding to N.W.B. (NE/I027800/1, NE/L011255/1, NE/W001519/1).Predicting the function of a biological structure solely from its morphology can be a very powerful tool in several fields of biology, but especially in evolutionary reconstruction. In the field of invertebrate acoustic communication, reconstructing the acoustic properties of sound-producing forewings in crickets has been based on two very divergent methods, finite element modelling (FEM) and vibrometric measurements from preserved specimens. Both methods, however, make strong simplifying assumptions that have not been tested and the reliability of inferences made from either method remains in question. Here, we rigorously test and refine both reconstruction methods using the well-known Teleogryllus oceanicus model system and determine the appropriate conditions required to reconstruct the vibroacoustic behaviour of male forewings. We find that when using FEM it is not necessary to assume simplified boundary conditions if the appropriate parameters are found. When using preserved specimens, we find that the sample needs to be rehydrated for reliable reconstruction; however, it may be possible to accomplish rehydration in silico using FEM. Our findings provide a refined methodology for the reliable reconstruction of cricket songs, whether from fossils or preserved specimens from museums or field collections.Peer reviewe
A 16 Myr super-Neptune in Upper Centaurus Lupus and a preliminary survey of transiting planets in Sco-Cen with TESS
Get PDFFunding: G.Z. thanks the support of the ARC DECRA program DE210101893 and ARC Future program FT230100517. CH thanks the support of the ARC DECRA program DE200101840.Measuring the properties of planets younger than about 50 Myr helps to test different planetary formation and evolution models. NASA’s Transiting Exoplanet Survey Satellite (TESS) has observed nearly the entire sky, including a wide range of star-forming regions and young stellar clusters, expanding our census of the newborn planet population. In this work, we present the discovery of the TIC 88785435 planetary system located in the Upper Centaurus Lupus (UCL) region of the Scorpius Centaurus OB association (Sco-Cen) and a preliminary survey of the planet population within Sco-Cen. TIC 88785435 is a pre-main-sequence, K7V dwarf (M⋆ = 0.72 M⊙, R⋆ = 0.91 R⊙, Teff = 3998 K, V = 11.7 mag) located within the bounds of UCL. We investigate the distribution of rotation periods measured from the TESS long-cadence data and the Hα and Li abundances from the spectra of TIC 88785435. TESS long-cadence data reveal that TIC 88785435 hosts a transiting super-Neptune (Rb = 5.03 R⊕, P = 10.51 days), TIC 88785435b. Ground-based follow-up validates the planetary nature of TIC 88785435b. Using the TESS data, we perform a preliminary survey to investigate how TIC 88785435b compares to the population of newly born planets located within Sco-Cen.Peer reviewe
First-order aboutness theory
Get PDFFunding: Fundação para a Ciência e Tecnologia (Grant number 2021.06938.BD).We seem to have a good grasp of how the subject matters of truth-functional composites depends on their components: it’s simply fusion (Hawke in Australas J Philos 96:697–723, 2018, Fine in Philos Studies 177:129–171, 2020, Plebani and Spolaore in Philos Q 71:605–622, 2021, Plebani and Spolaore in Philos Stud 181:247–265, 2021, Berto in Topics of Thought, Oxford University Press, Oxford, 2022). But what relation should the subject matter of subsentential components bear to the subject matter of the sentences they feature in, and what to say about the quantified sentences of first-order predicate logic? Given how well we seem to understand sentential subject matter in the context of propositional logic, I propose a reduction of the subject matter of subsentential components and of quantified sentences to the subject matter of quantifier-free sentences. I argue that the view squares with the Fregean intuitions that gave rise to the construction of first-order logic as we know it today, motivating its adequacy as a theory of subject matter for first-order languages. I then show that this first-order aboutness theory has predictive and explanatory power, leading us to accept a modified version of Yablo’s (Aboutness, Princeton University Press, Princeton, 2014) principle of immanent closure, as well as a new conception of arbitrary objects/reference. Finally, I propose some potential developments and restrictions.Peer reviewe
The people in modern political thought : an outline history
Get PDFThe people is a significant presence in the political thought of the modern era. Popular sovereignty is a key concept of modern political thinking. Yet the people itself, the possessor of that sovereignty, is given little attention in the history of modern political thought. This article sketches an outline history of how modern political thought has answered the question of how it is possible to conceive of the population of a nation as united into being a single corporate entity, such that the fact that a population comprises many individuals with many different preferences and points of view is no obstacle to describing it as having a single will and a capacity for single action. Hobbes is the point of departure, and the first half of the article describes responses to Hobbes on the part of, among others, Pufendorf, Locke, and Rousseau. It then turns to the conceptualisation of the revolutionary period and its aftermath, focusing in particular on liberalism’s failure to develop a proper theory of the people. The article ends with Schmitt’s critique of this failure, and with early twentieth-century liberalism’s move to dispense with the people altogether.Peer reviewe
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