Defending Against Transfer Attacks From Public Models

Adversarial attacks have been a looming and unaddressed threat in the industry. However, through a decade-long history of the robustness evaluation literature, we have learned that mounting a strong or optimal attack is challenging. It requires both machine learning and domain expertise. In other words, the white-box threat model, religiously assumed by a large majority of the past literature, is unrealistic. In this paper, we propose a new practical threat model where the adversary relies on transfer attacks through publicly available surrogate models. We argue that this setting will become the most prevalent for security-sensitive applications in the future. We evaluate the transfer attacks in this setting and propose a specialized defense method based on a game-theoretic perspective. The defenses are evaluated under 24 public models and 11 attack algorithms across three datasets (CIFAR-10, CIFAR-100, and ImageNet). Under this threat model, our defense, PubDef, outperforms the state-of-the-art white-box adversarial training by a large margin with almost no loss in the normal accuracy. For instance, on ImageNet, our defense achieves 62% accuracy under the strongest transfer attack vs only 36% of the best adversarially trained model. Its accuracy when not under attack is only 2% lower than that of an undefended model (78% vs 80%). We release our code at https://github.com/wagner-group/pubdef.Comment: Under submission. Code available at https://github.com/wagner-group/pubde

The post-common-envelope, binary central star of the planetary nebula Hen 2-11

We present a detailed photometric study of the central star system of the planetary nebula Hen 2-11, selected for study because of its low-ionisation filaments and bipolar morphology - traits which have been strongly linked with central star binarity. Photometric monitoring with NTT-EFOSC2 reveals a highly irradiated, double-eclipsing, post-common-envelope system with a period of 0.609 d. Modelling of the lightcurve indicates that the nebular progenitor is extremely hot, while the secondary in the system is probably a K-type main sequence star. The chemical composition of the nebula is analysed, showing Hen 2-11 to be a medium-excitation non-Type I nebula. A simple photoionisation model is constructed determining abundance ratios of C/O and N/O which would be consistent with the common-envelope cutting short the AGB evolution of the nebular progenitor. The detection of a post-common-envelope binary system at the heart of Hen 2-11 further strengthens the link between binary progeny and the formation of axisymmetric planetary nebulae with patterns of low-ionisation filaments, clearly demonstrating their use as morphological indicators of central star binarity.Comment: Accepted for publication in A&A. 9 pages, 5 figures, 4 table

Lessons from the Ionised and Molecular Mass of Post-CE PNe

Close binary evolution is widely invoked to explain the formation of axisymmetric planetary nebulae after a brief common envelope phase. The evolution of the primary would be interrupted abruptly, its still quite massive envelope being fully ejected to form the PN, which should be more massive than a planetary nebula coming from the same star, were it single. We test this hypothesis by investigating the ionised and molecular masses of a sample consisting of 21 post-common-envelope planetary nebulae, roughly one-fifth of their known total population, and comparing them to a large sample of regular planetary nebulae (not known to host close-binaries). We find that post-common-envelope planetary nebulae arising from single-degenerate systems are, on average, neither more nor less massive than regular planetary nebulae, whereas post-common-envelope planetary nebulae arising from double-degenerate systems are considerably more massive and show substantially larger linear momenta and kinetic energy than the rest. The reconstruction of the common envelope of four objects further suggests that the mass of single-degenerate nebulae actually amounts to a very small fraction of the envelope of their progenitor stars. This leads to the uncomfortable question of where the rest of the envelope is, raising serious doubts on our understanding of these intriguing objects

The planetary nebula IC 4776 and its post-common-envelope binary central star

We present a detailed analysis of IC 4776, a planetary nebula displaying a morphology believed to be typical of central star binarity. The nebula is shown to comprise a compact hourglass-shaped central region and a pair of precessing jet-like structures. Time-resolved spectroscopy of its central star reveals periodic radial velocity variability consistent with a binary system. While the data are insufficient to accurately determine the parameters of the binary, the most likely solutions indicate that the secondary is probably a low-mass main sequence star. An empirical analysis of the chemical abundances in IC 4776 indicates that the common-envelope phase may have cut short the AGB evolution of the progenitor. Abundances calculated from recombination lines are found to be discrepant by a factor of approximately two relative to those calculated using collisionally excited lines, suggesting a possible correlation between low abundance discrepancy factors and intermediate-period post-common-envelope central stars and/or Wolf-Rayet central stars. The detection of a radial velocity variability associated with binarity in the central star of IC 4776 may be indicative of a significant population of (intermediate-period) post-common-envelope binary central stars which would be undetected by classic photometric monitoring techniques.Comment: Accepted for publication in MNRA

A dyadic trust perspective of key account relationship development in the UK mortgage industry

The main purpose of this study is to examine how a dyadic trust perspective can support effective development of key account relationships. The need for Key Account Management in the UK Mortgage Industry is investigated, factors for effective key account relationship management are identified and a trust/Mortgage Lender and Intermediary perspective of Key Account relationship effectiveness is analysed. The results of this study have been achieved through a mixed methods research strategy and these have been discussed in relation to Key Account Management and Trust theory. This study responds to concerns about the lack of research in this area, challenging and building on existing Key Account Management theory, integrating trust theory and applying this to a new context. A survey instrument to assess the effectiveness of Key Account relationships has been devised and can be applied to different contexts. Results show that demonstrations of trustworthiness leads to better key account performance but there is not a strong association of perceptions of higher trust with performance. Mortgage Lenders and Intermediaries have different perspectives of key account effectiveness and Mortgage Lenders lead the way in Key Account Management initiatives but there is evidence of various degrees of interdependence and willingness to achieve mutual gains. Key account relationships are not locked in to integrated Key Account Management programmes and exit from these relationships is quite easy. An important aspect of this research in the context of the UK Mortgage Industry has been the perceived positive role of the Key Account individual and that of different types of trust throughout relationship development, compensating for the perceived negative role of organisational culture aspects that may influence those involved in key account development within and between organisations. The contribution of this research is to show the relevance of Key Account Management as a business model providing market conditions are appropriate for Key Account Management development and that it is based on mutual learning and a format that suits the orientation of supplier and buyer, their own organisational design and culture and resources available as well as the environment in which they operate. This research suggests that fully integrated Key Account Management is not a realistic expectation and dependence on a few suppliers or customers as Key Account Management theory suggests, is not sensible. This study contributes to KAM practice in that it shows it is the management of trustworthiness rather than trying to manage trust that leads to a satisfactory Key Account relationship format for both supplier and buyer in the UK Mortgage Industry. This does currently rely heavily on the `intrapreneurial' skills of key individuals. In understanding how trustworthiness is demonstrated (through concern and benevolence, expertise, communication, intrapreneurial skills, commitment, organisational culture and KAM organisation) leads to more appropriate actions and behaviours to facilitate a relationship that works best for particular seller and buyer organisations given the particular circumstances. Organisations need to work on improving trust that is placed in the institution by for example developing effective marketing communications effort internally as well as externally and knowledge based trust, relating in particular to the exchange of confidential and strategic information. The identified factors for key account effectiveness presented in the survey can serve as useful guidelines for managing key accounts as they also demonstrate signals of trustworthiness. These factors can be used specifically to add to the limited range of performance criteria of key accounts currently adopted by the industry. Further research is suggested that may consider a key account manager or client's disposition towards trust, an examination of perceptions of supply chain t...EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Protracted treatment with MDMA induces heteromeric nicotinic receptor up-regulation in rat brain: an autoradiography study.

Previous studies indicate that 3,4-methylenedioxy-methamphetamine (MDMA, ecstasy) can induce heteromeric nicotinic acetylcholine receptor (nAChR, mainly of α4β2 subtype) up-regulation. In this study we treated Sprague-Dawley rats twice-daily for 10 days with either saline or MDMA (7 mg/kg) and killed them on day 11 to perform [125I]epibatidine binding autoradiograms on serial coronal slices. Results showed significant increases in nAChR density in the substantia nigra, ventral tegmental area, nucleus accumbens, olfactory tubercle, anterior caudate-putamen, somatosensory cortex, motor cortex, auditory cortex, retrosplenial cortex, laterodorsal thalamus nuclei, amygdala, postsubiculum and pontine nuclei. These increases ranged from 3% (retrosplenial cortex) to 30 and 33% (amygdala and substantia nigra). No increased α4 subunit immunoreactivity was found in up-regulated areas compared with saline-treated rats, suggesting a post-translational mechanism as occurs with nicotine. The percentage of up-regulation correlated positively with the density of serotonin transporters, according to the serotonergic profile of MDMA. The heteromeric nAChR increase in concrete areas could account, at least in part, for the reinforcing, sensitizing and psychiatric disorders observed after long-term treatment with MDMA