Guarantees on learning depth-2 neural networks under a data-poisoning attack

In recent times many state-of-the-art machine learning models have been shown to be fragile to adversarial attacks. In this work we attempt to build our theoretical understanding of adversarially robust learning with neural nets. We demonstrate a specific class of neural networks of finite size and a non-gradient stochastic algorithm which tries to recover the weights of the net generating the realizable true labels in the presence of an oracle doing a bounded amount of malicious additive distortion to the labels. We prove (nearly optimal) trade-offs among the magnitude of the adversarial attack, the accuracy and the confidence achieved by the proposed algorithm.Comment: 11 page

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Taha Toros Arşivi, Dosya Adı: Nazım Hikmet. Gazetenin ''Kedi Gözü'' Köşesinde Yayımlanmıştır.İstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033

Twist/Writhe Partitioning in a Coarse-Grained DNA Minicircle Model

Here we present a systematic study of supercoil formation in DNA minicircles under varying linking number by using molecular dynamics simulations of a two-bead coarse-grained model. Our model is designed with the purpose of simulating long chains without sacrificing the characteristic structural properties of the DNA molecule, such as its helicity, backbone directionality and the presence of major and minor grooves. The model parameters are extracted directly from full-atomistic simulations of DNA oligomers via Boltzmann inversion, therefore our results can be interpreted as an extrapolation of those simulations to presently inaccessible chain lengths and simulation times. Using this model, we measure the twist/writhe partitioning in DNA minicircles, in particular its dependence on the chain length and excess linking number. We observe an asymmetric supercoiling transition consistent with experiments. Our results suggest that the fraction of the linking number absorbed as twist and writhe is nontrivially dependent on chain length and excess linking number. Beyond the supercoiling transition, chains of the order of one persistence length carry equal amounts of twist and writhe. For longer chains, an increasing fraction of the linking number is absorbed by the writhe.Comment: 21 pages, 7 figures, 1 tabl

Probing the Production of Actinides under Different r-process Conditions

Several extremely metal-poor stars are known to have an enhanced thorium abundance. These actinide-boost stars have likely inherited material from an r-process that operated under different conditions than the r-process that is reflected in most other metal-poor stars with no actinide enhancement. In this article, we explore the sensitivity of actinide production in r-process calculations to the hydrodynamical conditions as well as the nuclear physics. We find that the initial electron fraction Y e is the most important factor determining the actinide yields and that the abundance ratios between long-lived actinides and lanthanides like europium can vary for different conditions in our calculations. In our setup, conditions with high entropies systematically lead to lower actinide abundances relative to other r-process elements. Furthermore, actinide-enhanced ejecta can also be distinguished from the "regular" composition in other ways, most notably in the second r-process peak abundances.Peer reviewe

KÖYLÜ MEMLEKETİN EFENDİSİ MİDİR?

Uluslararası Bakalorya Diploma Programı A Türkçe Dersi kapsamında hazırlanmış olan bu uzun tezde, Fakir Baykurt’un Efendilik Savaşı adlı yapıtının konu edildiği dönemdeki devlet-birey arasındaki ilişki sosyal düzen ve toplumsal koşullar bağlamında incelenmiştir. Tez dört bölümden oluşturulmuştur. Giriş bölümünde yapıtta yer alan öykülerin kurulduğu temel iletiler verilmiştir. Gelişme bölümde devlet-birey ilişkisi alt başlıklarla ele alınıp değerlendirilmiştir. Yine bu bölümde yapıttaki öykülerde dönemdeki toplumsal koşullar cehalet, yoksulluk, bağnazlık ve batıl inançlar bağlamında incelenmiştir. Sonuç bölümünde tüm çalışmaya ilişkin genel bir değerlendirme yapılarak köylünün cehaletin, yoksulluğun, bağnazlığın ve batıl inançların esiri olduğu, bunun bir sonucu olarak sömürülere maruz kaldığı, bu dönemde devlet birey arasındaki ilişkinin sağlıklı işlemediği kanaatine varılmıştır

The problem of agency in the politics of victimhood: Nietzsche, Arendt, and Foucault

Victimhood as socio-political construction of a collective identity and as a rising phenomenon in politics especially in democracies has been problematized by many scholars in regard to the problem of agency. Although the politics of victimhood corresponds to a search for political recognition and correspondingly signifies political agency, the specific kind of relationships it produces carry the risk to result in undercut of agency. There are a number of researches on the functions and consequences of the politics of victimhood, however there is a gap in the literature in terms of examining it in Political Theory at length. In this thesis, the problem of agency in the politics of victimhood is examined under the theoretical framework of Nietzsche, Arendt, and Foucault in order both to investigate the relevancy of the problematizations about the functions and consequences of the politics of victimhood as dangers of undermining agency and to generate new approaches to overcome victimhood and the problem of agency. The analyses present creative values and political action along with different understandings of power, identity, and freedom as to enhance agency and to overcome victimhood

Vakfetmek: Empati Duygusunun Psikolojik Dayanakları

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