Bond disorder, frustration and polymorphism in the spontaneous crystallization of a polymer melt

The isothermal, isobaric spontaneous crystallization of a supercooled polymer melt is investigated by molecular-dynamics simulation of an ensemble of fully-flexible linear chains. Frustration is introduced via two incommensurate length scales set by the bond length and the position of the minimum of the non- bonding potential. Marked polymorphism with considerable bond disorder, distortions of both the local packing and the global monomer arrangements is observed. The analyses in terms of: i) orientational order parameters characterizing the global and the local order and ii) the angular distribution of the next-nearest neighbors of a monomer reach the conclusion that the polymorphs are arranged in distorted Bcc-like lattice

Community Membership Hiding as Counterfactual Graph Search via Deep Reinforcement Learning

Community detection techniques are useful tools for social media platforms to discover tightly connected groups of users who share common interests. However, this functionality often comes at the expense of potentially exposing individuals to privacy breaches by inadvertently revealing their tastes or preferences. Therefore, some users may wish to safeguard their anonymity and opt out of community detection for various reasons, such as affiliation with political or religious organizations. In this study, we address the challenge of community membership hiding, which involves strategically altering the structural properties of a network graph to prevent one or more nodes from being identified by a given community detection algorithm. We tackle this problem by formulating it as a constrained counterfactual graph objective, and we solve it via deep reinforcement learning. We validate the effectiveness of our method through two distinct tasks: node and community deception. Extensive experiments show that our approach overall outperforms existing baselines in both tasks

Large critical current density improvement in Bi-2212 wires through groove-rolling process

Recently the interest about Bi-2212 round wire superconductor for high magnetic field use has been enhancing despite the fact that an increase of the critical current is still needed to boost its successful use in such applications. Recent studies have demonstrated that the main obstacle to current flow, especially in long wires, is the residual porosity inside these Powder-In-Tube processed conductors which develops in bubbles-agglomeration when the Bi-2212 melts. Through this work we tried to overcome this issue acting on the wire densification by changing the deformation process. Here we show the effects of groove-rolling versus drawing process on the critical current density JC and on the microstructure. In particular, groove-rolled multifilamentary wires show a JC increased by a factor of about 3 with respect to drawn wires prepared with the same Bi-2212 powder and architecture. We think that this approach in the deformation process is able to produce the required improvements both because the superconducting properties are enhanced and because it makes the fabrication process faster and cheaper

Fasce di lana in un papiro latino (P.Masada 723 riedito)

P.Masada 723 is an important source on medical practice within the Roman army. A revision of the text shows the use of woollen bandages for the wounded, and gives us a better understanding of the section referring to the sick. A palaeographical reconsideration of the document proves it to be an example of duplex manus, the phenomenon by which different graphical levels correspond to different textual sections

Una ricevuta latina su ostracon: O.Brit.Mus. inv. EA 29745

Il reperto è stato acquisito dal British Museum nel 1898 ed è rimasto presso la medesima istituzione, che nel tempo ha ceduto parte degli ostraca trattenendo quelli in lingua egizia, conservato in un contenitore recante la dicitura ‘Coptic’. L’origine e la provenienza sono sconosciuti, ma sulla base dei paralleli contenutistici si può supporre che sia stato redatto nell’Alto Egitto (cf. infra)

Fragmentarische Notiz Einer Lateinischen Geburtsanzeige

The present papyrus -published here in editio princeps- preserves a fragmentary text related to a birth declaration, as evident by the mention of the lex Papia Poppaea, by the formula q(uae) p(roxumae) f(uerunt), and by the reference to the public display. A comparison with the professiones and the testationes preserved on tablets and in papyri proves that the text is likely to be closer to a professio than to a testatio. Its exact nature is unclear, but its brevity suggests it to be a notice