Hydrodynamics of domain walls in ferroelectrics and multiferroics: Impact on memory devices

The standard “Kittel Law” for the thickness and shape of ferroelectric, ferroelastic, or ferromagnet domains assumes mechanical equilibrium. The present paper shows that such domains may be highly nonequilibrium, with unusual thicknesses and shapes. In lead germanate and multiferroic lead zirconate titanate iron tantalate domain wall instabilities resemble hydrodynamics (Richtmyer–Meshkov and Helfrich–Hurault, respectively).

Fixed-boundary constituencies and the principle of equal representation in Ireland

The process of constituency boundary revision in Ireland, designed to satisfy what is perceived as a rigid requirement that a uniform deputy-population ratio be maintained across constituencies, has traditionally consumed a great deal of the time of politicians and officials. For almost two decades after a High Court ruling in 1961, the process was a political one, was highly contentious, and was marked by serious allegations of ministerial gerrymandering. The introduction in 1979 of constituency commissions made up of officials neutralised, for the most part, charges that the system had become too politicised, but it continued the process of micro-management of constituency boundaries. This article suggests that the continuing problems caused by this system – notably, the permanently changing nature of constituency boundaries and resulting difficulties of geographical identification – could be resolved by reversion to the procedure that is normal in proportional representation systems: periodic post-census allocation of seats to constituencies whose boundaries are based on those of recognised local government units and which are stable over time. This reform, replacing the principle of redistricting by the principle of reapportionment, would result in more recognisable constituencies, more predictable boundary trajectories over time, and a more efficient, fairer, and speedier process of revision.

Interface-mediated ferroelectric patterning and Mn valency in nano-structured PbTiO3/La0.7Sr0.3MnO3

We employed a multitechnique approach using piezo-force response microscopy and photoemission microscopy to investigate a self-organizing polarization domain pattern in PbTiO3/La0.7Sr0.3MnO3 (PTO/LSMO) nanostructures. The polarization is correlated with the nanostructure morphology as well as with the thickness and Mn valence of the LSMO template layer. On the LSMO dots, the PTO is upwards polarized, whereas outside the nanodots, the polarization appears both strain and interface roughness dependent. The results suggest that the electronic structure and strain of the PTO/LSMO interface contribute to determining the internal bias of the ferroelectric layer.

Achievable rates and outage probability of cognitive radio with dynamic frequency hopping under imperfect spectrum sensing

In this study, the authors propose simple methods to evaluate the achievable rates and outage probability of a cognitive radio (CR) link that takes into account the imperfectness of spectrum sensing. In the considered system, the CR transmitter and receiver correlatively sense and dynamically exploit the spectrum pool via dynamic frequency hopping. Under imperfect spectrum sensing, false-alarm and miss-detection occur which cause impulsive interference emerged from collisions due to the simultaneous spectrum access of primary and cognitive users. That makes it very challenging to evaluate the achievable rates. By first examining the static link where the channel is assumed to be constant over time, they show that the achievable rate using a Gaussian input can be calculated accurately through a simple series representation. In the second part of this study, they extend the calculation of the achievable rate to wireless fading environments. To take into account the effect of fading, they introduce a piece-wise linear curve fitting-based method to approximate the instantaneous achievable rate curve as a combination of linear segments. It is then demonstrated that the ergodic achievable rate in fast fading and the outage probability in slow fading can be calculated to achieve any given accuracy level.

A biologically inspired appearance model for robust visual tracking

In this work, we propose a biologically inspired appearance model for robust visual tracking. Motivated in part by the success of the hierarchical organization of the primary visual cortex (area V1), we establish an architecture consisting of five layers: whitening, rectification, normalization, coding and polling. The first three layers stem from the models developed for object recognition. In this paper, our attention focuses on the coding and pooling layers. In particular, we use a discriminative sparse coding method in the coding layer along with spatial pyramid representation in the pooling layer, which makes it easier to distinguish the target to be tracked from its background in the presence of appearance variations. An extensive experimental study shows that the proposed method has higher tracking accuracy than several state-of-the-art trackers.

Over 30% of patients with splenic marginal zone lymphoma express the same immunoglobulin heavy variable gene: ontogenetic implications.

We performed an immunogenetic analysis of 345 IGHV-IGHD-IGHJ rearrangements from 337 cases with primary splenic small B-cell lymphomas of marginal-zone origin. Three immunoglobulin (IG) heavy variable (IGHV) genes accounted for 45.8% of the cases (IGHV1-2, 24.9%; IGHV4-34, 12.8%; IGHV3-23, 8.1%). Particularly for the IGHV1-2 gene, strong biases were evident regarding utilization of different alleles, with 79/86 rearrangements (92%) using allele (*)04. Among cases more stringently classified as splenic marginal-zone lymphoma (SMZL) thanks to the availability of splenic histopathological specimens, the frequency of IGHV1-2(*)04 peaked at 31%. The IGHV1-2(*)04 rearrangements carried significantly longer complementarity-determining region-3 (CDR3) than all other cases and showed biased IGHD gene usage, leading to CDR3s with common motifs. The great majority of analyzed rearrangements (299/345, 86.7%) carried IGHV genes with some impact of somatic hypermutation, from minimal to pronounced. Noticeably, 75/79 (95%) IGHV1-2(*)04 rearrangements were mutated; however, they mostly (56/75 cases; 74.6%) carried few mutations (97-99.9% germline identity) of conservative nature and restricted distribution. These distinctive features of the IG receptors indicate selection by (super)antigenic element(s) in the pathogenesis of SMZL. Furthermore, they raise the possibility that certain SMZL subtypes could derive from progenitor populations adapted to particular antigenic challenges through selection of VH domain specificities, in particular the IGHV1-2(*)04 allele.

Sister Practices: Non-Normative Experiences of Time and Technology

This chapter summarises some of the learning from a material practice that sits in a sisterly manner next to architecture. Drawing on feminist writing and the experiences of women in professional life more generally, the chapter will examine how mainstream understanding of time and technology limit the engagement of those people in society who do not fit given norms. The chapter argues that when we examine such concepts in more detail and expand them to reflect diverse experiences those very same concepts offer new potentials and innovative openings for the progression of disciplines such as architecture.

Lost and Found? A Parable of the Architect (Male) and the Academic (Female)

The following text captures an interview, conducted over three evenings, between a practicing architect (male) and an architecture academic (female and feminist). This is a conversation between two long-standing friends who did their Part 3 professional exam together more than twenty-five years ago. Since then, they have taken different career paths and lived lives at different paces and in different places. Every so often they meet over coffee to laugh and argue about architecture, bemoan failures, and share successes.

The academic initiated the interview in order to hear an honest and open account of the career experience of a male architect. She hoped that their longstanding friendship would lead to less guarded responses. The answers to the questions were always going to be personally challenging to the interviewer and possibly to their friendship. The interview is a form of ethnographic study: a structured, qualitative process within a long term, immersed context. But when ‘the immersed context’ is a much-valued friendship, it is a precarious action. Nevertheless, for the future of gendered relationships both protagonists accepted the risks.