Electric field distortions in structures of the twist bend nematic (NTB) phase of a bent-core liquid crystal

Dielectric spectroscopy of a twist bend nematic phase of an achiral bent core liquid crystalline compound under DC bias is used to investigate its response to electric field. Two collective relaxation processes are revealed, these are assigned to distortions of helicoidal structure by the external bias field. Frequency of the mode depends primarily on the helicoidal angle and has anomalous, softening- like behaviour at the nematic to the twist bend nematic transition. A coupling of dielectric anisotropy with electric field gives rise to a new equilibrium periodic structure in the time scale involved. The modulus of the wave vector gradually vanishes on increasing the bias field (except for the initial behaviour, which is just the opposite). Transition from the twist bend to the splay bend structure is clearly observed by a sudden drop in the frequency of this mode, which decreases almost linearly with increasing field. Results agree with predictions from current models for the periodically distorted a twist bend nematic phase.Comment: 14 PAGES, 7 FIGURES, submitted to Physical Review Letter

Randomized Benchmarking as Convolution: Fourier Analysis of Gate Dependent Errors

We provide an alternative proof of Wallman's [Quantum 2, 47 (2018)] and Proctor's [Phys. Rev. Lett. 119, 130502 (2017)] bounds on the effect of gate-dependent noise on randomized benchmarking (RB). Our primary insight is that a RB sequence is a convolution amenable to Fourier space analysis, and we adopt the mathematical framework of Fourier transforms of matrix-valued functions on groups established in recent work from Gowers and Hatami [Sbornik: Mathematics 208, 1784 (2017)]. We show explicitly that as long as our faulty gate-set is close to some representation of the Clifford group, an RB sequence is described by the exponential decay of a process that has exactly two eigenvalues close to one and the rest close to zero. This framework also allows us to construct a gauge in which the average gate-set error is a depolarizing channel parameterized by the RB decay rates, as well as a gauge which maximizes the fidelity with respect to the ideal gate-set

‘Freelance isn’t free.’ Coworking as a critical urban practice to cope with informality in creative labour markets

For more than a decade, co-working spaces have proliferated in cities worldwide. The paper discusses co-working as a critical urban practice because these spaces give support to the rising number of freelance workers in culture and creative industries. Freelance workers are an ‘invisible’ workforce whose impact often remains ‘hidden’ (Mould et al. 2014), who are not sufficiently protected through social welfare regulations and do not enjoy the same social entitlements as employed workers. This paper uses the concept of informality to highlight ongoing informalisation processes of employment relationships as well as informal working practices in creative labour markets. It discusses the emergence of co-working as a practice of collective self-help and self-organisation to cope with and to potentially overcome the informality, uncertainty and risks associated with independent work. It argues that co-working can be seen in line with other practices of informal urbanism that become more prevalent in European and North American cities due to the lack of affordable housing, the retrenchment of the social welfare state and the imposed conditions of ‘austerity urbanism’ (Peck 2012

The Predictive Validity of Mathematics Curriculum-Based Measurement on Smarter Balanced Assessment Consortium Mathematics Scores

The purpose of this study was to examine the predicative validity of computation curriculumbased measurement (CBM) on mathematics Smarter Balanced Assessment Consortium scores (SBAC). This study looked at one cohort consisting of 2,741 participants in third, fourth, and fifth grade during the 2017-2018 school year in one school district in Oregon. This study used a hierarchical multiple regression to examine the relationship between CBM and mathematics SBAC. Additionally, this study looked at the extent to which gender, ethnicity, special education status (SPED) and English language learner (ELL) status interacted with CBM scores to predict end-of-year mathematics SBAC scores. The findings of this study indicate that CBM scores predict math SBAC scores in third, fourth, and fifth grade to a modest extent. The findings also indicate that taken together, CBM scores, gender, ethnicity, special education status, and English language learner status predict math SBAC scores to a moderate extent

Bedeutungsvolle Orte. Eine kultursoziologische Annäherung an kreative Handlungsressourcen in Städten

Die Großstadt mit ihrer heterogenen Bevölkerungszusammensetzung galt schon immer als der Ort, an dem das Neue in die Welt kommt. Im Zuge der gegenwärtigen Diskussion um die kreative Stadt sind neue Konzepte zum Zusammenhang von Stadtentwicklung und Kreativität entstanden. Gleichwohl bringen sie nach wie vor Größe und Heterogenität als materielle urbane Ressourcen in Anschlag, um die dynamische Entwicklung der Kultur- und Kreativwirtschaft in Städten zu erklären. In dem vorliegenden Beitrag wird demgegenüber argumentiert, dass eine kultursoziologisch erweiterte Untersuchung von städtischen Räumen zu differenzierteren Ergebnissen kommt: die Stadt mit ihren vielfältigen Angeboten bildet zwar den materiellen Kontext von Kreativität und Innovation; mindestens ebenso bedeutsam ist jedoch die Frage, inwieweit eine Stadt oder ein Stadtteil zugleich als bedeutungsvoller Ort für kreative Arbeit und kreatives Leben konstituiert und gewertet wird. Auf der Grundlage von Befunden aus zwei Projekten, die in Berlin und Offenbach zwischen 2007 und 2011 durchgeführt wurden, werden Diskurse und Praktiken von kreativ Tätigen rekonstruiert, die sich um Deutungen des Städtischen ranken. Dabei haben sich drei solcher geteilter Bedeutungsdimensionen herauskristallisiert, die aus Sicht der kreativ Tätigen die Attraktivität ihrer Stadt prägen, die sich als Offenheit, Beweglichkeit und Glaubwürdigkeit charakterisieren lassen. Diese Konstrukte tauchen in beiden Städten mit ähnlichen Konnotationen auf, sie stehen in engem Zusammenhang miteinander; und sie liegen quer zu den Dimensionen Größe und Heterogenität. (Autorenreferat) The relationship between creative processes and urban spaces is a rather old question in urban sociology, since the urban has long been seen as the locus for modernity and societal progress. The current creative city discourse in urban development has given rise to new urban growth theories based on creativity. Explanations focus on spatial-structural dimensions such as size and heterogeneity to emphasize urban spaces as a specific material context for creative processes. This paper, however, focuses on the social practices of creative practitioners in relation to cities, their ways of acting and talking, and how they attach meanings and ascribe qualities to particular places to constitute them as meaningful places for creative work and life. The aim of this paper is to present a cultural sociological view on creativity in the city. It is not just the urban context that breeds creativity, but culturally (re)produced perceptions of particular places that creative people value as meaningful for creative work. In a qualitative approach, discourses and practices of creative practitioners are reconstructed from the findings of two research projects undertaken between 2007 and 2011 in Berlin and Offenbach. The argument is that heterogeneity and size must be regarded as negotiable qualities rather than as fixed categories. Furthermore, three dimensions emerge from observations of these collective meaning-making processes that are important for urban spaces as places for creative work: openness, agility, and authenticity