Quantum Inflation of Classical Shapes

I consider a quantum system that possesses key features of quantum shape dynamics and show that the evolution of wave-packets will become increasingly classical at late times and tend to evolve more and more like an expanding classical system. At early times however, semiclassical effects become large and lead to an exponential mismatch of the apparent scale as compared to the expected classical evolution of the scale degree of freedom. This quantum inflation of an emergent and effectively classical system, occurs naturally in the quantum shape dynamics description of the system, while it is unclear whether and how it might arise in a constrained Hamiltonian quantization.Comment: 14 pages, Late

Can chaos be observed in quantum gravity?

Full general relativity is almost certainly 'chaotic'. We argue that this entails a notion of nonintegrability: a generic general relativistic model, at least when coupled to cosmologically interesting matter, likely possesses neither differentiable Dirac observables nor a reduced phase space. It follows that the standard notion of observable has to be extended to include non-differentiable or even discontinuous generalized observables. These cannot carry Poisson-algebraic structures and do not admit a standard quantization; one thus faces a quantum representation problem of gravitational observables. This has deep consequences for a quantum theory of gravity, which we investigate in a simple model for a system with Hamiltonian constraint that fails to be completely integrable. We show that basing the quantization on standard topology precludes a semiclassical limit and can even prohibit any solutions to the quantum constraints. Our proposed solution to this problem is to refine topology such that a complete set of Dirac observables becomes continuous. In the toy model, it turns out that a refinement to a polymer-type topology, as e.g. used in loop gravity, is sufficient. Basing quantization of the toy model on this finer topology, we find a complete set of quantum Dirac observables and a suitable semiclassical limit. This strategy is applicable to realistic candidate theories of quantum gravity and thereby suggests a solution to a long-standing problem which implies ramifications for the very concept of quantization. Our work reveals a qualitatively novel facet of chaos in physics and opens up a new avenue of research on chaos in gravity which hints at deep insights into the structure of quantum gravity.Comment: 6 pages + references -- matches published version (clarifications added for why GR with cosmologically interesting matter likely fails our notion of weak-integrability

Access to parenting leaves for recent immigrants: a cross-national view of policy architecture in Europe

Parenting leaves play a crucial part in supporting women’s labour force participation as well as men’s participation in infant care. A major question is who has access to such leave policies and earlier research has pointed out large variations in eligibility. This article focuses on the leaves that are available to recently arrived immigrants, parents who are in a specific situation of being in transition between systems. Using information from the database of leave policies, the International Review of Leave Policies and Research 2021 (leavenetwork.org), we map eligibility and entitlements in Belgium, Germany, Italy, Spain, Sweden and the UK, all countries with tiered systems of parenting leave entitlement as well as relatively large recent immigrant populations. Our findings indicate that the leave policies available to recent immigrants can be patchwork in nature and of a very different generosity to the benefits available to many other parents. In addition, the benefits available to this group are often (even) more gendered and perhaps suggest a fall back to a policy logic of maternalism. We discuss how parenting leave may facilitate (or not) an exit from the early vulnerable stage that many immigrant parents face during the first few years in a new country

Expectations, Challenges, and Frustrations: Faculty and Administrator Perceptions of Quality and Assessment

The purpose of this study was not to evaluate the means or methods by which outcomes assessment and quality are being enacted in higher education, or take sides in the raging state and federal policy debate on institutional accountability and efficiency, but rather to describe the reactions, feelings, and perceptions of one particular institutions internal stakeholders to the increasingly shrill rhetoric on such topics. The present research sought to provide a voice for current faculty and administrators who will be responsible for implementing these renewed calls for assessing educational quality: specifically, their perceptions of the value, challenges, opportunities, and frustrations involved. Finding that voice meant finding an institution who was struggling to fully embrace the principles of quality and outcomes assessment

Cross Cultural Intervention III: Some Corrections and an Update in The Case of the Hexed Hair

This is the third short article about Ms Koslowski, a woman who overcame an eleven year hex on her hair. It provides an update, corrects some mistakes, and presents an analysi

Phase-field Dislocation Dynamics Code Optimization

The importance of the study of nanocrystalline materials has gained a huge amount of attention these years due to its extraordinary mechanical, electrical and chemical properties. One significant way to progress in this field is by simulating the behavior of the particles in nano scale, which is not only a need but a challenge due to massive interactions that occur there. The phase-field dislocation dynamics (PFDD) method has been successfully employed in the modeling of plastic deformation, creep and grain boundary sliding. In PFDD, the plastic strain and the energy are functions of phase fields that obey a set of complex equations. In the algorithm approach this complexity increases depending on different factors that, in the end, increase the time and computational resource used, which this research pretend optimize. Even though Fast Fourier Transformation and MPI have been utilized in the PFDD code due to his optimal approach and matricial representation which makes the algorithms more understandable the efficiency is still a major concern in matters of computational time and resource consumption. This research intends to give an improvement to the programs that simulates the nanocrystalline materials and the models that follows the dynamics locations so outgoing researchers can use it in a more efficient way. The result will be a improved program that follows the PFDD models and simulates the nanocrystalline behavior with different materials and different constraints in the environment as in the materials itselfs with a more friendly and intelligent input for the user