A short proof of stability of topological order under local perturbations

Recently, the stability of certain topological phases of matter under weak perturbations was proven. Here, we present a short, alternate proof of the same result. We consider models of topological quantum order for which the unperturbed Hamiltonian $H_0$ can be written as a sum of local pairwise commuting projectors on a $D$-dimensional lattice. We consider a perturbed Hamiltonian $H=H_0+V$ involving a generic perturbation $V$ that can be written as a sum of short-range bounded-norm interactions. We prove that if the strength of $V$ is below a constant threshold value then $H$ has well-defined spectral bands originating from the low-lying eigenvalues of $H_0$. These bands are separated from the rest of the spectrum and from each other by a constant gap. The width of the band originating from the smallest eigenvalue of $H_0$ decays faster than any power of the lattice size.Comment: 15 page

Quantitative complementarity in two-path interferometry

The quantitative formulation of Bohr's complementarity proposed by Greenberger and Yasin is applied to some physical situations for which analytical expressions are available. This includes a variety of conventional double-slit experiments, but also particle oscillations, as in the case of the neutral-kaon system, and Mott scattering of identical nuclei. For all these cases, a unified description can be achieved including a new parameter, $\nu$, which quantifies the effective number of fringes one can observe in each specific interferometric set-up.Comment: 11 RevTex pages, 5 figure

Entropic Tightening of Vibrated Chains

We investigate experimentally the distribution of configurations of a ring with an elementary topological constraint, a ``figure-8'' twist. Using vibrated granular chains, which permit controlled preparation and direct observation of such a constraint, we show that configurations where one of the loops is tight and the second is large are strongly preferred. This agrees with recent predictions for equilibrium properties of topologically-constrained polymers. However, the dynamics of the tightening process weakly violate detailed balance, a signature of the nonequilibrium nature of this system.Comment: 4 pages, 4 figure

The association between home learning during COVID‐19 lockdowns and subsequent school attendance among children with neurodevelopmental conditions

Background: Children with neurodevelopmental conditions have high levels of schoolabsence. During the COVID-19 pandemic, schools closed for many students. Therelationship between home learning during school closures and subsequent schoolattendance requires attention to better understand the impact of pandemic educationpolicy decisions on this population. This study aims to investigate the associationbetween home learning, hybrid learning and school learning during school closures(in January–March 2021) with subsequent school attendance (in May 2021) in childrenwith neurodevelopmental conditions.Methods: An online survey was completed by 809 parents/carers of 5- to 15-yearoldautistic children and/or children with intellectual disability. Regression modelsexamined the association of learning location during school closures with subsequentschool absence (i.e., total days missed, persistent absence and school refusal).Results: Children who were learning from home during school closures later missed4.6 days of a possible 19. Children in hybrid and school learning missed 2.4 and 1.6school days, respectively. The rates of school absence and persistent absence weresignificantly higher in the home learning group even after adjusting for confounders.Learning location was not associated with subsequent school refusal.Conclusions: Policies for school closures and learning from home during public healthemergencies may exacerbate school attendance problems in this group of vulnerablechildren.Pathways through Adolescenc

Elective home education of children with neurodevelopmental conditions before and after the COVID-19 pandemic started

COVID-19 brought disruptions to children’s education and mental health, and accelerated school de-registration rates. We investigated Elective Home Education (EHE) in families of children with a neurodevelopmental condition. A total of 158 parents of 5–15 year-old children with neurodevelopmental conditions (80% autistic) provided information on reasons for de-registration, their experience of EHE, and children’s mental health. Few differences were found between children participating in EHE before and after the pandemic started. Low satisfaction with school for not meeting children’s additional needs was the main reason for deregistering in both groups. COVID-19 had a more limited role in parents’ decision to de-register. The main advantage of EHE reported in both groups was the provision of personalised education and one-to-one support. Levels of anxiety, internalising and externalising problems were similar between children participating in EHE before and after the pandemic started, and also similar between all children in EHE and school-registered children (N = 1,079).Pathways through Adolescenc

The Nursing Worklife Model: Extending and Refining a New Theory

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75205/1/j.1365-2834.2007.00670.x.pd

Ecological Invasion, Roughened Fronts, and a Competitor's Extreme Advance: Integrating Stochastic Spatial-Growth Models

Both community ecology and conservation biology seek further understanding of factors governing the advance of an invasive species. We model biological invasion as an individual-based, stochastic process on a two-dimensional landscape. An ecologically superior invader and a resident species compete for space preemptively. Our general model includes the basic contact process and a variant of the Eden model as special cases. We employ the concept of a "roughened" front to quantify effects of discreteness and stochasticity on invasion; we emphasize the probability distribution of the front-runner's relative position. That is, we analyze the location of the most advanced invader as the extreme deviation about the front's mean position. We find that a class of models with different assumptions about neighborhood interactions exhibit universal characteristics. That is, key features of the invasion dynamics span a class of models, independently of locally detailed demographic rules. Our results integrate theories of invasive spatial growth and generate novel hypotheses linking habitat or landscape size (length of the invading front) to invasion velocity, and to the relative position of the most advanced invader.Comment: The original publication is available at www.springerlink.com/content/8528v8563r7u2742

Can forest management based on natural disturbances maintain ecological resilience?

Given the increasingly global stresses on forests, many ecologists argue that managers must maintain ecological resilience: the capacity of ecosystems to absorb disturbances without undergoing fundamental change. In this review we ask: Can the emerging paradigm of natural-disturbance-based management (NDBM) maintain ecological resilience in managed forests? Applying resilience theory requires careful articulation of the ecosystem state under consideration, the disturbances and stresses that affect the persistence of possible alternative states, and the spatial and temporal scales of management relevance. Implementing NDBM while maintaining resilience means recognizing that (i) biodiversity is important for long-term ecosystem persistence, (ii) natural disturbances play a critical role as a generator of structural and compositional heterogeneity at multiple scales, and (iii) traditional management tends to produce forests more homogeneous than those disturbed naturally and increases the likelihood of unexpected catastrophic change by constraining variation of key environmental processes. NDBM may maintain resilience if silvicultural strategies retain the structures and processes that perpetuate desired states while reducing those that enhance resilience of undesirable states. Such strategies require an understanding of harvesting impacts on slow ecosystem processes, such as seed-bank or nutrient dynamics, which in the long term can lead to ecological surprises by altering the forest's capacity to reorganize after disturbance

What influences students in their development of socio-emotional intelligence whilst at university?

This qualitative study undertaken at a University in England investigates what influences the development of undergraduate students’ socio-emotional intelligence (SEI). Through a thematic analysis of semi-structured interviews with students and lecturers, the study highlights various approaches that the learning environment, both physical and cultural influenced their development of SEI. Learning in small groups where students felt safe and supported impacted on their sense of self, and helped develop their confidence. Reflecting on their own experience without constraints or assessed outcomes was also beneficial to these students. The lecturer’s knowledge and expertise, and how they modelled SEI were seen as imperative and meaningful to the development of students’ SEI. This paper concludes that students must be supported to develop holistically, integrating cognition and emotion, making practical suggestions as to how this may be achieved. Given the paucity of research in this area, opportunities for further research are highlighte

Ultrafast X-ray Studies of Structural Dynamics at SLAC

The melting dynamics of laser excited InSb have been studied with femtosecond x-ray diffraction. These measurements demonstrate that the initial stage of crystal disordering results from inertial motion on a laser softened potential energy surface. These inertial dynamics dominate for the first half picosecond following laser excitation, indicating that interatomic forces minimally influence atomic excursions from the equilibrium lattice positions, even for motions in excess of an {angstrom}. This also indicates that the atoms disorder initially without losing memory of their lattice reference