Length Distributions in Loop Soups

Statistical lattice ensembles of loops in three or more dimensions typically have phases in which the longest loops fill a finite fraction of the system. In such phases it is natural to ask about the distribution of loop lengths. We show how to calculate moments of these distributions using $CP^{n-1}$ or $RP^{n-1}$ and O(n) $\sigma$ models together with replica techniques. The resulting joint length distribution for macroscopic loops is Poisson-Dirichlet with a parameter $\theta$ fixed by the loop fugacity and by symmetries of the ensemble. We also discuss features of the length distribution for shorter loops, and use numerical simulations to test and illustrate our conclusions.Comment: 4.5 page

Charging of highly resistive granular metal films

We have used the Scanning Kelvin probe microscopy technique to monitor the charging process of highly resistive granular thin films. The sample is connected to two leads and is separated by an insulator layer from a gate electrode. When a gate voltage is applied, charges enter from the leads and rearrange across the sample. We find very slow processes with characteristic charging times exponentially distributed over a wide range of values, resulting in a logarithmic relaxation to equilibrium. After the gate voltage has been switched off, the system again relaxes logarithmically slowly to the new equilibrium. The results cannot be explained with diffusion models, but most of them can be understood with a hopping percolation model, in which the localization length is shorter than the typical site separation. The technique is very promising for the study of slow phenomena in highly resistive systems and will be able to estimate the conductance of these systems when direct macroscopic measurement techniques are not sensitive enough.Comment: 8 pages, 7 figure

Association of the clinical frailty scale with hospital outcomes.

BACKGROUND: The clinical frailty scale (CFS) was validated as a predictor of adverse outcomes in community-dwelling older people. In our hospital, the use of the CFS in emergency admissions of people aged ≥ 75 years was introduced under the Commissioning for Quality and Innovation payment framework. AIM: We retrospectively studied the association of the CFS with patient characteristics and outcomes. DESIGN: Retrospective observational study in a large tertiary university National Health Service hospital in UK. METHODS: The CFS was correlated with transfer to specialist Geriatric ward, length of stay (LOS), in-patient mortality and 30-day readmission rate. RESULTS: Between 1st August 2013 and 31st July 2014, there were 11 271 emergency admission episodes of people aged ≥ 75 years (all specialties), corresponding to 7532 unique patients (first admissions); of those, 5764 had the CFS measured by the admitting team (81% of them within 72 hr of admission). After adjustment for age, gender, Charlson comorbidity index and history of dementia and/or current cognitive concern, the CFS was an independent predictor of in-patient mortality [odds ratio (OR) = 1.60, 95% confidence interval (CI): 1.48 to 1.74, P < 0.001], transfer to Geriatric ward (OR = 1.33, 95% CI: 1.24 to 1.42, P < 0.001) and LOS ≥ 10 days (OR = 1.19, 95% CI: 1.14 to 1.23, P < 0.001). The CFS was not a multivariate predictor of 30-day readmission. CONCLUSIONS: The CFS may help predict in-patient mortality and target specialist geriatric resources within the hospital. Usual hospital metrics such as mortality and LOS should take into account measurable patient complexity.This is the author accepted manuscript. The final version is available via OUP at http://dx.doi.org/10.1093/qjmed/hcv06

New horizons in frailty: the contingent, the existential and the clinical

In the past decade, frailty research has focused on refinement of biomedical tools and operationalisations, potentially introducing a reductionist approach. This article suggests that a new horizon in frailty lies in a more holistic approach to health and illness in old age. This would build on approaches that view healthy ageing in terms of functionality, in the sense of intrinsic capacity in interplay with social environment, whilst also emphasising positive attributes. Within this framework, frailty is conceptualised as originating as much in the social as in the biological domain; as co-existing with positive attributes and resilience, and as situated on a continuum with health and illness. Relatedly, social science-based studies involving interviews with, and observations of, frail, older people indicate that the social and biographical context in which frailty arises might be more impactful on the subsequent frailty trajectory than the health crisis which precipitates it. For these reasons, the article suggests that interpretive methodologies, derived from the social sciences and humanities, will be of particular use to the geriatrician in understanding health, illness and frailty from the perspective of the older person. These may be included in a toolkit with the purpose of identifying how biological and social factors jointly underpin the fluctuations of frailty and in designing interventions accordingly. Such an approach will bring clinical approaches closer to the views and experiences of older people who live with frailty, as well as to the holistic traditions of geriatric medicine itself