Elastic building blocks for confined sheets

We study the behavior of thin elastic sheets that are bent and strained under the influence of weak, smooth confinement. We show that the emerging shapes exhibit the coexistence of two types of domains that differ in their characteristic stress distributions and energies, and reflect different constraints. A focused-stress patch is subject to a geometric, piecewise-inextensibility constraint, whereas a diffuse-stress region is characterized by a mechanical constraint - the dominance of a single component of the stress tensor. We discuss the implications of our findings for the analysis of elastic sheets that are subject to various types of forcing

A prototypical model for tensional wrinkling in thin sheets

The buckling and wrinkling of thin films has recently seen a surge of interest among physicists, biologists, mathematicians and engineers. This has been triggered by the growing interest in developing technologies at ever decreasing scales and the resulting necessity to control the mechanics of tiny structures, as well as by the realization that morphogenetic processes, such as the tissue-shaping instabilities occurring in animal epithelia or plant leaves, often emerge from mechanical instabilities of cell sheets. While the most basic buckling instability of uniaxially compressed plates was understood by Euler more than 200 years ago, recent experiments on nanometrically thin (ultrathin) films have shown significant deviations from predictions of standard buckling theory. Motivated by this puzzle, we introduce here a theoretical model that allows for a systematic analysis of wrinkling in sheets far from their instability threshold. We focus on the simplest extension of Euler buckling that exhibits wrinkles of finite length - a sheet under axisymmetric tensile loads. This geometry, whose first study is attributed to Lam´e, allows us to construct\ud a phase diagram that demonstrates the dramatic variation of wrinkling patterns from near-threshold to far-from-threshold conditions. Theoretical arguments and comparison to experiments show that for thin sheets the far-from-threshold regime is expected to emerge under extremely small compressive loads, emphasizing the relevance of our analysis for nanomechanics applications

Capillary deformations of bendable films

We address the partial wetting of liquid drops on ultrathin solid sheets resting on a deformable foundation. Considering the membrane limit of sheets that can relax compression through wrinkling at negligible energetic cost, we revisit the classical theory for the contact of liquid drops on solids. Our calculations and experiments show that the liquid-solid-vapor contact angle is modified from the Young angle, even though the elastic bulk modulus (E) of the sheet is so large that the ratio between the surface tension γ and E is of molecular size. This finding establishes a new type of “soft capillarity” that stems from the bendability of thin elastic bodies rather than from material softness. We also show that the size of the wrinkle pattern that emerges in the sheet is fully predictable, thus resolving a puzzle noticed in several previous attempts to model “drop-on-a-floating-sheet” experiments, and enabling a reliable usage of this setup for the metrology of ultrathin films

Unintended weight loss in the elderly living at home: the aged in homecare project (Adhoc)

Objective: To describe associations between unintended weight loss (UWL) and characteristics of nutritional status. Design: A comparative cross-sectional assessment study at 11 sites in Europe. The target population was a stratified random sample of 4,455 recipients of home care (405 in each random sample from 11 urban areas) aged 65 years and older. Measurements: the Resident Assessment Instrument for Home Care, version 2.0. Epidemiological and medical characteristics of clients and service utilisation were recorded in a standardized, comparative manner. UWL was defined as information of 5% or more weight loss in the last 30 days (or 10% or more in the last 180 days). Results: The final sample consisted of 4,010 persons; 74% were female. The mean ages were 80.9 ± 7.5 years (males) and 82.8 ± 7.3 years (females). No associations were found between single diagnoses and UWL, except for cancer. Cancer patients were excluded from further analyses. Persons with a Cognitive Performance Scale value (CPS) > 3 (impaired) had increased risk of UWL (OR = 2.0) compared with those scoring < 3 (less impaired). Only in the oldest group did we find a significant association between UWL and reduction in ADL and IADL functions, comparing those who scored 3 or less with those who scored more than 3 (disabled). A binary logistic regression model explained 26% of UWL: less than one meal/day, reduced appetite, malnutrition, reduced social activity, experiencing a flare-up of a recurrent or chronic problem, and hospitalisation were important indicators. Conclusion: We recommend a regular comprehensive assessment in home care to identify clients with potential risk factors for weight loss and malnutrition, in particular those discharged from hospital, and those with physical dependency or cognitive problems. This study may provide incentives to create tailored preventive strategies

Home care needs of extremely obese elderly european women

Objective: To examine the health and needs of extremely obese women aged over 65 years receiving home care in Europe. Study design: A cross-sectional assessment study based on the Aged in Home Care (AdHOC) project recruited 2974 women aged 65 or over who were receiving home care at 11 sites in European countries. Extreme obesity was defined as ‘Obesity of such a degree as to interfere with normal activities, including respiration’. Main outcome measures: Resident Assessment Instrument for Home Care (RAI-HC version 2.0); Activity of Daily Living Scale; Instrumental Activity of Daily Living Scale; the Minimum Data Set Cognitive Performance Scale; and a health profile. Results: One hundred and twenty women (4.0%) were extremely obese. They were younger than their thinner counterparts, with a median age of 78.3 versus 83.3 years, and they more often had multiple health complaints and needed more help with mobility outside the home. The extremely obese had received home care longer than the non-extremely obese (median 28.7 versus 36.6 months). Extremely obese women also needed more help with personal care than the other group and, due to lower age, they were less cognitively impaired. Conclusions: Extreme obesity is a problem that increasingly affects home care of elderly women

Geriatric Rehabilitation as an Integral Part of Geriatric Medicine in the Nordic Countries

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenObjective: Firstly to outline the theoretical and practical framework for geriatric rehabilitation in Iceland and other Nordic countries and secondly to survey the scientific medical publications for evidence based geriatric rehabilitation. Methods: Brain storming on geriatric rehabilitation in a working group of Nordic teachers in geriatric medicine. Papers on scientific programs for geriatric rehabilitation from Internet sources were collected and analyzed. All articles describing randomized studies in geriatric rehabilitation were selected for overview. The papers were divided into four groups according to diseases, infirmity and resource settings; 1) stroke, 2) hip-fractures, 3) acute admissions and 4) programs conducted in nursing homes, day hospitals and home services. Results: A spectrum of biological and social events creates the conditions underlying most causes for illness and disability in old people. The process of established geriatric services promotes the efficiency of geriatric rehabilitation. The literature survey included 27 scientific studies (8586 patients) on randomized studies with valid endpoints. Geriatric rehabilitation programs for stroke patients in geriatric settings, six studies (1138 patients), reduced mortality and the need for nursing home placement but the outcome for ADL. Function and length of stay was more variable between the studies. The outcome of geriatric rehabilitation was even more decisive in the randomized hip-fracture studies, six studies (2171 patients). Eight studies were found comparing the outcome between acute admission of frail elderly to either geriatric (GEMU, GRU) or general medical wards. The outcome as regards to mortality rate at one year, placement to a nursing home, physical function, contentment with services, readmission rate and cost was all significantly better in the geriatric settings. Internal comparisons of geriatric programs in nursing homes, day hospitals and in home service, seven studies (1261 patient), revealed some differences in outcomes in function, contentment and costs. Conclusions: Specialized geriatric rehabilitation is complicated but effective when properly performed. Interdisciplinary teamwork, targeting of patients, comprehensive assessment and intensive and patient-targeted rehabilitation seem to characterize the most effective programs. Rehabilitation of frail elderly people poses a major challenge for the future and has to be developed further for the sake of quality of life of elderly people as well as for economic reasons.Markmið: Að gera úttekt á öldrunarendurhæfingu á Íslandi og öðrum Norðurlöndum, marka hinn hugmyndafræðilega grunn, tengja hann norrænum veruleika og taka saman vísindalegar niðurstöður um árangur öldrunarendurhæfingar. Aðferð: Hugarflugsfundir vinnuhóps kennara í öldrunarlækningum um öldrunarendurhæfingu. Sértæk leit í helstu læknatímarita á Medline í greinum sem fjalla um aðferðir og meðferðarleiðir endurhæfingar fyrir aldraða á vísindalegan hátt. Um er að ræða samantekt á rannsóknum sem notast við slembiúrtök og taka til elstu aldurshópa. Greinunum var skipt niður í fjóra flokka eftir sjúkdómum, færni og staðsetningu; 1) heilablóðfall, 2) mjaðmarbrot, 3) bráðveikir og hrumir, 4) prógrömm á hjúkrunarheimilum, dagspítölum og í heimaþjónustu. Niðurstöður: Lífeðlisfræðilegir og félagslegir þættir marka veikindaferli og fötlun aldraðra. Verklag öldrunarþjónustunnar skiptir miklu um árangur öldrunarendurhæfingar. Leit í 27 tímaritsgreinum náði til 8586 sjúklinga en þær báru saman slembiúrtök og höfðu haldbærar viðmiðanir. Endurhæfing aldraðra heilablóðfallssjúklinga á öldrunarlækningadeild, sex rannsóknir (1138 sjúklingar), dró úr dánarlíkum og minnkaði þörf fyrir stofnanavist en breyting á mælanlegri færni og legudagafjöldi varð ekki afgerandi hjá öllum. Enn betri árangur náðist við endurhæfingu eftir mjaðmarbrot, sex rannsóknir (2171 sjúklingur). Átta rannsóknir (4016 sjúklingar) báru saman árangur öldrunarlækningadeilda borið saman við almennar lyflæknisdeildir í meðhöndlun bráðveikra og hrumra sjúklinga. Niðurstöður voru flestar afgerandi betri á öldrunarlækningadeildum hvað varðar dánartíðni að ári, vistun á hjúkrunarheimili, líkamlega færni, ánægju, endurinnlagnir og kostnað. Innbyrðis samanburður á endurhæfingaraðferðum fyrir aldraða á hjúkrunarheimilum, dagspítölum og í heimaþjónustu, sjö rannsóknir (1261 sjúklingur), sýndu mun á nokkrum viðmiðunum í færniþáttum, ánægju og kostnaði. Ályktanir: Sérhæfð endurhæfing aldraðra er flókin en skilar árangri þegar rétt er á haldið. Bestur árangur næst með fjölfaglegri teymisvinnu, val á þeim sjúklingum sem mestu áhættuna hafa, alhliða öldrunarmati og virkri og einstaklingsmiðaðri endurhæfingu. Endurhæfing á hrumu gömlu fólki er og verður vaxandi viðfangsefni fyrir heilbrigðisþjónustuna og mikilvægt að hún nái því markmiði að auka lífsgæði aldraðs fólks. Benda rannsóknir einnig til að við það skapist einnig efnahagslegur ávinningur fyrir land og þjóð

Nanoscale atomic waveguides with suspended carbon nanotubes

We propose an experimentally viable setup for the realization of one-dimensional ultracold atom gases in a nanoscale magnetic waveguide formed by single doubly-clamped suspended carbon nanotubes. We show that all common decoherence and atom loss mechanisms are small guaranteeing a stable operation of the trap. Since the extremely large current densities in carbon nanotubes are spatially homogeneous, our proposed architecture allows to overcome the problem of fragmentation of the atom cloud. Adding a second nanowire allows to create a double-well potential with a moderate tunneling barrier which is desired for tunneling and interference experiments with the advantage of tunneling distances being in the nanometer regime.Comment: Replaced with the published version, 7 pages, 3 figure

Filtering spin with tunnel-coupled electron wave guides

We show how momentum-resolved tunneling between parallel electron wave guides can be used to observe and exploit lifting of spin degeneracy due to Rashba spin-orbit coupling. A device is proposed that achieves spin filtering without using ferromagnets or the Zeeman effect.Comment: 4 pages, 4 figures, RevTex