Explosive Percolation: Unusual Transitions of a Simple Model

In this paper we review the recent advances on explosive percolation, a very sharp phase transition first observed by Achlioptas et al. (Science, 2009). There a simple model was proposed, which changed slightly the classical percolation process so that the emergence of the spanning cluster is delayed. This slight modification turns out to have a great impact on the percolation phase transition. The resulting transition is so sharp that it was termed explosive, and it was at first considered to be discontinuous. This surprising fact stimulated considerable interest in "Achlioptas processes". Later work, however, showed that the transition is continuous (at least for Achlioptas processes on Erdos networks), but with very unusual finite size scaling. We present a review of the field, indicate open "problems" and propose directions for future research.Comment: 27 pages, 4 figures, Review pape

Three-Dimensional Conformal Radiotherapy for Hepatocellular Carcinoma in Patients Unfit for Resection, Ablation, or Chemotherapy: A Retrospective Study

Purpose. The purpose is to evaluate the feasibility, efficacy, and the toxicity of three-dimensional conformal radiotherapy (3DCRT) in patients with advanced hepatocelluar carcinoma (HCC) and inferior vena cava tumor thrombosis (IVCTT). Methods. Between 2007 and 2012, in a retrospective way, 9 patients (median age 69 years) with advanced HCC and IVCTT unfit for surgery, radiofrequency ablation, embolization, or chemotherapy were treated with three-dimensional conformal radiotherapy (3DCRT). The radiotherapy volume included both primary tumor and IVTT. The radiotherapy schedule was 50–52 Gy in 2 Gy fractions. Overall survival (OS), response to radiotherapy, visual analogue scale (VAS), and toxicity were assessed. Results. All patients demonstrated a response rate up to 60%. During radiotherapy, 3 patients experienced grade 1 nausea/vomit toxicity. All patients demonstrated an elevation of the liver enzymes (3 patients with grade 1 and 6 patients with grade 2). The mean VAS-score was decreased from 6.11 to 3.11, while the median overall survival was 24 months. Conclusion. 3DCRT achieves a very high local control rate and is suitable for patients with HCC and IVTT, while the documented radiation induced toxicity is moderate. It can be recommended for palliation in patients unable to undergo curative therapies

Objective and Subjective Measurements of Motor Function: Results from the HELIAD Study

Background: Slow gait speed has recently emerged as a potential prodromal feature of cognitive decline and dementia. Besides objective measurements, subjective motor function (SMF) difficulties might be present prior to the manifestation of gait disorders. Objectives: To examine the association of walking time and the presence of SMF with future cognitive decline in cognitively normal individuals. Design: Longitudinal study. Settings: Athens and Larissa, Greece. Participants: 931 cognitively normal individuals over the age of 64 with longitudinal follow-up from the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD). Measurements: We used a simple chronometer for recording objective walking time (OWT) and SMF was assessed using a self-reported physical functioning questionnaire. Generalized estimating equations (GEE) models were deployed to explore the associations between baseline OWT and SMF difficulties and the rate of change of performance scores on individual cognitive domains over time. Models were adjusted for age, years of education and sex. Results: Each additional second of OWT was associated with 1.1% of a standard deviation more decline per year in the composite z-score, 1.6% in the memory z-score, 1.1% in the executive z-score and 1.8% in the attention-speed z-score. The presence of SMF difficulties was not associated with differential rates of decline in any cognitive domain. Conclusion: Gait speed can be indicative of future cognitive decline adding credence to the notion that gait speed might serve as a simple and easily accessible clinical tool to identify a larger pool of at risk individuals and improve the detection of prodromal dementia. © 2022, Serdi

Assessing functional status using the IADL-extended scale: Results from the HELIAD study

Objectives: Instrumental activities of daily living (IADL) have been operationalized as exhibiting a greater level of complexity than basic ADL. In the same way, incorporating more advanced ADLs may increase the sensitivity of functional measures to identify cognitive changes that may precede IADL impairment. Towards this direction, the IADL-extended scale (IADL-x) consists of four IADL tasks and five advanced ADLs (leisure time activities).Design: Retrospective, cross-sectional study.Setting: Athens and Larissa, Greece.Participants: 1,864 community-dwelling men and women aged over 64.Measurements: We employed both the IADL-x and IADL scales to assess functional status among all the participants. Diagnoses were assigned dividing the population of our study into three groups: cognitively normal (CN), mild cognitive impairment (MCI) and dementia patients. Neuropsychological evaluation was stratified in five cognitive domains: memory, language, attention-speed, executive functioning and visuospatial perception. Z scores for each cognitive domain as well as a composite z score were constructed. Models were controlled for age, sex, education and depression.Results: In both IADL-x and IADL scales dementia patients reported the most functional difficulties and CN participants the fewest, with MCI placed in between. When we restricted the analyses to the CN population, lower IADL-x score was associated with worse cognitive performance. This association was not observed when using the original IADL scale.Conclusion: There is strong evidence that the endorsement of more advanced IADLs in functional scales may be useful in detecting cognitive differences within the normal spectrum. © International Psychogeriatric Association 2019

Assessing functional status using the IADL-extended scale: Results from the HELIAD study

Objectives: Instrumental activities of daily living (IADL) have been operationalized as exhibiting a greater level of complexity than basic ADL. In the same way, incorporating more advanced ADLs may increase the sensitivity of functional measures to identify cognitive changes that may precede IADL impairment. Towards this direction, the IADL-extended scale (IADL-x) consists of four IADL tasks and five advanced ADLs (leisure time activities).Design: Retrospective, cross-sectional study.Setting: Athens and Larissa, Greece.Participants: 1,864 community-dwelling men and women aged over 64.Measurements: We employed both the IADL-x and IADL scales to assess functional status among all the participants. Diagnoses were assigned dividing the population of our study into three groups: cognitively normal (CN), mild cognitive impairment (MCI) and dementia patients. Neuropsychological evaluation was stratified in five cognitive domains: memory, language, attention-speed, executive functioning and visuospatial perception. Z scores for each cognitive domain as well as a composite z score were constructed. Models were controlled for age, sex, education and depression.Results: In both IADL-x and IADL scales dementia patients reported the most functional difficulties and CN participants the fewest, with MCI placed in between. When we restricted the analyses to the CN population, lower IADL-x score was associated with worse cognitive performance. This association was not observed when using the original IADL scale.Conclusion: There is strong evidence that the endorsement of more advanced IADLs in functional scales may be useful in detecting cognitive differences within the normal spectrum. © International Psychogeriatric Association 2019

Sex Differences in Frailty Incidence in Greek Community-Dwelling Older People: The HELIAD Study

Background: Previous frailty studies found higher prevalence of frailty in female than in male participants. This was mainly attributed to the fact that compared to men, women show increased longevity. Recent studies have reported that the observed difference between sexes applies irrespectively of the age of older people. Objectives: To provide data on sex differences in incident frailty by applying both phenotypic and multi-domain frailty measures in the same population of Greek community-dwelling older people. Design: Longitudinal study. Setting: Data were drawn from the Hellenic longitudinal Investigation of Aging and Diet (HELIAD), a population-based, multidisciplinary study designed to estimate the prevalence and incidence of dementia in the Greek population. Participants: 1104 participants aged 65 year and above were included in this longitudinal study. This incidence cohort was reevaluated after a mean follow-up period of 3.04±0.90 years. Measurements: Frailty was operationalized using 5 different definitions in the same population the Fried Frailty Phenotype (FFP) definition, the FRAIL Scale, the Frailty Index (FI), the Tilburg Frailty Indicator (TFI) and the Groningen Frailty Index (GFI). Frailty incidence was calculated a) for the whole sample, b) separately for men and women and c) after both age and sex stratification. Results: Age and sex stratification revealed that irrespective of age and frailty measurement, women showed higher incidence rates of frailty than men. Specifically, frailty seems to be a condition concerning women >65 years old, but when it comes to men, it is more frequent in those aged more than 75 years old. Finally, in relation to overall frailty incidence and comparing our results to previous studies, we detected a lower frailty incidence in the Greek population. Conclusions: Differences between the two sexes indicate that when exploring the factors that are related to frailty, studies should provide data disaggregated for men and women. © 2022, Serdi