Clustering and diffusion in a symplectic map lattice with non-local coupling

We study a symplectic chain with a non-local form of coupling by means of a standard map lattice where the interaction strength decreases with the lattice distance as a power-law, in Such a way that one can pass continuously from a local (nearest-neighbor) to a global (mean-field) type of coupling. We investigate the formation of map clusters, or spatially coherent structures generated by the system dynamics. Such clusters are found to be related to stickiness of chaotic phase-space trajectories near periodic island remnants, and also to the behavior of the diffusion coefficient. An approximate two-dimensional map is derived to explain some of the features of this connection. (C) 2008 Elsevier Ltd. All rights reserved.

Self-reported symptoms and motor tests via telemetry in a 36-month levodopa-carbidopa intestinal gel infusion trial

Objective To investigate if a home environment test battery can be used to measure effects of Parkinson’s disease (PD) treatment intervention and disease progression. Background Seventy-seven patients diagnosed with advanced PD were recruited in an open longitudinal 36-month study at 10 clinics in Sweden and Norway; 40 of them were treated with levodopa-carbidopa intestinal gel (LCIG) and 37 patients were candidates for switching from oral PD treatment to LCIG. They utilized a mobile device test battery, consisting of self-assessments of symptoms and objective measures of motor function through a set of fine motor tests (tapping and spiral drawings), in their homes. Both the LCIG-naïve and LCIG-non-naïve patients used the test battery four times per day during week-long test periods. Methods Assessments The LCIG-naïve patients used the test battery at baseline (before LCIG), month 0 (first visit; at least 3 months after intraduodenal LCIG), and thereafter quarterly for the first year and biannually for the second and third years. The LCIG-non-naïve patients used the test battery from the first visit, i.e. month 0. Out of the 77 patients, only 65 utilized the test battery; 35 were LCIG-non-naïve and 30 LCIG-naïve. In 20 of the LCIG-naïve patients, assessments with the test battery were available during oral treatment and at least one test period after having started infusion treatment. Three LCIG-naïve patients did not use the test battery at baseline but had at least one test period of assessments thereafter. Hence, n=23 in the LCIG-naïve group. In total, symptom assessments in the full sample (including both patient groups) were collected during 379 test periods and 10079 test occasions. For 369 of these test periods, clinical assessments including UPDRS and PDQ-39 were performed in afternoons at the start of the test periods. The repeated measurements of the test battery were processed and summarized into scores representing patients’ symptom severities over a test period, using statistical methods. Six conceptual dimensions were defined; four subjectively-reported: ‘walking’, ‘satisfied’, ‘dyskinesia’, and ‘off’ and two objectively-measured: ‘tapping’ and ‘spiral’. In addition, an ‘overall test score’ (OTS) was defined to represent the global health condition of the patient during a test period. Statistical methods Change in the test battery scores over time, that is at baseline and follow-up test periods, was assessed with linear mixed-effects models with patient ID as a random effect and test period as a fixed effect of interest. The within-patient variability of OTS was assessed using intra-class correlation coefficient (ICC), for the two patient groups. Correlations between clinical rating scores and test battery scores were assessed using Spearman’s rank correlations (rho). Results In LCIG-naïve patients, mean OTS compared to baseline was significantly improved from the first test period on LCIG treatment until month 24. However, there were no significant changes in mean OTS scores of LCIG-non-naïve patients, except for worse mean OTS at month 36 (p<0.01, n=16). The mean scores of all subjectively-reported dimensions improved significantly throughout the course of the study, except ‘walking’ at month 36 (p=0.41, n=4). However, there were no significant differences in mean scores of objectively-measured dimensions between baseline and other test periods, except improved ‘tapping’ at month 6 and month 36, and ‘spiral’ at month 3 (p<0.05). The LCIG-naïve patients had a higher within-subject variability in their OTS scores (ICC=0.67) compared to LCIG-non-naïve patients (ICC=0.71). The OTS correlated adequately with total UPDRS (rho=0.59) and total PDQ-39 (rho=0.59). Conclusions In this 3-year follow-up study of advanced PD patients treated with LCIG we found that it is possible to monitor PD progression over time using a home environment test battery. The significant improvements in the mean OTS scores indicate that the test battery is able to measure functional improvement with LCIG sustained over at least 24 months.

Automatic and objective assessment of alternating tapping performance in Parkinson’s disease

This paper presents the development and evaluation of a method for enabling quantitative and automatic scoring of alternating tapping performance of patients with Parkinson’s disease (PD). Ten healthy elderly subjects and 95 patients in different clinical stages of PD have utilized a touch-pad handheld computer to perform alternate tapping tests in their home environments. First, a neurologist used a web-based system to visually assess impairments in four tapping dimensions (‘speed’, ‘accuracy’, ‘fatigue’ and ‘arrhythmia’) and a global tapping severity (GTS). Second, tapping signals were processed with time series analysis and statistical methods to derive 24 quantitative parameters. Third, principal component analysis was used to reduce the dimensions of these parameters and to obtain scores for the four dimensions. Finally, a logistic regression classifier was trained using a 10-fold stratified cross-validation to map the reduced parameters to the corresponding visually assessed GTS scores. Results showed that the computed scores correlated well to visually assessed scores and were significantly different across Unified Parkinson’s Disease Rating Scale scores of upper limb motor performance. In addition, they had good internal consistency, had good ability to discriminate between healthy elderly and patients in different disease stages, had good sensitivity to treatment interventions and could reflect the natural disease progression over time. In conclusion, the automatic method can be useful to objectively assess the tapping performance of PD patients and can be included in telemedicine tools for remote monitoring of tapping.

Non-equivalence of direct and indirect measures of unrealistic optimism

Individuals typically believe that they are less likely than the average person to experience negative events. Such “unrealistic optimism” (UO) has been assessed in two ways: directly (via a single question, requiring comparison of own risk to that of the average person) and indirectly (via separate questions about own risk and that of the average person). The study examined the equivalence of the direct and indirect measures of female students' UO for unwanted pregnancy. Participants (N = 120) answered questions about their own risk, that of the average female student, and their own risk relative to that of the average female student; responses and response times were recorded. There was only a moderate association between direct- and indirect-UO. Direct-UO was strongly associated with estimate of own risk, but only moderately associated with estimate of the average student's risk. Response times for the comparative risk and own risk questions did not differ, but participants took significantly longer to answer the question about average student's risk. The results suggest that the two measures of UO are not equivalent, but, rather, that individuals answering a comparative risk question focus mainly on their own risk, at the expense of that of the average person.

Predicting consumer innovative behavior using alternative theories and likelihood measures: a longitudinal study

This paper reports on a longitudinal study of consumers, where two dominant theories that purport to predict innovative behavior are applied and compared directly, using a methodology suggested as ideal by past researchers. Predictions made prior to launch were then evaluated against multiple measures of purchase likelihood, and against actual adoption behavior up to 12 months after launch. The results of this study suggest that perceptions of the innovations characteristics (PIC) predicted the selfreported likelihood of adoption better than the Domain Specific Innovativeness (DSI) scale, a personality-based measure. Prediction of actual adoption was largely inaccurate and both theories massively over predicted adoption levels, however the DSI scale was slightly more accurate. The conclusions here are that no one theory could make adequate predictions of behavior, that purchase likelihood measures are a poor substitute for measuring actual behavior but that purchase probability scales should be used more often in adoption research.

Associations between neighbourhood safety and physical activity among youth

This thesis examined how perceptions of neighbourhood safety and objective measures of the local road environment were related to physical activity among youth. Results demonstrated that neighbourhoods with walking tracks and traffic-calming measures promote active transport (walking/cycling) and may help stem age-related declines in physical activity among children and adolescents.

Shared parenting : adding children's voices and their measures of adjustment to the evaluation

Shared parenting has been advocated to be a better arrangement for children than sole residence and access arrangements after parental separation. Although there is some research on this issue, studies have been restricted in their reliance on the reports of others. In this paper, we report on a study in Australia, in which children in each of these arrangements were compared with children in intact families on a range of adjustment measures and with each other in relation to their responses to their parents' separation, using both self- and parent-reporting. We found that there was little difference between children in the three family configurations, suggesting that shared parenting is not necessarily associated with better outcomes for the child. On other aspects of adjustment, the children in shared parenting and sole residence/access families did not differ. We also found that parents in all groups underestimated the emotional problems reported by children. In separated families, they also overestimated the children's desire for parents to re-unite. Finally, we found that parents in shared parenting families are more satisfied with their situation than are their children, and fathers are particularly so. The findings suggest that the promotion of shared parenting as the best post-separation family structure is contestable.

A correlation study of subjective sensorial evaluation and objective softness measurement of wool fabrics

Comfort is one of the most important aspects of clothing, especially for next-to-skin garments such as shirts and trousers for summer. Sensorial comfort has a strong relationship with both the mechanical and surface properties of apparel fabric. A comfortable textile material should have properties of softness, smooth surface or texture, be pleasant to touch and very flexible. When assessing fabric handle subjectively, the assessor usually strokes the fabric surface with one or several fingers and squash the fabric gently in hand. Thus, the perception of such handle includes complex parameters of compression, tactile sensation and textural effect. In this work, we attempted to use a simple technique of objectively evaluating fabric softness related properties, by measuring the force required to pull a fabric strip through a series of parallel pins (the pulling force). We also subjectively rated the fabric handle. The correlation analysis showed very good agreement between the fabric pulling force and subjective hand rating.