264 research outputs found

    Analyzing labour supply of elderly people: a life-cycle approach

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    In light of the ageing of the Dutch society, policy measures aim at increasing the participation rate of elderly workers, particularly in the age-group between 55 and 64. This paper develops a stylized numerical simulation model. This model describes consumption, savings and labour supply behaviour over the life cycle to analyze the labour-market implications of such proposals. For example, we simulate a shift in the (normal) retirement age from 65 to 67, the elimination of the Social Security premium exemption after age 65, and a premium on first-tier pension benefits if the commencement date of these benefits is postponed. Each of these reforms affect the economic outcomes via wealth effects, income effects and inter- and intratemporal substitution effects. The stylized model offers a profound theoretical underpinning which helps us to understand these policy effects over the entire life cycle of individuals. However, the numerical outcomes should be taken with some caution as the model ignores insights of behavioural economics (such as ‘framing effects’).

    Tactile Working Memory Capacity of Users Who Are Blind in an Electronic Travel Aid Application with a Vibration Belt

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    Electronic travel aids (ETAs) can increase the safety and comfort of pedestrians who have a visual impairment by displaying obstacles through a vibrotactile navigation belt. Building a complete picture of relevant obstacles and finding a safe route requires ETA users to integrate vibrotactile cues over time and space in their tactile working memory. Previous research suggests that the sense of touch exhibits a working memory that has characteristics similar to vision and audition. However, the capacity of the tactile working memory and the effects of secondary tasks are still under-researched. We investigated tactile working memory capacity of 14 adolescent participants who are blind in an immediate, whole report recall test. Participants received trials consisting of one to five vibration patterns presented sequentially at different locations on their torso representing obstacles with a direction (vibration location) and distance (vibration pattern). Recall performance was assessed under four conditions: baseline and with distracting background sounds and/or while walking with the long cane. Both walking and ignoring distracting sounds are relevant for everyday use of an ETA and were expected to decrease memory performance. We calculated the 75% correct scores for two memory performance measures: the number of items in a trial (numerosity), and item location and pattern correct. In the baseline condition, the scores were close to ceiling (i.e., 5 items). However, in the presence of distracting sounds and while walking, the scores were reduced to 3.2 items for numerosity and 1.6 items for location and identity correct. We recommend using 2 items as the maximum tactile working memory load in an applied setting unless users are trained and/or can adopt their strategy without unacceptable costs, such as reducing their walking speed

    Glycoprotein Metabolism in Skin Cancer: Synthesis, Pool Size, and Partial Characterization of Glycoproteins in the Rat Basosquamous Cell Carcinoma

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    Uptake of fucose, glucosamine, galactose, and mannose and the incorporation of these sugars into glycoconjugates have been quantified in a model epithelial tumor, the basosquamous cell carcinoma of the rat. Following isolation of glycoprotein and papain digestion, the fucosylated glycopeptides were fractionated according to molecular weight (Mr) and by affinity chromatography.Analysis of cellular material revealed a 2- to 3-fold reduction in the proportion of high-Mr fucopeptides synthesized by the tumor compared with normal epidermis, accompanied by a profound block in the incorporation of galactose into glycoconjugates. Parallel investigation of carbohydrate removed from the cell surface with trypsin or spontaneously shed into the medium indicated a striking decrease in the total release of fucopeptides from the tumor; the Mr was (respectively) normal or increased. Thus the fucopeptide abnormality appears to be accounted for almost entirely by a shift toward accumulation of low-Mr material at internal locations within the cell

    Obstacle detection display for visually impaired:Coding of direction, distance, and height on a vibrotactile waist band

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    Electronic travel aids (ETAs) can potentially increase the safety and comfort of blind users by detecting and displaying obstacles outside the range of the white cane. In a series of experiments, we aim to balance the amount of information displayed and the comprehensibility of the information taking into account the risk of information overload. In Experiment 1, we investigate perception of compound signals displayed on a tactile vest while walking. The results confirm that the threat of information overload is clear and present. Tactile coding parameters that are sufficiently discriminable in isolation may not be so in compound signals and while walking and using the white cane. Horizontal tactor location is a strong coding parameter, and temporal pattern is the preferred secondary coding parameter. Vertical location is also possible as coding parameter but it requires additional tactors and makes the display hardware more complex and expensive and less user friendly. In Experiment 2, we investigate how we can off-load the tactile modality by mitigating part of the information to an auditory display. Off-loading the tactile modality through auditory presentation is possible, but this off-loading is limited and may result in a new threat of auditory overload. In addition, taxing the auditory channel may in turn interfere with other auditory cues from the environment. In Experiment 3, we off-load the tactile sense by reducing the amount of displayed information using several filter rules. The resulting design was evaluated in Experiment 4 with visually impaired users. Although they acknowledge the potential of the display, the added of the ETA as a whole also depends on its sensor and object recognition capabilities. We recommend to use not more than two coding parameters in a tactile compound message and apply filter rules to reduce the amount of obstacles to be displayed in an obstacle avoidance ETA.</p

    Bilayered ceramic anterior restorations with reinforcement of the incisal edge by using lithium disilicate:A multicenter retrospective survival analysis with a maximum of 6-year follow-up

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    STATEMENT OF PROBLEM: The esthetics of anterior lithium disilicate restorations can be enhanced if the buccal aspect is layered with a feldspathic ceramic. However, whether fractures and chipping of this layer are a prevalent complication is unclear.PURPOSE: The purpose of this retrospective study was to evaluate the incidence of incisal fracture of a specially designed lithium disilicate reinforcement of the incisal edge for indirect anterior bilayered restorations on both teeth and implants.MATERIAL AND METHODS: A total of 924 anterior bilayered pressed lithium disilicate restorations in 324 patients and made in one dental laboratory were delivered by 4 restorative dentists. The restorations had the palatal side of the incisal edge in monolithic lithium disilicate and the facial side in feldspathic porcelain. The restorations were evaluated for survival and the occurrence of fracture or chipping. Survival analyses were performed by using the Kaplan-Meier and log rank (Mantel-Cox) tests (α=.05).RESULTS: Of the 924 restorations, 798 (236 complete crowns, 562 partial restorations) were placed on teeth and 126 on implants. The mean observation time was 38 months (3 to 72 months). The survival rate was 96.5%, with 14 failures occurring. The failures were fracture after dental trauma (n=5), ceramic fracture (n=1), debonding (n=6), poor shade match (n=1), and tooth loss (n=2). Restorations in patients with parafunctional habits and endodontically treated teeth showed a significant decrease in survival rate (P=.018). No significant differences were found between the survival of restorations on teeth and implants and between complete crowns and partial restorations (P=.021). No chipping was observed on any restorations in the study.CONCLUSIONS: Modified anterior bilayered ceramic restorations showed good survival rates, and no chipping was observed up to 6 years of follow-up. Parafunctional habits and endodontic treatment had a negative effect on the survival rate of restorations. The support of tooth or implant and the restoration type had no effect on the survival.</p
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