734 research outputs found
Periodic integration in quarterly UK macroeconomic variables
This paper presents empirical evidence on the seasonal patterns in several UK macroeconomic variables, additional to related evidence reported in Osborn (International Journal of Forecasting (1990), 6, 327–336). The method used is a test procedure for seasonal unit roots that allows parameters to vary over the seasons. This extension of currently applied procedures can select between seasonal and periodic integration. In a small Monte Carlo experiment, this new method is evaluated with respect to two rival procedures. The empirical results for the UK variables indicate that many of these are periodically integrated. The implications of this outcome on modelling and forecasting are discussed. One of the implications is that a periodic error correction model for the univariate series can outperform non-periodic models with respect to forecasting
Ageing effects around the glass and melting transitions in poly(dimethylsiloxane) visualized by resistance measurements
The process of ageing in rubbers requires monitoring over long periods (days
to years). To do so in non-conducting rubbers, small amounts of carbon-black
particles were dispersed in a fractal network through the rubber matrix, to
make the rubber conducting without modifying its properties. Continuous
monitoring of the resistance reveals the structural changes around the glass
and melting transitions and especially details about the hysteresis and ageing
processes. We illustrate the method for the semicrystalline polymer
poly(dimethylsiloxane) (PDMS).Comment: 4 pages, 4 figure
Metal-insulator transition in YHx: scaling of the sub-THz conductivity
The established scaling laws of the conductivity with temperature and doping
are strong indications for the quantum nature of the metal-insulator transition
in YH. Here we report the first results on the frequency scaling of the
conductivity. Samples were brought from the insulating to the metallic phase by
carrier doping via illumination. In the metallic phase, the sub-terahertz
conductivity coincides with the dc data. These results do not agree with the
simplest picture of a quantum-phase transition.Comment: 4 pages, accepted to PR
Older Cancer Patients’ User Experiences With Web-Based Health Information Tools:A Think Aloud Study
Background: Health information is increasingly presented on the Internet. Several Web design guidelines for older Web users have been proposed; however, these guidelines are often not applied in website development. Furthermore, although we know that older individuals use the Internet to search for health information, we lack knowledge on how they use and evaluate Web-based health information. Objective: This study evaluates user experiences with existing Web-based health information tools among older (≥ 65 years) cancer patients and survivors and their partners. The aim was to gain insight into usability issues and the perceived usefulness of cancer-related Web-based health information tools. Methods: We conducted video-recorded think-aloud observations for 7 Web-based health information tools, specifically 3 websites providing cancer-related information, 3 Web-based question prompt lists (QPLs), and 1 values clarification tool, with colorectal cancer patients or survivors (n=15) and their partners (n=8) (median age: 73; interquartile range 70-79). Participants were asked to think aloud while performing search, evaluation, and application tasks using the Web-based health information tools. Results: Overall, participants perceived Web-based health information tools as highly useful and indicated a willingness to use such tools. However, they experienced problems in terms of usability and perceived usefulness due to difficulties in using navigational elements, shortcomings in the layout, a lack of instructions on how to use the tools, difficulties with comprehensibility, and a large amount of variety in terms of the preferred amount of information. Although participants frequently commented that it was easy for them to find requested information, we observed that the large majority of the participants were not able to find it. Conclusions: Overall, older cancer patients appreciate and are able to use cancer information websites. However, this study shows the importance of maintaining awareness of age-related problems such as cognitive and functional decline and navigation difficulties with this target group in mind. The results of this study can be used to design usable and useful Web-based health information tools for older (cancer) patients
Safe use of radiopharmaceuticals in patients with chronic kidney disease:A systematic review
BACKGROUND: Patients with chronic kidney disease (CKD) may need to have their radiopharmaceutical dosage adjusted to prevent adverse effects and poor outcomes, but there are few recommendations on radiopharmaceutical dosing for this group of patients. The aim of this study is to provide an overview of the available information on radiopharmaceutical dose recommendations for patients with CKD. METHODS: We performed a systematic literature review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. We conducted a literature search in the MEDLINE (PubMed) and Embase databases and screened potentially relevant studies using inclusion and exclusion criteria. We independently assessed the included observational studies’ methodologies and extracted relevant data. RESULTS: Of the 5795 studies first identified, 34 were included in this systematic review. These studies described three radiopharmaceuticals: [(131)I]sodium iodine, [(18)F]fludeoxyglucose, and [(131)I]iobenguane. Twenty-nine studies (85.3%) reported data on patients with CKD stage 5, while only three studies mentioned CKD patients in other stages (8.8%). CONCLUSION: We found no consistent recommendations for radiopharmaceutical dosing in patients with CKD. Although some studies do mention dosing difficulties in patients with CKD, information is available for only a few radiopharmaceuticals, and recommendations are sometimes contradictory. Further research on radiopharmaceutical dosing in patients with CKD is needed to determine whether these patients require specific dosing, especially for therapeutic radiopharmaceuticals where a non-optimised dose may lead to an increased risk of toxicity for non-targeted organs. Including patients with CKD in studies and providing specific information about dosing in these patients should be a priority for the radiopharmaceutical community
Minimum-Cost Reachability for Priced Timed Automata
This paper introduces the model of linearly priced timed automata as an extension of timed automata, with prices on both transitions and locations. For this model we consider the minimum-cost reachability problem: i.e. given a linearly priced timed automaton and a targetstate, determine the minimum cost of executions from the initial state to the target state. This problem generalizes the minimum-time reachability problem for ordinary timed automata. We prove decidability of this problem by offering an algorithmic solution, which is based on a combination of branch-and-bound techniques and a new notion of priced regions. The latter allows symbolic representation and manipulation of reachable states together with the cost of reaching them.Keywords: Timed Automata, Verification, Data Structures, Algorithms,Optimization
Relativistically rotating dust
Dust configurations play an important role in astrophysics and are the
simplest models for rotating bodies. The physical properties of the
general--relativistic global solution for the rigidly rotating disk of dust,
which has been found recently as the solution of a boundary value problem, are
discussed.Comment: 18 pages, 11 figure
Clostridium difficile beyond stools : dog nasal discharge as a possible new vector of bacterial transmission
Zoonotic transmission of Clostridium difficile has been largely hypothesised to occur after direct or indirect contact with contaminated animal faeces. Recent studies have reported the presence of the bacterium in the natural environment, including in soils and rivers. If C. difficile spores are scattered in the environment, they can easily enter the respiratory tract of dogs, and therefore, dog nasal discharge could be a direct route of transmission not previously investigated. This study reports for the first time the presence of C. difficile in the respiratory tracts of dogs. The bacterium was isolated from 6 (17.1%) out of 35 nasal samples, with a total of 4 positive dogs (19%). C. difficile was recovered from both proximal and distal nasal cavities. All isolates were toxigenic and belonged to PCR- ribotype 014, which is one of the most predominant types in animals and in community- acquired C. difficile infections in recent years. The findings of this study demonstrate that the nasal cavity of dogs is contaminated with toxigenic C. difficile, and therefore, its secretions could be considered as a new route by which bacteria are spread and transmitted.Peer reviewe
- …