2,577 research outputs found
Local growth of icosahedral quasicrystalline tilings
Icosahedral quasicrystals (IQCs) with extremely high degrees of translational
order have been produced in the laboratory and found in naturally occurring
minerals, yet questions remain about how IQCs form. In particular, the
fundamental question of how locally determined additions to a growing cluster
can lead to the intricate long-range correlations in IQCs remains open. In
answer to this question, we have developed an algorithm that is capable of
producing a perfectly ordered IQC, yet relies exclusively on local rules for
sequential, face-to-face addition of tiles to a cluster. When the algorithm is
seeded with a special type of cluster containing a defect, we find that growth
is forced to infinity with high probability and that the resultant IQC has a
vanishing density of defects. The geometric features underlying this algorithm
can inform analyses of experimental systems and numerical models that generate
highly ordered quasicrystals.Comment: 13 pages, 15 figures, 1 tabl
The Value of Online Information Privacy: An Empirical Investigation
Concern over online information privacy is widespread and rising. However, prior research is silent about the value of information privacy in the presence of potential benefits from sharing personally identifiable information. We analyzed individuals' trade-offs between the benefits and costs of providing personal information to websites. We found that benefits - monetary reward and future convenience - significantly affect individuals' preferences over websites with differing privacy policies. We also quantified the value of website privacy protection. Among U.S. subjects, protection against errors, improper access, and secondary use of personal information is worth US$30.49 - 44.62. Finally, we identified three distinct segments of Internet consumers - privacy guardians, information sellers, and convenience seekers.Information privacy, conjoint analysis, cost-benefit tradeoff, privacy concern, monetary reward, time-saving service
The Value of Online Information Privacy: An Empirical Investigation
Concern over online information privacy is widespread and rising. However, prior research is silent about the value of information privacy in the presence of potential benefits from sharing personally identifiable information. Analyzing individuals' trade-offs between the benefits and costs of providing personal information to websites revealed that benefits, monetary reward and future convenience, significantly affect individuals' preferences over websites with differing privacy policies. Quantifying the value of website privacy protection revealed that among U.S. subjects, protection against errors, improper access, and secondary use of personal information is worth US $30.49 - 44.62. Finally, three distinct segments of Internet consumers were determined: privacy guardians, information sellers and convenience seekers.
Comprehensive analysis of common serum liver enzymes as prospective predictors of hepatocellular carcinoma in HBV patients.
BACKGROUND: Serum liver enzymes are frequently tested in clinics to aid disease diagnosis. Large observational studies indicated that these enzymes might predict cancer risk and mortality. However, no prospective study has reported on their relationships with the risk of HBV-related hepatocellular carcinoma (HCC). METHODOLOGY/PRINCIPAL FINDINGS: We evaluated the predictive values of four routinely tested liver enzymes (alanine aminotransferase [ALT], aspartate aminotransferase [AST], alkaline phosphatase [ALP], and gamma-glutamyltransferase [GGT]) in HCC risk in a prospectively enrolled clinical cohort of 588 Korean American HBV patients. For all four enzymes, the baseline level as well as the average and maximum levels during the first 1 or 2 years of follow-up were analyzed using multivariate Cox proportional hazards model. Patients were categorized into a normal or an elevated group based on the clinical cut-off of each enzyme. During a median follow-up of 7.5 years, 52 patients (incidence rate, 8.8%) developed HCC. The incidence rates were higher in the elevated groups for all four enzymes. The most significant finding was for GGT, with the highest incidence rate of 16.4% in the elevated group compared to 4.6% in the normal group (
Evaluation of the infant at risk for neurodevelopmental disability
Background. Infants with neurodevelopmental abnormality need to start therapy early, and because of this they should be detected as soon as possible. Currently, no widely accepted method of early evaluation exists.Objectives_ To assess and compare, in terms of predicting neurodevelopmental outcome at 1 year of age: (i) a perinatal risk rating (PRR); (ii) the DubQwitz Neurological Assessment. (DNA); and (iii) the Infant Neuromotor Assessment (INA). Design and setting. A prospective neurodevelopmental followup study on graduates from the Groote Schuur Hospital (GSH) neonatal intensive care unit (NICU). Subjects. A cohort of 130 consecutive NICD graduates were selected according to high-risk criteria_Outcome measures. Each infant was examined at term gestational age on the DNAbefore discharge, and a PRR was allocated_ Study infants were seen again at 18 weeks of age when an INA was done, and at 1 year of age a Griffiths Developmental Assessment and full neurological examination was carried out.Results. All of the 130 infants assessed at term were seen at 18 weeks. Thereafter 5 were lost to follow-up and 2 died. The outcome for the remaining 123 is known.Conclusions. Prediction of a normal outcome at 1 year of age was 96% on the DNA and 98% for the PRR, but for an abnormal outcome they predicted only 56% and 42%, respectively. The INA done at 18 weeks predicted a normal outcome at 1 year in 99% of cases if 3 or less abnormal signs were present and an abnormal outcome in 82% of cases with 4 or more abnormal signs. Based on these findings a protocol for follow-up of these high-risk infants is suggested
Relative telomere length: a novel non-invasive biomarker for the risk of non-cirrhotic hepatocellular carcinoma in patients with chronic hepatitis B infection.
BACKGROUND AND AIMS: Telomere length has emerged as a promising risk predictor of various cancers including hepatocellular carcinoma (HCC). However, the majority of studies in this area measured telomere length in hepatocytes and one in lymphocytes with conflicting results. Moreover, no studies have been reported on using circulating DNA telomere length as a non-invasive HCC biomarker.
METHODS: We conducted a nested case-control study to determine the relative telomere length (RTL) in serum DNA from 140 hepatitis B virus (HBV)-related HCC cases and 280 frequency-matched cancer-free HBV controls.
RESULTS: Cases had a significantly longer RTL (median, 0.31; range, 0.02-2.31) than controls (median, 0.20; range, 0.01-1.60) (P = 0.003). Consistently, longer RTLs conferred a significantly increased HCC risk compared to short RTLs in a univariate logistic regression analysis (odds ratio [OR] = 1.55, 95% confidence interval [CI] = 1.02-2.33, P = 0.038). This association attenuated after multivariate adjustment (OR = 1.40, 95% CI = 0.90-2.19, P = 0.132). In a quartile analysis, a significant dose-response relationship was noted in univariate analysis (P(trend) = 0.017) which was again attenuated in multivariate analysis (P(trend) = 0.079). Further analyses revealed that the significant association between serum RTL and HCC risk was evident in non-cirrhotic (OR = 3.54, 95% CI 1.58-7.93 P = 0.002), but not cirrhotic (OR = 0.95, 95% CI 0.55-1.64, P = 0.860) HBV patients. Moreover, the significantly increased HCC risk conferred by cirrhosis was modulated by RTL with a significant interaction effect (P(interaction) = 0.013).
CONCLUSIONS: RTL in circulating cell-free serum DNA could potentially be used as a novel non-invasive biomarker for non-cirrhotic HCC. Prospective cohort studies are warranted to validate this finding and assess its clinical significance in HCC prevention
Comparison of Identification Methods of a Time-varying Insulin Sensitivity Parameter in a Simulation Model of Glucose Metabolism in the Critically Ill
6-pages (invited)Models of glucose metabolism can help to simulate and predict the blood glucose
response in hyperglycaemic, critically ill patients. Model prediction performance depends on a su ciently accurate estimation of the patient's time-varying insulin sensitivity. The work presents three least squares approaches, the integral method and a Bayesian method that have been compared by prediction accuracy on an absolute and on a relative scale. Clinical data yields 1491 blood glucose predictions based on 10 critically ill patients were processed. The
Bayesian approach proved to be best with small errors (9:7% absolute percent error, 14:7 root mean square of logarithmic error for prediction times 2h), and fewer and smaller outliers compared to the other methods. Computationally, the Bayesian method took 1.5 times longer per prediction compared to the fastest method. It can be concluded that a Bayesian parameter estimation gives safe and e ective results for the insulin sensitivity estimation for this model
Supplementary information on early-stage floating offshore wind platform designs
This document serves as supplementary information to the authors' review paper on early-stage floating offshore wind turbine (FOWT) platform designs. The review paper is the second part in a study on FOWT platform designs, following a review of FOWT platforms which currently have or have previously had a prototype, demonstration, or farm scale project at-sea. The present review covers 86 past and current early-stage platform designs, ranging from early conceptual designs to platforms which have undergone lab tests simulating extreme conditions. In this supplementary information document, more details are provided about all 86 platforms reviewed. For each device, the following is included (if available): (i) a description of the platform and its unique features, (ii) a rough timeline of development, (iii) design goals and constraints, (iv) evolution of the design, (v) lab testing information, and (vi) published dimensions. Two sections are included: one section contains the platforms that are no longer in development (i.e., there has been no new development since 2018), and the other section contains the platforms still in development today. Within each sub-section, platforms designed to hold a single turbine are presented first, then platforms designed to hold multiple turbines, and finally hybrid platforms
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