2,055 research outputs found
Convergence of random zeros on complex manifolds
We show that the zeros of random sequences of Gaussian systems of polynomials
of increasing degree almost surely converge to the expected limit distribution
under very general hypotheses. In particular, the normalized distribution of
zeros of systems of m polynomials of degree N, orthonormalized on a regular
compact subset K of C^m, almost surely converge to the equilibrium measure on K
as the degree N goes to infinity.Comment: 16 page
Smoking patterns and stimulus control in intermittent and daily smokers
Intermittent smokers (ITS) - who smoke less than daily - comprise an increasing proportion of adult smokers. Their smoking patterns challenge theoretical models of smoking motivation, which emphasize regular and frequent smoking to maintain nicotine levels and avoid withdrawal, but yet have gone largely unexamined. We characterized smoking patterns among 212 ITS (smoking 4-27 days per month) compared to 194 daily smokers (DS; smoking 5-30 cigarettes daily) who monitored situational antecedents of smoking using ecological momentary assessment. Subjects recorded each cigarette on an electronic diary, and situational variables were assessed in a random subset (n = 21,539 smoking episodes); parallel assessments were obtained by beeping subjects at random when they were not smoking (n = 26,930 non-smoking occasions). Compared to DS, ITS' smoking was more strongly associated with being away from home, being in a bar, drinking alcohol, socializing, being with friends and acquaintances, and when others were smoking. Mood had only modest effects in either group. DS' and ITS' smoking were substantially and equally suppressed by smoking restrictions, although ITS more often cited self-imposed restrictions. ITS' smoking was consistently more associated with environmental cues and contexts, especially those associated with positive or "indulgent" smoking situations. Stimulus control may be an important influence in maintaining smoking and making quitting difficult among ITS. © 2014 Shiffman et al
Liver and Intestine Transplantation in the United States, 1995–2004
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74804/1/j.1600-6143.2006.01273.x.pd
Writing clinical practice guidelines in controlled natural language
Clinicians could benefit from decision support systems incorporating the knowledge contained in clinical practice guidelines. However, the unstructured form of these guidelines makes them unsuitable for formal representation. To address this challenge we translated a complete set of pediatric guideline recommendations into Attempto Controlled English (ACE). One experienced pediatrician, one physician and a knowledge engineer assessed that a suitably extended version of ACE can accurately and naturally represent the clinical concepts and the proposed actions of the guidelines. Currently, we are developing a systematic and replicable approach to authoring guideline recommendations in ACE
The GuideLine Implementability Appraisal (GLIA): development of an instrument to identify obstacles to guideline implementation
BACKGROUND: Clinical practice guidelines are not uniformly successful in influencing clinicians' behaviour toward best practices. Implementability refers to a set of characteristics that predict ease of (and obstacles to) guideline implementation. Our objective is to develop and validate a tool for appraisal of implementability of clinical guidelines. METHODS: Indicators of implementability were identified from the literature and used to create items and dimensions of the GuideLine Implementability Appraisal (GLIA). GLIA consists of 31 items, arranged into 10 dimensions. Questions from 9 of the 10 dimensions are applied individually to each recommendation of the guideline. Decidability and Executability are critical dimensions. Other dimensions are Global, Presentation and Formatting, Measurable Outcomes, Apparent Validity, Flexibility, Effect on Process of Care, Novelty/Innovation, and Computability. We conducted a series of validation activities, including validation of the construct of implementability, expert review of content for clarity, relevance, and comprehensiveness, and assessment of construct validity of the instrument. Finally, GLIA was applied to a draft guideline under development by national professional societies. RESULTS: Evidence of content validity and preliminary support for construct validity were obtained. The GLIA proved to be useful in identifying barriers to implementation in the draft guideline and the guideline was revised accordingly. CONCLUSION: GLIA may be useful to guideline developers who can apply the results to remedy defects in their guidelines. Likewise, guideline implementers may use GLIA to select implementable recommendations and to devise implementation strategies that address identified barriers. By aiding the design and operationalization of highly implementable guidelines, our goal is that application of GLIA may help to improve health outcomes, but further evaluation will be required to support this potential benefit
Simple matrix models for random Bergman metrics
Recently, the authors have proposed a new approach to the theory of random
metrics, making an explicit link between probability measures on the space of
metrics on a Kahler manifold and random matrix models. We consider simple
examples of such models and compute the one and two-point functions of the
metric. These geometric correlation functions correspond to new interesting
types of matrix model correlators. We study a large class of examples and
provide in particular a detailed study of the Wishart model.Comment: 23 pages, IOP Latex style, diastatic function Eq. (22) and contact
terms in Eqs. (76, 95) corrected, typos fixed. Accepted to JSTA
Equidistribution of zeros of holomorphic sections in the non compact setting
We consider N-tensor powers of a positive Hermitian line bundle L over a
non-compact complex manifold X. In the compact case, B. Shiffman and S.
Zelditch proved that the zeros of random sections become asymptotically
uniformly distributed with respect to the natural measure coming from the
curvature of L, as N tends to infinity. Under certain boundedness assumptions
on the curvature of the canonical line bundle of X and on the Chern form of L
we prove a non-compact version of this result. We give various applications,
including the limiting distribution of zeros of cusp forms with respect to the
principal congruence subgroups of SL2(Z) and to the hyperbolic measure, the
higher dimensional case of arithmetic quotients and the case of orthogonal
polynomials with weights at infinity. We also give estimates for the speed of
convergence of the currents of integration on the zero-divisors.Comment: 25 pages; v.2 is a final update to agree with the published pape
Using data mining techniques to explore physicians' therapeutic decisions when clinical guidelines do not provide recommendations: methods and example for type 2 diabetes
<p>Abstract</p> <p>Background</p> <p>Clinical guidelines carry medical evidence to the point of practice. As evidence is not always available, many guidelines do not provide recommendations for all clinical situations encountered in practice. We propose an approach for identifying knowledge gaps in guidelines and for exploring physicians' therapeutic decisions with data mining techniques to fill these knowledge gaps. We demonstrate our method by an example in the domain of type 2 diabetes.</p> <p>Methods</p> <p>We analyzed the French national guidelines for the management of type 2 diabetes to identify clinical conditions that are not covered or those for which the guidelines do not provide recommendations. We extracted patient records corresponding to each clinical condition from a database of type 2 diabetic patients treated at Avicenne University Hospital of Bobigny, France. We explored physicians' prescriptions for each of these profiles using C5.0 decision-tree learning algorithm. We developed decision-trees for different levels of detail of the therapeutic decision, namely the type of treatment, the pharmaco-therapeutic class, the international non proprietary name, and the dose of each medication. We compared the rules generated with those added to the guidelines in a newer version, to examine their similarity.</p> <p>Results</p> <p>We extracted 27 rules from the analysis of a database of 463 patient records. Eleven rules were about the choice of the type of treatment and thirteen rules about the choice of the pharmaco-therapeutic class of each drug. For the choice of the international non proprietary name and the dose, we could extract only a few rules because the number of patient records was too low for these factors. The extracted rules showed similarities with those added to the newer version of the guidelines.</p> <p>Conclusion</p> <p>Our method showed its usefulness for completing guidelines recommendations with rules learnt automatically from physicians' prescriptions. It could be used during the development of guidelines as a complementary source from practice-based knowledge. It can also be used as an evaluation tool for comparing a physician's therapeutic decisions with those recommended by a given set of clinical guidelines. The example we described showed that physician practice was in some ways ahead of the guideline.</p
A Kinesin Family Member 6 Variant Is Associated With Coronary Heart Disease in the Women’s Health Study
ObjectivesWe asked if carriers of the 719Arg allele of kinesin family member 6 (KIF6) have increased risk of coronary heart disease (CHD) in a cohort of initially healthy Caucasian American women.BackgroundThe 719Arg allele of KIF6 (rs20455) has been reported to be associated with increased risk of CHD in a large population-based prospective study, ARIC (Atherosclerosis Risk in Communities), and in the placebo arms of 2 statin trials, CARE (Cholesterol and Recurrent Events) and WOSCOPS (West of Scotland Coronary Prevention Study). However, this KIF6 variant was not specifically investigated in the female subgroup in the ARIC study, and the CARE and WOSCOPS trials included only a small number of female patients.MethodsGenotypes of the rs20455 single nucleotide polymorphism (SNP) were determined among 25,283 initially healthy Caucasian women, age 45 years and older, participating in the WHS (Women’s Health Study) who were prospectively followed over a 12-year period for incident cardiovascular events. The risk associated with the 719Arg allele of KIF6 was estimated using Cox proportional hazards models that adjusted for age and traditional risk factors.ResultsDuring follow-up, 953 women suffered a first-ever CHD event (myocardial infarction, coronary revascularization, or cardiovascular death) or first-ever ischemic stroke. Compared with noncarriers, carriers of the 719Arg allele had an increased risk of CHD (hazard ratio [HR] = 1.24 [95% confidence interval (CI) 1.04 to 1.46, p = 0.013]) and myocardial infarction (HR = 1.34 [95% CI 1.02 to 1.75, p = 0.034]) but not ischemic stroke.ConclusionsConfirming and extending previous reports, carriers of the 719Arg allele of KIF6 have 34% higher risk of myocardial infarction and 24% higher risk of CHD compared with noncarriers among 25,283 women from the WHS
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