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Search Results: 1 - 10 of 142182 matches for " Rose K. Baker "
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Application of some new heavy-tailed survival distributions
Rose Baker
Statistics , 2014,
Abstract: Some new survival distributions are introduced based on a generalised exponential function. This class of distributions includes heavy-tailed generalisations of exponential, Weibull and gamma distributions. Properties of the distributions are described, and R code is available for computation of pdf, quantiles, inverse quantiles, random numbers, etc. A use of these distributions for robust inference is suggested, and this is exemplified with a Monte-Carlo study.
Copulas from Order Statistics
Rose Baker
Statistics , 2014,
Abstract: A new class of copulas based on order statistics was introduced by Baker (2008). Here, further properties of the bivariate and multivariate copulas are described, such as that of likelihood ratio dominance (LRD), and further bivariate copulas are introduced that generalize the earlier work. One of the new copulas is an integral of a product of Bessel functions of imaginary argument, and can attain the Fr\'echet bound. The use of these copulas for fitting data is described, and illustrated with examples. It was found empirically that the multivariate copulas previously proposed are not flexible enough to be generally useful in data fitting, and further development is needed in this area.
Properties and Applications of some Distributions derived from Frullani's integral
Rose Baker
Statistics , 2014,
Abstract: Frullani's integral dates from 1821, but a probabilistic interpretation of it has never been made. In this paper, Frullani's integral formula is shown to result from mixing a lifetime distribution by allowing the logarithm of the scale factor to be uniformly distributed over a finite range. This gives a class of long-tailed distributions related to slash distributions, where the pdf is simply expressed in terms of the survival function of the `parent' distribution. The resulting survival distributions have all moments finite, and can exhibit the bimodal hazard functions sometimes seen in practice. A distribution of this type analogous to the t-distribution is derived, the corresponding multivariate distributions are given, and two skewed versions of this distribution are derived. The use of the mixed distributions for inference is exemplified by fitting them to several datasets. It is expected that there will be many applications, in health, reliability, telecommunications, finance, etc.
A new distribution for robust least squares
Rose Baker,Dan Jackson
Statistics , 2014,
Abstract: A new distribution is introduced, which we call the twin-t distribution. This distribution is heavy-tailed like the t distribution, but closer to normality in the central part of the curve. Its properties are described, e.g. the pdf, the distribution function, moments, and random number generation. This distribution could have many applications, but here we focus on its use as an aid to robustness. We give examples of its application in robust regression and in curve fitting. Extensions such as skew and multivariate twin-t distributions, and a twin of
CD4 Cell Counts at HIV Diagnosis among HIV Outpatient Study Participants, 2000–2009
Kate Buchacz,Carl Armon,Frank J. Palella,Rose K. Baker,Ellen Tedaldi,Marcus D. Durham,John T. Brooks
AIDS Research and Treatment , 2012, DOI: 10.1155/2012/869841
Abstract: Background. It is unclear if CD4 cell counts at HIV diagnosis have improved over a 10-year period of expanded HIV testing in the USA. Methods. We studied HOPS participants diagnosed with HIV infection ≤6 months prior to entry into care during 2000–2009. We assessed the correlates of CD4 count <200 cells/mm3 at HIV diagnosis (late HIV diagnosis) by logistic regression. Results. Of 1,203 eligible patients, 936 (78%) had a CD4 count within 3 months after HIV diagnosis. Median CD4 count at HIV diagnosis was 299 cells/mm3 and did not significantly improve over time ( ). Comparing periods 2000-2001 versus 2008-2009, respectively, 39% and 35% of patients had a late HIV diagnosis ( ). Independent correlates of late HIV diagnosis were having an HIV risk other than being MSM, age ≥35 years at diagnosis, and being of nonwhite race/ethnicity. Conclusions. There is need for routine universal HIV testing to reduce the frequency of late HIV diagnosis and increase opportunity for patient- and potentially population-level benefits associated with early antiretroviral treatment. 1. Introduction Recent HIV surveillance data suggest that approximately 33% of HIV-infected persons in the United States present for HIV testing late and have AIDS (CD4+ cell count <200?cells/mL or an AIDS-defining illness) within one year after HIV diagnosis [1, 2]. Patients are less likely to experience the full benefits of highly active combination antiretroviral (cART) therapy if they enter HIV care and initiate treatment at a CD4 count <350?cells/mm3 [3, 4]; the clinical cost is even more profound when the CD4 count is <200?cells/mm3 or the patient has already developed clinical AIDS [5–8]. In addition, persons who remain unaware of their HIV-positive status (estimated 21% to 25% of infected persons in the USA in recent years) [9, 10] may not only miss the benefits of earlier cART treatment, but are also more likely to remain chronically viremic and are thereby more likely to transmit HIV to their sexual and needle-sharing partners [9]. The CDC has been promoting strategies to encourage more widespread HIV screening to diagnose infected persons earlier in the course of their illness, including by releasing in 2006 the guidelines for implementing routine universal opt-out testing in healthcare settings [11]. Yet, the latest HIV surveillance data [1, 2] and epidemiologic studies in multiple US populations indicate that the proportion of persons who are diagnosed late in the course of HIV infection [2, 12, 13] or present late for HIV care [14, 15] remains unacceptably high. Stable or worsening
Alluvial Gold Mining Sites as Exposure Pathways for Methyl Mercury Toxicity in Children: A Systematic Review  [PDF]
Rose K. Begani, Alphonse Z. Begani
Health (Health) , 2017, DOI: 10.4236/health.2017.96066
Abstract:
Extensive studies have showed that alluvial gold mining is a predisposing factor for mercury toxicity through occupational exposure. In our systematic review of related literature, we aim to determine if children of alluvial gold miners were at risk of exposure to methyl mercury toxicity through dietary exposure. This was achieved through applying Cochrane PICO methodology for the research question. We selected only the most relevant articles from the thousands of articles that were generated by the Divine Word University (DWU) electronic data base system for our review. Further screening questions were applied based on the CASP method which filtered remaining 105 to only 9 papers for the review. The results from the nine (N = 9) studies analysed showed convincing results of the association between consumption of fish contaminated with methyl mercury and poor growth and development in children whose parents lived near mining sites. We conclude that since mercury is the predominant element used in the extraction of gold in alluvial mining, it is an exposure pathway for methyl mercury toxicity for children through dietary exposure.
Is Exposure to Titanium Dioxide Nanoparticle Associated with Occupational Lung Cancer among Titanium Dioxide Production Workers? An Emerging Issue  [PDF]
Alphonse Z. Begani, Rose K. Begani
Occupational Diseases and Environmental Medicine (ODEM) , 2018, DOI: 10.4236/odem.2018.62004
Abstract: This systemic literature review was conducted to find out if there was an association between exposure to TiO2 NP (Titanium dioxide nanoparticle) and occupational lung cancer among TiO2 production workers. An electronic database search was employed which generated several studies relating to TiO2 nanoparticle toxicity. From these studies only ten (10) articles were chosen for this study because they met the review criteria. Two articles were centered around cohort study design while other 8 studies were on experimental design. The two cohort studies did answer the review question that showed no association of TiO2 toxicity and respiratory diseases while the experimental design studies produced conflicting results. The conflicting results were attributed to their objective, sample size, and the study designs. Despite the different conclusions there is adequate evidence in the experimental studies that demonstrated evidence of TiO2 nanoparticle toxicity. Notable cases include cytotoxicity, genotoxicity, apoptotic and cell necrosis in rat and human cells exposed to TiO2 which is generally dose response related. The strengths and limitations of the 10 studies are also discussed. General understanding gained from these studies is for appropriate agencies to be proactive in developing mitigation and controls measures against nanoparticle exposure. This is necessary to avert repetition of previous experiences with exposure to asbestos fibers as a point of reference.
Immuned by Race: Ethnic Identity, Masculinity, and Attachment as Predictors of Cancer Screening among Black Men  [PDF]
Darlingtina K. Atakere, Tamara A. Baker
Psychology (PSYCH) , 2016, DOI: 10.4236/psych.2016.77103
Abstract: An individual’s motivation to screen for cancer is influenced by knowledge of cancer prevalence and perceived likelihood of being diagnosed. While the relationships between health and masculinity, identity, and attachment have been reported, much less is known as to how these factors influence the decision to screen for cancer. This study aimed to determine the influence identified health and social factors have on cancer screening among Black men. Participants (N = 369) were surveyed on questions assessing cancer knowledge, belief about cancer diagnoses, masculinity, self-esteem, attachment style, ethnic identity, and additional social and health characteristics. Results from the multivariate model showed that education, ethnic identity, masculinity, and attachment were significant indicators of cancer screening. Cancer screenings among Black men are contingent upon a myriad of psychological, social, and behavioral factors that are not exclusive, but rather coexisting determinants of health. Understanding the motivation for cancer screening among Black men may begin to diminish the prevalence of having an imminent and aggressive stage of diagnosis among this gendered population. Focusing exclusively on Black men enhances our understanding of this adult population by considering their identity as men of color, while recognizing unique factors that modify actions at the individual, institutional, and policy levels.
Negative refraction of photonic and polaritonic waves in periodic structures
K. Kempa , A. Rose
Bulletin of the Polish Academy of Sciences: Technical Sciences , 2009, DOI: 10.2478/v10175-010-0102-7
Abstract: Negative refraction can be achieved in photonic crystals. We briefly summarize recent studies in this field, and show that such effects are also possible in polaritonic and plasmonic structures, such as the dipole crystal. We propose a practical realization of this crystal, a periodic lattice of dielectric spheres. We study its mode structure, and preliminary results demonstrate the negative refraction on a polaritonic band.
SPARC: Igniting Change in Scholarly Communication
Shirley K. Baker
Liber Quarterly : The Journal of European Research Libraries , 2001,
Abstract: I am speaking today about the current state of SPARC, the Scholarly Publishing and Academic Resources Coalition, initiative of the Association of Research Libraries. I am titling my presentation Igniting Change in Scholarly Communication, because that is what has happened. When SPARC was formed, Ken Frazier, the engine behind its formation, said that a spark could be two things: something easily extinguished or the cause of a conflagration. We are delighted and proud to say that this SPARC seems to have ignited a conflagration. Your inviting us here to talk about SPARC is evidence of that.
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