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Search Results: 1 - 10 of 7447 matches for " Jennifer Clarke "
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Prediction in several conventional contexts
Bertrand Clarke,Jennifer Clarke
Statistics Surveys , 2012,
Abstract: We review predictive techniques from several traditional branches of statistics. Starting with prediction based on the normal model and on the empirical distribution function, we proceed to techniques for various forms of regression and classification. Then, we turn to time series, longitudinal data, and survival analysis. Our focus throughout is on the mechanics of prediction more than on the properties of predictors.
An ensemble approach to improved prediction from multitype data
Jennifer Clarke,David Seo
Statistics , 2008, DOI: 10.1214/074921708000000219
Abstract: We have developed a strategy for the analysis of newly available binary data to improve outcome predictions based on existing data (binary or non-binary). Our strategy involves two modeling approaches for the newly available data, one combining binary covariate selection via LASSO with logistic regression and one based on logic trees. The results of these models are then compared to the results of a model based on existing data with the objective of combining model results to achieve the most accurate predictions. The combination of model predictions is aided by the use of support vector machines to identify subspaces of the covariate space in which specific models lead to successful predictions. We demonstrate our approach in the analysis of single nucleotide polymorphism (SNP) data and traditional clinical risk factors for the prediction of coronary heart disease.
Clustering categorical data via ensembling dissimilarity matrices
Saeid Amiri,Bertrand Clarke,Jennifer Clarke
Statistics , 2015,
Abstract: We present a technique for clustering categorical data by generating many dissimilarity matrices and averaging over them. We begin by demonstrating our technique on low dimensional categorical data and comparing it to several other techniques that have been proposed. Then we give conditions under which our method should yield good results in general. Our method extends to high dimensional categorical data of equal lengths by ensembling over many choices of explanatory variables. In this context we compare our method with two other methods. Finally, we extend our method to high dimensional categorical data vectors of unequal length by using alignment techniques to equalize the lengths. We give examples to show that our method continues to provide good results, in particular, better in the context of genome sequences than clusterings suggested by phylogenetic trees.
A General Hybrid Clustering Technique
Saeid Amiri,Bertrand Clarke,Jennifer Clarke,Hoyt A. Koepke
Computer Science , 2015,
Abstract: Here, we propose a clustering technique for general clustering problems including those that have non-convex clusters. For a given desired number of clusters $K$, we use three stages to find a clustering. The first stage uses a hybrid clustering technique to produce a series of clusterings of various sizes (randomly selected). They key steps are to find a $K$-means clustering using $K_\ell$ clusters where $K_\ell \gg K$ and then joins these small clusters by using single linkage clustering. The second stage stabilizes the result of stage one by reclustering via the `membership matrix' under Hamming distance to generate a dendrogram. The third stage is to cut the dendrogram to get $K^*$ clusters where $K^* \geq K$ and then prune back to $K$ to give a final clustering. A variant on our technique also gives a reasonable estimate for $K_T$, the true number of clusters. We provide a series of arguments to justify the steps in the stages of our methods and we provide numerous examples involving real and simulated data to compare our technique with other related techniques.
Comparing Ginsenoside Production in Leaves and Roots of Wild American Ginseng (Panax quinquefolius)  [PDF]
James Matthew Searels, Karissa D. Keen, Jonathan L. Horton, H. David Clarke, Jennifer Rhode Ward
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.46154

American ginseng, Panax quinquefolius L., is an herbaceous perennial species that is destructively harvested for its bioactive compounds called ginsenosides. The demand for this herb fosters illegal poaching and over-harvesting that reduces genetic variability and population viability. Five wild populations in western North Carolina were studied to better understand the production of ginsenosides in leaf and root tissues. Total ginsenoside concentration was significantly higher in leaves than roots, though total yield was higher in roots due to greater root biomass. However, some ginsensosides (Rb2, Rd and Re) had higher or more consistent yields in leaves than roots, so might be developed into a sustainable source of these medicinally-active compounds. Additionally, we identified regional root chemotypes that differed in the production of the ginsenosides Rg1 and Re and could be developed into regional cultivars depending on the desired panel of ginsenosides.

A Validated Questionnaire for Quantifying Skin Oiliness  [PDF]
Leslie S. Baumann, Randall D. Penfield, Jennifer L. Clarke, Deysi K. Duque
Journal of Cosmetics, Dermatological Sciences and Applications (JCDSA) , 2014, DOI: 10.4236/jcdsa.2014.42012

Increased sebum production is a common skin complaint and plays an important role in acne and oily scalp conditions. To choose the correct skin care products, which mostly are marketed for dry, oily or normal skin, the consumer must self-assess their skin type. Studies show that individuals incorrectly self-assess their sebum secretion levels. In order to be able to correctly determine skin oiliness, we have developed a six-item skin oiliness scale (SOS) that correlates with sebumeter measurements. The resulting correlation was 0.54, which was significantly different from zero (p < 0.01). This result indicates a strong relationship between the SOS scores and the associated sebumeter measurements. This is easy to administer questionnaire to accurately determine skin oiliness and can be useful in screening and recruiting patients for research trials, performing outcome research, and recommending skin care products and procedures. Our study shows that this skin oiliness scale is an accurate way to identify and quantify skin oiliness.

The Effect of Ethnicity on 2D and 3D Frontomaxillary Facial Angle Measurement in the First Trimester
Jennifer Alphonse,Jennifer Cox,Jill Clarke,Philip Schluter,Andrew McLennan
Obstetrics and Gynecology International , 2013, DOI: 10.1155/2013/847293
Abstract: Objectives. To determine the existence and extent of ethnic differences in 2D or 3D fetal frontomaxillary facial angle (FMFA) measurements. Methods. During routine 11–14 weeks nuchal translucency screening undertaken in a private ultrasound practice in Sydney, Australia, 2D images and 3D volumes of the fetal profile were collected from consenting patients. FMFA was measured on a frozen 2D ultrasound image in the appropriate plane and, after a delay of at least 48 hours, was also measured on the reconstructed 3D ultrasound volume offline. Results. Overall 416 patients were included in the study; 220 Caucasian, 108 north Asian, 36 east Asian and 52 south Asian patients. Caucasians had significantly lower median FMFA measurements than Asians in both 2D (2.2°; ) and 3D (3.4°; ) images. Median 2D measurements were significantly higher than 3D measurements in the Caucasian and south Asian groups ( and ), but not in north and east Asian groups ( and ). Conclusions. Significant ethnic variations in both 2D and 3D FMFA measurements exist. These differences may indicate the need to establish ethnic-specific reference ranges for both 2D and 3D imaging. 1. Introduction Ultrasound-based screening for fetal aneuploidy in the first trimester has developed rapidly over the past 20 years. The original observation that faces of Down syndrome individuals were flat led to the investigation of frontomaxillary facial angle (FMFA) measurement as a risk factor for trisomy 21 [1]. Reference ranges for FMFA using offline three-dimensional (3D) reconstruction software were developed in the first trimester identifying the 95th percentile measurement as 85° [2]. In a previous study, we demonstrated that 2D FMFA measurements were similar, but not equivalent, to those obtained by the 3D method; thus, normative data would need to be collected from the normal population separately for both 2D and 3D [3]. Given the potential ethnic variations, normative data from local populations may also be necessary. A recent study has cast doubt on the efficacy of first trimester FMFA measurement as a screening method for Down syndrome in an Asian population. Kwon and colleagues demonstrated that 3D FMFA measurements in the normal Korean population were substantially wider than the previously reported mean which would increase the screening false positive rate [4]. A study by Chen et al. [5] contradicts this finding in the Asian population, as the difference in FMFA measurements between Caucasian and Chinese patients was thought to be so small that it was not clinically significant. Given the
Working Inside for Smoking Elimination (Project W.I.S.E.) study design and rationale to prevent return to smoking after release from a smoke free prison
Jennifer G Clarke, Rosemarie A Martin, LAR Stein, Cheryl E Lopes, Jennifer Mello, Peter Friedmann, Beth Bock
BMC Public Health , 2011, DOI: 10.1186/1471-2458-11-767
Abstract: This paper describes the design and rationale of a randomized clinical trial to enhance smoking abstinence rates among individuals following release from a tobacco free prison. The intervention is six weekly sessions of motivational interviewing and cognitive behavioral therapy initiated approximately six weeks prior to release from prison. The control group views six time matched videos weekly starting about six weeks prior to release. Assessments take place in-person 3 weeks after release and then for non-smokers every 3 months up to 12 months. Smoking status is confirmed by urine cotinine.Effective interventions are greatly needed to assist these individuals to remain smoke free and reduce health disparities among this socially and economically challenged group.NCT01122589Tobacco use contributes to over 400,000 deaths annually [1]. It is a major contributor to both cancer and heart disease risk, and is the leading cause of preventable morbidity, mortality and health expense in the United States [2]. There is an estimated $157 billion in annual health related and economic costs [2]. Quitting smoking reduces the risks of developing smoking related illnesses as well as the morbidity and mortality associated with these illnesses.In 2009 approximately 46.6 million American adults smoked, an overall prevalence of 20.6% [3]. The prevalence of smoking is much higher among incarcerated populations. Across the U.S. tobacco use among prisoners is approximately three times that of the general population, [4] and in some areas is even higher. For example approximately 80% of the women incarcerated in RI smoked prior to incarceration [5]. Moreover, incarcerated populations suffer disproportionately from health disparities due to tobacco associated illnesses, as minorities, poor, mentally ill and illicit substance using individuals are all overrepresented in correctional facilities. With approximately 9 million Americans passing through correctional institutions annually and an
Dentistry – a professional contained career in healthcare. A qualitative study of Vocational Dental Practitioners' professional expectations
Jennifer E Gallagher, Wendy Clarke, Kenneth A Eaton, Nairn HF Wilson
BMC Oral Health , 2007, DOI: 10.1186/1472-6831-7-16
Abstract: Purposive sampling of schemes was undertaken to include urban, rural and metropolitan schemes, schemes in areas with and without dental schools and geographic coverage across England and Wales. All VDPs in these schemes were initiated to participate in this qualitative study using focus groups. A topic guide was utilised to standardise data collection. Informants' views were recorded on tape and in field notes. Data were transcribed and analysed using Framework Methodology.A total of 99 VDPs participated in the 10 focus groups. Their choice of dentistry as a professional career was motivated by multiple categories of influence: 'academic', 'healthcare', 'lifestyle', the influence of 'family', 'friends', 'careers advice' and 'work experience'. Consideration of the features of the 'professional job' appears to have been key to their choice of dentistry and the 'active rejection of medicine' as an alternative career.Entry into the profession was proving a challenging process for some but not all VDPs. Informants perceived that their vision had been moderated as a result of 'personal student debt', 'national workforce initiatives', 'limitations on clinical practice' and the 'cost of additional training'.Short term goals focused around 'recovery from the past' and 'preparation for the future'. Longterm goals covered the spectrum of opportunities within dentistry. Factors influencing VDPs longterm career plans fell into six main categories: professional, personal, financial, political, social and cultural.VDPs chose dentistry because they perceived that it provides a financially lucrative, contained career in healthcare, with professional status, job security and the opportunity to work flexibly. They perceive that their vision is challenged by changes affecting education and the healthcare system. Longterm professional expectations were closely linked with their personal lives and support a vision of a favourable work/life balance.An understanding of the motivation of th
Non-peptidergic small diameter primary afferents expressing VGluT2 project to lamina I of mouse spinal dorsal horn
Jennifer N Clarke, Rebecca L Anderson, Rainer V Haberberger, Ian L Gibbins
Molecular Pain , 2011, DOI: 10.1186/1744-8069-7-95
Abstract: Neurobiotin-labeled VGluT2-immunoreactive (IR) terminals were restricted to lamina I, with a medial-to-lateral distribution similar to CGRP-IR terminals. Most VGluT2-IR terminals in lateral lamina I were not labeled by Neurobiotin implying that they arose mainly from central neurons. 38 ± 4% of Neurobiotin-labeled VGluT2-IR terminals contained CGRP-IR. Conversely, only 17 ± 4% of Neurobiotin-labeled CGRP-IR terminals expressed detectable VGluT2-IR. Neurobiotin-labeled VGluT2-IR or CGRP-IR terminals often aggregated into small clusters or microdomains partially surrounding intrinsic lamina I neurons.The central terminals of primary afferents which express high levels of VGluT2-IR but not CGRP-IR terminate mainly in lamina I. The spatial arrangement of VGluT2-IR and CGRP-IR terminals suggest that lamina I neurons receive convergent inputs from presumptive nociceptors that are primarily glutamatergic or peptidergic. This reveals a previously unrecognized level of organization in lamina I consistent with the presence of multiple nociceptive processing pathways.Most primary afferent neurons in dorsal root ganglia (DRG) are considered to use glutamate as their fast excitatory transmitter, [1-3], although some may use aspartate instead [4-6]. Many smaller DRG neurons, including nociceptors, express high levels of neuropeptides, usually both calcitonin gene-related peptide (CGRP) and substance P [7-12] or bind the lectin, IB4 [13-15]. The peptidergic neurons span a range of nociceptive modalities, including those associated with transient receptor potential cation channel subfamily V (TRPV1) receptor activation in response to noxious heat or inflammation, for example [16,17].Early microscopic identification of putative glutamatergic primary afferent neurons attempted to directly localize glutamate or glutaminase, for example [2,6,18-20], which also exist in metabolic pools not directly associated with neurotransmission. The subsequent discovery of the vesicular glutamate tr
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