Fares Qeadan

A Theory-Driven Approach to Tree-Ring Standardization: Defining the Biological Trend from Expected Basal Area Increment

Abstract One of the main elements of dendrochronological standardization is removing the biological trend, i.e. the progressive decline of ring width along a cross-sectional radius that is caused by the corresponding increase in stem size and tree age over time. The “conservative” option for removing this biological trend is to fit a modified negative exponential curve (or a straight line with slope ≤ 0) to the ring-width measurements. This method is based on the assumption that, especially for open-grown and/or shade-intolerant species, annual growth rate of mature trees fluctuates around a specific level, expressed by a constant ring width. Because this method has numerical and conceptual drawbacks, we propose an alternative approach based on the assumption that constant growth is expressed by a constant basal area increment distributed over a growing surface. From this starting point, we derive a mathematical expression for the biological trend of ring width, which can be easily calculated and used for dendrochronological standardization. The proposed C-method is compared to other standardization techniques, including Regional Curve Standardization (RCS), of tree-ring width from ponderosa pines (Pinus ponderosa Douglas ex P.Lawson & C.Lawson) located at the Gus Pearson Natural Area (GPNA) in northern Arizona, USA. Master ring-index chronologies built from ring area, RCS, and C-method reproduced stand-wide patterns of tree growth at the GPNA, whereas other standardization options, including the “conservative” one, failed to do so. In addition, the C-method has the advantage of calculating an expected growth curve for each tree, whereas RCS is based on applying the same growth curve to all trees. In conclusion, the C-method replaces the purely empirical “conservative” option with a theory-based approach, which is applicable to individual ring-width measurement series, does not require fitting a growth curve using nonlinear regression, and can be rigorously tested for improving tree-ring records of environmental changes.

Testing Exponentiality Versus Pareto Distribution via Likelihood Ratio

We consider the problem of maximum likelihood estimation of the parameters of the Pareto Type II (Lomax) distribution. We show that in certain parametrization and after modification of the parameter space to include exponential distribution as a special case, the MLEs of parameters always exist. Moreover, the MLEs have a non standard asymptotic distribution in the exponential case due to the lack of regularity. Further, we develop a likelihood ratio test for exponentiality versus Pareto II distribution. We emphasize that this problem is non standard, and the limiting null distribution of the deviance statistic in not chi-square. We derive relevant asymptotic theory as well as a convenient computational formula for the critical values for the test. An empirical power study and power comparisons with other tests are also provided. A problem from climatology involving precipitation data from hundreds of meteorological stations across North America provides a motivation for and an illustration of the new test.

Age‐specific prevalence of HPV16/18 genotypes in cervical cancer: A systematic review and meta‐analysis

The prevalence of HPV16/18 in cervical cancer has been reported to decline with age in some papers. However, whether this decline in proportion of cancers positive for HPV16/18 is consistently observed across studies remains to be elucidated. Thus, the aim of this study was to identify papers reporting data on age‐specific prevalence of HPV16/18 in cervical cancer and to summarize the results. We employed MEDLINE and Embase for a systematic literature search and thereby identified a total of 644 papers published in the period 1999–2015, of which 15 papers, reporting cross‐sectional data, were included for review (11,526 cervical cancers). The prevalence of HPV16/18 in cervical cancer declined significantly with age (ρ = −0.83, p = 0.04) from 74.8% (95% CI 67.6–80.8) in women aged 30–39 years to 56.8% (95% CI 43.9–68.8) in women aged ≥70 years. As the HPV16/18 positive cancers are prevented in fully vaccinated cohorts, the age‐specific epidemiology of cervical cancer is anticipated to change, with a shift in peak incidence rate to older ages. It will be important for integrated vaccination and screening strategies to consider predicted change in the age‐specific epidemiology of cervical cancer.

Soil-Transmitted Helminth Infections Are Associated With an Increase in Human Papillomavirus Prevalence and a T-Helper Type 2 Cytokine Signature in Cervical Fluids

BACKGROUND An ecological correlation between invasive cervical cancer incidence and burden of soil-transmitted helminths (STH) is hypothesized to explain the excess in detectable human papillomavirus (HPV) infection in Latin America, via a global T-helper type 2 (Th2)-biased mucosal immune response secondary to STH infection. METHODS The association between current STH infection and HPV prevalence was compared in regions of Peru where STH is or is not endemic. Adjusted prevalence ratios (PRs) with robust variance were estimated as an effect measure of STH infection on HPV prevalence in each study site. Soluble immune marker profiles in STH-infected and STH-uninfected women were compared using Spearman rank correlation with the Sidak correction. RESULTS Among women in the helminth-endemic region of the Peruvian Amazon, those with STH infection women had a 60% higher prevalence of HPV, compared with those without STH infection (PR, 1.6; 95% confidence interval, 1.0-2.7). Non-STH parasitic/protozoal infections in the non-STH-endemic population of Peru were not associated with HPV prevalence. In Iquitos, A Th2 immune profile was observed in cervical fluid from helminth-infected women but not helminth-uninfected women. CONCLUSIONS A proportion of the increased HPV prevalence at older ages observed in Latin America may be due to a population-level difference in the efficiency of immunological control of HPV across the lifespan due to endemic STH infection.

DECtalk™ and VeriVox™: Intelligibility, Likeability, and Rate Preference Differences for Four Listener Groups

The intelligibility, likeability, and speech presentation rates for two types of popular synthesized speech, DECtalk™ and VeriVox™, were investigated across four age groups ranging from 6–85 years old. Results for all age groups revealed differences in intelligibility between synthesized adult and child voices, with intelligibility scores for child synthesized voices significantly below those for adult synthesized voices. The most popular synthesized voices were from the VeriVox family. Of interest is that preferred speech presentation rate, expressed as mean words per minute, increased as a function of age, with the oldest listeners preferring the fastest speech presentation rate. This is inconsistent with previous studies that have investigated rate preferences among older adults, and could reflect the different synthesized speech options employed in this study. Implications of these findings for the improvement of text-to-speech products and the practice of AAC are discussed, along with suggestions for further research.

A novel cytokine profile associated with cancer metastasis to mediastinal and hilar lymph nodes identified using fine needle aspiration biopsy - A pilot study.

HighlightsCancer metastasis to the lymph node is associated with poor prognosis, especially in patient with lung cancer.The data presented in the current study shows that the cytokine expression of lymph nodes with metastases differ from a benign lymph node.Understanding the microenvironmental changes in a lymph node with cancer metastasis will allow for novel therapies to prevent and treat cancer metastasis. ABSTRACT Cancer metastasis to the lymph nodes is indicative of a poor prognosis. An endobronchial ultrasound‐guided fine needle aspiration (EBUS‐FNA) biopsy is increasingly being used to sample paratracheal lymph nodes for simultaneous cancer diagnosis and staging. In this prospective, single‐center study, we collected dedicated EBUS‐FNA biopsies from 27 patients with enlarged paratracheal and hilar lymph nodes. Cytokines were assayed using Bio‐Plex Pro human cancer biomarker panels (34 cytokines), in a Bio‐Rad 200 suspension array system. A mean cytokine value was taken from each subject with more than 1 lymph node station EBUS‐FNA biopsies. Malignant and benign histologic diagnoses were established in 16 and 12 patients, respectively. An initial analysis using the Kruskal–Wallis test with Sidak correction for multiple comparisons, showed significant elevation of sVEGFR‐1, IL‐6, VEGF‐A, Angiopoeintin‐2, uPA, sHER‐2/neu and PLGF in malignant lymph node samples compared to benign samples. The univariate logistic regression analyses revealed that 6 cytokines were significant predictors and 1 cytokine (PLGF) was marginally significant for discrimination between benign and malignant samples. The prediction power of these cytokines as biomarkers were very high according to the area under the ROC curve. Multiple logistic regression for subsets of the seven cytokine combined; provided an almost complete discrimination between benign and malignant samples (AUC = 0.989). For screening and diagnostic purposes, we presented the optimal discrimination cut‐off for each cytokine: sVEGFR‐1 (2124.5 pg/mL), IL‐6 (40.2 pg/mL), VEGF‐A (1060.1 pg/mL), Angiopoeintin‐2 (913.7 pg/mL), uPA (248.1 pg/mL), sHER‐2/neu (5010 pg/mL) and PLGF (93.4 pg/mL). For the very first time, a novel cytokine profile associated with cancer metastasis to the paratracheal lymph nodes were reported.

The Joint Distribution of the Sum and the Maximum of IID Exponential Random Variables

The authors establish the joint distribution of the sum X and the maximum Y of IID exponential random variables. They derive exact formuli describing the random vector (X, Y), including its joint PDF, CDF, and other characteristics; marginal and conditional distributions; moments and related parameters; and stochastic representations leading to further properties of infinite divisibility and self-decomposability. The authors also discuss parameter estimation and include an example from climatology that illustrates the modeling potential of this new bivariate model.

The effect of prenatal substance use and maternal contingent responsiveness on infant affect

BACKGROUND The effects of prenatal substance exposure on neurobehavioral outcomes are inherently confounded by the effects of the postnatal environment, making it difficult to disentangle their influence. The goal of this study was to examine the contributing effects of prenatal substance use and parenting style (operationalized as contingent responding during the play episodes of the Still-face paradigm [SFP]) on infant affect. METHODS A prospective cohort design was utilized with repeated assessment of substance use during pregnancy and the administration of the SFP, which measures infant response to a social stressor, at approximately 6months of age. Subjects included 91 dyads classified into four groups: 1) Control (n=34); 2) Medication assisted therapy for opioid dependence (MAT; n=19); 3) Alcohol (n=15); 4) Alcohol+MAT (n=23). Mean % of positive infant affect and mean % of maternal responsiveness (watching, attention seeking, and contingent responding) was compared among the five SFP episodes across the four study groups by MANOVA. Mixed effects modelling was used to estimate the contributing effects of the study groups and maternal responsiveness on infant affect. RESULTS Maternal contingent responding was associated with increase (β̂=0.84; p<0.0001) and attention seeking with decrease (β̂=-0.78; p<0.0001) in infant positive affect. The combined effect of prenatal exposures and covariates explained 15.8% of the variability in infant positive affect, while the model including contingent responding and covariates explained 67.1% of the variability. CONCLUSIONS Higher maternal responsiveness was a much stronger predictor of infant behavior than prenatal exposures, providing the basis for future intervention studies focusing on specific parenting strategies.

Examination of health behaviours in a dynamic population

Background An increasing USA population, especially as a result of foreign immigration, has been the recent focus of healthcare research and policy debate. However, little is known about domestic immigration and its impact on the measures of health conditions and behaviours used to develop and evaluate public health policies and programmes. The objective of this research is to compare health conditions and behaviours between domestic immigrants and established residents in Nevada, the fastest-growing state in the USA. Methods The Nevada 2004–2006 Behavioural Risk Factor Surveillance Survey and added state residency questions were used to examine the associations between length of residence and 24 explanatory variables on health behaviours and conditions. Weighted multiple logistic regressions were used for data analyses. Results Among the 8663 respondents weighted to the total Nevada population, long-term residents (5 to <10 years), compared with newcomers or short-term residents, were more likely to report fair or poor health (OR=1.98, 95% CI 1.15 to 3.40) and obesity (OR=2.18, 95% CI 1.10 to 4.32), and to live with firearms in the home (OR=6.34, 95% CI 1.75 to 22.9). They were less likely to report having diabetes (OR=0.49, 95% CI 0.25 to 0.96), having had an HIV test (OR=0.60 95% CI 0.41 to 0.89), having prostate cancer (OR=0.20 95% CI 0.04 to 0.93) or having had a mammogram (OR=0.41, 95% CI 0.25 to 0.70). Conclusions Long-term residents, compared with newcomers, provide a unique comparison group that share the same physical and policy environment but in different time periods. Knowledge of differences such as these can improve the specificity in identifying target groups for particular interventions.

Racial–Ethnic Disparities in Late-Stage Colorectal Cancer Among Hispanics and Non-Hispanic Whites of New Mexico

Introduction: Hispanics in New Mexico are diagnosed with more later-stage colorectal cancer (CRC) than non-Hispanic Whites (NHW). Our study evaluated the interaction of race/ethnicity and risk factors for later-stage III and IV CRC among patients in New Mexico. Method: CRC patients ages 30 to 75 years (n = 163, 46% Hispanic) completed a survey on key explanatory clinical, lifestyle, preventive health, and demographic variables for CRC risk. Adjusted logistic regression models examined whether these variables differentially contributed to later-stage CRC among NHW versus Hispanics. Results: Compared with NHW, Hispanics had a higher prevalence of later-stage CRC (p = .007), diabetes (p = .006), high alcohol consumption (p = .002), low education (p = .003), and CRC diagnosis due to symptoms (p = .06). Compared with NHW, Hispanics reporting high alcohol consumption (odds ratio [OR] = 7.59; 95% confidence interval [CI] = 1.31-43.92), lower education (OR = 3.5; 95% CI = 1.28-9.65), being nondiabetic (OR = 3.23; 95% CI = 1.46-7.15), or ever smokers (OR = 2.4; 95% CI = 1.03-5.89) were at higher risk for late-stage CRC. Adjusting for CRC screening did not change the direction or intensity of the odds ratios. Conclusion: The ethnicity–risk factor interactions, identified for late-stage CRC, highlight significant factors for targeted intervention strategies aimed at reducing the burden of later-stage CRC among Hispanics in New Mexico with broad applicability to other Hispanic populations.