Repeated significance tests of a multi-parameter in survival analysis

[[abstract]]This paper illustrates a martingale method of constructing repeated significance tests for a multi-dimensional parameter in survival analysis by reducing it to tests for one-dimensional parameters. This illustration is made with parametric survival data with staggered entry. A simulation study is included to indicate its numerical performance.[[notice]]補正完

Shape restricted regression with random Bernstein polynomials

Shape restricted regressions, including isotonic regression and concave regression as special cases, are studied using priors on Bernstein polynomials and Markov chain Monte Carlo methods. These priors have large supports, select only smooth functions, can easily incorporate geometric information into the prior, and can be generated without computational difficulty. Algorithms generating priors and posteriors are proposed, and simulation studies are conducted to illustrate the performance of this approach. Comparisons with the density-regression method of Dette et al. (2006) are included.Comment: Published at http://dx.doi.org/10.1214/074921707000000157 in the IMS Lecture Notes Monograph Series (http://www.imstat.org/publications/lecnotes.htm) by the Institute of Mathematical Statistics (http://www.imstat.org

Profiling time course expression of virus genes---an illustration of Bayesian inference under shape restrictions

There have been several studies of the genome-wide temporal transcriptional program of viruses, based on microarray experiments, which are generally useful in the construction of gene regulation network. It seems that biological interpretations in these studies are directly based on the normalized data and some crude statistics, which provide rough estimates of limited features of the profile and may incur biases. This paper introduces a hierarchical Bayesian shape restricted regression method for making inference on the time course expression of virus genes. Estimates of many salient features of the expression profile like onset time, inflection point, maximum value, time to maximum value, area under curve, etc. can be obtained immediately by this method. Applying this method to a baculovirus microarray time course expression data set, we indicate that many biological questions can be formulated quantitatively and we are able to offer insights into the baculovirus biology.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS258 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

A Bayesian measurement error model for two-channel cell-based RNAi data with replicates

RNA interference (RNAi) is an endogenous cellular process in which small double-stranded RNAs lead to the destruction of mRNAs with complementary nucleoside sequence. With the production of RNAi libraries, large-scale RNAi screening in human cells can be conducted to identify unknown genes involved in a biological pathway. One challenge researchers face is how to deal with the multiple testing issue and the related false positive rate (FDR) and false negative rate (FNR). This paper proposes a Bayesian hierarchical measurement error model for the analysis of data from a two-channel RNAi high-throughput experiment with replicates, in which both the activity of a particular biological pathway and cell viability are monitored and the goal is to identify short hair-pin RNAs (shRNAs) that affect the pathway activity without affecting cell activity. Simulation studies demonstrate the flexibility and robustness of the Bayesian method and the benefits of having replicates in the experiment. This method is illustrated through analyzing the data from a RNAi high-throughput screening that searches for cellular factors affecting HCV replication without affecting cell viability; comparisons of the results from this HCV study and some of those reported in the literature are included.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS496 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

ESTIMATION IN A PROPORTIONAL HAZARD MODEL FOR SEMI-MARKOV COUNTING PROCESS

Abstract: Estimation is studied in a regression model for counting processes whose baseline intensity processes are of semi-Markov form. Asymptotic normality is established for a Breslow-type estimator of the cumulative baseline hazard for each gap time of the counting process

Tuberculosis in Children and Adolescents, Taiwan, 1996–2003

Analysis of data from Taiwan’s National Tuberculosis (TB) Registry showed that incidence of TB in persons <20 years of age was 9.61/100,000 person-years, biphasic, and age-relevant, with a major peak in persons slightly >12 years. Aboriginal children were 8.1–17.4× more likely to have TB than non-Aboriginal children

Enhancing Mechanical Properties of a Lightweight TiAlCrNbVZr Medium-Entropy Alloy: Fine-Tuning Alloy Composition and Thermomechanical Treatment

Abstract: The quest to reduce fuel consumption and environmental pollution in the transportation sector has heightened the demand for developing lightweight alloys with enhanced mechanical properties. Accordingly, this study focused on optimizing the mechanical properties of a lightweight Ti65(AlCrNbV)28Zr7 medium entropy alloy (MEA) by strategically adjusting its Al, Cr, Nb, and V elemental contents. Hardness testing indicated a strengthening ability hierarchy of Cr &gt; Al &gt; V &gt; Nb. Furthermore, tensile tests revealed that although a high Cr content significantly enhances strength, it also reduces the ductility of an MEA. Drawing on mechanical insights gained from a previously studied Ti60Al10Cr10Nb10V10 MEA and the present findings, a novel Ti60Al10Cr4Nb10V9Zr7 (Ti60Zr7) MEA was developed. This new alloy retains a single body-centered cubic structure and demonstrated exceptional mechanical performance in tensile testing, with a yield strength of 1066 MPa and 22% ductility. The Ti60Zr7 MEA underwent a series of thermomechanical treatments, including 50% hot rolling, 80% cold rolling, and rapid annealing up to 800 °C at a rate of 25 °C/s. After thermal processing, the Ti60Zr7 MEA not only preserved its single body-centered cubic structure but also achieved a remarkable combination of yield strength (&gt;1200 MPa) and ductility (measured as &gt;15% elongation). These advancements underscore the alloy’s considerable potential for application in sports equipment and transportation vehicles

Epidemiological characteristics of varicella from 2000 to 2008 and the impact of nationwide immunization in Taiwan

[[abstract]]Background: Varicella has an important impact on public health. Starting in 2004 in Taiwan, nationwide free varicella vaccinations were given to 1-year-old children.Methods: Our study investigated the epidemiological characteristics of varicella from 2000 to 2008, and assessed the change of varicella epidemiology after the mass varicella immunization. ICD-9-CM codes related to varicella or chickenpox (052, 052.1, 052.2, 052.7, 052.8, 052.9) were analyzed for all young people under 20 years of age through the National Health Insurance database of Taiwan from 2000 to 2008.Results: Case numbers of varicella or chickenpox significantly declined after the nationwide immunization in 2004. Winter, particularly January, was the epidemic season of varicella. We found a significant post-vaccination decrease in incidence among preschool children, especially 3 to 6 year-old children-- the peak incidence was 66 per thousand for 4 and 5 year-old children before the nationwide immunization (2000 to 2003), and the peak incidence was 23 per thousand for 6 year-old children in 2008 (p < 0.001). Varicella-related hospitalization also significantly decreased in children younger than 6 years after the nationwide immunization.Conclusion: The varicella annual incidence and varicella-related hospitalization markedly declined in preschool children after nationwide varicella immunization in 2004

Bmi-1 Regulates Snail Expression and Promotes Metastasis Ability in Head and Neck Squamous Cancer-Derived ALDH1 Positive Cells

Recent studies suggest that ALDH1 is a putative marker for HNSCC-derived cancer stem cells. However, the regulation mechanisms that maintain the stemness and metastatic capability of HNSCC-ALDH1+ cells remain unclear. Initially, HNSCC-ALDH1+ cells from HNSCC patient showed cancer stemness properties, and high expression of Bmi1 and Snail. Functionally, tumorigenic properties of HNSCC-ALDH1+ cells could be downregulated by knockdown of Bmi-1. Overexpression of Bmi-1 altered in expression property ALDH1− cells to that of ALDH1+ cells. Furthermore, knockdown of Bmi-1 enhanced the radiosensitivity of radiation-treated HNSCC-ALDH1+ cells. Moreover, overexpression of Bmi-1 in HNSCC-ALDH1− cells increased tumor volume and number of pulmonary metastatic lesions by xenotransplant assay. Importantly, knock-down of Bmi1 in HNSCC-ALDH1+ cells significantly decreased distant metastases in the lungs. Clinically, coexpression of Bmi-1/Snail/ALDH1 predicted the worst prognosis in HNSCC patients. Collectively, our data suggested that Bmi-1 plays a key role in regulating Snail expression and cancer stemness properties of HNSCC-ALDH1+ cells