Physical Sciences and Mathematics Commons^™

Examining Failures Of Kc-135s Using Survival Analysis, Vanessa I. R. Unseth

Theses and Dissertations

The United States Air Force manages an inventory of 396 KC-135 Stratotanker aircraft. With mission capability rates falling and total non-mission capability supply rates increasing, it is necessary to take a deeper look at recurrent failures. The study applies non-parametric and semi-parametric survival models to a dataset retrieved from LIMS-EV to look at the duration(s) until failure for the KC-135. Results of non-parametric models show cumulative failure rates increase as sorties or flight hours increase. In addition, semi-parametric models or Cox proportional hazards models with frailty confirm that locations or air bases are not associated with recurrent failures.

Simulating Autonomous Cruise Missile Swarm Behaviors In An Anti-Access Area Denial (A2ad) Environment, Kyle W. Goggins

Theses and Dissertations

The increasingly sophisticated anti-access area denial (A2AD) threat imposed by the modern integrated air defense system (IADS), coupled with the decreasingly potent advantage provided by high-end stealth platforms, has prompted Air Force senior leaders to invest in radically changing the nature of air power for the year 2030 and beyond. A prominent element of this new vision is weapon swarming, which aims to address this challenge by overwhelming the IADS with huge numbers of low-cost, attritable aerial assets emboldened by autonomous capabilities. This research proposes a framework for classifying the different levels of autonomous capability along three independent dimensions—namely ability …

Comparison Of Lightning Warning Radii Distributions, Michael M. Maestas

Theses and Dissertations

Previous research investigating lightning warning radii about the Cape Canaveral space launch facilities have focused on reducing these radii from either 5 nautical miles (NM) to 4 NM or from 6 NM to 5 NM depending on the structures being protected. Some of these findings have suggested the possibility of both a seasonal difference (warm versus cold) and lightning detection events (cloud-to-ground lightning (CG) or total lightning (TL)) impacting these radii and associated risk levels. Utilizing the 2017-2020 data provided by the 45th Weather Squadron at Patrick Space Force Base via the Mesoscale Eastern Range Lightning Information System (MERLIN), this …

High Definition Tdcs Effect On Postural Control In Healthy Individuals: Entropy Analysis Of A Crossover Clinical Trial, Diandra B. Favoretto, Eduardo Bergonzoni, Diego Carvalho Nascimento, Francisco Louzada, Tenysson W. Lemos, Rosangela A. Batistela, Renato Moraes, João P. Leite, Brunna P. Rimoli, Dylan J. Edwards, Taiza G.S. Edwards

Research outputs 2022 to 2026

Objective: Converging evidence supporting an effect of transcranial direct current stimulation (tDCS) on postural control and human verticality perception highlights this strategy as promising for post-stroke rehabilitation. We have previously demonstrated polarity-dependent effects of high-definition tDCS (HD-tDCS) on weight-bearing asymmetry. However, there is no investigation regarding the time-course of effects on postural control induced by HD-tDCS protocols. Thus, we performed a nonlinear time series analysis focusing on the entropy of the ground reaction force as a secondary investigation of our randomized, double-blind, placebo-controlled, crossover clinical trial. Materials and Methods: Twenty healthy right-handed young adults received the following conditions (random order, …

Physical Investigation Of Downburst Winds And Applicability To Full Scale Events, Federico Canepa

Electronic Thesis and Dissertation Repository

Thunderstorm winds, i.e. downbursts, are cold descending currents originating from cumulonimbus clouds which, upon the impingement on the ground, spread radially with high intensities. The downdraft phase of the storm and the subsequent radial outflow that is formed can cause major issues for aviation and immense damages to ground-mounted structures. Thunderstorm winds present characteristics completely different from the stationary Gaussian synoptic winds, which largely affect the mid-latitude areas of the globe in the form of extra-tropical cyclones. Downbursts are very localized winds in both space and time. It follows that their statistical investigation, by means of classical full scale anemometric …

Body Image, Quality Of Life, And Their Predicting Factors In Pregnant Women: A Cross-Sectional Study, Zeynab Rezaei Fard, Arman Azadi, Yousef Veisani

Kesmas

Pregnancy can influence women’s psychological health, including body image and quality of life. This study aimed to examine the relationship between body image and quality of life and their predicting factors in pregnant women. This cross-sectional study was conducted on 250 pregnant women referred to health centers in Ilam City, Iran. Participants were selected using a random sampling method. Data collection tools comprised a sociodemographic questionnaire, Body Image Concern Inventory (BICI), and quality of life questionnaire (Short Form-12). Data were analyzed using statistical software. The mean ± SD of body image concern and quality of life was estimated at 31.77 …

The Estimation Of Excess Mortality During The Covid-19 Pandemic In Jakarta, Indonesia, Madona Yunita Wijaya

Kesmas

Indonesia is among the countries affected by the coronavirus disease 2019 (COVID-19) pandemic, and DKI Jakarta Province recorded the highest number of deaths. This study aimed to analyze the excess mortality across five administrative cities in Jakarta stratified by gender to assess the pandemic impact on mortality. The monthly mortality data from January 2018 to December 2020 was obtained through government sources. This data helped to measure excess mortality by estimating the baseline mortality had the COVID-19 pandemic not occurred. The analysis used a linear mixed model because of its ease and flexibility in forecasting subject-specific mortality. The results showed …

The Determinants Of Covid-19 Vaccine Acceptance In Sumatra, Cindy Sidarta, Andree Kurniawan, Nata P H Lugito, Jeremia Imanuel Siregar, Veli Sungono, Rivaldo Steven Heriyanto, Novia Lauren Sieto, Devina Adella Halim, Claudia Jodhinata, Saraswati Anindita Rizki, Terry Devita Sinaga, Chintya Marcella, Felix Wijovi, Billy Susanto, Elizabeth Marcella, Johan Wibowo, Jonathan Juniard Anurantha, Michelle Imanuelly, Michele Indrawan, Nadia Khoirunnisa Heryadi

Kesmas

In light of the current coronavirus disease 2019 (COVID-19) vaccination programs being implemented worldwide, this study aimed to evaluate the COVID-19 vaccine acceptance survey in Indonesia conducted by the World Health Organization (WHO), the Ministry of Health of the Republic of Indonesia, the National Immunization Technical Advisory Group (NITAG), and the United Nations Children's Fund (UNICEF), published in November 2020. It was found that Sumatra Island having lower COVID-19 vaccine acceptance rates, with Aceh Province displaying the lowest level of vaccine acceptance. Thus, a cross-sectional study was conducted, and a logistic regression analysis was used to identify the factors affecting …

Effectiveness Of Using Information, Education, And Communication Flowchart Media In Implementation Of Early Breastfeeding Initiation, Rizna Notarianti, Sandra Fikawati, Alifani Faiz Faradhila

Kesmas

Early initiation of breastfeeding (EIB) has many benefits for both the baby and the mother. However, in Bogor City, there are still many babies who do not get EIB when they are born (33.6%). The implementation of EIB is not optimal due to the absence of standard procedures to equalize its theory and perception. This study aimed to investigate the effectiveness of using Information, Education, and Communication (IEC) flowchart media concerning the standard procedure for EIB implementation in the Primary Health Care (PHC) in Bogor City. A quasi-experimental research was conducted on 58 midwives divided into the intervention and control …

A Study On The Impact Of Occupational Fatigue On Human Performance Among Oil And Gas Workers In Indonesia, Achmad Dahlan, Baiduri Widanarko

Kesmas

Occupational fatigue is a serious problem since it may cause several issues, including deteriorating human performance. Some major accidents in the oil and gas industries were associated with the lack of human performance due to occupational fatigue. This study aimed to analyze the impact of occupational fatigue on human performance among oil and gas workers in Indonesia. This study used a cross-sectional design using a self-administered validated questionnaire to gather information on demographic (gender and age), work characteristics (work rotation, work duration, shift work model, day/night shift, job position), sleep debt, sleep quality, occupational (acute and chronic) fatigue, and at-risk …

Consumption Of Sugar-Sweetened Beverages And Its Potential Health Implications In Indonesia, Ratu Ayu D. Sartika, Atmarita Atmarita, M. I Zulkarnain Duki, Saptawati Bardosono, Lindawati Wibowo, Widjaja Lukito

Kesmas

The broad availability of sugar-sweetened beverages (SSBs) in the Indonesian market is increasing consumption. It, combined with escalating incidence and prevalence of diabetes and related non-communicable diseases (NCDs), and the ongoing debate on policies, has called for a comprehensive review as described in this study. Data was compiled from various sources but mainly gathered from the reported or published documents because of no direct access to the necessary data set. The lack of studies that assessed the direct relationship between SSB consumption and health outcomes in the Indonesian context also became a strong reason for the preparation of this review …

Increased Thyroid Hormone Levels In Pesticide Sprayer At Agricultural Area, Aditya Pawitra, Khuliyah Candraning Diyanah, Mohd Talib Latif, Beni Hari Susanto, Muhammad F D Lusno

Kesmas

Pesticides used massively in the agricultural sector would cause many poisoning and serious health problems. Organophosphate pesticides have been identified as endocrine-disrupting chemicals. This study aimed to compare thyroid hormone levels between the sprayers chronically exposed to pesticides and the control respondents who had never been exposed to pesticides. This study was an analytical observational with a cross-sectional design. The total number of respondents was 150, 50 as sprayers and 100 as control respondents. The venous blood samples were examined using the Enzyme-Linked Immunosorbent Assay (ELISA). The findings significantly showed that the sprayer had a higher level of thyroid-stimulating hormone …

The Development Of A Work Stress Model For Air Traffic Controllers In Indonesia, Lalu Muhammad Saleh, Syamsiar Siang Russeng, Istiana Tadjuddin, Iva Hardi Yanti, Nurul Mawaddah Syafitri, Mahfuddin Yusbud, Yulianah Rahmadani

Kesmas

The workload complexity experienced by and expected air traffic controllers (ATCs) causes psychological fatigue, engenders stressful conditions, and affects their quality of life. This study investigated the development of a model of psychological fatigue in ATCs in Indonesia, which affected their work stress levels and quality of life. This cross-sectional, three-month study focused on 185 ATCs randomly selected from six AirNavs based on strata. The results indicated a relationship between work duration (p-value = 0.033) and stress on ATCs; additionally, a relationship between work time and the opportunity to meet personal life needs (p-value = 0.007) were found. Feelings of …

Aminolevulinic Acid Dehydratase Allelic Frequency And Lead Toxicity In Children Under-Five In A Former Used Lead-Acid Battery Area, Yana Irawati, Haryoto Kusnoputranto, Umar Fahmi Achmadi, Ahmad Safrudin, Alfred Sitorus, Rifqi Risandi, Suradi Wangsamuda, Dendi Hadi Permana, Lepa Syahrani, Farahana Kresno Dewayanti, Puji B S Asih, Din Syafruddin

Kesmas

Polymorphisms in the Aminolevulinic Acid Dehydratase (ALAD) gene responsible for the ALAD1 and ALAD2 alleles have been implicated in susceptibility to lead toxicity. This study aimed to determine the allelic frequency of ALAD2 among children living in Bogor District, Indonesia, and its association with blood lead levels (BLLs) and lead toxicity. A cross-sectional study involving 128 children was conducted during September-October 2019 in the former ULAB area in Cinangka Village. The ALAD polymorphism, BLLs, and hematological parameters were evaluated. Blood samples were taken for dried blood spotting on filter paper, blood film, and BLL measurement. The PCR amplification and sequencing …

Public Perception And Obedience With Social Distancing Policies During The Covid-19 Pandemic In Jakarta, Indonesia, Widyamurti Widyamurti, Edwina Bernita Sitorus, Dewi Susanna, Bambang Wispriyono, Aria Kusuma, Renti Mahkota

Kesmas

The Indonesian Government established a social distancing policy to prevent COVID-19 transmission. However, this implementation will be ineffective without the compliance of the people. This study aimed to analyze the relationship between public perception and obedience with social distancing in terms of the variables based on the Health Belief Model. This study used a cross-sectional design with a population of Daerah Khusus Ibukota (DKI) Jakarta’s indigenes within the productive age of 15-64 years. The sample comprised 408 participants, with the independent variables of sociodemographics (age, gender, occupation, and education) and health beliefs (perceived susceptibility, severity, benefits, barriers, and self-efficacy). Meanwhile, …

Neighborhood Deprivation And Risk Of Mortality Among Men With Prostate Cancer: Findings From A Long-Term Follow-Up Study, Madhav K.C., Ariane L. Rung, Edward J. Trapido, Laura S. Rozek, Elizabeth T.H. Fontham, Jeannette T. Bensen, Laura Farnan, Susan E. Steck Phd, Mph, Rd, Lixin Song, James L. Mohler, Edward S. Peters

Faculty Publications

Background The overall survival rate of prostate cancer (PCa) has improved over the past decades. However, huge socioeconomic and racial disparities in overall and prostate cancer-specific mortality exist. The neighborhood-level factors including socioeconomic disadvantage and lack of access to care may contribute to disparities in cancer mortality. This study examines the impact of neighborhood deprivation on mortality among PCa survivors. Methods North Carolina–Louisiana Prostate Cancer Project (PCaP) data were used. A total of 2113 men, 1046 AA and 1067 EA, with PCa were included in the analysis. Neighborhood deprivation was measured by the Area Deprivation Index (ADI) at the census …

Learning Latent Causal Dynamics, Weiran Yao, Guangyi Chen, Kun Zhang

Machine Learning Faculty Publications

One critical challenge of time-series modeling is how to learn and quickly correct the model under unknown distribution shifts. In this work, we propose a principled framework, called LiLY, to first recover time-delayed latent causal variables and identify their relations from measured temporal data under different distribution shifts. The correction step is then formulated as learning the low-dimensional change factors with a few samples from the new environment, leveraging the identified causal structure. Specifically, the framework factorizes unknown distribution shifts into transition distribution changes caused by fixed dynamics and time-varying latent causal relations, and by global changes in observation. We …

Diet Quality Scores And Cardiometabolic Risk Factors In Mexican Children And Adolescents: A Longitudinal Analysis, Abeer Ali Aljahdali, Karen E. Peterson, Alejandra Cantoral, Edward Ruiz-Narvaez, Martha M. Tellez-Rojo, Hyungjin Myra Kim, James R. Hébert Scd, Michael David Wirth Msph, Phd, Face, Libni A. Torres-Olascoaga, Nitin Shivappa Mbbs, Mph, Ph.D., Ana Baylin

Faculty Publications

There is limited evidence for the effects of diet on cardiometabolic profiles during the pubertal transition. We collected repeated measures of diet quality and cardiometabolic risk factors among Mexican youth. This analysis included 574 offspring of the Early Life Exposure in Mexico to Environmental Toxicants (ELEMENT) birth cohort followed up to three time points. Dietary Approaches to Stop Hypertension (DASH), alternate Mediterranean Diet (aMedDiet), and Children’s Dietary Inflammatory Index (C-DII^TM) scores were computed from food frequency questionnaires. Higher DASH and aMedDiet scores reflect a higher diet quality, and lower C-DII scores reflect an anti-inflammatory diet. Cardiometabolic risk factors …

How The Number Line Can Be Used To Promote Students' Understanding Of The Normal Distribution, Danri H. Delport

Numeracy

A strong foundation in early number concepts is crucial for students’ future success in statistics. Despite its importance in statistics, many first-year students struggle to comprehend the normal distribution due to a lack of basic number sense. Students get confused about the order and magnitude of negative z-scores on a standard normal curve or when problems about normally distributed random variables are presented in word questions which involve phrases that indicate inequalities. As a result, students shade wrong areas on the bell-shaped curve when they have to calculate probabilities for normally distributed variables. Visual representations such as the number …

Adverse Events Reporting Of Clinical Trials In Exercise Oncology Research (Advance): Protocol For A Scoping Review, Hao Luo, Oliver Schumacher, Daniel A. Galvão, Robert U. Newton, Dennis R. Taaffe

Research outputs 2022 to 2026

Introduction: Adequate, transparent, and consistent reporting of adverse events (AEs) in exercise oncology trials is critical to assess the safety of exercise interventions for people following a cancer diagnosis. However, there is little understanding of how AEs are reported in exercise oncology trials. Thus, we propose to conduct a scoping review to summarise and evaluate current practice of reporting of AEs in published exercise oncology trials with further exploration of factors associated with inadequate reporting of AEs. The study findings will serve to inform the need for future research on standardisation of the definition, collection, and reporting of AEs for …

Diet Quality And Dietary Inflammatory Index Score Among Women’S Cancer Survivors, Sibylle Kranz, Faten Hasan, Erin Kennedy, Jamie Zoellner, Kristin A. Guertin, Nitin Shivappa Mbbs, Mph, Ph.D., James R. Hébert, Roger Anderson, Wendy Cohn

Faculty Publications

The purpose of this study was to investigate Healthy Eating Index 2015 (HEI-2015) and Energy-Adjusted Dietary Inflammatory Index (E-DIITM) scores in women's cancer survivors and to examine socio-economic (SES) characteristics associated with these two diet indices. In this cross-sectional study, survivors of women's cancers completed a demographic questionnaire and up to three 24-h dietary recalls. HEI-2015 and E-DII scores were calculated from average intakes. One-way ANOVA was used to examine the association of various demographic factors on HEI-2015 and E-DII scores. Pearson Correlation was used to calculate the correlation between the two scores. The average HEI-2015 score was 55.0 +/- …

Session 13: On Statistical Estimates Of The Inverted Kumaraswamy Distribution Under Adaptive Type-I Progressive Hybrid Censoring, Qingqing Li, Yuhlong Lio

SDSU Data Science Symposium

The probability distribution modeling is investigated via maximum likelihood estimation method based on adaptive type-I progressively hybrid censored samples from the inverted Kumaraswamy distribution. The point estimates of model parameters, reliability, hazard rate and quantile are obtained and confidence intervals are also developed by using asymptotic distribution as well as bootstrap method. Monte Carlo simulation has been performed to evaluate the accuracy of estimations. Finally, a real data set is given for the application illustration.

An Alpha-Based Prescreening Methodology For A Common But Unknown Source Likelihood Ratio With Different Subpopulation Structures, Dylan Borchert, Semhar Michael, Christopher Saunders, Andrew Simpson

SDSU Data Science Symposium

Prescreening is a commonly used methodology in which the forensic examiner includes sources from the background population that meet a certain degree of similarity to the given piece of evidence. The goal of prescreening is to find the sources closest to the given piece of evidence in an alternative source population for further analysis. This paper discusses the behavior of an $\alpha-$based prescreening methodology in the form of a Hotelling $T^2$ test on the background population for a common but unknown source likelihood ratio. An extensive simulation study with synthetic and real data were conducted. We find that prescreening helps …

Identifying Subpopulations Of A Hierarchical Structured Data Using A Semi-Supervised Mixture Modeling Approach, Andrew Simpson, Semhar Michael, Christopher Saunders, Dylan Borchert

SDSU Data Science Symposium

The field of forensic statistics offers a unique hierarchical data structure in which a population is composed of several subpopulations of sources and a sample is collected from each source. This subpopulation structure creates a hierarchical layer. We propose using a semi-supervised mixture modeling approach to model the subpopulation structure which leverages the fact that we know the collection of samples came from the same, yet unknown, source. A simulation study based on a famous glass data was conducted and shows this method performs better than other unsupervised approaches which have been previously used in practice.

Session 5: Equipment Finance Credit Risk Modeling - A Case Study In Creative Model Development & Nimble Data Engineering, Edward Krueger, Landon Thompson, Josh Moore

SDSU Data Science Symposium

This presentation will focus first on providing an overview of Channel and the Risk Analytics team that performed this case study. Given that context, we’ll then dive into our approach for building the modeling development data set, techniques and tools used to develop and implement the model into a production environment, and some of the challenges faced upon launch. Then, the presentation will pivot to the data engineering pipeline. During this portion, we will explore the application process and what happens to the data we collect. This will include how we extract & store the data along with how it …

Angiotensin Blockade Therapy And Survival In Pancreatic Cancer: A Population Study, Scott W Keith, Vittorio Maio, Hwyda A Arafat, Matthew Alcusky, Thomas Karagiannis, Carol Rabinowitz, Harish Lavu, Daniel Z. Louis

College of Population Health Faculty Papers

Background: Pancreatic cancer (PC) is one of the most aggressive and challenging cancer types to effectively treat, ranking as the fourth-leading cause of cancer death in the United States. We investigated if exposures to angiotensin II receptor blockers (ARBs) or angiotensin I converting enzyme (ACE) inhibitors after PC diagnosis are associated with survival.

Methods: PC patients were identified by ICD-9 diagnosis and procedure codes among the 3.7 million adults living in the Emilia-Romagna Region from their administrative health care database containing patient data on demographics, hospital discharges, all-cause mortality, and outpatient pharmacy prescriptions. Cox modeling estimated covariate-adjusted mortality hazard ratios …

Comparison Of Human Urinary Exosomes Isolated Via Ultracentrifugation Alone Versus Ultracentrifugation Followed By Sec Column-Purification, Kun Huang, Sudha Garimella, Alyssa Clay-Gilmour, Lucia Vojtech, Bridget Armstrong, Madison Bessonny, Alexis Stamatikos

Faculty Publications

Chronic kidney disease is a progressive, incurable condition that involves a gradual loss of kidney function. While there are no non-invasive biomarkers available to determine whether individuals are susceptible to developing chronic kidney disease, small RNAs within urinary exosomes have recently emerged as a potential candidate to use for assessing renal function. Ultracentrifugation is the gold standard for urinary exosome isolation. However, extravesicular small RNA contamination can occur when isolating exosomes from biological fluids using ultracentrifugation, which may lead to misidentifying the presence of certain small RNA species in human urinary exosomes. Therefore, we characterized human urinary exosomal preparations isolated …

Periodicity On Isolated Time Scales, Martin Bohner, Jaqueline Mesquita, Sabrina Streipert

Mathematics and Statistics Faculty Research & Creative Works

In this work, we formulate the definition of periodicity for functions defined on isolated time scales. The introduced definition is consistent with the known formulations in the discrete and quantum calculus settings. Using the definition of periodicity, we discuss the existence and uniqueness of periodic solutions to a family of linear dynamic equations on isolated time scales. Examples in quantum calculus and for mixed isolated time scales are presented.

On Inclusions With Monotone-Type Mappings In Nonreflexive Banach Spaces, Vy Khoi Le

Mathematics and Statistics Faculty Research & Creative Works

We are concerned in this article with the existence of solutions to inclusions containing generalized pseudomonotone perturbations of maximal monotone mappings in general Banach spaces. Our approach is based on a truncation–regularization technique and an extension of the Moreau–Yosida–Brezis–Crandall–Pazy regularization for maximal monotone mappings in general Banach spaces. We also consider some applications to multivalued variational inequalities containing elliptic operators with rapidly growing coefficients in Orlicz–Sobolev spaces.

Marginal Proportional Hazards Models For Clustered Interval-Censored Data With Time-Dependent Covariates, Kaitlyn Cook, Wenbin Lu, Rui Wang

Harvard University Biostatistics Working Paper Series

The Botswana Combination Prevention Project was a cluster-randomized HIV prevention trial whose follow-up period coincided with Botswana’s national adoption of a universal test-and-treat strategy for HIV management. Of interest is whether, and to what extent, this change in policy (i) modified the observed preventative effects of the study intervention and (ii) was associated with a reduction in the population-level incidence of HIV in Botswana. To address these questions, we propose a stratified proportional hazards model for clustered interval-censored data with time-dependent covariates and develop a composite expectation maximization algorithm that facilitates estimation of model parameters without placing parametric assumptions on …