Discrete element method based scale-up model for material synthesis using ball milling

Mechanical milling is a widely used technique for powder processing in various areas. In this work, a scale-up model for describing this ball milling process is developed. The thesis is a combination of experimental and modeling efforts. Initially, Discrete Element Model (DEM) is used to describe energy transfer from milling tools to the milled powder for shaker, planetary, and attritor mills. The rolling and static friction coefficients are determined experimentally. Computations predict a quasi- steady rate of energy dissipation, Ed, for each experimental configuration. It is proposed that the milling dose defined as a product of Ed and milling time, t, divided by the mass of milled powder, mp characterizes the milling progress independently of the milling device or milling conditions used. Once the milling dose is determined for one experimental configuration, it can be used to predict the milling time required to prepare the same material in any milling configuration, for which Ed is calculated. The concept is validated experimentally for DEM describing planetary and shaker mills. For attritor, the predicted Ed includes substantial contribution from milling tool interaction events with abnormally high forces (\u3e103 N). The energy in such events is likely dissipated to heat or plastically deform milling tools rather than refine material. Indeed, DEM predictions for the attritor correlate with experiments when such events are ignored in the analysis. With an objective of obtaining real-time indicators of milling progress, power, torque, and rotation speed of the impeller of an attritor mill are measured during preparation of metal matrix composite powders in the subsequent portion of this thesis. Two material systems are selected and comparisons made between in-situ parameters and experimental milling progress indicators. It is established that real-time measurements can certainly be used to describe milling progress. However, they need to be interpreted carefully depending on hardness of brittle component relative to milling media. To improve the DEM model of the attritor mill, it is desired to avoid the removal of unrealistic, high-force events using an approach that would not predict such events in the first place. It is observed that during experiments in attritor, balls may jam causing an increased resistance to the impeller’s rotation. The impeller may instantaneously slow down, quickly returning to its pre-set rotation rate. Previous DEM models did not account for such rapid changes in the impeller’s rotation. In this work, this relationship between impeller’s torque and rotation rate is obtained experimentally and introduced in DEM. As a result, predicted Ed, are shown to correlate well with the experimental data. Finally, a methodology is proposed combining an experiment and its DEM description enabling one to identify the appropriate interaction parameters for powder systems. The experiment uses a miniature vibrating hopper and can be applied to characterize the powder flow for variety of materials. The hopper is designed to hold up to 20,000 particles of 50-tam diameter, which can be directly described in DEM. Based on comparison of discharge rate from experiments and model, all 6 interaction parameters were analyzed and the ideal conditions identified for Zirconia beads. The values of these parameters for powders are generally not the same as those established for macroscopic bodies. In addition, effects of some other experimental parameters such as particle size distribution and amplitude of vibration are also investigated

Condom tamponade in the management of atonic postpartum hemorrhage

Background: Postpartum hemorrhage (PPH) remains a leading direct cause of maternal death in both developed and developing countries. Millennium development goal of reducing maternal mortality rate cannot be achieved unless the prevention and treatment of PPH is prioritized. Objectives of the study were to study the efficacy of condom tamponade to arrest bleeding in cases of atonic PPH unresponsive to uterotonics.Methods: Prospective study conducted in the Kottayam Medical College where mothers who develop atonic PPH following childbirth unresponsive to uterotonics (after ruling out traumatic PPH) were included in study. Condom tamponade was applied in them and inflated with normal saline until the bleeding stops. Intrauterine drain was fitted with this to find out ongoing bleeding with tamponade in situ. The Condom tamponade was kept for 12-24 hrs and gradually deflated when bleeding ceased. Outcome measures were (1) Ability of condom catheter to stop bleeding; (2) Cases requiring further intervention; (3) Time required to stop bleeding and (4) Subsequent morbidity in terms of infection.Results: Of the 487 cases of atonic PPH, 61 required condom tamponade; bleeding controlled in 59 cases (96.7%); two patients (3.3%) needed further surgical intervention. No cases of maternal mortality due to PPH. No clinical evidence of intrauterine infection.Conclusions: The hydrostatic condom tamponade controls PPH quickly and effectively. It is simple, inexpensive, easily available, needs less expertise and life saving. Any healthcare provider may use this procedure as a timely measure to save the life of patients especially during referral to decrease ongoing loss

Problem Behaviors in ASD: Comparing Parent and Professional Concerns [Slides]

Slides presented at the ASHA Convention Atlanta, Georgia, November, 2012 by Siva priya Santhanam, Lisa Shattuck, Elizabeth Witter, Lynne E. Hewitt, and Louisa Ha

South Indian Children's Neurodevelopmental Outcomes After Group B Streptococcus Invasive Disease: A Matched-Cohort Study.

BACKGROUND: This study is part of a multicountry matched-cohort study designed to estimate the risk of long-term neurodevelopmental impairment (NDI) of children exposed to invasive group B Streptococcus (iGBS). The specific objective of this paper is to compare NDI across domains of iGBS survivors with a matched non iGBS group in our population. METHODS: Survivors of iGBS in a South Indian hospital were identified and recruited between January 2020 and April 2021. Cases were compared with age- and gender-matched non iGBS children. Participants were assessed using Bayley Scales of Infant and Toddler Development-3rd edition (BSID-III), Wechsler Preschool and Primary Scale of Intelligence-4th edition (WPPSI-IV), Wechsler Intelligence Scale for Children-5th edition (WISC-V), Child Behavior Checklist (CBCL), and Bruininks-Oseretsky Test of Motor Proficiency, 2nd edition (BOT-2), depending on age. RESULTS: Our cohort comprised 35 GBS-exposed and 65 matched non iGBS children, aged 1-14 years. The iGBS-exposed group had 17 (48.6%) children with impairment in ≥1 domain compared to 25 (38%) in the non iGBS group (unadjusted OR, 1.51; 95% CI, .65-3.46), 9 (26%) children with "multi-domain impairment" compared to 10 (15.4%) in the non iGBS group (unadjusted OR, 1.90; 95% CI, .69-5.24), and 1 (2.9%) child with moderate to severe impairment compared to 3 (4.6%) in the non iGBS group (unadjusted OR, .60; 95% CI, .06-6.07). In the iGBS group, more children had motor impairments compared with the non iGBS group (unadjusted OR, 10.7; 95% CI, 1.19-95.69; P = .034). CONCLUSIONS: Children with iGBS seem at higher risk of developing motor impairments compared with a non iGBS group

Learning from the Experts: Evaluating a Participatory Autism and Universal Design Training for University Educators

Autistic students experience strengths and challenges that can impact their full inclusion in higher education, including stigma. A participatory team of autistic and non-autistic scholars developed an Autism and Universal Design (UD) training. This participatory approach centered the voices of autistic collaborators in training design and evaluation. Ninety-eight educators from 53 institutions across 5 countries completed assessments before training (pre-tests), 89 completed post-tests (after training), and 82 completed maintenance assessments (a month after post-test). Pre-test autism stigma was heightened among males, educators with less autism knowledge, and those who reported heightened social dominance orientation. Autism knowledge, autism stigma, and attitudes toward UD improved with training. Improvements remained apparent a month after post-test but were somewhat attenuated for knowledge and stigma. To the best of our knowledge, this is the first evidence of maintenance of benefits of an autism training over time. Participants’ main reason for enrolling in the study was to gain a better understanding about neurodiversity. Feedback indicates that this goal was reached by most with the added benefit of gaining understanding about UD. Results suggest that interest in one type of diversity (e.g., autism) can motivate faculty to learn UD-aligned teaching strategies that benefit diverse students more generally.Output Status: Forthcomin

Recursive Cluster Elimination Based Support Vector Machine for Disease State Prediction Using Resting State Functional and Effective Brain Connectivity

Brain state classification has been accomplished using features such as voxel intensities, derived from functional magnetic resonance imaging (fMRI) data, as inputs to efficient classifiers such as support vector machines (SVM) and is based on the spatial localization model of brain function. With the advent of the connectionist model of brain function, features from brain networks may provide increased discriminatory power for brain state classification.In this study, we introduce a novel framework where in both functional connectivity (FC) based on instantaneous temporal correlation and effective connectivity (EC) based on causal influence in brain networks are used as features in an SVM classifier. In order to derive those features, we adopt a novel approach recently introduced by us called correlation-purged Granger causality (CPGC) in order to obtain both FC and EC from fMRI data simultaneously without the instantaneous correlation contaminating Granger causality. In addition, statistical learning is accelerated and performance accuracy is enhanced by combining recursive cluster elimination (RCE) algorithm with the SVM classifier. We demonstrate the efficacy of the CPGC-based RCE-SVM approach using a specific instance of brain state classification exemplified by disease state prediction. Accordingly, we show that this approach is capable of predicting with 90.3% accuracy whether any given human subject was prenatally exposed to cocaine or not, even when no significant behavioral differences were found between exposed and healthy subjects.The framework adopted in this work is quite general in nature with prenatal cocaine exposure being only an illustrative example of the power of this approach. In any brain state classification approach using neuroimaging data, including the directional connectivity information may prove to be a performance enhancer. When brain state classification is used for disease state prediction, our approach may aid the clinicians in performing more accurate diagnosis of diseases in situations where in non-neuroimaging biomarkers may be unable to perform differential diagnosis with certainty

Structural and functional neuroimaging of individuals with prenatal exposure to addictive substances

Although the hazards of prenatal exposure to addictive substances have been documented for decades, it continues to be a prevalent social and health concern today. Alcohol and cocaine are two commonly abused substances during pregnancy, often leading to behavioral and cognitive disorders in exposed children. At present, the relationship between teratogenic effects of prenatal alcohol exposure (PAE) and prenatal cocaine exposure (PCE) on the brain and observed behavioral outcomes is still unclear. A primary reason for this incomplete understanding is the lack of information regarding neuronal functioning in these populations. Functional MRI, which measures real-time brain activation in response to certain stimuli, can be utilized to bridge the gap between known structural damage and observed behavioral outcomes. This thesis aims to examine structural and functional alterations in PAE and PCE populations as compared to unexposed, socio-economic status-matched populations. As the PAE population is highly affected by structural dysmorphology, the applicability of a newly developed diffeomorphic image registration method to this population is examined. Additionally, task-positive and task-negative functional connectivity and activity are investigated in the PAE population, and related to underlying structural alterations. Neural correlates of global arousal and emotional regulation are investigated in the PCE population, as these behavioral outcomes are most notable. Similarly, functional connectivity and activation in task-positive and task-negative networks, as well as correlated structural measures, are examined in the PCE population. The diffeomorphic image registration algorithm was found to improve both structural and functional image registration for the PAE population. In the examination of specific deficits in arithmetic processing, poorer performance in the PAE group was attributed to a multi-level effect produced by altered structural and functional connectivity and functional activity in calculation and default mode networks. Baseline arousal levels were found to be higher in adolescents with PCE as compared to healthy controls (by altered default mode network functioning); emotional regulation also appeared to be affected in the PCE group by a prefrontal-amygdala structural and functional disconnect. The findings of this thesis give insights into the relationship between task-positive and task-negative duality and cognitive impairment, and contribute to a more comprehensive understanding of the spectrum of clinical disorders caused by prenatal exposure to alcohol and cocaine.Ph.D.Committee Chair: Hu, Xiaoping; Committee Member: Coles, Claire; Committee Member: Hamann, Stephan; Committee Member: Keilholz, Shella; Committee Member: Oshinski, Joh

Perspectives of Adults With Autism on Social Communication Intervention

© Hammill Institute on Disabilities 2020. Social communication difficulties are part of the core difficulties experienced by individuals with autism. Speech-language pathologists provide intervention and supports for these difficulties. Little is known about the own experiences and views of adults with autism about these services. Using semi-structured ethnographic interviewing, perspectives of eight adults (six currently attending college) with autism on social communication intervention were investigated. Participants articulated strengths and weaknesses in social communication, offering frank views of interventions received. Five themes regarding social communication intervention emerged: belief that intervention was ineffective and unnecessary; preference for one-on-one intervention; need for more real-world practice; friend and peer challenges and successes; and desire for more neurotypical understanding. Participants additionally offered general views on social functioning as well as advice for communication partners and other people with autism. In designing interventions for social communication impairments, the experiences and beliefs of those receiving the interventions should be a central element