A Tale of Two Campuses: Local and global approaches to reducing textbook costs

Poster presented at Association of College and Research Libraries 2017 National Conference, Baltimore, Maryland. March 24, 201

Low temperature lithographically patterned metal oxide transistors for large area electronics

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 167-184).Optically transparent, wide bandgap metal oxide semiconductors are a promising candidate for large-area electronics technologies that require lightweight, temperature-sensitive flexible substrates. Because these thin films retain relatively high carrier mobilities even in an amorphous state, metal oxide-based field effect transistors (FETs) can be processed at near-room temperatures. Compared to amorphous silicon FETs, which are the dominant technology used in display backplanes, metal oxide FETs have been demonstrated with higher charge carrier mobilities, higher current densities, and faster response performance. In this thesis we present a low-temperature ('1000C), scalable, fully lithographic process for top-gate, bottom-contact amorphous zinc indium oxide FETs using parylene, a room-temperature-deposited CVD polymer, as gate dielectric. Electrical characteristics were compared for FETs of varying device dimensions (W, L) using a standard set of extracted device parameters. We show in both simulation and experiment that the FET threshold voltage can be modified by varying the channel thickness alone, without requiring the additional complexity of multiple channel materials or different dopings. The baseline lithographic process was further developed to enable the integration of FETs of different channel thicknesses, and hence threshold voltages, on a single substrate. The availability of FETs with different threshold voltages allows the implementation of enhancement-depletion (E/D) logic circuits that have faster speeds and smaller device areas than single-VT topologies. Using the two-VT lithographic process, we fabricated integrated E/D inverters that operate at VDD as low as 3V with gains > 20 and symmetric noise margins ~1.2V. Furthermore, we demonstrated integrated 11-stage and 21-stage E/D ring oscillators that operated rail-to-rail at VDD= 3V and maintained oscillation for VDD as low as 1.7V. These results demonstrate the potential for low VDD metal oxide-based integrated circuits fabricated in a low temperature budget, fully lithographic process for large-area transparent electronics.by Annie I. Wang.Ph.D

Threshold voltage in pentacene field effect transistors with parylene dielectric

Thesis (M. Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 59-63).Organic field effect transistors (OFETs) offer a suitable building block for many flexible, large-area applications such as display backplanes, electronic textiles, and robotic skin. Besides the organic semiconductor itself, an important area in the development of OFETs is the gate dielectric material. In this thesis the organic polymer parylene is studied as a gate dielectric for pentacene OFETs. The three main areas of study were: (1) parylene's performance as a dielectric, (2) possible improvement of OFETs by surface treatments, and (3) the effects of interface traps on threshold voltage and parasitic bulk conductivity. Parylene was found to provide a favorable, hydrophobic interface for pentacene growth, yielding transistors with mobilities > 0.5cm²/Vs at -100V. While the two surface treatments explored did increase contact angle by 10-20⁰, neither the ammonium sulfide nor the polystyrene treatment significantly improved pentacene packing or mobility. Modification of the parylene surface using an oxygen plasma introduced traps at the semiconductor-dielectric interface, observable through a variety of characterization techniques. A model is developed to explain how the fixed and mobile charges these traps introduce influence the threshold voltage and parasitic conductivity in the device.by Annie I. Wang.M.Eng.and S.B

Advancing the World Federation of Music Therapy: Strategic Planning Process

The World Federation of Music Therapy (WFMT) is a nonprofit organization committed to its mission of developing and promoting music therapy throughout the world as an art and science. Since the organization’s inception in 1985, there have been significant changes in the world and many positive developments within the organization. These are reviewed providing a rationale for the initiation of this executive work. Methods utilized to complete the strategic planning process are outlined, along with the challenges and discoveries encountered throughout. outcomes of the strategic planning process are also highlighted

Water-soluble saponins accumulate in drought-stressed switchgrass and may inhibit yeast growth during bioethanol production

Background: Developing economically viable pathways to produce renewable energy has become an important research theme in recent years. Lignocellulosic biomass is a promising feedstock that can be converted into second-generation biofuels and bioproducts. Global warming has adversely affected climate change causing many environmental changes that have impacted earth surface temperature and rainfall patterns. Recent research has shown that environmental growth conditions altered the composition of drought-stressed switchgrass and directly influenced the extent of biomass conversion to fuels by completely inhibiting yeast growth during fermentation. Our goal in this project was to find a way to overcome the microbial inhibition and characterize specific compounds that led to this inhibition. Additionally, we also determined if these microbial inhibitors were plant-generated compounds, by-products of the pretreatment process, or a combination of both. Results: Switchgrass harvested in drought (2012) and non-drought (2010) years were pretreated using Ammonia Fiber Expansion (AFEX). Untreated and AFEX processed samples were then extracted using solvents (i.e., water, ethanol, and ethyl acetate) to selectively remove potential inhibitory compounds and determine whether pretreatment affects the inhibition. High solids loading enzymatic hydrolysis was performed on all samples, followed by fermentation using engineered Saccharomyces cerevisiae. Fermentation rate, cell growth, sugar consumption, and ethanol production were used to evaluate fermentation performance. We found that water extraction of drought-year switchgrass before AFEX pretreatment reduced the inhibition of yeast fermentation. The extracts were analyzed using liquid chromatography–mass spectrometry (LC–MS) to detect compounds enriched in the extracted fractions. Saponins, a class of plant-generated triterpene or steroidal glycosides, were found to be significantly more abundant in the water extracts from drought-year (inhibitory) switchgrass. The inhibitory nature of the saponins in switchgrass hydrolysate was validated by spiking commercially available saponin standard (protodioscin) in non-inhibitory switchgrass hydrolysate harvested in normal year. Conclusions: Adding a water extraction step prior to AFEX-pretreatment of drought-stressed switchgrass effectively overcame inhibition of yeast growth during bioethanol production. Saponins appear to be generated by the plant as a response to drought as they were significantly more abundant in the drought-stressed switchgrass water extracts and may contribute toward yeast inhibition in drought-stressed switchgrass hydrolysates

Can a GP be a generalist and a specialist? Stakeholders views on a respiratory General Practitioner with a special interest service in the UK

Peer reviewedPublisher PD

Genetic Drivers of Heterogeneity in Type 2 Diabetes Pathophysiology

Type 2 diabetes (T2D) is a heterogeneous disease that develops through diverse pathophysiological processes1,2 and molecular mechanisms that are often specific to cell type3,4. Here, to characterize the genetic contribution to these processes across ancestry groups, we aggregate genome-wide association study data from 2,535,601 individuals (39.7% not of European ancestry), including 428,452 cases of T2D. We identify 1,289 independent association signals at genome-wide significance (P \u3c 5 × 10-8) that map to 611 loci, of which 145 loci are, to our knowledge, previously unreported. We define eight non-overlapping clusters of T2D signals that are characterized by distinct profiles of cardiometabolic trait associations. These clusters are differentially enriched for cell-type-specific regions of open chromatin, including pancreatic islets, adipocytes, endothelial cells and enteroendocrine cells. We build cluster-specific partitioned polygenic scores5 in a further 279,552 individuals of diverse ancestry, including 30,288 cases of T2D, and test their association with T2D-related vascular outcomes. Cluster-specific partitioned polygenic scores are associated with coronary artery disease, peripheral artery disease and end-stage diabetic nephropathy across ancestry groups, highlighting the importance of obesity-related processes in the development of vascular outcomes. Our findings show the value of integrating multi-ancestry genome-wide association study data with single-cell epigenomics to disentangle the aetiological heterogeneity that drives the development and progression of T2D. This might offer a route to optimize global access to genetically informed diabetes care

Genetic drivers of heterogeneity in type 2 diabetes pathophysiology

Type 2 diabetes (T2D) is a heterogeneous disease that develops through diverse pathophysiological processes1,2 and molecular mechanisms that are often specific to cell type3,4. Here, to characterize the genetic contribution to these processes across ancestry groups, we aggregate genome-wide association study data from 2,535,601 individuals (39.7% not of European ancestry), including 428,452 cases of T2D. We identify 1,289 independent association signals at genome-wide significance (P &lt; 5 × 10-8) that map to 611 loci, of which 145 loci are, to our knowledge, previously unreported. We define eight non-overlapping clusters of T2D signals that are characterized by distinct profiles of cardiometabolic trait associations. These clusters are differentially enriched for cell-type-specific regions of open chromatin, including pancreatic islets, adipocytes, endothelial cells and enteroendocrine cells. We build cluster-specific partitioned polygenic scores5 in a further 279,552 individuals of diverse ancestry, including 30,288 cases of T2D, and test their association with T2D-related vascular outcomes. Cluster-specific partitioned polygenic scores are associated with coronary artery disease, peripheral artery disease and end-stage diabetic nephropathy across ancestry groups, highlighting the importance of obesity-related processes in the development of vascular outcomes. Our findings show the value of integrating multi-ancestry genome-wide association study data with single-cell epigenomics to disentangle the aetiological heterogeneity that drives the development and progression of T2D. This might offer a route to optimize global access to genetically informed diabetes care.</p

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Digital Stress as a Mediator of the Relationship between Mobile and Social Media Use and Psychological Functioning

The present investigation uses Apple iPhone Screen Time to assess the association between mobile and social media use and psychological functioning with digital stress as a mediator in a sample of young adult (N = 267) and adolescent (N = 213) participants. The results of preregistered hypotheses suggest that as a five-factor composite (i.e., connection overload, approval anxiety, fear of missing out, availability stress, online vigilance) digital stress does not mediate the primary association. Connection overload, however, was a mediator of this relationship for all participants. Conditional process analyses revealed that for adolescents, FoMO and approval anxiety also mediated the primary association, but these digital stress subfactors were not mediators for young adult participants. Additionally, for young adults, mobile and social media use was associated with more positive peer relationships. The results suggest digital stress is closely tied to individuals’ social environment and peer-related sources of stress