Showing papers by "University of Massachusetts Boston published in 2022"

A systematic review of loneliness in bereavement: Current research and future directions.

Abstract: Bereaved people suffer from loneliness and loneliness is associated with poor mental health. In this study, this topic is reviewed. An agenda is suggested for future research. Research that is theory-driven, addresses measurement consistency, correlates of loneliness in bereaved and non-bereaved, and treatment is necessary for prevention and intervention.

Achievable Performance of Uncooled Homojunction GeSn Mid-Infrared Photodetectors

Abstract: Ge1-xSnx photodetectors (PDs) have emerged as a new type of mid-infrared (MIR) CMOS-compatible PDs for a wide range of applications. Here we present a comprehensive theoretical study to evaluate the achievable performance of Ge1-xSnx p-i-n homojunction PDs with strain-free and defect-free Ge1-xSnx active layer for the purpose of demonstrating its potential in advancing the MIR detection technology. Starting from the Sn-composition-dependent band structures, the theoretical model calculates optical absorption, responsivity, dark current density, and detectivity. The results show that the optical responsivity can be enhanced with the Sn incorporation due to the improved optical absorption and the large mobilities and diffusion lengths of the photo-generated electrons and holes. The dark current density, however, increases with the increasing Sn composition. Our model suggests that not only the photodetection range of the Ge1-xSnx PDs can be extended to the MIR region but their detectivity at room temperature can be competitive with the existing MIR technology, and in some cases better than some commercial PDs operating at lower temperatures. This study establishes the ultimate performance that can be potentially achieved with the Ge1-xSnx MIR technology with the maturity of its material development in due time in addition to its much anticipated CMOS-compatible advantages.

Cerebrovascular Involvement in Mucormycosis in COVID-19 Pandemic

Abstract: BackgroundMany countries have seen an unprecedented rise of cases of coronavirus disease 2019 (COVID-19) associated mucormycosis (CAM). Cerebrovascular involvement in CAM has not been studied so far. We describe clinico-radiological manifestations of cerebrovascular complications observed in CAM.MethodsIn this multicentric retrospective observational study from India, patients with CAM who developed cerebrovascular involvement were studied. Their demographics, risk factors, clinical manifestations, imaging, laboratory profile and outcomes were noted.ResultsOut of 49 subjects with cerebrovascular involvement, 71.4% were males while average age was 52.9 years. Ischemic stroke was commonest (91.8%) followed by intracranial haemorrhage (6.1%) and subarachnoid haemorrhage (2%). The incidence of cerebrovascular complications in CAM was found to be 11.8% in one center. Cerebrovascular symptoms appeared a median of 8.3 days from the onset of mucormycosis. Commonest presentation of mucormycosis was rhino-orbito-cerebral syndrome in 98%. Diabetes mellitus was present in 81.7%. Forty percent developed stroke despite being on antiplatelet agent and/or heparin. Amongst subjects with ischemic strokes, location of stroke was unilateral anterior circulation (62.2%); bilateral anterior circulation (17.8%); posterior circulation (11.1%) and combined anterior and posterior circulation (8.9%). Vascular imaging revealed intracranial occlusion in 62.1%; extracranial occlusion in 3.4% and normal vessels in 34.5%. Mortality was 51% during hospital stay.ConclusionsCerebrovascular involvement was seen in 11.8% patients of CAM. Angio-invasive nature of the fungus, prothrombotic state created by COVID-19, and diabetes were important causative factors. Subjects with CAM should be screened for involvement of the brain as well as its vessel. Antiplatelet agents/heparin did not seem to provide complete protection from this type of stroke.

Qualifying domains of student struggle in undergraduate general chemistry laboratory

Abstract: Learning and learning goals in undergraduate chemistry laboratory have been a popular research topic for the past three decades due to calls for curriculum reform, cost justification, and overall efficacy of necessary skill development. While much work has been done to assess curricular interventions on students’ learning and attitudes towards lab, few have discussed the increased difficulties of these non-traditional laboratory activities or the obstacles students must overcome in the laboratory setting. The work presented here focuses on student struggles in undergraduate general chemistry laboratory activities, the source of these struggles, and the actions students take to overcome them. Using an activity theoretical lens and multiple domains (cognitive, epistemological, socioemotional, and psychomotor), we developed a domains-of-struggle framework which encompasses how struggles emerge through contradictions within the laboratory activity system. This framework was extended and refined through iterative analysis of two consecutive semesters of undergraduate general chemistry laboratory (GC1 and GC2) video (n = 51), survey (n = 327), and interview (n = 44) data. In this paper, we model the activity system of the general chemistry laboratory, define the domains of struggle observed, and present actions the students took to move past these obstacles, while illustrating the interconnected complexity of the activity system. We then discuss how this framework may be used in future curriculum design or teacher training, as well as potential for future research on the learning outcomes associated with moments of struggle.

Rationale and design of the brain magnetic resonance imaging protocol for FutureMS: a longitudinal multi-centre study of newly diagnosed patients with relapsing-remitting multiple sclerosis in Scotland

Abstract: Introduction: Multiple sclerosis (MS) is a chronic neuroinflammatory and neurodegenerative disease. MS prevalence varies geographically and is notably high in Scotland. Disease trajectory varies significantly between individuals and the causes for this are largely unclear. Biomarkers predictive of disease course are urgently needed to allow improved stratification for current disease modifying therapies and future targeted treatments aimed at neuroprotection and remyelination. Magnetic resonance imaging (MRI) can detect disease activity and underlying damage non-invasively in vivo at the micro and macrostructural level. FutureMS is a prospective Scottish longitudinal multi-centre cohort study, which focuses on deeply phenotyping patients with recently diagnosed relapsing-remitting MS (RRMS). Neuroimaging is a central component of the study and provides two main primary endpoints for disease activity and neurodegeneration. This paper provides an overview of MRI data acquisition, management and processing in FutureMS. FutureMS is registered with the Integrated Research Application System (IRAS, UK) under reference number 169955. Methods and analysis: MRI is performed at baseline (N=431) and 1-year follow-up, in Dundee, Glasgow and Edinburgh (3T Siemens) and in Aberdeen (3T Philips), and managed and processed in Edinburgh. The core structural MRI protocol comprises T1-weighted, T2-weighted, FLAIR and proton density images. Primary imaging outcome measures are new/enlarging white matter lesions (WML) and reduction in brain volume over one year. Secondary imaging outcome measures comprise WML volume as an additional quantitative structural MRI measure, rim lesions on susceptibility-weighted imaging, and microstructural MRI measures, including diffusion tensor imaging and neurite orientation dispersion and density imaging metrics, relaxometry, magnetisation transfer (MT) ratio, MT saturation and derived g-ratio measures. Conclusions: FutureMS aims to reduce uncertainty around disease course and allow for targeted treatment in RRMS by exploring the role of conventional and advanced MRI measures as biomarkers of disease severity and progression in a large population of RRMS patients in Scotland.

FutureMS cohort profile: a Scottish multicentre inception cohort study of relapsing-remitting multiple sclerosis

Abstract: Purpose Multiple sclerosis (MS) is an immune-mediated, neuroinflammatory disease of the central nervous system and in industrialised countries is the most common cause of progressive neurological disability in working age persons. While treatable, there is substantial interindividual heterogeneity in disease activity and response to treatment. Currently, the ability to predict at diagnosis who will have a benign, intermediate or aggressive disease course is very limited. There is, therefore, a need for integrated predictive tools to inform individualised treatment decision making. Participants Established with the aim of addressing this need for individualised predictive tools, FutureMS is a nationally representative, prospective observational cohort study of 440 adults with a new diagnosis of relapsing-remitting MS living in Scotland at the time of diagnosis between May 2016 and March 2019. Findings to date The study aims to explore the pathobiology and determinants of disease heterogeneity in MS and combines detailed clinical phenotyping with imaging, genetic and biomarker metrics of disease activity and progression. Recruitment, baseline assessment and follow-up at year 1 is complete. Here, we describe the cohort design and present a profile of the participants at baseline and 1 year of follow-up. Future plans A third follow-up wave for the cohort has recently begun at 5 years after first visit and a further wave of follow-up is funded for year 10. Longer-term follow-up is anticipated thereafter.

Cuticular sclerotization in insects – A critical review

Abstract: Sclerotization of cuticle is a vital process for the survival of insects. It is caused by covalent crosslinking of structural proteins and chitin to form hard and often coloured cuticle. During sclerotization, N-acetyldopamine and N-β-alanyldopamine are activated by cuticular enzymes such as phenoloxidase—both laccase and o-diphenoloxidase, peroxidase, quinone isomerase and quinone methide isomerase to reactive intermediates that can form adducts and crosslinks. Four major mechanisms—quinone tanning, quinone methide sclerotization, α,β-sclerotization, and free radical tanning have been identified so far for gluing and bonding the structural proteins with chitin. The biochemistry of the quinone tanning, the first discovered mechanism for hardening is critically evaluated and assessed. The enzymatic and nonenzymatic production of quinone methide, and the critical role of quinone isomerase in quinone methide sclerotization is discussed. The biosynthesis of two sclerotizing precursor associated with α,β-sclerotization is outlined. The critical roles of dehydro N-acetyldopamine and dehydro N-β-alanyldopamine in α,β-sclerotization, and the differential use of N-acetyldopamine and N-β-alanyldopamine in producing coloured versus colourless cuticle is considered. Potential contribution of both peroxidase and laccase for free radical tanning is also briefly examined. The mechanisms of formation of catecholic products in cuticular hydrolysates are investigated. The genes associated with cuticular hardening are briefly described. Sclerotization in other animal systems that use dehydro dopa and its derivatives is also assessed. Melanisation reactions that occur in cuticle and hemolymph and its role in wound healing, defence reactions and cuticular pigmentation is critically evaluated.

Educational attainment as a modifier for the effect of polygenic scores for cardiovascular risk factors: cross-sectional and prospective analysis of UK Biobank

Abstract: Understanding the interplay between educational attainment and genetic predictors of cardiovascular risk may improve our understanding of the aetiology of educational inequalities in cardiovascular disease.In up to 320 120 UK Biobank participants of White British ancestry (mean age = 57 years, female 54%), we created polygenic scores for nine cardiovascular risk factors or diseases: alcohol consumption, body mass index, low-density lipoprotein cholesterol, lifetime smoking behaviour, systolic blood pressure, atrial fibrillation, coronary heart disease, type 2 diabetes and stroke. We estimated whether educational attainment modified genetic susceptibility to these risk factors and diseases.On the additive scale, higher educational attainment reduced genetic susceptibility to higher body mass index, smoking, atrial fibrillation and type 2 diabetes, but increased genetic susceptibility to higher LDL-C and higher systolic blood pressure. On the multiplicative scale, there was evidence that higher educational attainment increased genetic susceptibility to atrial fibrillation and coronary heart disease, but little evidence of effect modification was found for all other traits considered.Educational attainment modifies the genetic susceptibility to some cardiovascular risk factors and diseases. The direction of this effect was mixed across traits considered and differences in associations between the effect of the polygenic score across strata of educational attainment was uniformly small. Therefore, any effect modification by education of genetic susceptibility to cardiovascular risk factors or diseases is unlikely to substantially explain the development of inequalities in cardiovascular risk.

Comparative phylotranscriptomics reveals putative sex differentiating genes across eight diverse bivalve species

Abstract: Mollusks, especially bivalves, exhibit a great diversity of sex determining mechanisms, including both genetic and environmental sex determination. Some bivalve species can be gonochoristic (separate sexes), while others are hermaphroditic (sequential or simultaneous). Several models have been proposed for specific bivalve species, utilizing information gained from gene expression data, as well as limited RAD-seq data (e.g., from Crassostrea gigas). However, these mechanisms are not as well studied as those in model organisms (e.g., Mus musculus, Drosophila melanogaster, Caenorhabditis elegans) and many genes involved in sex differentiation are not well characterized. We used phylotranscriptomics to better understand which possible sex differentiating genes are in bivalves and how these genes relate to similar genes in diverse phyla. We collected RNAseq data from eight phylogenetically diverse bivalve species: Argopecten irradians, Ensis directus, Geukensia demissa, Macoma tenta, Mercenaria mercenaria, Mya arenaria, Mytilus edulis, and Solemya velum. Using these data, we assembled representative transcriptomes for each species. We then searched for candidate sex differentiating genes using BLAST and confirmed the identity of nine genes using phylogenetics analyses from nine phyla. To increase the confidence of identification, we included ten bivalve genomes in our analyses. From the analysis of doublesex and mab-3 related transcription factor (DMRT) genes, we confirmed the identify of a Mollusk-specific sex determining DMRT gene: DMRT1L. Based on gene expression data from M. edulis and previous research, DMRT1L and FoxL2 are key genes for male and female development, respectively.

Hardening and tanning of insect ootheca, egg cases, egg sac, chorion, and silk

Abstract: Insects lay eggs that must survive in nature often several days to months. The eggs need to be protected from desiccation and other harsh environmental challenges. The structural components of eggshells are mostly proteins, but in some cases the polysaccharide, chitin is also used as an essential matrix material. In addition, several eggshells also contain minerals and catecholamine derivatives. Enzymic components often include peroxidase, laccase and/or phenoloxidase and other sclerotizing enzymes. In this review, some of the aspects of eggshell and chorion tanning in insects are reviewed. Four major systems representing different way of hardening are considered. They are hardening of the cockroach ootheca, tanning of the mosquito egg chorion, crosslinking of Drosophila eggshell, and sclerotization of praying mantis egg sacs. Cockroach ootheca, which is devoid of chitin, mostly use sclerotization mechanism to harden its case using 3,4-dihydroxybenzyl alcohol. Mosquito eggs which possess chitin on the other hand, employ both melanisation and peroxidase mediated dityrosine and trityrosine formation for tanning reactions. Drosophila egg chorion primarily utilize peroxidase mediated crosslinking process only. While these three systems seem to differ from the normal sclerotization process employed by most insect cuticles which use N-acetyldopamine and N-β-alanyldopamine as sclerotizing precursors and phenoloxidase (both laccase and o-diphenoloxidase), quinone isomerase, and quinone methide isomerase as the sclerotizing enzymes, the egg sacs of praying mantis recruit a variety of N-acyldopamine derivatives and the two enzymes—phenoloxidase and quinone isomerase—for hardening their sacs. In addition, tanning of silk is also considered briefly in this review. The biochemical mechanisms of these reactions are discussed in detail.

Churning and profitability in the U.S. corporate sector

Abstract: This paper establishes that entry and exit stabilize the top half of the profitability distribution in the post-1970 U.S. economy. We, first, document stability in the distribution of total profits earned on tangible, intangible, and financial capital. Whereas a narrower measure of returns on tangible capital, instead, suggests rising dispersion, it fails to capture post-1970 growth in intangible and financial assets. Second, we use quantile decompositions to show that churning—specifically, exit for cause—regulates median and top-end profitability. Thus, the process by which competition drives out unprofitable firms acts to stabilize profit rates in the U.S. economy.

Understandable multifunctionality measures using Hill numbers

Abstract: In ecology, multifunctionality metrics measure the simultaneous performance of multiple ecosystem functions. If species diversity describes the variety of species that together build the ecosystem, multifunctionality attempts to describe the variety of functions these species perform. A range of methods have been proposed to quantify multifunctionality, successively attempting to alleviate problems that have been identified with the previous methods. This has led to a proliferation of more-or-less closely related metrics which, however, lack an overarching theoretical framework. Here we borrow from the comprehensive framework of species diversity to derive a new metric of multifunctionality. Analogously to the effective number of species used to quantify species diversity, the metric we propose is influenced both by the number of functions as well as, crucially, the evenness of performance levels across functions. In addition, the effective multifunctionality also considers the average level at which the functions are performed. The result is a measure of the cumulative performance of the system were all functions provided equally. The framework allows for the inclusion of the correlation structure among functions, thus allowing it to account for non-independence between functions. We show that the average metric is a special case of the newly proposed metric when all functions are uncorrelated and performed at equal levels. We hope that by providing a new metric of multifunctionality anchored in the rigorous framework of species diversity based on effective numbers, we will overcome the considerable skepticism that the larger community of ecologists has built against indices of multifunctionality. We thereby hope to help popularize this important concept which, like biological diversity, describes a fundamental property of ecosystems and thus lies at the heart of ecology.

Exploring different textures of a nematic liquid crystal for quantitative Fourier phase contrast microscopy

Abstract: Quantitative phase microscopy (QPM) has emerged as a viable technique for investigating biological and biomedical samples in its natural environment. Contrary to well established phase microscopes, QPM provides phase map of the optical path length delays introduced by the specimen. Building on our prior technology of the Fourier phase contrast microscopy (FPCM) technique, we present a low-cost and robust quantitative Fourier phase contrast microscopy system that can easily be attached to most commercial brightfield microscopes. This is derived by merging the FPCM technique with phase shifting interferometry. By applying voltages across a nematic liquid crystal cell with various anchoring properties, Stokes’ parameters are obtained to unwrap the object information quantitatively. Further three different nematic textures were considered to improve the utility of the phase unwrapping: planar, twisted, and hybrid. Our results indicate that the hybrid nematic film presents the best phase contrast filter.

A Deeper Dive into the Digital Divide: Reducing Coverage Bias in Internet Surveys

Abstract: Survey research is increasingly turning to online research and as a consequence, sampling only, or disproportionately from, households with internet access. While the percentage of non-internet households has declined, it persists at about one in ten households. This raises the question of coverage error and bias, and whether there is an approach to reduce possible biases in internet-only samples. We processed nearly 5000 variables from over a dozen major public and private datasets to assess the extent of the bias. Finding substantive differences, we then applied a series of data-reducing techniques to arrive at 38 variables that independently skew across internet and non-internet populations. We then developed and fielded a survey of these metrics to assess which dozen or less could be used to construct an efficient propensity model to reduce bias in internet-only samples. Our analyses revealed that many variables noted in prior research are important predictors of non-internet use, but also identified others. Our final propensity model of 10 variables was highly effective, reducing bias significantly. Many variables tested had bias reduced fourfold. Contributions: Prior research has not investigated the digital divide from a wide array of public datasets, nor done enough to consider the bias inherent in internet users-only samples. Our novel random-forest approach and subsequent survey of key candidate variables controlled for correlations among the variables in identifying the most important variables across multiple datasets. Our coding of 542 significant predictors of internet use contributes to the sociological understanding of internet access.

Comparative single-cell transcriptional atlases of<i>Babesia</i>species reveal conserved and species-specific expression profiles

Abstract: ABSTRACT Babesia is a genus of Apicomplexan parasites that infect red blood cells in vertebrate hosts. Pathology occurs during rapid replication cycles in the asexual blood-stage of infection. Current knowledge of Babesia replication cycle progression and regulation is limited and relies mostly on comparative studies with related parasites. Due to limitations in synchronizing Babesia parasites, fine-scale time-course transcriptomic resources are not readily available. Single-cell transcriptomics provides a powerful unbiased alternative for profiling asynchronous cell populations. Here, we applied single-cell RNA sequencing to three Babesia species ( B. divergens, B. bovis , and B. bigemina) . We used analytical approaches and algorithms to map the replication cycle and construct pseudo-synchronized time-course gene expression profiles. We identify clusters of co-expressed genes showing just-in-time expression profiles, with gradually cascading peaks throughout asexual development. Moreover, clustering analysis of reconstructed gene curves reveals coordinated timing of peak expression in epigenetic markers and transcription factors. Using a regularized Gaussian Graphical Model, we reconstructed co-expression networks and identified conserved and species-specific nodes. Motif analysis of a co-expression interactome of AP2 transcription factors identified specific motifs previously reported to play a role in DNA replication in Plasmodium species. Finally, we present an interactive web-application to visualize and interactively explore the datasets.

Assessing the Modern Multi‐Decadal Scale Aridification Over the Northern China From a Historical Perspective

Abstract: Northern China (35°–50°N; 105°–125°E) has experienced a multidecadal aridification since 1950s, which was mainly manifested by multi-decadal scale decreases of regional precipitation and soil moisture, and brought severe influences on societal and economic developments. However, the position of this aridification among the historical aridification events over northern China during the last millennium has not been fully assessed. Furthermore, the contributions from anthropogenic forcings, natural forcings, and internal variability on this aridification have not been quantitatively differentiated. In this study, observations, proxy reconstructions, and model simulations from community Earth system model last millennium ensemble archive were used to assess this aridification from a historical perspective, and differentiate the contributions from different forcings and internal variability. It was found that duration and magnitude of this aridification are more prominent than most of aridifications during the last millennium. The comparisons between control experiment and sensitivity experiments show that the external forcings, especially anthropogenic forcings, result in a significant larger aridification rate than other historical aridifications. Only combined impacts from internal variability (i.e., Pacific Decadal oscillation, PDO and Atlantic Multidecadal oscillation (AMO)) and anthropogenic forcings (e.g., greenhouses gas emission, anthropogenic aerosol emission, and land use cover changes) can result in such a severer aridification than historical aridifications. The results also confirm that the phase shifts of PDO and AMO trigger this aridification over the northern China, and, whether external forcings contribute to these phase shifts were also discussed.

Development of a framework to capture abstraction in physical chemistry problem solving

Abstract: Productive problem solving, concept construction, and sense making occur through the core process of abstraction. Although the capacity for domain-general abstraction is developed at a young age, the role of abstraction in increasingly complex and disciplinary environments, such as those encountered in undergraduate STEM education, is not well understood. Undergraduate physical chemistry relies particularly heavily on abstraction because it uses many overlapping and imperfect mathematical models to represent and interpret phenomena occurring on multiple scales; however, studying and identifying abstraction in-the-moment in physical chemistry is challenging, because current conceptions of abstraction neglect the domain-specific features. This work uses an approach guided by informed grounded theory to develop a conceptual framework that makes abstraction in physical chemistry problem solving visible. Problem solving teaching interviews with individuals and pairs (n = 18) on thermodynamics and kinetics topics are analyzed using an abductive approach. The resulting Epistemic Actions of Abstraction framework characterizes eight epistemic actions along two dimensions: increasing abstractness relative to the context (concretizing, manipulating, restructuring, and generalizing) and nature of the object the action operates on (conceptual or symbolic). These actions are used to identify two types of abstraction: horizontal and vertical abstraction. We discuss how abstraction in problem solving is contextually dependent and implications this work has for problem solving in physical chemistry, as well as implications for physical chemistry instruction.

Nonlinear Responses of Droughts Over China to Volcanic Eruptions at Different Drought Phases

Abstract: Previous studies show that volcanic eruptions can intensify and extend drought events triggered by internal variability over Eastern China. However, it has remained unclear whether volcanic eruptions occurring in different drought phases have different impacts. Here, based on multiple reconstructions, simulations, as well as volcanic sensitivity experiments with volcanic forcing imposed in the early and late phases of droughts, we propose a nonlinear effect of volcanic eruptions on drought events. Late-phase volcanic eruptions exert greater impact on drought persistence and intensity while early-phase volcanic eruptions induce modest and weaker impacts. The evolutions of drought differ substantially from the typical volcanic-only influence or the linear combination of the drought triggered by internal variability and volcanic-only influences, which are hypothesized to be associated with positive feedbacks of soil moisture to precipitation, as well as its interaction with the evolution of the East Asia Summer monsoon.