23 research outputs found
COVID-19 infodemic and health-related quality of life in patients with chronic respiratory diseases: A multicentre, observational study
No full textBackground: The explosion of information, misinformation and disinformation (the "infodemic") related to the coronavirus disease 2019 (COVID-19) pandemic on digital and social media is reported to affect mental health and quality of life. However, reports assessing the COVID-19 infodemic on health-related quality of life (HRQL) in patients with chronic diseases are scarce. In this study, we investigated the associations between the infodemic and HRQL in uninfected individuals with pre-existing chronic respiratory diseases (CRDs) such as asthma, chronic obstructive pulmonary disease (COPD) and other CRDs. Methods: We conducted a multi-national, cross-sectional, observational study in Canada, India, New Zealand and the United Kingdom where we distributed a set of digitised questionnaires among 1018 participants with chronic respiratory diseases who were not infected with the SARS-CoV-2 virus at least three months prior to the study. We collected information about the infodemic such as news watching or social media use more than usual during the pandemic. HRQL was assessed using the short form of the chronic respiratory questionnaire (SF-CRQ). Demographic information, comorbidities, compliance, mental health, behavioural function, and social support were also recorded. We analysed the direct and indirect relationships between infodemic and HRQL using structural equation models (SEM). Results: Of all participants, 54% were females and had a mean (standard deviation (SD)) age of 53 (17) years. We found that higher infodemic was associated with worse emotional function (regression coefficient β = -0.08; 95% confidence interval (CI) = -0.14 to -0.01), which means a one SD change of the higher infodemic latent variable was associated with a 0.08 SD change of emotional function level. The association between higher infodemic and worse emotional function was mediated by worse mental health and behavioural functions but is marginally ameliorated by improved social support. In stratification analysis, we found significant disease and country-wise variations in the associations between infodemic and SF-CRQ domain scores. Conclusions: These results provide new evidence that the COVID-19 infodemic significantly influences the HRQL in patients with CRDs through a complex interplay between mental health, behavioural function, and social support. This new dimension of research also opens avenues for further research on infodemic-related health effects in other chronic diseases
Less social deprivation is associated with better health-related quality of life (HRQoL) in asthma and is mediated by less anxiety and better sleep quality
No full textBackground Previous studies on health-related quality of life (HRQoL) in asthma have mainly focused on clinical and environmental determinants. Little is known about the role of social determinants on HRQoL in asthma. Objectives We aimed to investigate the association between social deprivation and HRQoL in asthma. Methods 691 adult asthmatics from Canada, India, New Zealand, and the United Kingdom were administered a digital questionnaire containing demographic information, and questions about social and psychological attributes, sleep disturbances, and alcohol abuse. HRQoL was measured using the short-form chronic respiratory disease questionnaire (SF-CRQ). We analyzed the direct and indirect relationships between social deprivation and HRQoL using structural equation models with social deprivation as a latent variable. We tested for mediation via anxiety, depression, sleep disturbances, and alcohol abuse. Results We found that less social deprivation (latent variable) was directly associated with better SF-CRQ domain scores such as dyspnea (β: 0.33; 95%CI: 0.07 to 0.58), fatigue (β: 0.39; 95%CI: 0.14 to 0.64), and emotional function (β: 0.37; 95%CI: 0.11 to 0.62), but with worse mastery score (β: -0.29; 95%CI: -0.55 to -0.03); however, those associations varied across participating countries. We also observed that among all individual social deprivation indicators, education, companionship, emotional support, instrumental support, and social isolation were directly associated with HRQoL and the relationship between social deprivation and HRQoL was mediated through anxiety and sleep disturbances. Conclusions Our results demonstrated that less social deprivation was directly, and indirectly through less anxiety and better sleep quality, associated with better HRQoL in asthma
Parent – Adolescent Communication and Delinquency: A Comparative study in Kolkata, India.
No full textThe present study assessed the impact of one of the dimension of parenting practices, that is, parent- adolescent communication and its influence on the development of delinquent behavior. The data was collected from 200 adolescents (100 delinquents and 100 non- delinquents) aged 11- 18 years. Results indicated that there exists a significant difference between delinquent and non- delinquent adolescents, in their perception of satisfactory parental communication. Further analyses revealed that both mother’s and father’s separate communication as well as their interaction effect was linked to the development of delinquent behavior. It was further noted that a satisfactory mother- adolescent communication was much more important compared to the father- adolescent communication in the present context. Furthermore, age of the adolescent was also related to delinquency and it was observed that early adolescence was a richer breeding ground of delinquency, although a satisfactory parental communication was crucial all throughout the adolescent period to serve as a protective factor against delinquency. The theoretical and practical implications of the findings are discussed
Parenting Behavior and Juvenile Delinquency Among Low-Income Families
No full textIt is widely known that parenting behavior has an impact on the development of delinquent behavior among adolescents. However, there is paucity of studies focusing on parenting behavior and its relation to juvenile delinquency among low-income families from India. The authors examined a wide range of parenting behavior and its relationship to juvenile delinquency in low-income families among Indians. Data were collected from 27 juvenile delinquent boys who were residing temporarily in an observation home in Kolkata (West Bengal, India) and 100 matched control (with respect to their socioeconomic status) juvenile boys, 11–18 years old, also from the same city. The overall findings revealed that there were higher levels of permissive parenting in the families of delinquent adolescents. It may be because low-income families have many family members that initiated the adolescents to take up some jobs to increase the family income, and this in turn affected their parents’ parenting behavior
INVESTIGATIONS INTO MECHANISMS UNDERLYING EXTREME WAVE FORMATIONS AND COMPUTATIONALLY INTENSIVE SIMULATIONS
No full textVarious mechanisms have been proposed to explain extreme waves or rogue waves in an oceanic environment including directional focusing, dispersive focusing, wave-current interaction, and nonlinear modulational instability. The Benjamin-Feir instability (nonlinear modulational instability), however, is considered to be one of the primary mechanisms for rogue-wave occurrence. The nonlinear Schrodinger equation is a well-established approximate model based on the same assumptions as required for the derivation of the Benjamin-Feir theory. Solutions of the nonlinear Schrodinger equation, including new rogue-wave type solutions are presented in the author's dissertation work. The solutions are obtained by using a predictive eigenvalue map based predictor-corrector procedure developed by the author. Features of the predictive map are explored and the influences of certain parameter variations are investigated. The solutions are rescaled to match the length scales of waves generated in a wave tank. Based on the information provided by the map and the details of physical scaling, a framework is developed that can serve as a basis for experimental investigations into a variety of extreme waves as well localizations in wave fields.
To derive further fundamental insights into the complexity of extreme wave conditions, Smoothed Particle Hydrodynamics (SPH) simulations are carried out on an advanced Graphic Processing Unit (GPU) based parallel computational platform. Free surface gravity wave simulations have successfully characterized water-wave dispersion in the SPH model while demonstrating extreme energy focusing and wave growth in both linear and nonlinear regimes. A virtual wave tank is simulated wherein wave motions can be excited from either side. Focusing of several wave trains and isolated waves has been simulated. With properly chosen parameters, dispersion effects are observed causing a chirped wave train to focus and exhibit growth. By using the insights derived from the study of the nonlinear Schrodinger equation, modulational instability or self-focusing has been induced in a numerical wave tank and studied through several numerical simulations. Due to the inherent dissipative nature of SPH models, simulating persistent progressive waves can be problematic. This issue has been addressed and an observation-based solution has been provided. The efficacy of SPH in modeling wave focusing can be critical to further our understanding and predicting extreme wave phenomena through simulations.
A deeper understanding of the mechanisms underlying extreme energy localization phenomena can help facilitate energy harnessing and serve as a basis to predict and mitigate the impact of energy focusing
Thermo-mechanical model of steel shell behavior in continuous slab casting
No full textThe behavior of the solidifying shell in the early stages of solidification has an important influence on the final quality of continuously-cast steel slabs. In order to understand the thermal and mechanical behavior of the shell, a two-dimensional transient stepwise-coupled finite-element model has been developed. The model simulates a transverse section of the slab as it moves down through the mold and below and incorporates the effects of heat conduction, solidification, shrinkage, non-uniform superheat dissipation due to turbulent fluid flow, thermal distortion of the mold and the visco-plastic mechanical behavior of the steel. Coupling between the thermal and the mechanical portions of the model are based on the mutual dependence of heat transfer across the interface between the shell and the mold and the size of the gap. The effects of mold distortion and taper on the gap size are also included. The effect of fluid flow has been incorporated via a heat flux imposed at the solid-liquid interface, which is obtained from a separate fluid flow model. The high temperature creep and plasticity of the steel is incorporated through a unified constitutive law defining the inelastic strain rates as a function of temperature, composition, accumulated plastic strain and the stress state. The model has been successfully verified with analytical solutions and measurements of temperature and shell thickness on an operating caster. Non-uniform dissipation of superheat caused by asymmetrical fluid flow has been found to have a critical influence on shell growth in the mold, in places where the interfacial gap size is significant. Model results suggest that a simple linear taper necessary to compensate for the slab shrinkage is not sufficient for low carbon steels because of the non-linear shrinkage associated with the - phase transformation. Model simulations extending below the mold suggest that bulging of the shell between rollers is responsible for the formation of off-corner depressions when the off-corner region of the shell leaving the mold is relatively thinner than other places. The model developed in this work is an effective tool and can be judiciously used to understand the formation mechanisms of various defects in continuous slab casting.Made available in DSpace on 2011-05-07T12:02:15Z (GMT). No. of bitstreams: 2
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Variability in the survival to sepsis: inhibitory immunoglobulin G in plasma blocks macrophage mediated killing of enteric bacteria
No full textThesis (Ph.D.)--Boston University
PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at [email protected]. Thank you.The humoral response of an individual can act as a critical factor in mediating survival during sepsis. We hypothesized that the presence of pre-existing, plasma IgG antibodies in mice prior to the onset of sepsis accounts for the differences in their survival and provides a mechanism for the variability in survival in the Cecal Ligation and Puncture (CLP) model of sepsis.
Naive pre-CLP plasma was classified as Killing-Plasma or Non-Killing-Plasma based on its ability to kill enteric bacteria in presence of elicited phagocytes using a Plasma Enhanced Killing (PEK) assay. The constant parameters in the assay were bacteria and phagocytes. The variable parameter was pre-CLP plasma obtained from individual mice. The PEK capacity correlated with the CLP survival. Plasma IL-6 levels 24 hours post CLP were used to predict mortality (Die-P) or survival (Live-P). Die-P mice had Non-Killing-Plasma (determined by PEK) and developed higher peritoneal bacterial counts 24 hours
post CLP.
To understand the defense mechanism conferred by the pre-existing antibodies, IgM immunodepletion did not alter PEK but removing IgG improved PEK capacity suggesting that pre-existing IgG inhibited killing in Non-Killing- Plasma.
To evaluate the mechanism of action for lgG, the steps of antibody mediated bacterial killing were evaluated. Plasma by itself was unable to kill bacteria. Addition of macrophages post-opsonization inhibited killing by the Non- Killing-Plasma. Removal of unbound plasma fraction post-opsonization improved killing for the Non-Killing-Plasma. Incubation of macrophages with plasma made bacterial killing worse indicating that lgG in Non-Killing-Plasma interfered with the macrophage mediated killing of opsonized bacteria. De-glycosylation of IgG, which limits its ability to bind to Fcy receptors (FcyRs), improved the PEK capacity of the Non-Killing-Plasma. Blocking FcyRs on macrophages inhibited bacterial killing suggesting that the antibody mediated bacterial killing is through the Fc-FcyR pathway.
This study indicates that the possibility of the presence of an inhibitory IgG in naive plasma which may block plasma enhanced killing of bacteria and may be one of the factors conferring increased susceptibility to sepsis induced mortality by CLP
Spectral methods from tensor networks
No full text© 2019 Copyright held by the owner/author(s). Publication rights licensed to ACM. A tensor network is a diagram that specifies a way to “multiply” a collection of tensors together to produce another tensor (or matrix). Many existing algorithms for tensor problems (such as tensor decomposition and tensor PCA), although they are not presented this way, can be viewed as spectral methods on matrices built from simple tensor networks. In this work we leverage the full power of this abstraction to design new algorithms for certain continuous tensor decomposition problems. An important and challenging family of tensor problems comes from orbit recovery, a class of inference problems involving group actions (inspired by applications such as cryo-electron microscopy). Orbit recovery problems over finite groups can often be solved via standard tensor methods. However, for infinite groups, no general algorithms are known. We give a new spectral algorithm based on tensor networks for one such problem: continuous multi-reference alignment over the infinite group SO(2). Our algorithm extends to the more general heterogeneous case
Understanding the crucial roles of lipid synthesis in Leishmania proliferation and stress response
No full textLeishmaniasis are a group of neglected tropical diseases transmitted through the bite of female phlebotomine sandflies. The causative agents are protozoan parasites of the genus Leishmania which alternate between flagellated promastigotes colonizing the midgut of sandflies and non-flagellated amastigotes residing in the macrophages of mammals. The 3 forms of Leishmaniasis are cutaneous, mucocutaneous and visceral caused by L. major, L. mexicana and L. donovani. Without a safe vaccine, disease management primarily depends on vector control and drugs like pentavalent antimonials, itraconazole, myriocin administered in high doses, having adverse side effects and increased drug resistance Discoveries that reveal fundamental insights into Leishmania biology can lead to new drug targets, better treatments, and improved vector control strategies. Therefore, research involving the identification and characterization of metabolic pathways that could provide new drug targets is of considerable value. Understanding biology behind lipid synthesis and acquisition in Leishmania is important because lipids play a crucial role in cell homeostasis. Plasma membrane and other organelle membrane contain lipids as important constituents, so understanding how important lipids like PC, sterol and sphingolipid are synthesized de novo and utilized for both life stages of Leishmania in sandfly and mammalian hosts, respectively is crucial. The long-term goal can be utilizing this new biological knowledge about lipid synthesis and acquisition by applying them to identify possible novel drug targets against the parasite. Potentially, we can generate novel inhibitors or use this knowledge to create combinatorial treatment with existing chemotherapeutics helping to cure Leishmaniasis (second-deadliest parasitic disease after malaria).
Phosphatidylcholine (PC) is the most abundant group of phospholipids in eukaryotes constituting 30–35% of total lipids in Leishmania. PC synthesis mainly occurs via the choline branch of the Kennedy pathway (choline choline-phosphate CDP-choline PC) and the N-methylation of phosphatidylethanolamine (PE). In addition, Leishmania parasites can also acquire lipids from the host or culture medium. Our previous study on the choline-phosphate cytidylyltransferase (CPCT) demonstrates that the formation of CDP-choline from choline-phosphate and CTP is dispensable for the promastigotes and amastigotes of Leishmania major. Thus, these parasites may bypass CPCT through an alternative route of CDP-choline production, PE N-methylation or lipid salvage. In this study, we assessed the function and essentiality of choline ethanolamine phosphotransferase (CEPT) which is directly responsible for the de novo synthesis of both PC and PE. This is important because in addition to being principle membrane components, PC and PE are precursors for a number of vital intermediates including diacylglycerol, lysophospholipid and phosphatidic acid. Understanding how Leishmania generate PC and PE may reveal new ways to block their growth. Our data indicate that L. major CEPT is localized in the ER and possesses the activity to synthesize PC from CDP-choline and diacylglycerol. Targeted deletion of CEPT is only possible in the presence of an episomal CEPT in the promastigote stage of L. major. These chromosomal null parasites require the episomal expression of CEPT for survival in culture, confirming its essentiality during the promastigote stage. In contrast, during in vivo infection of BALB/c mice, these chromosomal null parasites appeared to lose the episomal copy of CEPT while maintaining a normal level of virulence, replication and cellular PC. Therefore, while the de novo synthesis of PC/PE is indispensable for proliferation of promastigotes, intracellular amastigotes could acquire the majority of their lipids from the host.
Within the mid gut of sand fly, Leishmania promastigotes need to colonize, proliferate and differentiate while facing a number of challenges including sand fly immunity, nutrient competition, potential microbial toxins and osmolality changes associated with sugar and blood meal digestion. Sterols and sphingolipids are key components of the plasma membrane and regulate diverse processes including membrane stability, ligand-receptor interaction, and vesicular trafficking. Previous findings show, sphingolipids and sterol biosynthetic pathway enzymes are crucial for stress response and virulence. To decipher the protective role of these lipids in Leishmania, we examined the sensitivity of ergosterol and sphingolipid mutants to membrane perturbation agents, bacterial toxins and osmotic stress. My results show sterol and sphingolipid inhibition result in mitochondrial abnormalities, making Leishmania hypersensitive to temperature, osmostress and Pentamidine (mitochondrion targeting drug), thereby indicating sterols and sphingolipids crucially maintain Leishmania homeostasis during temperature and osmotic stress encountered in its lifecycle. Alteration of lipid synthesis can make Leishmania extremely vulnerable to membrane stress and nutrient deprivation. My work also tries to improve current drug efficacy by combined usage of lower doses of existing drugs like Pentamidine and Antimony tartrate respectively with sterol inhibitor Itraconazole and sphingolipid inhibitor Myriocin respectively against Leishmania spp ( L.major, L. mexicana and L. donovani) in vitro with least to no side effects. My results show various Leishmania spp. (L. major, L. mexicana, L. donovani) on sterol inhibition with sublytic Itraconazole doses, and sphingolipid inhibition with sublytic Myriocin doses will show hypersensitivity to sublytic doses of Pentamidine and Antimony tartrate when used in combination. The significance of this proposed work is to find better combinatorial treatment strategies against Leishmaniasis with existing drugs and inhibitors with least possible doses, having least to no side effects.
Future work will elucidate: 1) how sterol/sphingolipid synthesis affects the composition and physiology of plasma membrane, and 2) how lipids in plasma membrane affect the transmission of Leishmania parasites in the sand fly.Embargo status: Restricted until 01/2027. To request the author grant access, click on the PDF link to the left
