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Harvard, United States

Kalapurakkel S.,Harvard College | Carpino E.A.,Perioperative and Pain Medicine | Simons L.E.,Perioperative and Pain Medicine | Simons L.E.,Harvard University
Journal of Pediatric Psychology | Year: 2014

Objective To examine pain self-efficacy and pain acceptance in relation to functioning in pediatric patients with chronic headache. Methods Participants were 209 youth aged 8-17 years who presented for a multidisciplinary pediatric headache clinic evaluation. They completed measures of pain self-efficacy and pain acceptance and a standard battery of clinical measures including indicators of emotional functioning. Results Pain self-efficacy and acceptance were associated with less disability, better school functioning, and fewer depressive symptoms. While taking into account several demographic and pain-related variables, pain self-efficacy had a greater association with less functional disability, while pain acceptance had a greater association with less depressive symptoms and better school functioning. Conclusions These findings indicate that both resilience processes can serve to positively interact with functioning and symptoms of depression. Ultimately, this study suggests that higher levels of pain self-efficacy and pain acceptance in an individual experiencing pain are associated with more positive outcomes. © The Author 2014. Published by Oxford University Press on behalf of the Society of Pediatric Psychology. All rights reserved.

Raoof S.,Harvard University | Raoof S.,Harvard College | Heo M.,Pusan National University | Shakhnovich E.I.,Harvard University
Physical Biology | Year: 2013

The germinal center reaction is the process by which low-affinity B cells evolve into potent, immunoglobulin-secreting plasma and memory B cells. Since the recycling hypothesis was created, experimental studies have both tracked movement of a small population of B cells from the light zone into the dark zone, supporting the recycling model, and parallel to the light zone-dark zone interface, indicating a one-way trajectory. We present a novel, sequence-based ab initio model of protein stability and protein interactions. Our model contains a dark zone region of clonal expansion and somatic hypermutation and a light zone site of antigenic selection. We show not only that a one-shot model is sufficient to achieve biologically-realistic rates of affinity growth, population dynamics, and silent:non-silent mutation ratios in the complementary determining region and framework region of antibodies, but also that a stochastic recycling program with or without realistic constraints on the structural stabilities of GC antibodies cannot produce biologically-observed affinity growth, population dynamics or silent:non-silent mutation profiles. The effect of recycling erases affinity gains made by potent antibodies cycling back from the light zone and causes B cells to pool in the dark zone under high replication rates. © 2013 IOP Publishing Ltd.

Sovacool B.K.,National University of Singapore | Rafey W.,Harvard College
Electricity Journal | Year: 2011

The proposed 4,800 MW coal-fired power plant Medupi in South Africa demonstrates how different aspects of energy security can conflict with each other. © 2010 Elsevier Inc.

Gong J.J.,Harvard College
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference | Year: 2011

Understanding the physiological impact of drug treatments on patients is important in assessing their performance and determining possible side effects. While this effect might be best determined in individual subjects, conventional methods assess treatment performance by averaging a physiological measure of interest before and after drug administration for n subjects. Summarizing large numbers of time-series observations in two means for each subject in this way results in significant information loss. Treatment effect can instead be analyzed in individual subjects. Because serial dependence of observations from the same animal must then be considered, methods that assume independence of observations, such as the t-test and z-test, cannot be used. We address this issue in the case of respiratory data collected from anesthetized rats that were injected with a dopamine agonist. In order to accurately assess treatment effect in time-series data, we begin by formulating a method of conditional likelihood maximization to estimate the parameters of a first-order autoregressive (AR) process. We show that treatment effect of a dopamine agonist can be determined while incorporating serial effect into the analysis. In addition, while maximum likelihood estimators of a large sample with independent observations may converge to an asymptotically normal distribution, this result of large sample theory may not hold when observations are serially dependent. In this case, a parametric bootstrap comparison can be used to approximate an appropriate measure of uncertainty.

Runa S.,Georgia Institute of Technology | Hill A.,Georgia Institute of Technology | Cochran V.L.,Harvard College | Payne C.K.,Georgia Institute of Technology
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

Nanoparticles have important biological and biomedical applications ranging from drug and gene delivery to biosensing. In the presence of extracellular proteins, a “corona†of proteins adsorbs on the surface of the nanoparticles, altering their interaction with cells, including immune cells. Nanoparticles are often functionalized with polyethylene glycol (PEG) to reduce this non-specific adsorption of proteins. To understand the change in protein corona that occurs following PEGylation, we first quantified the adsorption of blood serum proteins on bare and PEGylated gold nanoparticles using gel electrophoresis. We find a threefold decrease in the amount of protein adsorbed on PEGylated gold nanoparticles compared to the bare gold nanoparticles, showing that PEG reduces, but does not prevent, corona formation. To determine if the secondary structure of corona proteins was altered upon adsorption onto the bare and PEGylated gold nanoparticles, we use CD spectroscopy to characterize the secondary structure of bovine serum albumin following incubation with the nanoparticles. Our results show no significant change in protein secondary structure following incubation with bare or PEGylated nanoparticles. Further examination of the secondary structure of bovine serum albumin, α2-macroglobulin, and transferrin in the presence of free PEG showed similar results. These findings provide important insights for the use of PEGylated gold nanoparticles under physiological conditions.

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