Concealed concern: Fathers' experience of having a child with Juvenile Idiopathic Arthritis

Despite increased research into families of chronically ill children, more needs to be known about the father’s experience. We address this issue through asking: ‘What is it like to be the father of a child with juvenile idiopathic arthritis?’ (JIA). Four members of eight families with an adolescent diagnosed with JIA, including seven fathers, were interviewed and transcripts analyzed using grounded theory. This study suggests that fathers of children with JIA experience several severe losses which are exacerbated through comparisons they make between their own situation and that of fathers of healthy children. In addition, the fathers faced several constraints which reduced their opportunities to communicate with their ill child through shared activities. Fathers appeared to conceal their distress by adopting strategies of denial and distraction however their adjustment was facilitated, to some extent, by social support. They could also develop greater acceptance of their situation over time as the care of their ill child became assimilated into family life and constraints upon their life gradually reduced through the increased maturity of their son or daughter with JIA. These findings have implications for healthcare professionals and voluntary organizations

Atomic-Scale Cryogenic Electron Microscopy Imaging of Synthetic Polymers

Materials engineering depends on a thorough understanding of the structure-property relationships in order to rationally design better materials. In polymer science, information about the structure of the material generally comes from scattering techniques, such as wide angle X-ray scattering or neutron scattering. These scattering experiments produce information about the material's structure in reciprocal space, so there can at times be ambiguity in the results when transitioning to real space. Transmission electron microscopy (TEM) is widely used in the materials science community to produce direct, atomic-scale images of hard materials. However, special techniques are needed to image polymeric materials with TEM due to the inherent radiation sensitivity in these soft materials. A series of techniques termed cryo-EM have been developed by the structural biology community to produce atomic-resolution images of proteins. Cryo-EM has only sparingly been applied to synthetic polymers, yet it is a promising tool to advance polymer science. This dissertation focuses on the application of cryo-EM techniques to study the atomic structure of synthetic polymers. The atomic-scale images of the polymers are combined with other material characterization data, molecular dynamics simulations, and TEM image simulations in order to understand the governing interactions that control self-assembly at the atomic level. The direct, atomic-scale imaging of synthetic polymer materials serves to advance material engineering by uncovering the structure-property relationships starting at the atomic scale. Chapters 2, 3, and 4 provide detailed studies in using polypeptoids, which are synthetic polymers with a monomer unit similar to peptides, to uncover the effect of single atom substitutions, ionic interactions, and fixed charges on the self-assembly of these materials. Polypeptoids are a great model system to study self-assembly because their unique submonomer synthesis method grants the ability to precisely vary single atoms within the polymer structure. Chapter 2 starts with using this ability to study the effect of halogen substitutions on the self-assembly and crystal motifs of polypeptoid nanosheets. Chapter 3 investigates the effect of fixed charges and condensed counterions in polypeptoid nanofibers. Chapter 4 details an investigation into the effect of fixed charges and charge density on polypeptoid self-assembly. Chapter 5 applies the same cryo-EM techniques to a conventional diblock copolymer in poly(ethylene oxide)-b-polystyrene (SEO). New synthetic routes were established to create single crystals of SEO with a lithium salt whereby the lithium salt was fully incorporated in the crystal. The single crystals of SEO were imaged with atomic-scale resolution to study how the arrangement of polymer chains changes in response to different amounts of lithium salt. Image simulation based on known crystal structures was used to bring greater understanding to the atomic-scale images

The organizational construction of hegemonic masculinity: the case of the US Navy

This article examines the construction of hegemonic masculinity within the US Navy. Based on life history interviews with 27 male officers, this study explores alternative discourses and identities of officers from three different communities in the Navy: aviation, surface warfare, and the supply corps. Definitions of masculinity are relationally constructed through associations of difference: aviators tend to draw upon themes of autonomy and risk taking; surface warfare officers draw upon themes of perseverance and endurance; and supply officers draw upon themes of technical rationality. Further,these masculinities depend upon various contrasting definitions of femininity. Finally,this article explores a series of contradictions that threaten the secure construction of masculinity within this military culture

Evaluating Cryo‐TEM Reconstruction Accuracy of Self‐Assembled Polymer Nanostructures

Cryogenic transmission electron microscopy (cryo-TEM) combined with single particle analysis (SPA) is an emerging imaging approach for soft materials. However, the accuracy of SPA-reconstructed nanostructures, particularly those formed by synthetic polymers, remains uncertain due to potential packing heterogeneity of the nanostructures. In this study, the combination of molecular dynamics (MD) simulations and image simulations is utilized to validate the accuracy of cryo-TEM 3D reconstructions of self-assembled polypeptoid fibril nanostructures. Using CryoSPARC software, image simulations, 2D classifications, ab initio reconstructions, and homogenous refinements are performed. By comparing the results with atomic models, the recovery of molecular details is assessed, heterogeneous structures are identified, and the influence of extraction location on the reconstructions is evaluated. These findings confirm the fidelity of single particle analysis in accurately resolving complex structural characteristics and heterogeneous structures, exhibiting its potential as a valuable tool for detailed structural analysis of synthetic polymers and soft materials

Crystalline Peptoid Nanofibers with a Single-Unit Cell Cross Section

Ultranarrow crystalline one-dimensional nanostructures formed from soft materials facilitate precise structural control in nanomaterial design, which is essential for biomedicine and nanotechnology applications. Systematic control of their hierarchical structure is challenging due to the complexities of simultaneously manipulating multiple noncovalent interactions at such small scales. We employed a polypeptoid crystal motif as a supramolecular synthon to engineer ultranarrow crystalline nanofibers constrained to a single lattice axis by incorporating a single ionizable side chain into the hydrophobic core of a nanosheet-forming peptoid. Cryogenic transmission electron microscopy of the nanofibers revealed detailed molecular arrangements of a unit-cell cross-section and the presence of distinct pH-dependent lattice isoforms that resulted in morphological transformations. Molecular dynamics simulations demonstrated that the ionizable side chain plays a critical role in changing the local conformation of the unit cell, which further impacts the dimensionality of hierarchical structures. Moreover, these fibers were readily functionalized with biological ligands to afford one-dimensional (1D) protein arrays. This approach for the high-precision bottom-up assembly of ultranarrow 1D nanostructures offers significant potential for developing novel biomimetic nanostructures

Nested case-control study of occupational chemical exposures and prostate cancer in aerospace and radiation workers

Background To date, little is known about the potential contributions of occupational exposure to chemicals to the etiology of prostate cancer. Previous studies examining associations suffered from limitations including the reliance on mortality data and inadequate exposure assessment. Methods We conducted a nested case-control study of 362 cases and 1,805 matched controls to examine the association between occupational chemical exposures and prostate cancer incidence. Workers were employed between 1950 and 1992 at a nuclear energy and rocket engine-testing facility in Southern California. We obtained cancer-incidence data from the California Cancer Registry and seven other state cancer registries. Data from company records were used to construct a job exposure matrix (JEM) for occupational exposures to hydrazine, trichloroethylene (TCE), polycyclic aromatic hydrocarbons (PAHs), benzene and mineral oil. Associations between chemical exposures and prostate cancer incidence were assessed in conditional logistic regression models. Results With adjustment for occupational confounders, including socioeconomic status, occupational physical activity, and exposure to the other chemicals evaluated, the odds ratio for low/moderate TCE exposure was 1.3; 95%CI = 0.8 to 2.1, and for high TCE exposure was 2.1; 95%CI = 1.2 to 3.9. Furthermore, we noted a positive trend between increasing levels of TCE exposure and prostate cancer ( P -value for trend = 0.02). Conclusion Our results suggest that high levels of TCE exposure are associated with prostate cancer among workers in our study population. Am. J. Ind. Med. 50:383–390, 2007. © 2007 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/56006/1/20458_ftp.pd