1,625 research outputs found

    An Analysis of Insulated Concrete Forms for Use in Sustainable Military Construction

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    Insulated Concrete Forms are a block style construction material more typically comprised of expanded polystyrene which fit together and are filled with reinforced concrete to construct the exterior wall systems of a building. By design, this material provides a higher level of insulation and greater structural integrity that stands up to damaging winds, fire, and explosive blasts. This study shows that utilizing this material is not the most cost effective material choice when constructing new facilities, however, it does reduce energy consumption and contributes towards total energy reduction goals established by the Department of Defense. This study also showed there are multiple barriers preventing increased use of Insulated Concrete Forms to include a lack of knowledge of the advantages of this material, a resistance to change from more traditional materials, and to some degree the increased initial cost of utilizing this material. This study concludes there is merit in considering Insulated Concrete Forms for use in sustainable military construction

    AFM pulling and the folding of donor-acceptor oligorotaxanes: phenomenology and interpretation

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    The thermodynamic driving force in the self-assembly of the secondary structure of a class of donor-acceptor oligorotaxanes is elucidated by means of molecular dynamics simulations of equilibrium isometric single-molecule force spectroscopy AFM experiments. The oligorotaxanes consist of cyclobis(paraquat-\emph{p}-phenylene) rings threaded onto an oligomer of 1,5-dioxynaphthalenes linked by polyethers. The simulations are performed in a high dielectric medium using MM3 as the force field. The resulting force vs. extension isotherms show a mechanically unstable region in which the molecule unfolds and, for selected extensions, blinks in the force measurements between a high-force and a low-force regime. From the force vs. extension data the molecular potential of mean force is reconstructed using the weighted histogram analysis method and decomposed into energetic and entropic contributions. The simulations indicate that the folding of the oligorotaxanes is energetically favored but entropically penalized, with the energetic contributions overcoming the entropy penalty and effectively driving the self-assembly. In addition, an analogy between the single-molecule folding/unfolding events driven by the AFM tip and the thermodynamic theory of first-order phase transitions is discussed and general conditions, on the molecule and the cantilever, for the emergence of mechanical instabilities and blinks in the force measurements in equilibrium isometric pulling experiments are presented. In particular, it is shown that the mechanical stability properties observed during the extension are intimately related to the fluctuations in the force measurements.Comment: 42 pages, 17 figures, accepted to the Journal of Chemical Physic

    Isolated familial pheochromocytoma as a variant of von Hippel-Lindau disease.

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    Inherited pheochromocytomas are often part of familial syndromes, especially multiple endocrine neoplasia type 2 (MEN 2), retinal cerebellar hemangioblastomatosis [von Hippel-Lindau (vHL) disease] or neurofibromatosis type 1. It is not clear whether isolated familial pheochromocytoma exists as a separate clinical entity. In a family with pheochromocytomas in three generations and with at least seven affected members, we investigated by clinical and genetic analyses the presence or absence of associated conditions. The clinical investigations included ophthalmological and radiological studies for von Hippel-Lindau disease (magnetic resonance imaging of the brain, computed tomography of the abdomen, and direct ophthalmoscopy after mydriasis) and annual calcitonin stimulation tests for C cell disease in five members who agreed to regular follow-up. Besides the pheochromocytomas (so far, these have been multiple in five of seven individuals) no definite second associated condition was found. Genetic analysis did not identify any MEN 2-specific RET protooncogene point mutations (which are present in 97% of MEN 2a families). However, despite the complete absence of other clinical manifestations of the vHL disease (besides pheochromocytomas), a previously undescribed germline missense mutation in the vHL tumor suppressor gene was found (C775G transversion with a predicted substitution of a leucine by a valine at codon 259 in the putative vHL protein). We conclude that in this family the sole occurrence of pheochromocytoma is a variant of vHL disease

    Delayed Diagnoses: Nonspecific Findings and Diagnostic Challenges in Eating Disorders

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    Objective. Eating disorders commonly present with nonspecific findings, masquerading as other, more common etiologies of malnutrition and wasting. In low-prevalence populations, these ambiguities can complicate clinicians' diagnostic reasoning, resulting in delayed or missed diagnoses. Method. We report the atypical case of a 51-year-old male with a five-year history of unexplained weight loss despite extensive past medical evaluation. Previous documentation of profound lymphopenia and bone marrow atrophy had not been linked to a known association with eating disorders. Results. Evaluation for medical etiologies of wasting was negative. Following psychiatric evaluation, the patient was diagnosed with an eating disorder, not otherwise specified, and admitted to a specialized nutritional rehabilitation program. Conclusion. The nonspecific clinical history, physical exam, and laboratory abnormalities of eating disorders can make these diagnoses challenging and delay appropriate treatment. Clinicians should consider eating disorders in patients with malnutrition, severe lymphopenias, and gelatinous marrow transformation early in their workup, so as to avoid potentially negative outcomes

    A microfluidic chip based model for the study of full thickness human intestinal tissue using dual flow

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    © 2016 Author(s). The study of inflammatory bowel disease, including Ulcerative Colitis and Crohn's Disease, has relied largely upon the use of animal or cell culture models; neither of which can represent all aspects of the human pathophysiology. Presented herein is a dual flow microfluidic device which holds full thickness human intestinal tissue in a known orientation. The luminal and serosal sides are independently perfused ex vivo with nutrients with simultaneous waste removal for up to 72 h. The microfluidic device maintains the viability and integrity of the tissue as demonstrated through Haematoxylin & Eosin staining, immunohistochemistry and release of lactate dehydrogenase. In addition, the inflammatory state remains in the tissue after perfusion on the device as determined by measuring calprotectin levels. It is anticipated that this human model will be extremely useful for studying the biology and tes ting novel interventions in diseased tissue

    Differences in Suicidality in Non–Treatment-Seeking and Treatment-Seeking Law Enforcement Officers: A Cross-sectional Study

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    Objective: Law enforcement officers (LEOs) are exposed to high levels of occupational trauma and face added stress from heightened public scrutiny and COVID-19, which may result in suicide. It is crucial to understand differences between LEOs who seek treatment and those who do not. Method: We compared LEOs from the same greater metropolitan area who sought treatment with those who did not. Participants completed validated measures assessing posttraumatic stress disorder, generalized anxiety, depression, and suicidality. Results: The treatment-seeking sample scores were higher on all standardized assessments. Bivariate logistic regression results indicated that the non–treatment-seeking sample\u27s odds of experiencing suicidality were 1.76 times the odds for the treatment seeking sample. Conclusions: This suggests that many LEOs experiencing suicidality may not be seeking treatment and highlights the role that posttraumatic stress disorder may play in determining whether LEOs seek treatment or not
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