The sacroiliac joint (SIJ) was considered the primary source of low back pain in the early 20th century (1). It became overshadowed by the herniated nucleus pulposus after the hallmark 1934 article by Mixter and Barr (2). Mounting evidence on computed tomography (CT), magnetic resonance imaging (MRI), and scintography demonstrating destructive, inflammatory, and degenerative pathology (3-9) sug...

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The rigidity of frameworks examines points constrained by fixed distances between pairs of points, using vocabulary and linear techniques drawn from structural engineering: bars and joints, first-order rigidity and first-order flexes, and static rigidity and static self-stresses (Section 61.1. Section 61.2 describes some extended structures and their applications. Scene analysis and the dual co...

Smoking is a common addiction and a leading cause of disease. Chronic nicotine exposure is known to activate nicotinic acetylcholine receptors (nAChRs) in immune cells. We demonstrate a novel role for a4 nAChRs in the effect of nicotine on T-cell proliferation and immunity. Using cell-based sorting and proteomic analysis we define an a4 nAChR expressing helper T-cell population (a4CD3CD4) and s...

In 1922 the Russian geologist Vladimir Vernadsky coined the term “biogeochemistry” in recognition of the intimate connections that exist between living organisms and the physical components of the Earth. This insight came after many failed attempts to understand the chemical makeup of the Earth’s atmosphere and crust through strictly geochemical processes, ignoring the influence of element inte...

Cytosine methylation, a common form of DNA modification that antagonizes transcription, is found at transposons and repeats in vertebrates, plants and fungi. Here we have mapped DNA methylation in the entire Arabidopsis thaliana genome at high resolution. DNA methylation covers transposons and is present within a large fraction of A. thaliana genes. Methylation within genes is conspicuously bia...