Michael J. Callahan

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Is it possible to implement a distributed file system, retaining some of the advanced protocol features of systems like Coda, while getting an implementation that is an order of magnitude simpler? We claim the answer is " yes " , and InterMezzo is well on its way towards being a prototype of such a system. The key design decisions were to exploit local file(More)
BACKGROUND Early serous carcinomas predominate in the fimbria of women with BRCA mutations (BRCA+). An entity in non-neoplastic mucosa sharing several properties of early serous carcinomas--the "p53 signature"--has been described in the distal fallopian tube and proposed as a precursor to serous carcinomas. This study compared the prevalence of p53(More)
A key commonality of most age-related neurodegenerative diseases is the accumulation of aggregation-prone proteins in the brain. Except for the prionoses, the initiation and propagation of these proteopathies in vivo remains poorly understood. In a previous study, we found that the deposition of the amyloidogenic peptide Abeta can be induced by injection of(More)
Many neurodegenerative diseases are associated with the abnormal sequestration of disease-specific proteins in the brain, but the events that initiate this process remain unclear. To determine whether the deposition of the ␤-amyloid peptide (A␤), a key pathological feature of Alzheimer's disease (AD), can be induced in vivo, we infused dilute supernatants(More)
Using microPET and (18)F-fluorodeoxyglucose ((18)F-FDG) as a tracer, we investigated regional brain activation in a rat model of visceral hypersensitivity induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS). TNBS injection into the proximal colon through laparotomy resulted in a significant, sustained decrease in the pain threshold to mechanical(More)
Neurofibrillary tangles, one of the pathologic hallmarks of Alzheimer's disease (AD), are composed of abnormally polymerized tau protein. The hyperphosphorylation of tau alters its normal cellular function and is thought to promote the formation of neurofibrillary tangles. Growing evidence suggests that cyclin-dependent kinase 5 (cdk5) plays a role in tau(More)
Diffusion-weighted MRI of the body has the potential to provide important new insights into physiological and microstructural properties. The intra-voxel incoherent motion (IVIM) model relates the observed DW-MRI signal decay to parameters that reflect perfusivity (D*) and its volume fraction (f), and diffusivity (D). However, the commonly used voxel-wise(More)
PURPOSE To characterize fast and slow diffusion components in diffusion-weighted magnetic resonance imaging (DW-MRI) of pediatric Crohn's disease (CD). Overall diffusivity reduction as measured by the apparent diffusion coefficient (ADC) in patients with CD has been previously demonstrated. However, the ADC reduction may be due to changes in either fast or(More)
PURPOSE To assess the optimal b-values range for perfusion-insensitive apparent diffusion coefficient (ADC) imaging of abdominal organs using short-duration DW-MRI acquisitions with currently available ADC estimation methods. METHODS DW-MRI data of 15 subjects were acquired with eight b-values in the range of 5-800 s∕mm(2). The reference-standard, a(More)