A Lattice Calculation of the Heavy Quark Universal Form Factor

A computation of the Isgur-Wise universal form factor using a lattice implementation of the heavy quark effective theory is described, and the results of a lattice simulation are presented.Comment: 3 pages in postscrip

Bioresorbable Polylactide Interbody Implants in an Ovine Anterior Cervical Discectomy and Fusion Model: Three-Year Results

Study Design. In vivo study of anterior discectomy and fusion using a bioresorbable 70:30 poly(l-lactide-co-d,l-lactide) interbody implant in an ovine model. Objective. To evaluate the efficacy of the polylactide implant to function as an interbody fusion device, and to assess the tissue reaction to the material during the resorption process. Summary of Background Data. The use of polylactide as a cervical interbody implant has several potential advantages when compared with traditional materials. Having an elastic modulus very similar to bone minimizes the potential for stress shielding, and as the material resorbs additional loading is transferred to the developing fusion mass. Although preclinical and clinical studies have demonstrated the suitability of polylactide implants for lumbar interbody fusion, detailed information on cervical anterior cervical discectomy and fusion (ACDF) with polylactide devices is desirable. Methods. Single level ACDF was performed in 8 skeletally mature ewes. Bioresorbable 70:30 poly (l-lactide-co-d,l-lactide) interbody implants packed with autograft were used with single-level metallic plates. Radiographs were made every 3 months up to 1 year, and yearly thereafter. The animals were killed at 6 months (3 animals), 12 months (3 animals), and 36 months (2 animals). In addition to the serial plain radiographs, the specimens were evaluated by nondestructive biomechanical testing and undecalcified histologic analysis. Results. The bioresorbable polylactide implants were effective in achieving interbody fusion. The 6-month animals appeared fused radiographically and biomechanically, whereas histologic sections demonstrated partial fusion (in 3 of 3 animals). Radiographic fusion was confirmed histologically and biomechanically at 12 months (3 of 3 animals) and 36 months (2 of 2 animals). A mild chronic inflammatory response to the resorbing polylactide implant was observed at both 6 months and 12 months. At 36 months, the operative levels were solidly fused and the implants were completely resorbed. No adverse tissue response was observed in any animal at any time period. Conclusion. Interbody fusion was achieved using bioresorbable polylactide implants, with no evidence of implant collapse, extrusion, or adverse tissue response to the material. The use of polylactide as a cervical interbody device appears both safe and effective based on these ACDF animal model results

Frequency domain secondary pulse estimation

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (leaves 44-45).by Jeffrey Crawford Dickerson.M.Eng

Design of a robotic hand and simple EMG input controller with a biologically-inspired parallel actuation system for prosthetic applications

This paper presents the mechatronic design of a robotic hand for prosthetic applications. The main characteristic of this robotic hand is its biologically-inspired parallel actuation system, which is based on the behavior/strength space of the Flexor Digitorum Profundus (FDP) and the Flexor Digitorum Superficialis (FDS) muscles. The design separates the strength space of the FDS and FDP muscles into a lighter strength region where finer manipulation and general approach tasks are executed, and a higher strength region where the more robust grasps are achieved. Two parallel actuator types and kinematic structures are designed to complement the requirements of both strength space regions.This unique structure is intended to be driven by electromyographical (EMG) signals captured at the surface of the skin. The direct relation between signal and actuation system lends itself well to interpreting the EMG signals from the FDP and FDS muscles into effective task execution, with the goal of helping the user to achieve a good approximation of the full capabilities associated with the human hand, without compromising strength, dexterity, appearance, or weight; which are common issues associated with prosthetic hands. The designed finger’s capability of having a strength space similar to that of the FDS and FDP muscles is validated via direct inputs from a power supply and then via a controller using an actual EMG signal input from the human forearm. The controller is a simple feed forward system at this point in the research but provides the appropriate framework to integrate more elaborate control schemes and EMG signal conditioning as this portion of the research area matures.Peer ReviewedPostprint (author’s final draft

Characterization of serum anyloid P and Fc gamma receptor: A critical engagement implicated in fibrosing diseases

Fibrotic diseases have a poor prognosis with no FDA approved therapies. Monocyte-derived, fibroblast-like cells called fibrocytes participate in the formation of fibrotic lesions. The conserved pentraxin protein serum amyloid P (SAP) inhibits fibrocyte differentiation in cell culture, and injections of SAP significantly reduce fibrosis in several animal models. SAP binds to the receptors for the Fc portion of immunoglobulin G (FcγR), and has been crystallized bound to FcγRIIa. The in vivo activity of SAP appears to be dependent on the common γ chain (FcγR) of activating Fc receptors. The goal of my project is to elucidate the functional domains of SAP and the receptor responsible for SAP bioactivity, which could lead to refinements for SAP as a therapeutic agent and additional drug targets. I found that mutagenesis of the residues critical for SAP binding to FcγRIIa only moderately decreases SAP's ability to inhibit fibrocyte differentiation. In murine cells, deletion of FcγR or FcγRI significantly reduced sensitivity to SAP. Deletion of the combination of FcγRIIb/FcγRIIIa/FcγRIV did not significantly affect sensitivity to SAP, while deletion of just the inhibitory receptor FcγRIIb increased sensitivity to SAP. In human cells, siRNA-mediated reduction of FcγR or FcγRI levels significantly decreased sensitivity to SAP, while reduction of FcγRIIb levels increased sensitivity to SAP. These observations suggest that SAP, at least in part, uses FcγRI and FcγR to inhibit fibrocyte differentiation. I am also interested in how SAP functions in various disease states. SAP is known to be elevated in Alzheimer's disease (AD) and binds to amyloid plaques in the brain, a key hallmark of AD. There is a significant population of individuals that have key hallmarks of AD but show no signs of cognitive impairment, termed non-demented with AD neuropathology (NDAN). I evaluated SAP levels in post mortem samples of hippocampus and frontal cortex in age-matched controls, AD, and NDAN individuals. AD individuals had significantly increased SAP levels, while NDAN samples had no significant difference in SAP levels compared to controls. These results suggest that low levels of SAP in plaques marks the brains of individuals that escape dementia despite the presence of beta amyloid plaques

Time-Dependent Quantum Reactive Scattering in Hyperspherical Coordinates

We present a time-dependent hyperspherical, wave packet method for calculating three atom state-to-state S-matrix elements.The wave packet is propagated in time using adiabatically adjusting, principal axes hyperspherical (APH) coordinates that treat all arrangement channels equivalently, allowing the simultaneous analysis of the products in all three arrangement channels.We take advantage of the symmetry of the potential energy surface and decompose the initial wave packet into its component irreducible representations, propagating each component separately.Each packet is analyzed by projecting it onto the hyperspherical basis at a fixed, asymptotic hyperradius, andirreducible representation dependent S-matrix elements are obtained by matching the hyperspherical projections to symmetry-adapted Jacobi coordinate boundary conditions.We obtain arrangement channel-dependent S-matrix elements as linear combinations of the irreducible representation dependent elements.We derive and implement a new three-dimensional Sylvester-like algorithm that reduces the number of multiplications required to apply the Hamiltonian to the wave packet, dramatically increasing the computational efficiency.A convergence study is presented to show the behavior of the results as the initial parameters are varied and to determine the values of those parameters that give accurate results.State-to-state H+H2 and F+H2 results for zero total angular momentum are presented and show excellent agreement with time-independent benchmark results

A Randomized Trial Comparing Immediate versus Delayed Treatment of Anemia with Once-Weekly Epoetin Alfa in Patients with Non-small Cell Lung Cancer Scheduled to Receive First-Line Chemotherapy

Introduction:This study evaluated the safety/efficacy of once-weekly (QW) epoetin alfa measured by quality of life (QOL), hemoglobin (Hb), transfusion incidence, tumor response, and survival in patients with chemotherapy-naïve, advanced non-small cell lung cancer (NSCLC).Methods:Stage IIIB/IV NSCLC patients with Hb ≥11 to <15 g/dl scheduled for at least 8 weeks of first-line chemotherapy were randomized to subcutaneously receive 40,000 U of epoetin alfa QW at chemotherapy initiation (immediate) or no epoetin alfa unless Hb decreased to ≤10 g/dl (delayed). The primary efficacy variable was change in QOL for immediate versus delayed intervention. Target accrual was 320 patients.Results:The study was terminated early because of slow accrual; of 216 patients enrolled, 211 were evaluable for efficacy. Hb was maintained in the immediate group, but it decreased in the delayed group (12.9 versus 11.6 g/dl final values, respectively). Numerically, fewer immediate patients required transfusions versus delayed patients. Mean QOL scores, modestly declining in both groups from baseline to final measurement, were not significantly different between groups. Tumor response and median overall survival were similar between groups. Epoetin alfa was well tolerated, with a similar thrombovascular event rate between groups.Conclusion:Epoetin alfa in subcutaneous doses of 40,000 U QW, given immediately at chemotherapy initiation for advanced NSCLC, was well tolerated, and it effectively maintained Hb, leading to a reduced transfusion incidence versus delayed epoetin alfa. Overall QOL scores were higher than typical in this population, decreasing slightly during treatment in both groups. Overall survival was similar between groups, with no evidence of a negative effect by early epoetin alfa intervention

Recent Paleoanthropological Excavations of In Situ Deposits at Makapansgat, South Africa – A First Report

The Makapansgat Limeworks is a significant Pliocene site both for its sample of 35 hominin fossils as well as its wealth of fossil fauna. The lithological and paleontological successions reveal local environmental changes that are important for understanding the context of hominin evolution in southern Africa. Yet most of the site’s fossils were found in dumps left behind by quarry operations, and the paleoecological interpretations rest upon debatable assumptions about the original fossil provenience. We have recently initiated systematic paleoanthropological excavations at Makapansgat to recover well provenanced fossils in order to: 1) assess whether faunal successions are discernable in the Makapansgat sequence; 2) assist environmental interpretations of the site; 3) and potentially recover the oldest hominins in South Africa, roughly coincident with Australopithecus afarensis in East Africa. This paper presents a summary of our current paleoenvironmental research at the Limeworks and preliminary results of ongoing in situ excavations