Formation and optogenetic control of engineered 3D skeletal muscle bioactuators

Densely arrayed skeletal myotubes are activated individually and as a group using precise optical stimulation with high spatiotemporal resolution. Skeletal muscle myoblasts are genetically encoded to express a light-activated cation channel, Channelrhodopsin-2, which allows for spatiotemporal coordination of a multitude of skeletal myotubes that contract in response to pulsed blue light. Furthermore, ensembles of mature, functional 3D muscle microtissues have been formed from the optogenetically encoded myoblasts using a high-throughput device. The device, called “skeletal muscle on a chip”, not only provides the myoblasts with controlled stress and constraints necessary for muscle alignment, fusion and maturation, but also facilitates the measurement of forces and characterization of the muscle tissue. We measured the specific static and dynamic stresses generated by the microtissues and characterized the morphology and alignment of the myotubes within the constructs. The device allows testing of the effect of a wide range of parameters (cell source, matrix composition, microtissue geometry, auxotonic load, growth factors and exercise) on the maturation, structure and function of the engineered muscle tissues in a combinatorial manner. Our studies integrate tools from optogenetics and microelectromechanical systems (MEMS) technology with skeletal muscle tissue engineering to open up opportunities to generate soft robots actuated by a multitude of spatiotemporally coordinated 3D skeletal muscle microtissues.National Science Foundation (U.S.) (Science and Technology Center—Emergent Behaviors of Integrated Cellular Systems (EBICS) grant No. CBET-0939511)National Institutes of Health (U.S.) (EB00262)National Science Foundation (U.S.) (GM74048)National Science Foundation (U.S.) (HL90747)National Institute for Biomedical Imaging and Bioengineering (U.S.) (RESBIO, Integrapted Technologies for Polymeric Biomaterial)University of Pennsylvania. Center for Engineering Cells and RegenerationSingapore-MIT Alliance for Research and Technolog

Chemical and physical methods of the templated direction of block copolymers

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references.This thesis discusses the investigation of various aspects of templated self-assembly of block copolymer (BCP) thin films for nanofeature fabrication. Two chapters outline the research of a combined physical and chemical templating method with two BCPs. The method was not effective in templating poly(styrene-block-methyl methacrylate) (PS-b-PMMA) BCP because of limited template wettability. The method effectively templated poly(octofluro pentamethacrylate-block-hydroxystyrene) (OFPMA-b-HSM) BCP to fabricate orthogonally-directed lamellar microdomains and nanohole-mesh arrays. Chapter 4 discusses the achievement of a mean overlay accuracy of 52 nm and 0' for two electron-beam-based lithographic features as a result of an investigated overlay process. Lastly, the thesis reports the fabrication of a wide-range of nanofeatures - from two-dimensional and three dimensional nanoholes arrays to elliptical and cylindrical meshes - by the sacrificial-post templating method with poly(styreneblock- dimethylsiloxane) (PS-b-PDMS) BCP.by Samuel M. Nicaise.S.M

"In Bits and Pieces Remembered": Revisiting the Archaeology of Fort Vasquez, a Nineteenth Century Trading Post

This study examines the archaeology of Fort Vasquez, a nineteenth century fur trade fort in the South Platte River Basin of Colorado that operated from 1835-1842. I use artifact analysis, historical documentation, historical and archaeological analogue, expert opinion, and the excavation notes of Dr. James Judge from 1970 to address two research questions. 1) What are the global trade connections that can be identified from the Fort Vasquez artifact collection? 2) Is Dr. James Judge’s hypothesis about the function of Fort Vasquez as being primarily a storage facility out of which traders operated remotely, supported by an in-depth analysis of specific artifact categories and updated historical and archaeological research regarding the Fur Trade Era. I determined through my analysis of beads, pipes, ceramics, buttons, leather, and miscellaneous ornamentation that Fort Vasquez had global trading connections to countries in Europe and Asia. Additionally, my examination of these artifact categories combined with other lines of evidence leads me to conclude that Judge’s hypothesis is not well supported. I instead propose that Fort Vasquez primarily functioned as a nexus of social events and trade

On Tail Distribution Of Interpost Distance

A partial order on Z obtained by taking the transitive closure of a random relation < j and there is an edge ij} is studied. Randomness stems from postulating that an edge ij exists with probability p , independently of all other edges. While studying the random order on the subset [n] , Alon et al. introduced a remarkable notion of a post, defined as an element in Z comparable to all other elements in the random order. In particular they proved that the interpost distance L has a distribution with a tail Pr(L > x) decreasing at an exponential rate x at least, whence having all the moments finite. The latter information about L was all they needed in a proof of the central result, asymptotic lognormality of linear extension number. However, it remained unclear whether the exponential rate is actually linear. Our goal in this note is to confirm the conjecture.