5,457 research outputs found
System description document for the Anthrobot-2: A dexterous robot hand
The Anthrobot-2 is an anatomically correct, fully functioning robot hand. The number of fingers, the proportions of the links, the placement and motion of the thumb, and the shape of the palm follow those of the human hand. Each of the finger and thumb joints are servo-controlled. The Anthrobot-2 also includes a two-degree-of-freedom wrist. The entire package, including wrist, hand, and actuators, will mount on the ends of a variety of industrial manipulators. A patent has been applied for on the design. The Anthrobot-2 will be useful in tasks where dexterous manipulation or telemanipulation are required
Hysteresis in the cell response to time-dependent substrate stiffness
Mechanical cues like the rigidity of the substrate are main determinants for
the decision making of adherent cells. Here we use a mechano-chemical model to
predict the cellular response to varying substrate stiffness. The model
equations combine the mechanics of contractile actin filament bundles with a
model for the Rho-signaling pathway triggered by forces at cell-matrix
contacts. A bifurcation analysis of cellular contractility as a function of
substrate stiffness reveals a bistable response, thus defining a lower
threshold of stiffness, below which cells are not able to build up contractile
forces, and an upper threshold of stiffness, above which cells are always in a
strongly contracted state. Using the full dynamical model, we predict that
rate-dependent hysteresis will occur in the cellular traction forces when cells
are exposed to substrates of time-dependent stiffness.Comment: Revtex, 4 PDF figure
A phenomenological case study of a graduate comprehensive deaf education teacher preparation program : implications for collaborative educational leadership in diverse contexts
"July 2014."Dissertation Supervisor: Dr. Cynthia MacGregor.Includes vita.There exists a critical shortage of teachers of students who are d/Deaf or hard of hearing in the United States; yet, deaf education teacher preparation programs are on the decline. Little is known about the functioning of deaf education teacher preparation programs that exist, namely, how they prepare teacher candidates while simultaneously providing services to learners who are d/Deaf or hard of hearing. A phenomenological case study of a Midwest, graduate, comprehensive deaf education teacher preparation program was conducted. This study explored the essence of empowered and enabled learning of program teacher candidates centered on MO-DESE's educator pillars deemed critical to the development of quality teachers. Data from the study revealed a strong connection between the program's espoused comprehensive philosophy and its practice. Embracing diversity of d/Deafness and differentiated instruction were the two strongest themes that resonated from the participants. Teacher candidates displayed outstanding commitment to the profession and strong proficiency in practice, within the first two pillars. Program improvement was most needed in navigating the public school system.Includes bibliographical references (pages 225-238)
Microchemistry-dependent simulation of yield stress and flow stress in non-heat treatable Al sheet alloys
Aperture Valve for the Mars Organic Molecule Analyzer (MOMA)
NASA's participation in the multi-nation ExoMars 2018 Rover mission includes a critical astrobiology Mass Spectrometer Instrument on the Rover called the Mars Organic Molecule Analyzer (MOMA). The Aperture Valve is a critical electromechanical valve used by the Mass Spectrometer to facilitate the transfer of ions from Martian soil to the Mass Spectrometer for analysis. The MOMA Aperture Valve development program will be discussed in terms of the Initial valve design and subsequent improvements that resulted from prototype testing. The Initial Aperture Valve concept seemed promising, based on calculations and perceived merits. However, performance results of this design were disappointing, due to delamination of TiN and DLC coatings applied to the Titanium base metals, causing debris from the coatings to seize the valve. While peer reviews and design trade studies are important forums to vet a concept design, results from testing should not be underestimated. Despite the lack of development progress to meet requirements, valuable information from weakness discovered in the Initial Valve design was used to develop a second, more robust Aperture valve. Based on a check-ball design, the ETU /flight valve design resulted in significantly less surface area to create the seal. Moreover, PVD coatings were eliminated in favor of hardened, nonmagnetic corrosion resistant alloys. Test results were impressive, with the valve achieving five orders of magnitude better sealing leak rate over end of life requirements. Cycle life was equally impressive, achieving 280,000 cycles without failure
Conserved Endonuclease Function of Hantavirus L Polymerase.
Hantaviruses are important emerging pathogens belonging to the Bunyaviridae family. Like other segmented negative strand RNA viruses, the RNA-dependent RNA polymerase (RdRp) also known as L protein of hantaviruses lacks an intrinsic "capping activity". Hantaviruses therefore employ a "cap snatching" strategy acquiring short 5' RNA sequences bearing 5'cap structures by endonucleolytic cleavage from host cell transcripts. The viral endonuclease activity implicated in cap snatching of hantaviruses has been mapped to the N-terminal domain of the L protein. Using a combination of molecular modeling and structure-function analysis we confirm and extend these findings providing evidence for high conservation of the L endonuclease between Old and New World hantaviruses. Recombinant hantavirus L endonuclease showed catalytic activity and a defined cation preference shared by other viral endonucleases. Based on the previously reported remarkably high activity of hantavirus L endonuclease, we established a cell-based assay for the hantavirus endonuclase function. The robustness of the assay and its high-throughput compatible format makes it suitable for small molecule drug screens to identify novel inhibitors of hantavirus endonuclease. Based on the high degree of similarity to RdRp endonucleases, some candidate inhibitors may be broadly active against hantaviruses and other emerging human pathogenic Bunyaviruses
Development of Epithelial Attachment and Gingival Sulcus in Rhesus Monkeys
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141260/1/jper0044.pd
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