Flex-Gears

Flex-Gears are being developed as an alternative to brushes and slip rings to conduct electricity across a rotating joint. Flex-Gears roll in the annulus of sun and ring gears for electrical contact while maintaining their position by using a novel application of involute gears. A single Flex-Gear is predicted to transfer up to 2.8 amps, thereby allowing a six inch diameter device, holding 30 Flex-Gears, to transfer over 80 amps. Semi-rigid Flex-Gears are proposed to decrease Flex-Gear stress and insure proper gear meshing

Potential Mechanisms of Photopheresis in Hematopoietic Stem Cell Transplantation

AbstractImmune tolerance describes specific unresponsiveness to antigens. In clinical situations such as graft-versus-host disease it may be useful to capitalize on these pre-existing tolerance mechanisms to treat patients. Extracorporeal photopheresis is a pheresis treatment whereby the approximately 5 × 109 leukocytes are treated with a photoactivatable compound (8-methoxypsoralen) and UVA light, and immediately returned to the patient in a closed-loop, patient-connected system. This therapy induces apoptosis of virtually all the treated leukocytes. There is growing evidence that infusion of apoptotic cells may trigger certain tolerance mechanisms and, thus, be of therapeutic use in graft-versus-host disease. These apoptotic cells are taken up by phagocytes (antigen-presenting cells) in the body of the patient. Apoptotic cell engagement has been reported to induce several changes and functional activities in the engulfing antigen-presenting cell. These antigen-presenting cells: (1) decrease production of proinflammatory cytokines; (2) increase production of anti-inflammatory cytokines; (3) lower ability to stimulate T-cell responses; (4) delete CD8 T effector cells; and (5) induce regulatory T cells. Any and all of these mechanisms could explain the noted effect in graft-versus-host disease. It is still unclear which one or ones are truly responsible. Ongoing studies in animals and human trials will ultimately unravel these details

Flex-gear electrical power transmission

This study was conducted to develop an alternative way of transferring electricity across a continuously rotating joint, with little wear and the potential for low electrical noise. The problems with wires, slip rings, electromagnetic couplings, and recently invented roll-rings are discussed. Flex-gears, an improvement of roll-rings, are described. An entire class of flexgear devices is developed. Finally, the preferred flex-gear device is optimized for maximum electrical contact and analyzed for average mechanical power loss and maximum stress. For a device diameter of six inches, the preferred device is predicted to have a total electrical contact area of 0.066 square inches. In the preferred device, a small amount of internal sliding produces a 0.003 inch-pound torque that resists the motion of the device

The 1991-1992 walking robot design

The University of Maryland Walking Machine team designed and constructed a robot. This robot was completed in two phases with supervision and suggestions from three professors and one graduate teaching assistant. Bob was designed during the Fall Semester 1991, then machined, assembled, and debugged in the Spring Semester 1992. The project required a total of 4,300 student hours and cost under $8,000. Mechanically, Bob was an exercise in optimization. The robot was designed to test several diverse aspects of robotic potential, including speed, agility, and stability, with simplicity and reliability holding equal importance. For speed and smooth walking motion, the footpath contained a long horizontal component; a vertical aspect was included to allow clearance of obstacles. These challenges were met with a leg design that utilized a unique multi-link mechanism which traveled a modified tear-drop footpath. The electrical requirements included motor, encoder, and voice control circuitry selection, manual controller manufacture, and creation of sensors for guidance. Further, there was also a need for selection of the computer, completion of a preliminary program, and testing of the robot

Functional and phenotypic analysis of human cytotoxic cell subsets

Cytotoxic cells are an arm of the immune system important in clearing virally infected cells and tumors from the body. These cells also produce cytokines that help regulate the immune response. The proper identification of mechanisms regulating their function is essential in our understanding of their role in disease and devising methods of modulating their activities. Cytotoxic effector function is mediated primarily by major histocompatability (MHC) restricted cytotoxic T lymphocytes and non-MHC restricted natural killer (NK) cells. Antigen-specific cytotoxic T lymphocytes recognize their target in association with MHC class I while NK cells are inhibited by autologous MHC class I structures and their activation is surface molecule mediated. We have analyzed the function of a novel surface molecule (C1.7 Ag) on both NK and cytotoxic T cells. On NK cells it is an important activating molecule which, upon ligation, upregulates NK cytokine production and cytotoxic activity. On cytotoxic T cells, C1.7 Ag expression is activation dependent and appears to be involved in the target cell coupling but does not signal. C1.7 Ag expression is associated with higher cytotoxic activity and greater cytokine secretion. Its expression on peripheral blood CD8+ T cells corresponds to other known activation markers, all of which are elevated in HIV-infected patients. Via limiting dilution cloning we have found a small number of activated C1.7– cytotoxic cells which have a decreased cytotoxic activity, release type 2 cytokine profile and have lower levels of CD8α on their surface. These cells may be an important down-modulatory mechanism for cell-mediated immune responses and an early source of IL-4. NK cells have traditionally been thought to secrete a type 1 cytokine profile. We have found that if NK cells are generated in conditions used to generate type 2 T cells, NK cells can be generated that secrete IL-5, IL-13, have less IL-12Rβ1 and more IFNγR2 expression. In addition to these novel findings NK type 1 cells can be induced to secrete. IL-10 if acutely treated with IL-12. Taken together we believe that this work adds a significant amount of understanding to the role of type 2 cells in the cytotoxic lymphocyte compartment and their regulation via cytokines and surface molecule expression

Functional and phenotypic analysis of human cytotoxic cell subsets

Cytotoxic cells are an arm of the immune system important in clearing virally infected cells and tumors from the body. These cells also produce cytokines that help regulate the immune response. The proper identification of mechanisms regulating their function is essential in our understanding of their role in disease and devising methods of modulating their activities. Cytotoxic effector function is mediated primarily by major histocompatability (MHC) restricted cytotoxic T lymphocytes and non-MHC restricted natural killer (NK) cells. Antigen-specific cytotoxic T lymphocytes recognize their target in association with MHC class I while NK cells are inhibited by autologous MHC class I structures and their activation is surface molecule mediated. We have analyzed the function of a novel surface molecule (C1.7 Ag) on both NK and cytotoxic T cells. On NK cells it is an important activating molecule which, upon ligation, upregulates NK cytokine production and cytotoxic activity. On cytotoxic T cells, C1.7 Ag expression is activation dependent and appears to be involved in the target cell coupling but does not signal. C1.7 Ag expression is associated with higher cytotoxic activity and greater cytokine secretion. Its expression on peripheral blood CD8+ T cells corresponds to other known activation markers, all of which are elevated in HIV-infected patients. Via limiting dilution cloning we have found a small number of activated C1.7– cytotoxic cells which have a decreased cytotoxic activity, release type 2 cytokine profile and have lower levels of CD8α on their surface. These cells may be an important down-modulatory mechanism for cell-mediated immune responses and an early source of IL-4. NK cells have traditionally been thought to secrete a type 1 cytokine profile. We have found that if NK cells are generated in conditions used to generate type 2 T cells, NK cells can be generated that secrete IL-5, IL-13, have less IL-12Rβ1 and more IFNγR2 expression. In addition to these novel findings NK type 1 cells can be induced to secrete. IL-10 if acutely treated with IL-12. Taken together we believe that this work adds a significant amount of understanding to the role of type 2 cells in the cytotoxic lymphocyte compartment and their regulation via cytokines and surface molecule expression

The Development of Flex-Gears for the Conduction of Electricity Across a Continuously Rotating Joint

The transfer of electricity across a continuously rotating joint is especially important in robot joints and brush-type motors. In this paper, the shortfalls of present technologies, such as electric brushes, are discussed. Flex-gears are presented as an alternative method of transferring electricity across a continuously rotating joint. A new type gear, called a pitch- folling-gear, is developed from involute gear technology for use as a flex-gear. Finally, the design of planetary flex-gear devices using pitch-rolling-gears is studied