Pressure control valve

A control valve is provided which is adapted to be connected between a pressure source, such as a vacuum pump, and a pressure vessel so as to control the pressure in the vessel. The valve comprises a housing having a longitudinal bore which is connected between the pump and vessel, and a transversely movable valve body which controls the air flow through an air inlet in the housing. The valve body includes cylindrical and conical shaped portions which cooperate with reciprocally shaped portions of the housing to provide flow control. A filter in the air inlet removes foreign matter from the air. The bottom end of the valve body is screwed into the valve housing control knob formed integrally with the valve body and controls translation of the valve body, and the opening and closing of the valve

Professional Development\u27s Complex Ecology: Examining a Whole-School Balanced Literacy Professional Development

This descriptive study reports on the structure and implementation of a school wide professional development model in a southwest public elementary school. The professional development effort was designed to support educators’ understanding and teaching of balanced literacy. The paper reports on the components of this professional development and discusses the strengths of this model in relation to educational research and findings on professional development. We conclude by discussing this model from the perspective of involved administration, facilitators, and teachers, as they consider the process of crossing the borders from professional development into their classrooms. The study is strengthened by teachers’ opinions about the model in their school

Spine immobilization apparatus

The apparatus makes use of a normally flat, flexible bladder filled with beads or micro-balloons that form a rigid mass when the pressure within the bladder is decreased below ambient through the use of a suction pump so that the bladder can be conformed to the torso of the victim and provide the desired restraint. The bladder is strapped to the victim prior to being rigidified by an arrangement of straps which avoid the stomach area. The bladder is adapted to be secured to a rigid support, i.e., a rescue chair, so as to enable removal of a victim after the bladder has been made rigid. A double sealing connector is used to connect the bladder to the suction pump and a control valve is employed to vary the pressure within the bladder so as to soften and harden the bladder as desired

Market Structure and Schumpeterian Growth

We present a discrete-time version of an otherwise standard Schumpeterian growth model. Discrete time exhibits two important differences from continuous time. First, the probability of successful innovation cannot be homogeneous of degree one in inputs. A natural R&D analogue to constant returns to scale implies a Poisson production function with diminishing marginal product of inputs. Second, R&D firms sometimes innovate simultaneously. The resulting market conduct is critical. We consider both Bertrand competition and collusion among successful innovators. Surprisingly, the industry demand for R&D inputs does not depend on the number of firms in the R&D sector if Bertrand competition ensues following ties. In contrast, demand for R&D inputs is higher if ties are expected to result in collusion. In general equilibrium, Bertrand competition leads to random switching between monopoly and competitive production. Under collusion, production is always at the monopoly level, but there is faster growth. Numerical simulations suggest that this also leads to higher welfare.growth, market structure

Sunk costs, Profit Volatility, and Turnover

Dynamic competitive models of industry evolution suggest that firm profit will be more volatile and turnover will be lower in industries with higher sunk costs. These implications are consistent with empirical observation.

Empirical Evidence for Collusion in the U.S. Auto Market?

A supergame theoretic price-setting model of collusion is calibrated to data from the North American passenger car market before, during, and after the voluntary restraint arrangements (VRAs) with Japan. Conclusions about whether the model is consistent with the bans from the various regimes depend on assumptions about market structure, demand elasticities, and discount factors. If one believes that the price elasticity of auto demand is about one, for example, then the calibrations suggest that in, the pre-VRA and VRA regimes, only General Motors and Ford could conceivably have colluded, and even this limited potential broke down in the post-VRA regime.