Pneumatically Actuated Miniature Peristaltic Vacuum Pumps

Pneumatically actuated miniature peristaltic vacuum pumps have been proposed for incorporation into advanced miniature versions of scientific instruments that depend on vacuum for proper operation. These pumps are expected to be capable of reaching vacuum-side pressures in the torr to millitorr range (from .133 down to .0.13 Pa). Vacuum pumps that operate in this range are often denoted roughing pumps. In comparison with previously available roughing pumps, these pumps are expected to be an order of magnitude less massive and less power-hungry. In addition, they would be extremely robust, and would operate with little or no maintenance and without need for oil or other lubricants. Portable mass spectrometers are typical examples of instruments that could incorporate the proposed pumps. In addition, the proposed pumps could be used as roughing pumps in general laboratory applications in which low pumping rates could be tolerated. The proposed pumps could be designed and fabricated in conventionally machined and micromachined versions. A typical micromachined version (see figure) would include a rigid glass, metal, or plastic substrate and two layers of silicone rubber. The bottom silicone layer would contain shallow pump channels covered by silicone arches that could be pushed down pneumatically to block the channels. The bottom silicone layer would be covered with a thin layer of material with very low gas permeability, and would be bonded to the substrate everywhere except in the channel areas. The top silicone layer would be attached to the bottom silicone layer and would contain pneumatic- actuation channels that would lie crosswise to the pump channels. This version is said to be micromachined because the two silicone layers containing the channels would be fabricated by casting silicone rubber on micromachined silicon molds. The pneumatic-actuation channels would be alternately connected to a compressed gas and (depending on pump design) either to atmospheric pressure or to a partial vacuum source. The design would be such that the higher pneumatic pressure would be sufficient to push the silicone arches down onto the substrates, blocking the channels. Thus, by connecting pneumatic- actuation channels to the two pneumatic sources in spatial and temporal alternation, waves of opening and closing, equivalent to peristalsis, could be made to move along the pump channels. A pump according to this concept could be manufactured inexpensively. Pneumatic sources (compressors and partial vacuum sources) similar those needed for actuation are commercially available; they typically have masses of .100 g and power demands of the order of several W. In a design-optimization effort, it should be possible to reduce masses and power demands below even these low levels and to integrate pneumatic sources along with the proposed pumps into miniature units with overall dimensions of no more than a few centimeters per side

Understanding and Incentivizing Biosimilars

Congress recently passed the Biosimilars Act in an attempt to replicate the success that generic small molecule drugs have enjoyed under the Hatch-Waxman Act. The Biosimilars Act provides a pathway for biosimilars to achieve quicker and less expensive FDA approval than what is required for a new biopharmaceutical. There is, however, greater uncertainty and cost associated with achieving the coveted biosimilarity status. This reflects the complex production methods of biopharmaceuticals, along with the many factors that can alter the structure and function of such drugs. This Article analyzes the Biosimilars Act and the draft guidances recently released by the FDA. The Article identifies areas of uncertainty and other aspects of the current regime that create disincentives for the development of biosimilars, as well as suggesting improvements. If we are serious about reducing the price of biological drugs and encouraging the creation of biosimilars, we will need to develop a more effective pathway for approval. This is no easy task. The greater risks associated with the production of biosimilars should prompt a fair degree of caution in establishing the pathway for approval. Balancing consumer safety with appropriate market incentives is a delicate mission. Nevertheless, under the current regime, we risk the possibility that companies will focus on developing so-called biodifferents and biobetters (new drugs designed to mimic an existing biological drug), completely forgoing the opportunity to develop biosimilars. The loser, of course, is the consumer. It is doubtful that biobetters and biosimilars will have the same price-lowering effects as generics. These drugs will be patented, creating full exclusivity in the market, and prices will remain high in the biological drug space. It would be unfortunate if the tremendous energy and creativity invested in designing and implementing the Biosimilars Act were to have very little effect in the long run

Superoperator Analysis of Entanglement in a Four-Qubit Cluster State

In this paper we utilize superoperator formalism to explore the entanglement evolution of four-qubit cluster states in a number of decohering environments. A four-qubit cluster state is a resource for the performance of an arbitrary single logical qubit rotation via measurement based cluster state quantum computation. We are specifically interested in the relationship between entanglement evolution and the fidelity with which the arbitrary single logical qubit rotation can be implemented in the presence of decoherence as this will have important experimental ramifications. We also note the exhibition of entanglement sudden death (ESD) and ask how severely its onset affects the utilization of the cluster state as a means of implementing an arbitrary single logical qubit rotation.Comment: 9 pages, 9 composite figures, presentation of results completely rewritte

Comparison of the clinical characteristics of hospital-acquired and non-hospital-acquired Acinetobacter calcoaceticus-baumannii complex in a large midwest US health care system

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