Abstract: The present invention provides a method and device for placement of a gastric line in the digestive tract of a patient. A guide element is either formed integrally with the end of a gastric line or it is formed separately to be fixed on the end segment of a gastric line to reduce the flexibility of the gastric line segment and facilitate the positioning of the gastric line in a patient's digestive tract. The guide element is provided with means for slideably engaging a previously positioned transepiglottal guide line so that the guide element when engaged with the guide line, can be pushed down the guide line to position the gastric line in an esophageal or post-esophageal position. An optional mouthpiece is provided to receive and guide the gastric tube toward the middle of the posterior oral pharynx during insertion and to protect the gastric line from the biting surfaces of the teeth and maintain its position in the mouth after insertion.

Abstract: A mathematical model to optimize protocols for the addition or removal of cryoprotectant to or from sperm cells. This disclosure describes the use of four equations to predict optimal protocols to add or remove cryoprotectant to or from sperm cells. The equations particularly require experimentally found data, specific to a species of sperm, regarding the osmotic tolerance of sperm cells, where osmotic tolerance refers to the sperm cells ability to shrink or swell to various changes in osmolality without injury. The equations further require the cryoprotectant permeability coefficient and the water permeability coefficient of the particular sperm cells' plasma membrane. Also disclosed are two particularly preferred methods to add or remove cryoprotectant to or from sperm. These preferred methods are Fixed-Volume-Step addition/removal of cryoprotectant or Fixed-Molarity-Step addition/removal of cryoprotectant.