Effect Of Regurgitation Research Articles

Signs of predation in the Middle Jurassic of south‐central Poland: evidence from echinoderm taphonomy

Distinct faunal aggregates are described from the Middle Jurassic (uppermost Bajocian/lowermost Bathonian and Middle Bathonian) clay deposits of Częstochowa area, south-central Poland. These aggregates are composed of molluscs (scaphopods, gastropods, bivalves, ammonites and belemnites), articulate brachiopods and echinoderms (asteroids, crinoids and echinoids). A large percentage of the fossils, especially bivalves, are fragmented, but some fossils are complete. Although most of the fossils are crushed and fragmented, they are still identifiable to at least the genus level. Thorough statistical analysis of taphonomic features indicates that the preservation of asteroid marginal plates is distinct from the ossicles derived from the host clays. The high frequency of bite marks and the good state of preservation suggest that the accumulations are the products of predation activities and most probably are the effect of regurgitation. Taking into account the rich and diverse fauna, the predator was a bottom-feeding generalist. Possible predators include palaeospinacid sharks, a tooth of which was collected from the same bedding surface, but not associated with regurgitated remains. Although the bite marks on the asteroid ossicles point to sharks as potential producers of regurgitates, other vertebrates, like durophagous pycnodontiform fish, cannot be excluded.

The CobraPLA – a response from the manufacturer

The CobraPLA – a response from the manufacturer

The Effect of Sudden Failure of a Rotary Blood Pump on Left Ventricular Performance in Normal and Failing Hearts

We investigated the hemodynamic effect of regurgitation (or back-flow) due to sudden failure of a rotary blood pump (diagonal pump). Seven healthy sheep (Group C) and 7 with chronic heart failure (Group F) were studied. Chronic heart failure was obtained by intracoronary injection of microspheres several weeks earlier. Left ventricular function and ventricular efficacy were assessed by the pressure-volume relationship. The back-flow through the stopped pump was significantly lower in Group F (2.3 +/- 0.34 L/min) than in Group C (2.8 +/- 0.33 L/min). Mean aortic blood pressure dropped significantly from 68.3 +/- 9.65 to 61.9 +/- 9.75 mm Hg in Group C and from 62.5 +/- 9.12 to 51.5 +/- 9.08 in Group F but remained stable during the 15 min period of pump stop. Parameters of left ventricular contractility (preload recruitable stroke work) dropped significantly in both groups, remained stable during the pump stop, and returned to baseline values 30 min after the end of back-flow. The ventricular efficacy (in terms of energy transfer) was tolerant against this acute volume overload even in the failing hearts. Sudden pump failure of a rotary blood pump leads to an acute depression of the hemodynamic state and myocardial contractility. However, this depression remained stable over 15 min, did not lead to further deterioration of the animals, and was completely reversible.

Electrostatic Getter-Ion Pump Performance

Important characteristics of electrostatic getter-ion pumps are examined from the standpoint of the typical user. Results are presented from an experimental comparison of a sputter ion pump with an electrostatic getter-ion pump, both of which are commericially available and of about the same installed cost. Care was taken to insure identical conditions of use and operation during the testing on both baked and unbaked systems. A quadrupole RGA was used to insure that system conditions and gas composition were known. Data are presented for how well the pumps maintain their rated speeds, the ultimate pressures achieved, the ability to handle pressure bursts of N2, CO, H2, H2+N2, H2O, air, Ar, He, CH4, C3H8, memory, and regurgitation effects, and the ability to pump and rapidly cycle a very dirty unbaked glass bell jar evaporator.

Effects of quantitatively controlled left ventricular-atrial regurgitation on indicator-dilution curves in the dog.

Dye-dilution curves were recorded from the aortic arch of dogs with left ventricular-atrial regurgitation produced surgically by a shunt from the apex of the left ventricle to the left atrial appendage. Rate of regurgitation was monitored by an electroturbinometer and was varied from 0.9 to 3.3 liters per minute. In each dog, reciprocal of the downslope and variance of curves obtained after injection of dye into the left atrium varied directly with rate of backflow and inversely with net cardiac output. These effects of regurgitation were not due to change in transit volume. Estimates of regurgitation based on change in reciprocal of slope correlated closely with flowmeter values and were more accurate than estimates based on change in variance. Back flow was underestimated by curves recorded after injection of dye into the pulmonary artery.