Asymmetric speed modulation of a rotary blood pump affects ventricular unloading

Rotary blood pumps (RBPs) running at a constant speed are routinely used for the mechanical support of the heart in various clinical applications, from short-term use in heart-lung machines to long-term support of a failing heart. Their operating range is delineated by suction and regurgitation events, leaving limited control on the cardiac workload. This study investigates whether different ratios of systolic/diastolic support are advantageous over a constant-speed operation.

Pulsatile control of rotary blood pumps: Does the modulation waveform matter?

Mechanical support of a failing heart is typically performed with rotary blood pumps running at constant speed, which results in a limited control on cardiac workload and nonpulsatile hemodynamics. A potential solution to overcome these limitations is to modulate the pump speed to create pulses. This study aims at developing a pulsatile control algorithm for rotary pumps, while investigating its effect on left ventricle unloading and the hemodynamics.

Physiologic and hematologic concerns of rotary blood pumps: what needs to be improved?

Over the past few decades, advances in ventricular assist device (VAD) technology have provided a promising therapeutic strategy to treat heart failure patients. Despite the improved performance and encouraging clinical outcomes of the new generation of VADs based on rotary blood pumps (RBPs), their physiologic and hematologic effects are controversial. Currently, clinically available RBPs run at constant speed, which results in limited control over cardiac workload and introduces blood flow with reduced pulsatility into the circulation. In this review, we first provide an update on the new challenges of mechanical circulatory support using rotary pumps including blood trauma, increased non-surgical bleeding rate, limited cardiac unloading, vascular malformations, end-organ function, and aortic valve insufficiency. Since the non-physiologic flow characteristic of these devices is one of the main subjects of scientific debate in the literature, we next emphasize the latest research regarding the development of a pulsatile RBP. Finally, we offer an outlook for future research in the field.

Focal Epilepsy: MR Imaging of Nonhemodynamic Field Effects by Using a Phase-cycled Stimulus-induced Rotary Saturation Approach with Spin-Lock Preparation.

Purpose To investigate whether nonhemodynamic resonant saturation effects can be detected in patients with focal epilepsy by using a phase-cycled stimulus-induced rotary saturation (PC-SIRS) approach with spin-lock (SL) preparation and whether they colocalize with the seizure onset zone and surface interictal epileptiform discharges (IED). Materials and Methods The study was approved by the local ethics committee, and all subjects gave written informed consent. Eight patients with focal epilepsy undergoing presurgical surface and intracranial electroencephalography (EEG) underwent magnetic resonance (MR) imaging at 3 T with a whole-brain PC-SIRS imaging sequence with alternating SL-on and SL-off and two-dimensional echo-planar readout. The power of the SL radiofrequency pulse was set to 120 Hz to sensitize the sequence to high gamma oscillations present in epileptogenic tissue. Phase cycling was applied to capture distributed current orientations. Voxel-wise subtraction of SL-off from SL-on images enabled the separation of T2* effects from rotary saturation effects. The topography of PC-SIRS effects was compared with the seizure onset zone at intracranial EEG and with surface IED-related potentials. Bayesian statistics were used to test whether prior PC-SIRS information could improve IED source reconstruction. Results Nonhemodynamic resonant saturation effects ipsilateral to the seizure onset zone were detected in six of eight patients (concordance rate, 0.75; 95% confidence interval: 0.40, 0.94) by means of the PC-SIRS technique. They were concordant with IED surface negativity in seven of eight patients (0.88; 95% confidence interval: 0.51, 1.00). Including PC-SIRS as prior information improved the evidence of the standard EEG source models compared with the use of uninformed reconstructions (exceedance probability, 0.77 vs 0.12; Wilcoxon test of model evidence, P < .05). Nonhemodynamic resonant saturation effects resolved in patients with favorable postsurgical outcomes, but persisted in patients with postsurgical seizure recurrence. Conclusion Nonhemodynamic resonant saturation effects are detectable during interictal periods with the PC-SIRS approach in patients with epilepsy. The method may be useful for MR imaging-based detection of neuronal currents in a clinical environment. (©) RSNA, 2016 Online supplemental material is available for this article.

Blade guard for rotary lawn mowers

A blade guard for rotary lawn mowers comprising a plurality of spaced apart elongated members which extend longitudinally in the intended direction of travel of the mower device. The space between the forward ends of the elongated members and the forward end of the mower cowling is open and free from obstructions to permit the grass to be sucked upwardly for cutting by the mower blade. The elongated members have varying lengths to define an effective area substantially the same as the area defined by the unsharpened center portion of the mower blade when rotating so that the sharpened ends of the blade extend outwardly beyond the effective area of the guard means. The guard means is hinged to the mower cowling to permit convenient cleaning of the mower. An ignition interlock means is also connected to the guard.

Rotary tiller slot planter and method for using the same

The rotary tiller slot planter of the present invention comprises a subsoiler shank positioned to engage the soil and make a trench therein. A pair of rotary tiller blades are rotatably mounted on the opposite sides of the sub-soil shank in planes parallel thereto. The center-lines of the rotary tiller wheels are located behind the subsoil shank. Each of the wheels have a plurality of blades extending radially outwardly from the rotational axis thereof and terminating in outer radial ends which engage the soil slightly ahead of the subsoiler shank and adjacent the lateral edges of the trench. A seed tube shank is positioned behind the subsoiler shank and between the tiller wheels. The seed tube shank has a lower end positioned to extend below the soil surface. A seed tube is positioned behind the seed tube shank for depositing seed in the soil. The rotation of the blades on opposite sides of the subsoil shank causes the soil to be mechanically aggregated and aerated and helps prepare a seed bed for the seeds. Also, the rotating tiller blades chop the debris which may be along the trench and throw soil backwards so as to cover the planted seed. Shorter rotary blades on the tiller wheels are shaped to throw debris and the upper one-half inch of soil sideways away from the row.

The preferred stoichiometry of c subunits in the rotary motor sector of Escherichia coli ATP synthase is 10

The stoichiometry of c subunits in the H+-transporting Fo rotary motor of ATP synthase is uncertain, the most recent suggestions varying from 10 to 14. The stoichiometry will determine the number of H+ transported per ATP synthesized and will directly relate to the P/O ratio of oxidative phosphorylation. The experiments described here show that the number of c subunits in functional complexes of FoF1 ATP synthase from Escherichia coli can be manipulated, but that the preferred number is 10. Mixtures of genetically fused cysteine-substituted trimers (c3) and tetramers (c4) of subunit c were coexpressed and the c subunits crosslinked in the plasma membrane. Prominent products corresponding to oligomers of c7 and c10 were observed in the membrane and purified FoF1 complex, indicating that the c10 oligomer formed naturally. Oligomers larger than c10 were also observed in the membrane fraction of cells expressing c3 or c4 individually, or in cells coexpressing c3 and c4 together, but these larger oligomers did not copurify with the functional FoF1 complex and were concluded to be aberrant products of assembly in the membrane.

Large conformational changes of the ɛ subunit in the bacterial F1F0 ATP synthase provide a ratchet action to regulate this rotary motor enzyme

The F1F0 ATP synthase is the smallest motor enzyme known. Previous studies had established that the central stalk, made of the γ and ɛ subunits in the F1 part and c subunit ring in the F0 part, rotates relative to a stator composed of α3β3δab2 during ATP hydrolysis and synthesis. How this rotation is regulated has been less clear. Here, we show that the ɛ subunit plays a key role by acting as a switch of this motor. Two different arrangements of the ɛ subunit have been visualized recently. The first has been observed in beef heart mitochondrial F1-ATPase where the C-terminal portion is arranged as a two-α-helix hairpin structure that extends away from the α3β3 region, and toward the position of the c subunit ring in the intact F1F0. The second arrangement was observed in a structure determination of a complex of the γ and ɛ subunits of the Escherichia coli F1-ATPase. In this, the two C-terminal helices are apart and extend along the γ to interact with the α and β subunits in the intact complex. We have been able to trap these two arrangements by cross-linking after introducing appropriate Cys residues in E. coli F1F0, confirming that both conformations of the ɛ subunit exist in the enzyme complex. With the C-terminal domain of ɛ toward the F0, ATP hydrolysis is activated, but the enzyme is fully coupled in both ATP hydrolysis and synthesis. With the C-terminal domain toward the F1 part, ATP hydrolysis is inhibited and yet the enzyme is fully functional in ATP synthesis; i.e., it works in one direction only. These results help explain the inhibitory action of the ɛ subunit in the F1F0 complex and argue for a ratchet function of this subunit.

Performance characteristics of automotive engines in the United States. First series-- report no. 14. 1975 Mazda Rotary 70 CID (1.1 liters), 4V. Interim report.

Transportation Systems Center, Cambridge, Mass.

A rotary seed harvester for crimson clover.

Mode of access: Internet.

The rotary-vane attenuator as an interlaboratory standard /

Includes bibliographical references.