A novel order-separated generalized feedforward design for motion control in energy-efficient electrohydraulic system with proportional and integral feedback.

Existing feedforward, or FF, controllers are based on differentially flat models. For double-acting single-rod cylinders, more compact than the double-rod ones, flat models could be constructed either under an incompressible-flow assumption for low-pressure, slow-response applications or for a matched valve-cylinder combination. Contrasting the existing models tackling only a single nonlinear aspect like valve leakage, oil compressibility or friction, a novel FF controller, generalized for different types of valve-cylinder-pump combinations, has been developed here. It is based on the highest-order assumption of incompressible flow that sustains the piston motion. An FFPI controller has been implemented in a laboratory setup for displacement tracking against sinusoidal demands up to 9 Hz frequency. The FF parameters has been estimated by minimizing the deviation of simulation prediction from an offline experimental time-varying response. The PI gains have been selected through a stability analysis by extending Routh criteria for linearized time-variant error dynamics. Comparison against a PI-only controller with identical gains has established the energy-saving potential of the FFPI controller both working with the same variable-displacement pump. In comparison to existing nonlinear adaptive controllers, more precise and smoother responses have been obtained over wider frequency range at lower control expenses, admittedly with occasional marginal penalty in the phase variation. The FFPI controller has exhibited the shortest transient and the highest resilience against measurement noise.

A Nuclear Zip Code in SKS1 mRNA Promotes Its Slow Export, Nuclear Retention, and Degradation by the Nuclear Exosome/DRN in Saccharomyces cerevisiae.

In Saccharomyces cerevisiae, a special class of mRNAs representing a subset of otherwise normal transcripts displays very slow export and an unusually long intra-nuclear dwell time. This prolonged nuclear retention leads to their rapid degradation in the nucleus by the nuclear exosome and DRN (Decay of RNA in the Nucleus) apparatus. We previously attributed their slow export to one or more hypothetical cis-acting, export-retarding element(s). Here, we identified such a cis-element (hereafter referred to as "nuclear zip code") in SKS1 mRNA, a representative of this class of transcripts. Deletion analysis of SKS1 mRNA identified a 202-nt RNA segment within the SKS1 ORF, which harbors the nuclear zip code. Removal of this segment (i) abolished slow export of the transcripts, as revealed by in situ confocal microscopy-based localization experiments, and (ii) abrogated the susceptibility of the transcripts to degradation by the nuclear exosome/DRN. Remarkably, fusing the SKS1 mRNA 202-nt nuclear zip code to the 5'-segment of CYC1 mRNA resulted in inefficient export, and susceptibility of the chimeric transcript to the nuclear exosome/DRN. These findings identify a cis-acting zip code element that is necessary and sufficient to impede nuclear export and results in its preferential nuclear retention, thereby impacting its abundance and cellular repertoire. We conclude that this element posttranscriptionally regulates SKS1 gene expression levels.

Nitrogen deprivation elicits dimorphism, capsule biosynthesis and autophagy in Papiliotrema laurentii strain RY1.

Stress response due to the lack of essential nutrient(s) for an organism has been a focal point of several scientific investigations. The present study investigates the cellular adaptations behind the ability of Papiliotrema laurentii strain RY1 to perpetuate without added nitrogen and propagate robustly in growth- limiting amount of nitrogen. We executed phenotypic (using scanning electron microscopy, differential interference contrast microscopy and transmission electron microscopy), microbiological and computational analyses to show multiple responses of dimorphism, capsule formation and autophagy as a survival strategy by the yeast upon nitrogen starvation. The roles of phosphomannose isomerase, phosphomannomutase and several autophagy-related transcripts aiding in such a response have been discussed.