Third order LPF type compensator for flexible rotor suspension

The tuning job of the compensator for levitating flexible rotors supported by active magnetic bearings (AMB) concerns providing a good damping effect to the critical speed modes while avoiding the spillover problem on the instability of higher bending modes. In this paper, an idea for design of the control law of the compensator based on utilizing a third order low pass filter (LPF) is proposed to essentially enable elimination of the spillover instability. According to the proposed design method, good damping effects for the critical speeds are obtained by the usual phase lead/lag function. Stabilization for all of higher bending modes is completed by the additional function of the 3rd order LPF due to its phase lag approaching about -270 degrees in the high frequency domain. This idea is made clear by experiments and simulations

Meteorological characteristics of Antarctic inland station, Dome Fuji (scientific paper)

Surface meteorological observations were carried out during 1995 and 1997, and extended atmospheric science observations were carried out in 1997 as a sub program of "Atmospheric Circulation and Material Cycle in the Antarctic (1997-2001)" at Dome Fuji Station (77°19\u27S, 39°42\u27E) where deep ice core drilling was done. The annual mean surface air temperature was -54.4°C with the lowest record of -79.7°C. The mean wind speed was 5.8 m/s with no clear prevailing wind direction. From aerological soundings, temperature profiles are described; they are characterized by a strong surface inversion such as 25°C, on a normal winter day. Abrupt warming occurred several times a year; the largest showed 40 degree temperature increase within two days between 17 and 19 July 1997. The event was associated with the intrusion of an anticyclone, "a blocking high", and many drastic phenomena such as large accumulation of snow followed this event

New therapeutic target for the non-electrophysiological signaling in atrial fibrosis and fibrillation such as inflammation

AbstractWe have experimentally established appropriate models of atrial fibrillation (AF) with atrial interstitial fibrosis. Two approaches were adopted. Firstly, left atrial fibrosis was induced by continuous infusion of angiotensin II (AII). In an electrophysiological study using isolated perfused heart, AF was easily induced following AII treatment. Repeated whole-body hyperthermia led to the induction of heat-shock protein 72, which resulted in attenuation of AII-induced left atrial fibrosis and suppression of AF inducibility. Secondly, atrial fibrosis was induced by pressure overload by abdominal aortic constriction (AAC). AAC enhanced left atrial expression of monocyte chemoattractant protein-1 and activity of matrix metalloproteinase-9. Treatment with pioglitazone, a peroxisome proliferator-activated receptor-γ agonist, resulted in attenuation of pressure overload-induced left atrial fibrosis and suppression of AF inducibility. In the same AAC model, the effects of candesartan on gap junction remodeling were investigated. Connexin 43 (Cx43) of the left atria was firmly located in the intercalated disks in control rats. A progressive redistribution of Cx43 from the intercalated disk to the lateral surface (lateralization) was observed in AAC rats. Candesartan prevented left Cx43 lateralization. Thus, heat-shock proteins, pioglitazone, and candesartan could be novel therapeutic approaches to prevent atrial fibrosis and AF

Torsional-Lateral Coupled Vibration Of Centrifugal Compressor System At Interharmonic Frequencies Related To Control Loop Frequencies In Voltage Source Inverter.

Case StudyCentrifugal compressor train in a refinery experienced high vibration problem due to torsional resonance. Sidebands in the VFD output current based on VFD control loop frequencies were identified as the root cause. In this VFD, stator current was used for torque and speed control, hence control loop frequencies had a potential to generate such sidebands. Frequencies of this type of sidebands widely vary with the rotation speed (proportional to harmonics of the fundamental frequency), hence it is difficult to avoid resonance at the train torsional natural frequency. In addition, even if a compressor system is proven to have sufficient safety margin against high cycle fatigue failure due to the torque pulsation by this mechanism, such minute torque pulsation may have a potential to excite high lateral vibration at speed adjusting gear. If unpredicted or overlooked during design stage, such high vibration may disturb plant operation. This case study therefore proposes guidelines to predict such vibration levels by a simplified torsional-lateral coupled vibration analysis

Molecular cloning and functional expression of a novel brain-specific inward rectifier potassium channel

AbstractWe have cloned a novel brain-specific inward rectifier K+ channel from a mouse brain cDNA library and designated it MB-IRK3. The mouse brain cDNA library was screened using a fragment of the mouse macrophage inward rectifier K+ channel (IRK1) cDNA as a probe. The amino acid sequence of MB-IRK3 shares 61% and 64% identity to MB-IRK1 and RB-IRK2, respectively.Xenopus oocytes injected with cRNA derived from this clone expressed a potassium current which showed inward-rectifying channel characteristics similar to MB-IRK1 and RB-IRK2 currents, but distinct from ROMK1 or GIRK1 current. However, the single channel conductance of MB-IRK3 was ∼ 10 pS with 140 mM extracellular K+, which was distinct from that of MB-IRK1 (20 pS). MB-IRK3 mRNA expressed specifically in the forebrain, which clearly differed from MB-IRK1 and RB-IRK2 mRNAs. These results indicate that members of the IRK family with distinct electrophysiological properties express differentially and may play heterogenous functional roles in brain functions

A case report of acute cardiac tamponade creation in a macaque

Although acute cardiac tamponade is one of the major problems in clinical practice, a suitable animal model is still lacking. We tried to create acute cardiac tamponade in macaques by echo-guided catheter manipulation. A 13-year-old male macaque was anesthetized, and a long sheath was inserted into the left ventricle via the left carotid artery under the guidance of transthoracic echocardiography. The sheath was then inserted into the orifice of the left coronary artery to perforate the proximal site of the left anterior descending branch. A cardiac tamponade was successfully created. Injection of diluted contrast agent into the pericardial space via a catheter made it possible to clearly distinguish between the hemopericardium and the surrounding tissues on postmortem computed tomography. This procedure did not need an X-ray imaging system during catheterization. Our present model would help us examine the intrathoracic organs in the presence of acute cardiac tamponade

PARM-1 Is an Endoplasmic Reticulum Molecule Involved in Endoplasmic Reticulum Stress-Induced Apoptosis in Rat Cardiac Myocytes

To identify novel transmembrane and secretory molecules expressed in cardiac myocytes, signal sequence trap screening was performed in rat neonatal cardiac myocytes. One of the molecules identified was a transmembrane protein, prostatic androgen repressed message-1 (PARM-1). While PARM-1 has been identified as a gene induced in prostate in response to castration, its function is largely unknown. Our expression analysis revealed that PARM-1 was specifically expressed in hearts and skeletal muscles, and in the heart, cardiac myocytes, but not non-myocytes expressed PARM-1. Immunofluorescent staining showed that PARM-1 was predominantly localized in endoplasmic reticulum (ER). In Dahl salt-sensitive rats, high-salt diet resulted in hypertension, cardiac hypertrophy and subsequent heart failure, and significantly stimulated PARM-1 expression in the hearts, with a concomitant increase in ER stress markers such as GRP78 and CHOP. In cultured cardiac myocytes, PARM-1 expression was stimulated by proinflammatory cytokines, but not by hypertrophic stimuli. A marked increase in PARM-1 expression was observed in response to ER stress inducers such as thapsigargin and tunicamycin, which also induced apoptotic cell death. Silencing PARM-1 expression by siRNAs enhanced apoptotic response in cardiac myocytes to ER stresses. PARM-1 silencing also repressed expression of PERK and ATF6, and augmented expression of CHOP without affecting IRE-1 expression and JNK and Caspase-12 activation. Thus, PARM-1 expression is induced by ER stress, which plays a protective role in cardiac myocytes through regulating PERK, ATF6 and CHOP expression. These results suggested that PARM-1 is a novel ER transmembrane molecule involved in cardiac remodeling in hypertensive heart disease

Noninvasive assessment of the cardiac baroreflex Response to downward tilting and comparison with the phenylephrine method

AbstractOBJECTIVESWe studied the relation between changes in systolic blood pressure and RR interval during downward tilting in comparison with assessment of baroreflex sensitivity (BRS) measured by the phenylephrine method (Phe-BRS) and with measures of heart rate variability (HRV).BACKGROUNDThe method most extensively used for assessing BRS involves bolus injections of phenylephrine. Several noninvasive methods proposed to assess BRS have not been widely applied in the clinical setting.METHODSSixteen healthy male volunteers were studied (mean age ± SD 27.5 ± 4.6 years). Arterial blood pressure using tonometry and electrocardiogram was simultaneously recorded. After 20 min of 70° upright tilting, the table was returned to supine position at a speed of 3.2°/s. Subsequently, BRS was assessed using an intravenous bolus injection of phenylephrine (2 to 3 μg/kg). Heart rate variability under resting conditions also was analyzed.RESULTSIn all subjects, a beat to beat systolic blood pressure increase associated with corresponding RR interval lengthening was observed during downward tilting as well as during phenylephrine administration. During both testing procedures, these two variables showed linear correlation, and the slope of regression line during downward tilting (DT-BRS) correlated significantly with Phe-BRS (r = 0.79, p = 0.0003). The DT- and Phe-BRS also correlated significantly with the high frequency component of resting HRV (r = 0.70, p = 0.0023 for DT-BRS; r = 0.58, p = 0.0185 for Phe-BRS).CONCLUSIONSWe conclude that in a small homogeneous group DT-BRS provided an assessment of reflex cardiac vagal function comparable to that obtained by the phenylephrine method

Outcomes after stepwise ablation for persistent atrial fibrillation in patients with heart failure

AbstractBackgroundThere is limited data regarding the outcomes after stepwise ablation for persistent atrial fibrillation (AF) in patients with heart failure (HF).Methods and resultsPatients without structural heart disease undergoing stepwise ablation for persistent AF (continuous AF≤1 year) were studied (n=108; age, 61±10 years) and 32 patients had a history of HF. The HF patients were further grouped on the basis of left ventricular ejection fraction (LVEF)≤45% (n=15) and >45% (n=17). During a median follow-up period of 2.2 years, repeated ablations were necessary in 65 patients. The proportion of patients that were arrhythmia free 1 year after the last ablation was 67% in patients with LVEF≤45%, 86% in LVEF>45%, and 91% in no HF (p=0.0009). In patients with LVEF≤45%, the AF burden was reduced to less than one paroxysmal episode per month, and patients with and without recurrences both showed significant increases in LVEF over the follow-up period (38±7% to 60±10% and 37±6% to 53±10%, respectively).ConclusionsHF patients with LVEF≤45% had lower chances to remain free from arrhythmias after stepwise ablation for persistent AF than those with LVEF>45%. Nevertheless, LVEF also improved in patients with recurrences, reflecting the observed reduction in AF burden and emphasizing the benefits of ablation