State-space forms for higher-order discrete-time models

This paper presents a fundamental study of the connection between continuous- and discrete-time systems. Provided is a definition for discrete-time models, that is discrete-time systems with a continuous-time counterpart, whose order can be higher than that of the continuous-time system. This definition is based on a comparison in a certain sense on the time responses of continuous- and discrete-time systems. A theorem is presented for relating the higher-order discrete-time models to their continuous-time counterparts, which is an extension of a previous theorem for models with order equal to that of the continuous-time system. State-space forms are derived for models obtained through the use of a certain class of hold elements and through the use of mapping models, and these discrete-time systems are shown to be valid according to the definition. Special cases are models obtained using first-order and slewer hold devices, whose convergence to a continuous-time counterpart has not been shown mathematically before, and mapping models corresponding to two-step linear multi-step methods, which have not previously presented in the state-space form. The derived state-space forms provide a convenient way to implement these models for purposes of analysis, design, and implementation of discrete-time systems and finds applications in such areas as digital signal processing, digital simulation, and digital control.     

Determination method of equivalent insulation test voltage at room temperature for high temperature superconducting power apparatus with coil structure

This paper deals with the determination method of the equivalent insulation test voltage at room temperature that secures the reliability of the cryogenic electrical insulation of the high temperature superconducting (HTS) power apparatus. The high voltage test is related to the apparatus with coil structure at the stages of its development, manufacturing and shipment. In the test method, the equivalent insulation test voltage at room temperature is derived from the standard test voltage at cryogenic temperature, based on the idea that the HTS power apparatus should be operated without partial discharges (PDs). The conversion factor between the two voltages is given by the product of the two medium factors, i.e. the one relating to the potential distribution along the coil winding and the other relating to the PD inception condition at the weakest part in the electrical insulation system. In order to determine the latter factor concerned with the non-linear phenomena against electrical stresses, the PD inception voltages at cryogenic and room temperatures are theoretically and experimentally estimated for modeled turn-to-turn insulation system. The results show that both estimated and measured values are in fairly good agreement and the proposed method is useful for the equivalent high voltage test at room temperature for the HTS power apparatus.     

Positive chronotropic actions of parathyroid hormone and parathyroid hormone-related peptide are associated with increases in the current, I(f), and the slope of the pacemaker potential

BACKGROUND: The classic calciotropic hormone parathyroid hormone (PTH) and its paracrine factor parathyroid hormone-related protein (PTHrP) both increase heart rate. METHODS AND RESULTS: We used standard electrophysiological techniques to study the effects of PTH and PTHrP on isolated rabbit sinus node, isolated canine Purkinje fibers, and disaggregated rabbit sinus node myocytes. Sinus node maximum diastolic potential, activation voltage, and amplitude were unchanged by PTH or PTHrP (P>.05). However, the slope of phase 4 and the automatic rate were increased at PTH and PTHrP > or = 10 nmol/L (P<.05). Comparable results were seen in canine Purkinje fibers. We then used the perforated-patch technique to study the I(f) pacemaker current in sinus node. PTH 12.5 nmol/L and PTHrP 12.5 to 18 nmol/L increased I(f) at -65 mV by 68+/-41% (n=5) and 69+/-50% (n=5), respectively. Actions of both agents were reversible. The increase in I(f) appeared to result from a change in maximal conductance and not a shift in the voltage dependence of activation. CONCLUSIONS: These observations provide, for the first time, direct electrophysiological support for the chronotropic actions of PTH and PTHrP. They suggest that classic hormones and paracrine factors can have multiple functions and that in the case of PTH and PTHrP, a newly recognized action is to alter automaticity directly.     

Potent Activation of Human but Not Mouse TRPA1 by JT010

Transient receptor potential (TRP) ankyrin repeat 1 (TRPA1), which is involved in inflammatory pain sensation, is activated by endogenous factors, such as intracellular Zn²⁺ and hydrogen peroxide, and by irritant chemical compounds. The synthetic compound JT010 potently and selectively activates human TRPA1 (hTRPA1) among the TRPs. Therefore, JT010 is a useful tool for analyzing TRPA1 functions in biological systems. Here, we show that JT010 is a potent activator of hTRPA1, but not mouse TRPA1 (mTRPA1) in human embryonic kidney (HEK) cells expressing hTRPA1 and mTRPA1. Application of 0.3–100 nM of JT010 to HEK cells with hTRPA1 induced large Ca²⁺ responses. However, in HEK cells with mTRPA1, the response was small. In contrast, both TRPA1s were effectively activated by allyl isothiocyanate (AITC) at 10–100 μM. Similar selective activation of hTRPA1 by JT010 was observed in electrophysiological experiments. Additionally, JT010 activated TRPA1 in human fibroblast-like synoviocytes with inflammation, but not TRPA1 in mouse dorsal root ganglion cells. As cysteine at 621 (C621) of hTRPA1, a critical cysteine for interaction with JT010, is conserved in mTRPA1, we applied JT010 to HEK cells with mutations in mTRPA1, where the different residue of mTRPA1 with tyrosine at 60 (Y60), with histidine at 1023 (H1023), and with asparagine at 1027 (N1027) were substituted with cysteine in hTRPA1. However, these mutants showed low sensitivity to JT010. In contrast, the mutation of hTRPA1 at position 669 from phenylalanine to methionine (F669M), comprising methionine at 670 in mTRPA1 (M670), significantly reduced the response to JT010. Moreover, the double mutant at S669 and M670 of mTRPA1 to S669E and M670F, respectively, induced slight but substantial sensitivity to 30 and 100 nM JT010. Taken together, our findings demonstrate that JT010 potently and selectively activates hTRPA1 but not mTRPA1.     

Effect of Hypoxia on Pulmonary Endothelial Cells from Bleomycin-Induced Pulmonary Fibrosis Model Mice

Pulmonary fibrosis is a progressive and fatal disorder characterized by dysregulated repair after recurrent injury. Destruction of the lung architecture with excess extracellular matrix deposition induces respiratory failure with hypoxia and progressive dyspnea. The impact of hypoxia on pulmonary endothelial cells during pulmonary fibrogenesis is unclear. Using a magnetic-activated cell sorting system, pulmonary endothelial cells were isolated from a mouse model of pulmonary fibrosis induced by intratracheally administered bleomycin. When endothelial cells were exposed to hypoxic conditions, a hypoxia-inducible factor (HIF)-2α protein was detected in CD31- and α-smooth muscle actin (SMA)-positive cells. Levels of plasminogen activator inhibitor 1, von Willebrand factor, and matrix metalloproteinase 12 were increased in endothelial cells isolated from bleomycin-treated mice exposed to hypoxic conditions. When endothelial cells were cultured under hypoxic conditions, levels of fibrotic mediators, transforming growth factor-β and connective tissue growth factor, were elevated only in endothelial cells from bleomycin-treated and not from saline-treated lungs. The increased expression of α-SMA and mesenchymal markers and collagen production in bleomycin- or hypoxia-stimulated endothelial cells were further elevated in endothelial cells from bleomycin-treated mouse lungs cultured under hypoxic conditions. Exposure to hypoxia damaged endothelial cells and enhanced fibrogenesis-related damage in bleomycin-treated pulmonary endothelial cells.     

Purification and characterisation of cathepsin L from the skeletal muscle of blue scad (Decapterus maruadsi) and comparison of its role with myofibril-bound serine proteinase in the degradation of myofibrillar proteins

The modori phenomenon during surimi production is caused by endogenous proteinases, especially cathepsin L and myofibril-bound serine proteinase (MBSP). Cathepsin L from the skeletal muscle of blue scad (Decapterus maruadsi) was purified to homogeneity by ammonium sulphate fractionation and a series of column chromatographies and revealed a single band with molecular mass of 30 kDa on SDS–PAGE. Peptide mass fingerprinting (PMF) obtained three fragments with 48 amino acid residues, which were highly identical to cathepsin L from other fish species. Its optimal pH and temperature were 5.5 and 55 °C, respectively. Meanwhile, MBSP was purified from the skeletal muscle of blue scad, and the roles of cathepsin L and MBSP in the degradation of myofibrillar proteins were compared. The results indicated that MBSP is more effective than cathepsin L in promoting the degradation of myofibrillar proteins, especially myosin heavy chain (MHC), suggesting that MBSP plays a more significant role.     

Inactivation of Bacillus spores by the combination of moderate heat and low hydrostatic pressure in ketchup and potage

The combination effect of moderate heat and low hydrostatic pressure (MHP) on the reduction of Bacillus subtilis, Bacillus coagulans and Geobacillus stearothermophilus spores in food materials (potage and ketchup) was investigated. These bacterial spores were suspended in potage (pH 7), acidified potage (pH 4), neutralized ketchup (pH 7) and ketchup (pH 4). The suspensions were treated with and without pressure (100 MPa) and temperatures of 65-85 degrees C for 3 to 12 h. The bacterial spores were inactivated by 4-8 log cycles during MHP treatment in potage, acidified potage and ketchup, whereas the spores were highly resistant to long time heat treatment in potage and neutralized ketchup. The degrees of spore destruction were mostly dependent on pH and medium composition during MHP treatment. The inactivation effect in MHP treatment was higher at the pH 7 than at pH 4 both in ketchup and potage. The bacterial spores showed higher inactivation in potage than ketchup during MHP treatment.     

Thermal spray coating on conductor rolls in electroplating line

In electroplating lines,many conductor rolls are installed in electroplating bath.Typical electroplatings are tin plating(ETL) and zinc plating(EGL),and from required product qualities,a vertical cell for the former and a horizontal cell for the latter is often used.Generally,chrome plating or WC cermet thermal spray coating is applied to stainless steel conductor roll in ETL for prolonging service life by improvement of wear resistance and corrosion resistance.On the other hand,Hastelloy type alloy subs...