A locally minimal, but not globally minimal bridge position of a knot

We give a locally minimal, but not globally minimal bridge position of a knot, that is, an unstabilized, nonminimal bridge position of a knot. It implies that a bridge position cannot always be simplified so that the bridge number monotonically decreases to the minimal.Comment: 27 pages, 12 figures, v3: minor corrections throughout the pape

Optimum Sampled-Data Control System Design by Dynamic Programming Technique

In this paper, the authors deal with an application of dynamic programming technique to an optimum sampled-data control system design. Since the optimum sampled-data control problem may be treated as an n-stage decision process, the determination of the optimum control law is carried out by means of the dynamic programming technique. Optimum control policies are derived to fulfill the minimum integral squared error for the deterministic case and the minimum expected value of integral squared error for the stochastic case. It is shown that the control signal of the optimum system consists of a linear combination of system variables. The over-all optimum control system is a time-varying system. However, the quasi-optimum control can be achieved by feeding back all the state variables through appropriate constant multipliers and the quasi-optimum control system can be considered as a good approximation of the optimum system

Role of protein kinase C in angiotensin II-induced constriction of renal microvessels

Role of protein kinase C in angiotensin II-induced constriction of renal microvesselsBackgroundAlthough angiotensin II (Ang II) exerts its action through multiple vasomotor mechanisms, the contribution of phosphoinositol hydrolysis products to Ang II-induced renal vasoconstriction remains undetermined.MethodsThe role of protein kinase C (PKC) in Ang II-induced afferent (AFF) and efferent (EFF) arteriolar constriction was examined using the isolated perfused hydronephrotic rat kidney.ResultsAng II (0.3 nmol/L)-induced EFF constriction was refractory to inhibition of voltage-dependent calcium channels by pranidipine (1 μmol/L, 19 ± 2% reversal) but was completely reversed by a PKC inhibitor, chelerythrine (1 μmol/L, 96 ± 2% reversal). Furthermore, direct PKC activation by phorbol myristate acetate (PMA; 1 μmol/L) caused prominent EFF constriction, and this constriction was inhibited by manganese and free calcium medium. In contrast, Ang II-induced AFF constriction was completely abolished by pranidipine (98 ± 4% reversal) and was partially inhibited by chelerythrine (55 ± 3% reversal). Although PMA elicited marked AFF constriction, this constriction was insensitive to the calcium antagonist, but was totally inhibited by manganese or free calcium medium.ConclusionsPKC plays an obligatory role in Ang II-induced EFF constriction that requires extracellular calcium entry through nonselective cation channels. In contrast, in concert with our recent findings demonstrating a complete dilation by thapsigargin, Ang II-induced AFF constriction is mainly mediated by inositol trisphosphate (IP3) and voltage-dependent calcium channel pathways, but could not be attributed to the PKC-activated calcium entry pathway (for example, nonselective cation channels). Rather, Ang II-stimulated PKC may cross-talk to the IP3/voltage-dependent calcium channel pathway and could modulate the vasoconstrictor mechanism of the AFF. Thus, the role of PKC during Ang II stimulation differs in AFF and EFF, which may constitute segmental heterogeneity in the renal microvasculature

Status of Acute Stroke Practice in Patients with a Cardiac Implantable Electronic Device

Although diagnostic and therapeutic strategies for acute stroke patients in Japan depend largely on magnetic resonance imaging (MRI), patients with cardiac implantable electronic devices (CIED) must still rely on com-puted tomography (CT). We retrospectively analyzed clinical and neuroimaging data of ischemic stroke patients with CIED treated at our hospital. Forty-five patients were enrolled in the study. Patients were divided into two groups according to whether corresponding lesions were detected (group A, n = 21) or not detected (group B, n = 24) by the first brain CT. We also evaluated in detail the clinical courses of patients who arrived at hospital within therapeutic time windows for recanalization therapy. Negative fresh infarct in the first CT was associated, though not significantly, with early onset-to-arrival time and subcortical white matter infarction. Five patients did not undergo recanalization therapy because their families did not agree to the procedure. The reasons for their lack of consent included inadequate information about the safety and efficacy of recanalization therapy because MRI could not be performed. Our study confirmed delayed detection of the corresponding lesion and undertreatment for acute stroke in patients with CIED