Effects of Wall Length and Vent on Attaching Jet and Its Switching

The effects of some geometries peculiar to the wallattachment fluidic devices on the attaching jet flow and the switching mechanism were experimentally made clear. And the propriety of the analytical mOdel, which has been used for the theoretical study of these devices, was investigated. The results can be summarized as follows: 1) The existing analytical model of the attaching jet flow is not applicable to the case of relatively short wall length of vent distance. 2) The attaching jet flow never detaches from a sufficiently long side wall with vent. 3) The switching mechanism of the vent type device is always the opposite wall switching. 4) From the viewpoint of the output characteristics of the device, the vent distance has a lower limit in relation to the vent width

Approach to the asymptomatic patients with Brugada syndrome

Brugada syndrome is an arrhythmogenic disease characterized by an ECG pattern of coved-type ST segment elevation in the right precordial leads and an increased risk of sudden cardiac death (SCD) as a result of polymorphic ventricular tachyarrhythmia or ventricular fibrillation (VF). Data from large patient studies and a meta-analysis of previous reports have shown that patients with a history of syncope or SCD and a spontaneous type 1 Brugada type ECG are at high risk for SCD. However, risk stratification of asymptomatic patients with Brugada type ECG is still a challenge. In particular, the use of electrophysiological study (EPS) for risk stratification remains controversial. Although some investigators have reported the possibility of use of EPS for distinguishing between high- and low-risk patients with Brugada type ECG, no precise predictor of risk for SCD in asymptomatic patients has yet been determined. The approach to treatment of these patients is thus still unclear. Large clinical prospective studies with uniform diagnostic criteria and protocols for EPS as well as extended follow-up periods of over ten years are required for prediction of SCD

The effects of nifekalant hydrochloride on the spatial dispersion of repolarization after direct current defibrillation in patients with oral amiodarone and β-blocker therapy

AbstractBackgroundAlthough nifekalant hydrochloride (NIF) has been demonstrated to suppress ventricular tachyarrhythmias, especially electrical storms, the mechanism by which it does so is still unclear. We examined the effects of NIF on the spatial dispersion of repolarization (SDR) after implantable cardioverter-defibrillator (ICD) shock.Methods and ResultsIn 35 patients with oral amiodarone and β-blocker therapy, and an ICD, we recorded the 87-lead electrocardiogram during sinus rhythm (CONTROL-1 group) under general anesthesia, and just after the termination of induced ventricular fibrillation (VF) by ICD shock, with or without NIF administration. In all recordings, the corrected QT interval (QTc) was measured in each lead. The dispersion of QTc (QTc-D; maximum QTc minus minimum QTc) was also measured. Compared with that in the CONTROL-1 group, the QTc-D exhibited significant deterioration after ICD shock (61±14 and 90±19ms1/2, respectively; p<0.05). However, after the termination of induced VF by ICD shock with NIF administration, the QTc-D did not differ significantly from that in the CONTROL-1 group (63±20 and 61±14ms1/2, respectively).ConclusionsNIF suppressed the deterioration of the SDR after ICD shock. This might be one of the mechanisms by which NIF suppresses recurrence of ventricular tachyarrhythmia just after ICD shock in patients with oral amiodarone and β-blocker therapy

Inhibition of the photoinduced structural phase transition in the excitonic insulator Ta2_2NiSe5_5

Femtosecond time-resolved mid-infrared reflectivity is used to investigate the electron and phonon dynamics occurring at the direct band gap of the excitonic insulator Ta$_2$NiSe$_5$ below the critical temperature of its structural phase transition. We find that the phonon dynamics show a strong coupling to the excitation of free carriers at the \Gamma\ point of the Brillouin zone. The optical response saturates at a critical excitation fluence $F_C = 0.30~\pm~0.08$~mJ/cm$^2$ due to optical absorption saturation. This limits the optical excitation density in Ta$_2$NiSe$_5$ so that the system cannot be pumped sufficiently strongly to undergo the structural change to the high-temperature phase. We thereby demonstrate that Ta$_2$NiSe$_5$ exhibits a blocking mechanism when pumped in the near-infrared regime, preventing a nonthermal structural phase transition

Optimal call admission control for voice traffic in cellular mobile communication networks

We propose a new call admission control (CAC) scheme for voice calls in cellular mobile communication networks. It is assumed thatthe rejection of a hand-off call is less desirable than that of a new call,for a hand-off call loss would cause a severe mental pain to a user. We consider the pains of rejecting new and hand-off calls as differentcosts. The key idea of our CAC is to restrict the admission of new calls in order to minimize the total expected costs per unit time over thelong term. An optimal policy is derived from a semi-Markov decision process in which the intervals between successive decision epochs areexponentially distributed. Based on this optimal policy, we calculate the steady state probability for the number of established voice connections in a cell. We then evaluate the probability of blocking new calls and the probability of forced termination of hand-odd calls. In the numerical experiments, it is found that the forced termination probability of hand-off calls is reduced significantly by our CAC scheme at the slight expense of the blocking probability of new calls and the channel utilization.Includes bibliographical reference

Ultrafast Electronic Band Gap Control in an Excitonic Insulator

We report on the nonequilibrium dynamics of the electronic structure of the layered semiconductor Ta$_2$NiSe$_5$ investigated by time- and angle-resolved photoelectron spectroscopy. We show that below the critical excitation density of $F_{C} = 0.2$ mJ cm$^{-2}$, the band gap $narrows$ transiently, while it is $enhanced$ above $F_{C}$. Hartree-Fock calculations reveal that this effect can be explained by the presence of the low-temperature excitonic insulator phase of Ta$_2$NiSe$_5$, whose order parameter is connected to the gap size. This work demonstrates the ability to manipulate the band gap of Ta$_2$NiSe$_5$ with light on the femtosecond time scale

Inhibition of the photoinduced structural phase transition in the excitonic insulator Ta2NiSe5{\mathrm{Ta}}_{2}{\mathrm{NiSe}}_{5}

Femtosecond time-resolved midinfrared reflectivity is used to investigate the electron and phonon dynamics occurring at the direct band gap of the excitonic insulator Ta2NiSe5 below the critical temperature of its structural phase transition. We find that the phonon dynamics show a strong coupling to the excitation of free carriers at the Γ point of the Brillouin zone. The optical response saturates at a critical excitation fluence FC=0.30±0.08 mJ/cm2 due to optical absorption saturation. This limits the optical excitation density in Ta2NiSe5 so that the system cannot be pumped sufficiently strongly to undergo the structural change to the high-temperature phase. We thereby demonstrate that Ta2NiSe5 exhibits a blocking mechanism when pumped in the near-infrared regime, preventing a nonthermal structural phase transition