Wide Pulse Research Articles

636 Quantified Evaluation of the Ductus Arteriosus

Introduction: We evaluated and quantified all ductal scans requested for predefined clinical signs and determined associations between clinical signs, ultrasound parameters and hemodynamic significance (HSDA) defined as ductal diameter (DAd) > 1.5 or >2.0 mm. Methods: Clinical signs were scored as mild (murmur, wide pulse pressure, hyperactive precordium), respiratory (difficulties to wean from or increase in respiratory support) or serious (hypotension, pulmonary edema or haemorrhage, congestive heart failure). Scans included central blood flow, DAd, ductal maximum velocity (Vmax), left pulmonary artery diastolic flow velocity (LPAd), LA/Ao ratio and flow pattern in the descending Aorta (DAo). Results: Eighty scans in 48 patients were analysed. Median (range) gestational age was 26 (23-31) weeks, postnatal age 7 (1-60) days. No associations were found between clinical signs and DAd > 1.5 or 2.0 mm. A murmur was best correlated with Vmax (Pearson 0.52, p 0.000). Hypotension and pulmonary haemorrhage were correlated with a larger ductal diameter (Pearson 0.34, p 0.002 and 0.40, p 0.000). A DAd > 1.5 mm was associated with higher LPAd, LA/Ao ratio and LVO (mean difference 15 cm/s; 95%CI 8 to 23, 0.24; 95%CI 0.12 to 0.36, 93 ml/kg/min; 95%CI 30 to 156 respectively). A DAd > 2.0 mm was associated with a lower Vmax (mean difference -95 cm/s; 95%CI -53 to -136) and more cases with reverse flow in the DAo (5% vs 55%). Conclusion: Clinical signs cannot predict ductal size. A DAd >1.5 is associated with known ultrasound parameters, a DAd >2.0 only with Vmax and DAo pattern.

Application of transient pulses on power supply cables by using commercial of the shelf components

Abstract. This paper deals with the development of ultra wide band pulse devices using merchantable hardware. The major goal is to create wide band transients and pulses with simple electronic equipment and to achieve high voltages and low pulse rise times. The propagation of these signals on common power lines are examined to analyse and forecast the effects on attached devices.

Influence of stimulus pulse width on M‐waves, H‐reflexes, and torque during tetanic low‐intensity neuromuscular stimulation

Neuromuscular electrical stimulation (NMES) has been shown to generate contractions that include a central recruitment of motoneurons; however, the effect of pulse width on electromyographic (EMG) and torque responses during NMES are not well documented. Soleus EMG and isometric plantarflexion torque were recorded from 14 subjects with NMES delivered to the tibial nerve using 50, 200, 500, and 1000 μs pulse widths. M-waves were significantly smaller during 20 Hz NMES compared with responses evoked by single pulses of 200, 500, and 1000 μs, but not 50 μs pulse widths. At all pulse widths, stimulation at 20 Hz depressed soleus H-reflexes compared with single pulses. Two seconds of 100 Hz NMES significantly increased H-reflexes and torque during the subsequent 20 Hz NMES with 200, 500, and 1000 μs, but not 50 μs, pulse widths. NMES delivered using wide pulses generated larger contractions with a relatively greater central contribution than narrow pulses. This may help reduce atrophy and produce fatigue-resistant contractions for rehabilitation.

Nonlinear envelope equation for broadband optical pulses in quadratic media

We derive a nonlinear envelope equation to describe the propagation of broadband optical pulses in second order nonlinear materials. The equation is first order in the propagation coordinate and is valid for arbitrarily wide pulse bandwidth. Our approach goes beyond the usual coupled wave description of $\chi^{(2)}$ phenomena and provides an accurate modelling of the evolution of ultra-broadband pulses also when the separation into different coupled frequency components is not possible or not profitable.

Noise-induced oscillations in an actively mode-locked laser

Oscillations induced by noise are examined for an actively mode-locked laser. Additive noise, proportional noise, and combined noise are considered. Spatial noise is approximated by Hermite expansions and temporal noise is approximated via an approximation of the variance of the random variable using a fourth-order Adams–Bashforth scheme. The approach is verified on a sample problem and used to explore the governing equations for a mode-locked laser. The inclusion of multiplicative noise leads to much wider pulses and much longer intervals between pulses.

Evaluation of stimulus parameters and electrode geometry for an effective suprachoroidal retinal prosthesis

Several approaches have been proposed for placement of retinal prostheses: epiretinal, subretinal and suprachoroidal. We aimed to systematically evaluate the effectiveness of varying a range of stimulus parameters and electrode geometry for a suprachoroidal electrode array, using cortical evoked responses to monopolar electrical stimulation in cats. Our results indicate that charge thresholds were not dependent on electrode size, pulse widths or position of the return electrode tested, but were dependent on the number of sites stimulated in parallel. Further, we found that the combination of monopolar stimulation with large diameter electrodes, wide pulse widths and parallel stimulation minimized the voltage requirements for stimulation. These results provide useful insights for the design specifications of a low voltage suprachoroidal stimulator.

The pathophysiology of vascular calcification in a rodent model of chronic kidney disease

Vascular calcification (VC) occurs in aging populations, but is markedly accelerated in patients with chronic kidney disease (CKD). Through manipulation of dietary adenine, we produced a Sprague Dawley rat model characterized by graded severity of CKD with VC. Circulatory changes were determined by arterial radiotelemetry (n=6) and by assessment of aortic pulse wave velocity (PWV; n=32). VC was assessed using the calcium‐O‐cresophthalein assay and von Kossa staining. At sacrifice, kidney function (creatinine (μmol/L)) was worst in the CKD group with VC (251±60 μmol/L), compared to CKD alone (200±69 μmol/L) or control (50±16 μmol/L). Longitudinal serum phosphate measures revealed that those CKD animals with the highest serum phosphate mid‐study and prior to the development of circulatory changes (i.e. radiotelemetry) subsequently developed calcification (5.96±1.3 mM in calcifying CKD versus 4.4±1.3 mM in CKD versus 2.8±0.2 mM in control). VC animals also demonstrated elevated PWV (3.2±0.3 log(cm/s) vs control 2.9±0.1 log(cm/s)) and widening pulse pressure ((PP) 38±4.7 mmHg to 58 ±15.2 mmHg). Furthermore, there were positive correlations between the phosphate regulating hormone, fibroblast growth factor 23, and PP with left ventricular hypertrophy (LVH; r2=0.32 & r2=0.58 respectively, p<0.005). Hyperphosphatemia and VC in CKD are likely mechanistically linked and are key factors in enhanced LVH.

Resonance enhanced large third order nonlinear optical response in slow light GaInP photonic-crystal waveguides

We report a large nonlinear response in a 1.3mm long GaInP photonic crystal waveguide. The wide band gap of GaInP (1.9 eV) ensures that no two photon absorption takes place for photons at 1.55mm improving the nonlinear performance. The nonlinearity is enhanced by a resonance effect due to the waveguide end facet reflectivities as well as by the low group velocity exhibited by the waveguide. A low CW input pump power of approximately 2mW causes a very large change in the nonlinear refractive index coefficient which manifests itself in a large, approximately p /3 phase shift in the Fabry Perot fringes. The extracted effective nonlinear coefficient g varies from 3.4 x 105W-1m-1 at short wavelengths to 2.2 x 106W-1m-1 near the band edge. These values are several orders of magnitude larger than those obtained in reported nonlinear experiments which exploit the Kerr effect. We postulate therefore that the observed nonlinearity is due to a hybrid phenomenon which combines the Kerr effect and an index change which is induced by local heating that results from the residual linear absorption. The efficient nonlinear phase shift was also exploited in a fast dynamic experiment where we demonstrated wavelength conversion with 100ps wide pulses proving the potential for switching functionalities at multi GHz rates. The index change required for this switching experiment can not be obtained, at the power levels used here, with a g value of a few thousands W-1m-1 which is a typical Kerr coefficient in similar waveguides. Hence, we conclude that the hybrid nonlinearity is sufficiently fast to enable switching with a time scale of at least 100ps.

Generation of electrical short pulses using a Schottky transmission line periodically loaded with tunnelling diodes

We propose a method of generating electrical short pulses on a Schottky transmission line periodically loaded with resonant tunnelling diodes as a key device. Applying perturbative analysis, we show that the dynamics of the modified Schottky line is reduced to an expanded KdV–Burgers equation. The behaviour of the wave on the line is studied by computer experiment. As a result, the problem of a wide pulse breaking up into multiple pulses rather than a single pulse is solved.

超宽带电磁脉冲对腔体孔缝耦合效应的数值模拟

超宽带电磁脉冲对腔体孔缝耦合效应的数值模拟

A comparison of blood pressure and pulse pressure values obtained by oscillometric and central measurements in hypertensive patients

Objective. Wide pulse pressure (PP) affects the accuracy of oscillometric blood pressure measurements (OBPM): however, the degree of this impact on different patient groups with wide PPs is unclear. This study will investigate the accuracy of OBPM in achieving target BP and PP in isolated systolic hypertension (ISH) group compared with mixed hypertension (MHT) group. Method. A total of 115 patients (70 with ISH and 45 with MHT) were enrolled in the study. Upper arm and wrist OBPM, obtained by OmronM3 and OmronR6 devices respectively, were compared with the simultaneously measured values from the ascending aorta. The ISH was defined as a systolic blood pressure (SBP) ≥140 mmHg and a diastolic blood pressure (DBP) <90 mmHg. MHT was defined as a SBP≥140 mmHg and a DBP≥90 mmHg. Results. The mean central arterial blood pressure (BP) and central PP were higher in the ISH group than those in the MHT group. The upper arm OBPM underestimated the central SBP in two groups (−5 mmHg, −3 mmHg, p=0.5, respectively), but overestimated DBP in the ISH group compared with MHT patients (6.8 mmHg, 1 mmHg, p=0.04, respectively). Wrist OBPM similarly underestimated to the central SBP in each group (−16 mmHg, −19 mmHg, p=0.15), whereas the sum of overestimation of DBP was significantly higher in the ISH than in the MHT group (+6 mmHg, − 1 mmHg, p=0.001, respectively). Also, each of the devices underestimated the central PP in the ISH group (about 10 mmHg) as being higher than that of the MHT group. Conclusion. Oscillometric devices may be used for self-BP measurement in patients with ISH without clinically important disadvantages compared with the patients with MHT. For PP measurement in patients with ISH, there were substantial differences between intra-arterial and indirect arm BP measurements.

宽脉冲电流测量线圈

宽脉冲电流测量线圈

Heavy Ion and High Energy Proton-Induced Single Event Transients in 90 nm Inverter, NAND and NOR Gates

We measure heavy ion and proton-induced SETs in inverters, and NAND and NOR gates from a 90 nm RHBD library. NAND and NOR gates have higher SET cross section and generate wider pulses than inverters.

Effect of target surface orientation on the range precision of laser detection and ranging systems

Airborne laser detection and ranging (LADAR) systems are used for applications such as three-dimensional imaging, topographic mapping, and target recognition. Typical systems transmit laser beams through apertures that are a few inches wide and use pulses that are roughly a nanosecond in duration. If the pulse reflects off a target that is tilted with respect to the LADAR's line-of-sight, then the reflection process will elongate the received signal as compared to the transmitted pulse. If the range is more than a few kilometers and the target is tilted more than about forty-five degrees, the increase in the width of the received pulse produces a signifcant drop in range precision as compared to when the target is perpendicular to the line-of-sight.

Exciton condensation in homoepitaxial chemical vapor deposition diamond

In this work, the characteristics of the edge emission of a homoepitaxial diamond sample grown by chemical vapor deposition (CVD) are reported. Photoluminescence has been excited at 220 nm by using a tunable optical parametric oscillator laser, giving ∼5 ns wide laser pulses. The temperature of the sample has been decreased from room temperature down to 30 K. Free exciton emission and its phonon replicas have been observed at all the temperatures explored. Excitonic lifetime shows a nonmonotonic dependence on the sample temperature. Luminescence at low temperatures from electron-hole drops at approximately 5.18 eV has been observed for the first time in CVD diamond.

Distributed cooperative data relaying for diversity in impulse-based UWB ad-hoc networks

In this paper we develop and investigate two families of efficient distributed cooperative data relaying schemes that can be adopted to forward data in the impulse-based ultra wide band wireless ad-hoc network composed of a pair of source and destination and multiple parallel two-hop relays. The new schemes combine the mechanism of the medium access control and physical layers in a cooperative and distributed way to either select the best relay from multiple available ones for data forwarding or optimally combine the synchronized data forwarding of all participating relays, such as to improve the data transfer diversity. For distributed cooperative routing, we propose efficient protocols for use at all relays to perform an enhanced ultra wide band pulse sensing multiple access with the backoff periods deterministically and optimally mapped from associated instantaneous source-relay-destination route qualities, to ensure that only the best relay can firstly and successfully forward its received data to the destination; For distributed cooperative beamforming, we propose efficient protocols for use at all relays to take advantages of the widely spread and independently distributed multiple paths of the fading ultra wide band channels in the synchronized data forwarding combination, to create an optimally combined route for source-destination data transfer. Performance analysis and simulation studies show the effectiveness and efficiency of our proposed schemes.

Patent arterial duct

Patent arterial duct (PAD) is a congenital heart abnormality defined as persistent patency in term infants older than three months. Isolated PAD is found in around 1 in 2000 full term infants. A higher prevalence is found in preterm infants, especially those with low birth weight. The female to male ratio is 2:1. Most patients are asymptomatic when the duct is small. With a moderate-to-large duct, a characteristic continuous heart murmur (loudest in the left upper chest or infraclavicular area) is typical. The precordium may be hyperactive and peripheral pulses are bounding with a wide pulse pressure. Tachycardia, exertional dyspnoea, laboured breathing, fatigue or poor growth are common. Large shunts may lead to failure to thrive, recurrent infection of the upper respiratory tract and congestive heart failure. In the majority of cases of PAD there is no identifiable cause. Persistence of the duct is associated with chromosomal aberrations, asphyxia at birth, birth at high altitude and congenital rubella. Occasional cases are associated with specific genetic defects (trisomy 21 and 18, and the Rubinstein-Taybi and CHARGE syndromes). Familial occurrence of PAD is uncommon and the usual mechanism of inheritance is considered to be polygenic with a recurrence risk of 3%. Rare families with isolated PAD have been described in which the mode of inheritance appears to be dominant or recessive. Familial incidence of PAD has also been linked to Char syndrome, familial thoracic aortic aneurysm/dissection associated with patent arterial duct, and familial patent arterial duct and bicuspid aortic valve associated with hand abnormalities. Diagnosis is based on clinical examination and confirmed with transthoracic echocardiography. Assessment of ductal blood flow can be made using colour flow mapping and pulsed wave Doppler. Antenatal diagnosis is not possible, as PAD is a normal structure during antenatal life. Conditions with signs and symptoms of pulmonary overcirculation secondary to a left-to-right shunt must be excluded. Coronary, systemic and pulmonary arteriovenous fistula, peripheral pulmonary stenosis and ventricular septal defect with aortic regurgitation and collateral vessels must be differentiated from PAD on echocardiogram. In preterm infants with symptomatic heart failure secondary to PAD, treatment may be achieved by surgical ligation or with medical therapy blocking prostaglandin synthesis (indomethacin or ibuprofen). Transcatheter closure of the duct is usually indicated in older children. PAD in preterm and low birth weight infants is associated with significant co-morbidity and mortality due to haemodynamic instability. Asymptomatic patients with a small duct have a normal vital prognosis but have a lifetime risk of endocarditis. Patients with moderate-to-large ducts with significant haemodynamic alterations may develop irreversible changes to pulmonary vascularity and pulmonary hypertension.

Acute Valvular Regurgitation

Acute severe valvular regurgitation is a surgical emergency, but accurate and timely diagnosis can be difficult. Although cardiovascular collapse is a common presentation, examination findings to suggest acute regurgitation may be subtle, and the clinical presentation may be nonspecific. Consequently, the presentation of acute valvular regurgitation may be mistaken for other acute conditions, such as sepsis, pneumonia, or nonvalvular heart failure. Although acute regurgitation may affect any valve, acute regurgitation of the left-sided valves is more common and has greater clinical impact than acute regurgitation of right-sided valves. Data to guide appropriate management of patients with acute regurgitation are sparse; there are no randomized trials, and much of the literature describes either small series or the experiences of specific centers. Despite these limitations, the available data are sufficient to allow identification of general principles as well as development of applicable guidelines from both the American College of Cardiology/American Heart Association and European Society of Cardiology. The guidelines recommend valve surgery for symptomatic patients with aortic or mitral regurgitation, including those with acute regurgitation.1–3 The data and guidelines emphasize overarching clinical principles, including the need for a high clinical suspicion of acute regurgitation, timely use of echocardiography, and, in the majority of patients, rapid progression to surgery. Causes of acute regurgitation overlap with causes of chronic regurgitation and vary depending on the valve affected (Table 1). Endocarditis may affect either the aortic or mitral valve, whereas other causes are unique to the specific valve involved. The majority of causes of acute regurgitation present as an acute or subacute event. However, acute regurgitation can occur in patients with chronic regurgitation, when regurgitant severity is exacerbated by factors such as coronary ischemia, chordal rupture, or leaflet perforation from endocarditis. Acute regurgitation of either the aortic or mitral valve may result from procedural …

Usefulness of Wide Pulse Pressure as a Predictor of Poor Outcome After Renal Artery Angioplasty and Stenting

Renal artery stenosis is a common cause of secondary hypertension and ischemic nephropathy. Percutaneous angioplasty and stent placement has allowed select patients with renal artery stenosis to use fewer antihypertensive agents and improve or stabilize renal function. The associations of baseline systolic, diastolic, and pulse pressures (PPs) with outcomes of blood pressure (BP) and renal function were examined in 243 patients who underwent renal angioplasty and stent placement. The average PP before the procedure in patients with improvements or stabilizations in renal function was 53 +/- 20 mm Hg, compared to 107 +/- 18 mm Hg (p <0.05) in those with poorer outcomes. The average PPs before procedure were 47 +/- 15 mm Hg in those with improvements in BP, 82 +/- 10 mm Hg in those with stabilizations of BP, and 111 +/- 14 mm Hg in those with worsening BP. All findings were statistically significant (p <0.05). In conclusion, wide PP may reflect more advanced vascular stiffness and renal disease distinguishing patients less likely to benefit from revascularization.

871 Gastric Electrical Stimulation with Wider Pulses Inhibits Food Intake and Gastric Motility in Dogs

871 Gastric Electrical Stimulation with Wider Pulses Inhibits Food Intake and Gastric Motility in Dogs