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Pulses
Kinds of Pulses Terms modified by Pulses Selected AbstractsPULSES OF PHOSPHATE PROMOTE DOMINANCE OF THE TOXIC CYANOPHYTE CYLINDROSPERMOPSIS RACIBORSKII IN A SUBTROPICAL WATER RESERVOIR,JOURNAL OF PHYCOLOGY, Issue 3 2009Amanda J. Posselt The role of dissolved inorganic phosphorus (DIP) in promoting dominance of the toxic nitrogen (N)-fixing cyanobacterium Cylindrospermopsis raciborskii (Wo,osz.) Seenayya et Subba Raju was examined in a subtropical water reservoir, Lake Samsonvale (=North Pine reservoir). A novel in situ bioassay approach, using dialysis tubing rather than bottles or bags, was used to determine the change in C. raciborskii dominance with daily additions of DIP. A statistically significant increase in dominance of C. raciborskii was observed when DIP was added at two concentrations (0.32 ,M and 16 ,M) in a daily pulse over a 4 d period in three separate experiments in the summer of 2006/2007. There was an increase in both C. raciborskii cell concentrations and biovolume in two DIP treatments, but not in the ammoniacal N + DIP treatment. In addition, overall phytoplankton cell concentrations increased with DIP addition, indicating that Lake Samsonvale was DIP limited at the time of experiments. Given the bioassay response, it is likely that dominance of C. raciborskii could increase in Lake Samsonvale with periodic injections of DIP such as inflow events. [source] Cell type-specific transgene expression of the prion protein in Xenopus intermediate pituitary cellsFEBS JOURNAL, Issue 4 2006Jos W. G. Van Rosmalen The cellular form of prion protein (PrPC) is anchored to the plasma membrane of the cell and expressed in most tissues, but predominantly in the brain, including in the pituitary gland. Thus far, the biosynthesis of PrPC has been studied only in cultured (transfected) tumour cell lines and not in primary cells. Here, we investigated the intracellular fate of PrPCin vivo by using the neuroendocrine intermediate pituitary melanotrope cells of the South-African claw-toed frog Xenopus laevis as a model system. These cells are involved in background adaptation of the animal and produce high levels of its major secretory cargo proopiomelanocortin (POMC) when the animal is black-adapted. The technique of stable Xenopus transgenesis in combination with the POMC gene promoter was used as a tool to express Xenopus PrPC amino-terminally tagged with the green fluorescent protein (GFP,PrPC) specifically in the melanotrope cells. The GFP,PrPC fusion protein was expressed from stage-25 tadpoles onwards to juvenile frogs, the expression was induced on a black background and the fusion protein was subcellularly located mainly in the Golgi apparatus and at the plasma membrane. Pulse,chase metabolic cell labelling studies revealed that GFP,PrPC was initially synthesized as a 45-kDa protein that was subsequently stepwise glycosylated to 48-, 51-, and eventually 55-kDa forms. Furthermore, we revealed that the mature 55-kDa GFP,PrPC protein was sulfated, anchored to the plasma membrane and cleaved to a 33-kDa product. Despite the high levels of transgene expression, the subcellular structures as well as POMC synthesis and processing, and the secretion of POMC-derived products remained unaffected in the transgenic melanotrope cells. Hence, we studied PrPC in a neuroendocrine cell and in a well-defined physiological context. [source] Quantized Double-Layer Charging of Rhodium2057(Tridecylamine)321 Clusters Using Differential Pulse and Cyclic Voltammetry,ADVANCED MATERIALS, Issue 2 2007A. Kakade Rhodium nanoclusters show a series of quantized double-layer-charging events in solution-phase voltammetry at room temperature (see figure). The unusual variation in the FWHM for both the cathodic and anodic regions in differential pulse voltammetry experiments can be explained by several complex factors including reorganization and disproportionation of charged clusters coupled with electron-transfer processes pertaining to the Rh,Rh bonds. [source] Ventricular Fibrillation Induced by Stretch Pulse: Implications for Sudden Death Due to Commotio CordisJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2006FRANK BODE M.D. Introduction: Nonpenetrating chest wall impact (commotio cordis) may lead to sudden cardiac death due to the acute initiation of ventricular fibrillation (VF). VF may result from sudden stretch during a vulnerable window, which is determined by repolarization inhomogeneity. Methods: We examined action potential morphologies and VF inducibility in response to sudden myocardial stretch in the left ventricle (LV). In six Langendorff perfused rabbit hearts, the LV was instrumented with a fluid-filled balloon. Increasing volume and pressure pulses were applied at different times of the cardiac cycle. Monophasic action potentials (MAPs) were recorded simultaneously from five LV epicardial sites. Inter-site dispersion of repolarization was calculated in the time and voltage domains. Results: Sudden balloon inflation induced VF when pressure pulses of 208,289 mmHg were applied within a window of 35,88 msec after MAP upstroke, a period of intrinsic increase in repolarization dispersion. During the pressure pulse, MAPs revealed an additional increase in repolarization dispersion (time domain) by 9 ± 6 msec (P < 0.01). The maximal difference in repolarization levels (voltage domain) between sites increased from 19 ± 3% to 26 ± 3% (P < 0.05). Earliest stretch-induced activation was observed near a site with early repolarization, while sites with late repolarization showed delayed activation. Conclusions: Sudden myocardial stretch can elicit VF when it occurs during a vulnerable window that is based on repolarization inhomogeneity. Stretch pulses applied during this vulnerable window can lead to nonuniform activation. Repolarization dispersion might play a crucial role in the occurrence of fatal tachyarrhythmias during commotio cordis. [source] Intraoperative Comparison of a Subthreshold Test Pulse with the Standard High-Energy Shock Approach for the Measurement of Defibrillation Lead ImpedanceJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 1 2006ANDREAS SCHUCHERT M.D. There are two methods to measure shocking lead impedance: delivery of high-energy shocks that require patient sedation, and the painless measurement of impedance from subthreshold test pulses. The aim of this study was to compare the two methods. Methods: The study included 131 patients implanted with a standard DR (n = 71) or VR (n = 60) ICD connected to either single-coil (n = 39) or dual-coil (n = 92) defibrillation leads. The noninvasive high-energy impedance test was done using a 17 J shock after induction of ventricular tachyarrhythmias and compared to a 0.4 ,J test pulse used by the ICD for the subthreshold measurements. Results: Defibrillation lead impedance measurements were not significantly different between patients with the same shocking vector configuration. In patients with a single-coil defibrillation lead the impedance was 62 ± 9 , with the high-energy shock and 62 ± 8 , with the subthreshold test pulses (P = 0.13). Patients with a dual-coil configuration recorded average impedances of 40 ± 5 , from both tests (P = 0.44). While there was no difference in values recorded within each lead configuration, there was a significant difference in impedance between the single-coil and the dual-coil patient groups (P = 0.001). Conclusions: There was no significant difference between shocking lead impedances measured with the high-energy shock or the subthreshold test pulses. This offers the possibility of noninvasive, low-energy serial measurements of shocking lead impedance at follow-up visits and removing the need for sedation. [source] Photodamage therapy using an electro-optic q-switched Nd:YAG laserLASERS IN SURGERY AND MEDICINE, Issue 8 2010Dina Yaghmai MD Abstract Background and Objective Q-Switched Nd:YAG lasers produce photoacoustic effects in addition to photothermal effects which may allow for greater tissue collagen production. The objective of the study is to determine the effectiveness and tolerability of an Electro-Optic (EO) Q-switched Nd:YAG laser with Single Pulse and novel Double Pulse (DP) options in the treatment of photodamaged skin. Materials and Methods Sixteen subjects with photoaging were enrolled in this prospective, randomized, split-faced study. Subjects received 6 bi-weekly laser treatments. One half of the face was treated with a Single Pulse while the other half was treated with energies divided into a DP. Blinded investigators and subjects assessed improvement after the sixth treatment for wrinkles, coarseness, pigmentation, redness, laxity, comedones, pore size, and overall skin condition. Subjects also rated the tolerability of the treatments. Results For the Single Pulse side of the face, the investigators rated 33% of the patients as having a good to excellent (51% or greater) improvement in the overall condition of the skin while 47% of the subjects reported these levels. On the DP side, the overall improvement was good to excellent at a 27% rate by the investigators and 54% by the subjects. Distributions of improved ratings among investigators and subjects were similar for both sides of the treatment area. The majority of stinging/burning sensations during treatment were reported as mild on the DP side (62.8%) and moderate (63.8%) on the Single Pulse side. The chance of reporting none or only mild stinging/burning sensation during treatment was four times greater on the side of the face treated with the DP (P,<,0.0001). Conclusions Results have shown that treatment with the EO QS Nd:YAG laser provides a safe and effective method of skin rejuvenation with the additional benefit of significantly lower patient discomfort during use of the DP mode. Lasers Surg. Med. 42:699,705, 2010 © 2010 Wiley-Liss, Inc. [source] Pulse on health and nursing in IndiaNURSING & HEALTH SCIENCES, Issue 2 2007Elizabeth J. Abraham mscn [source] Pulse oximetry-induced third-degree burn in recovery roomANZ JOURNAL OF SURGERY, Issue 4 2009Hee Y. Kwak MD No abstract is available for this article. [source] Pricing to Market Behavior by Canadian and U.S. Agri-food Exporters: Evidence from Wheat, Pulse and ApplesCANADIAN JOURNAL OF AGRICULTURAL ECONOMICS, Issue 2 2003Richard Carew A fixed-effects model to control for time variation in marginal costs is employed to pinpoint evidence of price discriminatory behavior of Canadian and U.S. exporters of agri-food products. We test for evidence of pricing to market behavior and whether price discrimination or commodity/country characteristics may provide a plausible explanation. A distinguishing feature of our approach is to examine the time-series properties of the data by the conventional augmented Dickey-Fuller and recently developed panel unit root test. The panel data set employed in this paper consists of annual exchange rates and export prices for three agri-food products (wheat, pulse and apples) exported by Canada and the U.S. in foreign markets during 1980,98. Our fixed-effects model suggests that U.S. exporters are sensitive to exchange rate changes, while Canadian exporters in most cases raised price markups in response to a depreciated currency in overseas markets. The results highlight the differences in pricing policy that both countries employ to merchandise agri-food products in export markets. Les auteurs ont recouru à un modèle à effets fixes pour contrôler la fluctuation des coûts marginaux dans le temps et montrer que les exportateurs canadiens et américains de produits agroalimentaires se comportent différemment dans l'établissement des prix. Ils ont tenté de vérifier si ce comportement varie avec les cours en vigueur sur le marché et essayé d'établir s'il s'explique par une discrimination au niveau des prix ou par les paramètres propres au produit ou au pays. Une particularité de cette approche est qu'elle tient compte des propriétés historiques des données en recourant à la version augmentée du test classique de Dickey Fuller et au tout nouveau test de racine unitaire reposant sur les panels. Le jeu de données recueillies par panel dont les auteurs se sont servis comprend le taux du change annuel et le prix d'exportation de trois produits agroalimentaires (blé, légumineuses à graine et pommes) que le Canada et les États-Unis ont écoulés sur les marchés étrangers entre 1980 et 1998. Le modèle à effets fixes laisse croire que les exportateurs américains sont sensibles au taux du change alors que, dans la plupart des cas, leurs homologues canadiens majorent les prix davantage consécutivement à une dépréciation des devises à l'étranger. Les résultats font ressortir les divergences entre les politiques de fixation des prix qu'emploient les deux pays pour écouler leurs produits agroalimentaires sur les marchés étrangers. [source] Effects in B,doped KDP crystals irradiated with neutrons of large spectra energyCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2004G. Fischfeld Abstract The results obtained for the r63 electro-optic coefficient of B-doped and undoped KDP (KH2PO4) crystals irradiated with neutrons (including thermalized neutrons) produced by scattering of 30 Mev cyclotron protons on a target of Ta201, are presented and compared to those obtained for non-irradiated doped and undoped crystals. The B-doped (H3BO3, Na2B4O7 and Li2B4O7) crystals were obtained by the conventional growth method by temperature decrease with 1 wt % dopant concentration in solution. The thermal neutron flux was around , = 1. 1010 n/cm2 s. Pulses of ,15 ,s long, in damped oscillatory mode (V= 8 kV, ,=1.95 ,s) were used for the electro-optic measurements. A Pockels cell, a photomultiplier, a He-Ne laser (,=632.8 nm, 5 mW, linearly polarized) and a Tk 720 A oscilloscope complete the experimental setup. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Some Parameters of Correlated Current and Radiated Field Pulses from Lightning to the Gaisberg TowerIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 1 2010Hannes Pichler Non-member Abstract Simultaneous measurements of lightning current and associated radiated electromagnetic field are of fundamental interest for various applications in lightning research. These data can be used for the evaluation of return stroke (RS) models or to investigate the so-called tower effect when lightning hits an elevated object. In this paper, we show the results of simultaneous measurements of current pulses from lightning strikes on the instrumented Gaisberg tower (Austria) and the correlated vertical E-field components at a distance of 78.8 and 108.7 km, respectively. We have analyzed some main lightning current parameters (peak current Ip, 30,90% rise time TI_30-90, and full width at half maximum TI_FWHM and the time-correlated field waveform parameters (Ep, 30,90% rise time TE_30-90, TE_FWHM, and the peak-to-zero time TE_PTZ. With a geometric mean of TI_FWHM = 19 ,s and Ip = 9.6 kA (N = 73) of the RS current pulses used in this study, those strokes are very similar to the strokes in triggered lightning in Florida and Alabama1. With a TE_PTZ of about 10 µs, the zero-crossing time of the radiated E-fields from the tower strokes are significantly shorter than the typical values of 30 , 40 µs (e.g.2). Correlation between the current and field parameters TI_FWHM versus TE_FWHM and TE_PTZ, respectively, is low (R2 = 0.29 and 0.14). We assume that the relatively short lightning channel in the case of the RSs in object-triggered upward flashes is the main reason for the observed short zero-crossing time. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Intravenous dexamethasone-cyclophosphamide pulse therapy in comparison with oral methylprednisolone-azathioprine therapy in patients with pemphigus: Results of a multicenter prospectively randomized studyJOURNAL DER DEUTSCHEN DERMATOLOGISCHEN GESELLSCHAFT, Issue 3 2005Intravenöse Dexamethason-Cyclophosphamid-Pulstherapie im Vergleich zu einer oralen Methylprednisolon-Azathioprin-Therapie bei Patienten mit Pemphigus-Erkrankungen: Ergebnisse einer multizentrischen, prospektiven, randomisierten Studie Azathioprin; Cyclophosphamid; Pemphigus; Pulstherapie Summary Background: Pemphigus is a potentially life-threatening autoimmune blistering skin disease usually treated with high-dose corticosteroids in combination with immunosuppressive drugs. In a multicenter, prospectively randomized study we compared efficacy and side effects of a dexamethasone-cyclophosphamide (D/C) pulse therapy with a methylprednisolone-azathioprine (M/A) therapy in 22,patients with newly diagnosed pemphigus vulgaris and pemphigus foliaceus. Patients and methods: The 11,patients of the M/A group were treated with daily doses of methylprednisolone (initially 2,mg/kg body weight) and azathioprine (2,,,2,5,mg/kg body weight) which were subsequently tapered. D/C pulse therapy in 11,patients consisted of intravenous administration of 100,mg dexamethasone/d on 3 consecutive days along with cyclophosphamide (500,mg) on day one. Pulses were initially repeated every 2,,,4 weeks and then at increasing intervals. In between the pulses, oral cyclophosphamide (50,mg) was given daily for 6,months. Results: Within 24,months after treatment initiation, 5/11,patients of the D/C group had a remission (complete remissions after discontinuation of therapy in 3,patients) and 6/11,patients had a progression. In the M/A group, there were remissions in 9/11,patients (complete remissions after discontinuation of therapy in 3,patients) and progression in 1/11,patients. There were more relapses in M/A therapy after remission than in D/C therapy. Side effects were more common in the M/A group. These differences were not significant (p > 0,05). Conclusion: Because of the high number of progressions in patients treated with D/C therapy, we can not confirm the encouraging results of earlier reports about pulse D/C therapy. Nevertheless D/C therapy seemed to be better tolerated and, in case of primary efficacy, was associated with fewer recurrences than M/A therapy. Zusammenfassung Hintergrund: Pemphiguserkrankungen sind potentiell lebensbedrohliche blasenbildende Autoimmunerkrankungen, die üblicherweise mit hochdosierten Kortikosteroiden in Kombination mit Immunsuppressiva behandelt werden. In einer multizentrischen, prospektiven, randomisierten Studie verglichen wir die Wirksamkeit und Nebenwirkungen einer Dexamethason-Cyclophosphamid (D/C)-Pulstherapie mit einer Methylprednisolon-Azathioprin (M/A)-Therapie bei 22,Patienten mit neu diagnostiziertem Pemphigus vulgaris und Pemphigus foliaceus. Patienten und Methoden: 11,Patienten der M/A-Gruppe wurden kontinuierlich oral mit Methylprednisolon (initial 2,mg/kg Körpergewicht/Tag) und Azathioprin (2,,,2,5,mg/kg Körpergewicht/Tag) behandelt; die Dosen wurden schrittweise reduziert. Die Therapie bei den 11,Patienten der D/C-Gruppe erfolgte durch intravenöse Gabe von 100,mg Dexamethason/Tag an 3 aufeinander folgenden Tagen und 500,mg Cyclophosphamid am ersten Tag. Die Pulstherapie wurde zunächst alle 2,,,4 Wochen, dann in längeren Abständen wiederholt. Im Intervall wurden 50,mg Cyclophosphamid/Tag oral für 6,Monate verabreicht. Ergebnisse: Innerhalb von 24,Monaten nach Therapiebeginn kam es bei 5 von 11,Patienten der D/C-Gruppe zu einer Remission (komplette Remission nach Absetzen der Therapie bei 3,Patienten); bei 6 der 11,Patienten verlief die Erkrankung progredient. In der M/A-Gruppe kam es bei 9 von 11,Patienten zu einer Remission (komplette Remission nach Absetzen der Therapie bei 3,Patienten) und bei einem Patienten zu einer Progression. In der M/A-Gruppe traten häufiger Rezidive nach Remission auf als in der D/C-Gruppe. Therapienebenwirkungen kamen in der M/A-Gruppe häufiger vor. Diese Unterschiede waren nicht signifikant (p > 0,05). Schlußfolgerungen: Aufgrund der hohen Anzahl von Progressionen bei Patienten der D/C-Gruppe können wir die positiven Ergebnisse früherer Berichte über die D/C-Pulstherapie nicht bestätigen. Dennoch scheint die D/C-Therapie, beim einzelnen Patienten einmal erfolgreich, seltener zu Rezidiven zu führen und möglicherweise auch besser verträglich zu sein als die M/A-Therapie. [source] Fluorescence Spectroscopy of Color Centers Generated in Phosphate Glasses after Exposure to Femtosecond Laser PulsesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2002James W. Chan A confocal fluorescence microscopy setup was used to observe, in situ, spectral changes in phosphate glasses which were modified using 0.3 ,J of tightly focused 800 nm, 130 fs laser pulses. On 488 nm excitation, the modified glass shows a broad fluorescence centered at roughly 600 nm, which decays with prolonged exposure to the 488 nm light. The decay behavior is dependent on the 488 nm power, with a faster decay rate for higher powers. A mechanism whereby color centers, formed by the femtosecond pulses, fluoresce when excited by the 488 nm light and are simultaneously photobleached is proposed to explain the observed behavior. [source] Generation of sub-5 fs pulses through cascade of filamentation and hollow fiber compressionLASER PHYSICS LETTERS, Issue 11 2008D. Wang Abstract A pulse-compression scheme based on cascade of filamentation and hollow fiber has been demonstrated. Pulses with duration of sub-5 fs and energy of 0.2 mJ near 800 nm have been generated by compressing the ,40 fs pulses from a commercial laser system. This method is promising to generate near monocycle high energy pulses. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Switchable pulses generation in passively Q-switched multilongitudinal-mode microchip laserLASER PHYSICS LETTERS, Issue 2 2007J. Dong Abstract Periodical switching laser pulses with nanosecond pulse width and several kilowatts peak power from wideseparated multilongitudinal-mode oscillation were observed experimentally in laser-diode pumped passively Q-switched Yb:YAG microchip laser with Cr4+:YAG as saturable absorber. Pulses from different longitudinal modes oscillate alternatively. Periodical pulses oscillation dynamics induced by spatial hole burning effect and mode competition was investigated numerically by the evolution of the inversion population of different modes and the bleaching and recovery of the inversion population of the saturable absorber. The numerical simulations of switchable periodical pulsation of multilongitudinal-mode passively Q-switched Yb:YAG/Cr4+:YAG microchip lasers are in good agreement with experimental results and confirmed that such pulsations are an intrinsic property in passively Q-switched Yb:YAG/Cr4+:YAG microchip lasers. (© 2007 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Laser Sources for Ultrashort Pulses , Oscillators and Amplifiers for Various ApplicationsLASER TECHNIK JOURNAL, Issue 1 2007Rüdiger Paschotta Dr. [source] Single-shot all-optical sampling oscilloscope using a polarization-maintaining resonator for pulse replicationMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2010j Komanec Abstract An all-optical single-shot sampling oscilloscope with a picosecond resolution is developed. An innovative approach for data pulse replication using a polarization-maintaining resonator is used. Pulses are sampled in a highly nonlinear fiber. Acquired data are used for pulse shape reconstruction. Proposed setup eliminates the need of a delay line. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2452,2456, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25509 [source] The design of excitation pulses for spin systems using optimal control theory: With application to NMR spectroscopyOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 5 2009Naum I. Gershenzon Abstract This paper considers the use of optimal control theory in designing radio frequency excitation pulses for magnetic spin systems satisfying Bloch dynamics. Such pulses are required in applications of nuclear magnetic resonance to initially transfer sample magnetization vectors to the transverse plane. Once transferred, signals released by nuclei as they respond to a static magnetic field normal to the transverse plane are then analyzed and interpreted. Continuous time deterministic optimal control theory is employed to determine time-dependent pulse amplitudes and frequencies that minimize the distance between final magnetization vectors and a chosen target vector. Pulses are designed to excite a range of resonant frequencies and to tolerate miscalibration errors in applied fields. The model presented permits a unified treatment of the control problem as considered by a variety of authors, and a thorough mathematical analysis of the existence, and characteristics of, optimal excitation pulses. Practical numerical algorithms for designing optimal pulses are given, and the effectiveness of the algorithms is illustrated by comparing the pulses that they generate with those commonly used in high-resolution spectroscopy. Copyright © 2008 John Wiley & Sons, Ltd. [source] Subthreshold Test Pulses Versus Low Energy Shock Delivery to Estimate High Energy Lead Impedance in Implanted Cardioverter Defibrillator PatientsPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1p2 2003DIRK VOLLMANN VOLLMANN, D., et al.: Subthreshold Test Pulses Versus Low Energy Shock Delivery to Estimate High Energy Lead Impedance in Implanted Cardioverter Defibrillator Patients. The high energy lead impedance is valuable for detecting lead failure in ICDs, but until recently shock delivery was necessary for high energy impedance measurement. This study compared the use of subthreshold test pulses and low energy test shocks to estimate the high energy impedance. Immediately after implantation of Ventak Prizm ICDs in 29 patients, the lead impedance was measured with five subthreshold (0.4 ,J) test pulses, 5 low energy (1.1 J) shocks, and two to three high energy(16 ± 4.5 J)shocks. The mean impedances measured using high energy shocks, low energy shocks, and subthreshold pulses were42.0 ± 7.3 ,, 46.5 ± 8.1 ,, and42.4 ± 7.1 ,, respectively. The impedances measured using high and low energy shocks differed significantly(P <0.0001), while those obtained by high energy shocks and low energy pulses did not(P = 0.63). According to the Pearson correlation coefficient, the impedance measurements with subthreshold pulses and low energy shocks were both closely correlated(P < 0.0001)with impedance values determined with high energy shocks. However, while the impedance values tended to be higher when measured with low energy shocks, the concordance correlation coefficient (c) was higher for subthreshold test pulse versus high energy shock(c = 0.92)than for low versus high energy shock(c = 0.73). Furthermore, the intraindividual variability of impedance measurements was lower with subthreshold pulse measurements than with low energy shocks. Compared with low energy shocks, impedance measurement with subthreshold pulses has higher reproducibility and a higher correlation with the impedance obtained by high energy shock delivery. Safe and painless high energy impedance estimation with subthreshold pulses might, therefore, help to detect ICD lead failure during routine follow-up. (PACE 2003; 26:[Pt. II]:457,460) [source] Circadian rhythms and the evolution of photoperiodic timing in insectsPHYSIOLOGICAL ENTOMOLOGY, Issue 4 2009DAVID S. SAUNDERS Abstract. This review discusses possible evolutionary trends in insect photoperiodism, mainly from a chronobiological perspective. A crucial step was the forging of a link between the hormones regulating diapause and the systems of biological rhythms, circadian or circannual, which have independently evolved in eukaryotes to synchronize physiology and behaviour to the daily cycles of light and darkness. In many of these responses a central feature is that the circadian system resets to a constant phase at the beginning of the subjective night, and then ,measures' the duration of the next scotophase. In ,external coincidence', one version of such a clock, light now has a dual role. First, it serves to entrain the circadian system to the stream of pulses making up the light/dark cycle and, second, it regulates the nondiapause/diapause switch in development by illuminating/not illuminating a specific light sensitive phase falling at the end of the critical night length. Important work by A. D. Lees on the aphid Megoura viciae using so-called ,night interruption experiments' demonstrates that pulses falling early in the night lead to long-day effects that are reversible by a subsequent dark period longer than the critical night length and also show maximal sensitivity in the blue,green range of the spectrum. Pulses falling in the latter half of the night, however, produce long-day effects that are irreversible by a subsequent long-night and show a spectral sensitivity extending into the red. With movement to higher latitudes, insects develop genetic clines in various parameters, including critical night length, the number of long-night cycles needed for diapause induction, the strength of the response, and the ,depth' or intensity of the diapause thus induced. Evidence for these and other types of photoperiodic response suggests that they provided strong selective advantages for insect survival. [source] Size-Controlled Synthesis of Conducting-Polymer Microspheres by Pulsed Sonoelectrochemical Polymerization,ANGEWANDTE CHEMIE, Issue 33 2009Mahito Atobe Prof. Am Puls der Zeit: Die Größe von Mikrokugeln aus leitfähigen Polymeren lässt sich steuern, indem man die Dauer des elektrischen Pulses in einem sonoelektrochemischen Polymerisationsprozess einstellt (siehe Bild). Aus Lösung auf einer Elektrode aufgetragene Filme der Mikrokugeln zeigen scharfe Redoxsignale in Abhängigkeit vom Potential. [source] Nanosecond pulsed electric field generators for the study of subcellular effectsBIOELECTROMAGNETICS, Issue 3 2006Juergen F. Kolb Abstract Modeling and experimental studies have shown that pulsed electric fields of nanosecond duration and megavolt per meter amplitude affect subcellular structures but do not lead to the formation of large pores in the outer membrane. This "intracellular electromanipulation" requires the use of pulse generators which provide extremely high power but low energy pulses. In this study, we describe the concept of the required pulsed power sources, their design, operation, and the necessary diagnostics. Two types of pulse generators based on the Blumlein line principle have been developed and are described here. One system is designed to treat a large number of cells in cuvettes holding volumes from 0.1 to 0.8 ml. Pulses of up to 40 kV amplitude, with a duration of 10 ns and a rise time close to 1 ns can be applied to the cuvette. For an electrode gap of 1 mm this voltage corresponds to an average electric field of 40 MV/m. The second system allows for real time observation of individual cells under a microscope. It generates pulses of 10,300 ns duration with a rise time of 3.5 ns and voltage amplitudes up to 1 kV. Connected to a microreactor with an electrode gap of 100 µm, electric fields up to 10 MV/m are applied. Bioelectromagnetics 27:172,187, 2006. © 2005 Wiley-Liss, Inc. [source] N2O Decomposition over Fe-ZSM-5 Studied by Transient TechniquesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2009P. M. Prechtl Abstract N2O decomposition to gaseous N2 and O2 catalyzed by a commercial Fe-ZSM-5 has been studied by different transient techniques: (i) via the transient response methods at ambient pressure, (ii) via the temporal analysis of products (TAP) reactor under vacuum, and (iii) by temperature-programmed desorption (TPD) under vacuum. The catalyst was activated in He at 1323 K. Two main steps can be distinguished within the transient period of N2O decomposition under constant N2O feed at 603 K: the first step consists of molecular N2 formation and surface atomic oxygen (O)Fe. It follows a period of stoichiometric N2O decomposition to gaseous N2 and O2 with increasing conversion until steady state is reached. The observed rate increase is assigned to a slow accumulation on the surface of NOx,ads species formed from N2O and participating as co-catalyst in the N2O decomposition. The NOx,ads species accelerates the atomic oxygen recombination/desorption, which is the rate-determining step of N2O decomposition. The formation and accumulation of NOx,ads species during N2O interaction with the catalyst was confirmed by TAP studies. The amount of NOx,ads was found to depend on the number of N2O pulses injected into the TAP reactor. In the presence of adsorbed NOx on the catalyst surface (NOx,ads) the desorption of dioxygen is facilitated. This results in a shift of the oxygen desorption temperature from 744 K to considerably lower temperatures of 580 K in TPD experiments. Pulses of gaseous NO had a similar effect leading to the formation NOx,ads, thus facilitating the oxygen recombination/desorption. [source] Electrochemical Microstructuring with Short Voltage PulsesCHEMPHYSCHEM, Issue 1 2007Rolf Schuster Prof. Dr. Abstract The application of short (nanosecond) voltage pulses between a tool electrode and a workpiece immersed in an electrolyte solution allows the three-dimensional machining of electrochemically active materials with submicrometer resolution. The method is based on the finite charging time constant of the double-layer capacitance, which varies approximately linearly with the local separation between the electrode surfaces. Hence, the polarization of the electrodes during short pulses and subsequent electrochemical reactions are confined to regions where the electrodes are in sufficiently close proximity. This Minireview describes the principles behind electrochemical microstructuring with short voltage pulses, and its current achievements and limitations. [source] In vitro evaluation of Er:YAG laser scaling of subgingival calculus in comparison with ultrasonic scalingJOURNAL OF PERIODONTAL RESEARCH, Issue 5 2000A. Aoki The purpose of the present study was to evaluate the effectiveness of Er:YAG laser scaling and the morphological and histological changes of the laser-scaled root surface in comparison with the effectiveness and root surface changes produced by conventional ultrasonic scaling. Fifty-three periodontally involved human extracted teeth with a band of subgingival calculus were used. The teeth were divided randomly into 2 groups for laser scaling and ultrasonic scaling. Laser irradiation was performed at an energy output of 40 mJ/pulse and 10 pulses/s under water spray, with the probe tip contacted obliquely to the root surface. Ultrasonic scaling was performed at a clinically standard power setting. The time required for scaling, the scaled area and the temperature changes were determined using both methods of treatment. The features of the scaled surfaces were examined by histological and scanning electron microscope (s.e.m.) observations. The Er:YAG laser provided subgingival calculus removal on a level equivalent to that provided by the ultrasonic scaler, without major thermal elevation. Macroscopically, the laser-treated root surface was somewhat rougher than or similar to the ultrasonically scaled root. However, the efficiency of the laser scaling was lower than that of the ultrasonic scaling. In addition, histological examination revealed a thin deeply stained zone on the lased root surface, and s.e.m. analysis revealed a characteristic microroughness on the lased surface. The laser scaling provided a level of calculus removal that was similar to that provided by the ultrasonic scaling. However, the Er:YAG laser produced superficial, structural and thermal microchanges on the root cementum. [source] Electro-optic Q-switched Yb:YAG slab laserLASER PHYSICS LETTERS, Issue 5 2006Q. Liu Abstract A novel side-pumped structure with microlens-free diode arrays and a lensduct was demonstrated. This structure is much more robust and simple than traditional approach of a microlens-conditioned diode arrays with a lensduct. A quasi-CW diode arrays side-pumped KD*P Q-switched Yb:YAG slab laser has been demonstrated. An output energy of ,10 mJ/pulse with pulse width as short as ,20ns is obtained at 1,10 Hz repetition rate. To our knowledge, this is the shortest pulse width of Electro-optic Q-switched laser output by using Yb:YAG as the gain medium. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Micromorphology of resin,dentin interfaces using one-bottle etch&rinse and self-etching adhesive systems on laser-treated dentin surfaces: A confocal laser scanning microscope analysisLASERS IN SURGERY AND MEDICINE, Issue 7 2010Marcelo Tavares de Oliveira DDS Abstract Background and Objectives This study evaluated the hybrid layer (HL) morphology created by three adhesive systems (AS) on dentin surfaces treated with Er:YAG laser using two irradiation parameters. Study Design Occlusal flat dentin surfaces of 36 human third molars were assigned into nine groups (n,=,4) according to the following ASs: one bottle etch&rinse Single Bond Plus (3M ESPE), two-step Clearfil Protect Bond (Kuraray), and all-in-one S3 Bond (Kuraray) self-etching, which were labeled with rhodamine B or fluorescein isothiocyanate,dextran and were applied to dentin surfaces that were irradiated with Er:YAG laser at either 120 (38.7,J/cm2) or 200,mJ/pulse (64.5,J/cm2), or were applied to untreated dentin surfaces (control group). The ASs were light-activated following MI and the bonded surfaces were restored with resin composite Z250 (3M ESPE). After 24,hours of storage in vegetable oil, the restored teeth were vertically, serially sectioned into 1-mm thick slabs, which had the adhesive interfaces analyzed with confocal laser microscope (CLSM,LSM 510 Meta). CLSM images were recorded in the fluorescent mode from three different regions along each bonded interface. Results Non-uniform HL was created on laser-irradiated dentin surfaces regardless of laser irradiation protocol for all AS, while regular and uniform HL was observed in the control groups. "Stretch mark"-like red lines were found within the HL as a result of resin infiltration into dentin microfissures, which were predominantly observed in 200,mJ/pulse groups regardless of AS. Poor resin infiltration into peritubular dentin was observed in most regions of adhesive interfaces created by all ASs on laser-irradiated dentin, resulting in thin resin tags with neither funnel-shaped morphology nor lateral resin projections. Conclusion Laser irradiation of dentin surfaces at 120 or 200,mJ/pulse resulted in morphological changes in HL and resin tags for all ASs evaluated in the study. Lasers Surg. Med. 42:662,670, 2010. © 2010 Wiley-Liss, Inc. [source] Low Thresholds in Polymer Lasers on Conductive Substrates by Distributed Feedback Nanoimprinting: Progress Toward Electrically Pumped Plastic LasersADVANCED MATERIALS, Issue 7 2009Ebinazar B. Namdas A light-emitting transistor (LEFET) architecture with a distributed feedback (DFB) resonator structure nanoimprinted into the gain medium offers a route to achieving an electrically pumped plastic laser. A 2D DFB laser provides lower lasing thresholds than a 1D DFB laser under identical conditions. The 2D DFB lasers exhibit excellent characteristics with lasing threshold and slope efficiency of 32,nJ/pulse and 1.2%, respectively. [source] Enhanced Solid-State Luminescence and Low-Threshold Lasing from Starburst Macromolecular Materials,ADVANCED MATERIALS, Issue 3 2009Wen-Yong Lai High solid-state quantum efficiency (,PL,,,0.90) materials with attractive properties for OLED and laser applications are reported. Our results show that long fluorene chain-lengths are not a necessary prerequisite for efficient solid-state luminescence. Isolated-molecule-like solid-state emission, stable pure-deep-blue electroluminescence, and low-threshold lasing (,laser,=,437,nm, Ethlaser,,,0.4,nJ/pulse, 1.3,µJ cm,2) are demonstrated. [source] NMR and the uncertainty principle: How to and how not to interpret homogeneous line broadening and pulse nonselectivity.CONCEPTS IN MAGNETIC RESONANCE, Issue 5 2008IV. (Un?)certainty Abstract Following the treatments presented in Parts I, II, and III, I herein address the popular notion that the frequency of a monochromatic RF pulse as well as that of a monochromatic FID is "in effect" uncertain due to the (Heisenberg) Uncertainty Principle, which also manifests itself in the fact that the FT-spectrum of these temporal entities is spread over a nonzero frequency band. I will show that the frequency spread should not be interpreted as "in effect" meaning a range of physical driving RF fields in the former, and "spin frequencies" in the latter case. The fact that a shorter pulse or a more quickly decaying FID has a wider FT-spectrum is in fact solely due to the Fourier Uncertainty Principle, which is a less well known and easily misunderstood concept. A proper understanding of the Fourier Uncertainty Principle tells us that the FT-spectrum of a monochromatic pulse is not "broad" because of any "uncertainty" in the RF frequency, but because the spectrum profile carries all of the pulse's features (frequency, phase, amplitude, length, temporal location) coded into the complex amplitudes of the FT-spectrum's constituent eternal basis harmonic waves. A monochromatic RF pulse's capability to excite nonresonant magnetizations is in fact a purely classical off-resonance effect that has nothing to do with "uncertainty". Analogously, "Lorentzian lineshape" means exactly the same thing physically as "exponential decay," and all inferences as to the physical reasons for that decay must be based on independent assumptions or observations. © 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part A 32A: 373,404, 2008. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||