Variable Number Of Pulses Research Articles

Pulsed-field ablation: analysis of a new ablation technique for atrial fibrillation. A single centre experience

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Pulsed-field ablation (PFA) is a new non-thermal, tissue-specific ablation technique. Through the application of a local electric field, it is possible to induce a selective electroporation of cardiomyocytes membranes, resulting in myocytic apoptosis and sparing of non-myocardial structures (nerves, connective tissue, esophagus, vessels). Purpose A new PFA system for atrial fibrillation (AF) ablation has recently been introduced in our hospital. The aim of this retrospective review is to share the initial results of our experience in terms of acute efficacy and safety. Methods A total of 41 adult patients suitable for AF percutaneous ablation underwent PFA between April and November 2022 in our Institute. PFA system consisted of a current generator, a deflectable sheath and a multielectrode PFA catheter. Once inside the left atrium (LA), the PFA catheter was directed to the pulmonary veins (PVs) ostia through an over-the-wire system. Then, 8 electric impulses were applied for each PV to achieve electrical isolation; in some cases, applications to the posterior left atrium wall (LAPW) were delivered to obtain LAPW isolation (LAPWI). A moderate-to-deep sedation was provided by an anesthesiologist during all the procedures. Acute ablation efficacy was defined as absence of intracavitary signals at the electroanatomic mapping and local capture failure at the pacing maneuvers. Intra and peri-procedural safety was defined as the absence of major complications (pericardial effusion/ tamponade, stroke, vascular complications, death) during the procedure and the hospitalization period. Results Of the 41 patients included, 24 (58.5%) were treated for paroxysmal AF and 17 (41.5%) for persistent AF. In almost all cases (n=40, 97.6%) pulmonary veins isolation (PVI) was performed; in 14 cases (34.1%, almost all persistent AF patients) a LAPWI was performed with the application of a variable number of pulses (mean value = 13). In most of the cases (n=28, 68.3%) an electroanatomic mapping was acquired before and after the ablation. Acute efficacy was observed in all PVI cases (n=40, 100%) and in all LAPWI cases (n=14, 100%). No periprocedural major complications were observed (n=0, 0%). Conclusions PFA is a promising ablation technique capable of inducing selective myocytic apoptosis through electroporation, causing a thick damage across the muscle with no injury of other tissues, and could become a game changer in electrophysiology in the next future. Our initial data report a combination of ease of use and high efficacy and safety profiles.

Compact picosecond mid-IR PPLN OPO with controllable peak powers

We report a high-repetition-rate, compact, mid-infrared picosecond (ps) optical parametric oscillator (OPO) based on periodically poled lithium niobate (PPLN). The OPO is synchronously pumped by an ytterbium-doped-fibre (YDF) master-oscillator-power-amplifier (MOPA) system, seeded by a 1040-nm gain-switched laser diode (GSLD). Under continuous-wave (cw) pulsed operation, at a 1.5-GHz repetition rate and 14-W pump power, an idler average power of 2.4 W (∼30 W peak power) was achieved, with an idler wavelength tunability of 2260–3573 nm. Through the addition of an electro-optic modulator (EOM) to the MOPA system, acting as a time gate to suppress a variable number of pulses per 1 µs, a quasi-cw pumping regime was realized, allowing burst-mode operation of the OPO at a 1-MHz inter-burst repetition rate. By varying the burst window time with the EOM, controllable idler peak powers of up to 1.2 kW were then realized.

Direct amplification of sub-300 fs pulses in a versatile thin-disk multipass amplifier

We report on a kW-class ultrafast laser amplifier emitting sub-300 fs pulses with a pulse peak power exceeding 1 GW. It is based on the direct amplification of 260 fs pulses in a versatile thin-disk multipass amplifier which provides fast modulation of the amplified beam on the workpiece by the implementation of a novel and robust polarization multiplexing scheme for the seed beam that is launched into the amplifier. Furthermore, the laser can be operated in a single-pulse or burst mode with a variable number of pulses per burst. Second harmonic conversion of the amplified beam by means of a lithium triborate crystal additionally led to an output power of up to 282 W in the green spectral range.

Seasonal Variation of Captive Meagre Acoustic Signalling: A Manual and Automatic Recognition Approach

Many species rely on acoustic communication to fulfil several functions such as advertisement and mediation of social interactions (e.g., agonistic, mating). Therefore, fish calls can be an important source of information, e.g., to recognize reproductive periods or to assess fish welfare, and should be considered a potential non-intrusive tool in aquaculture management. Assessing fish acoustic activity, however, often requires long sound recordings. To analyse these long recordings automatic methods are invaluable tools to detect and extract the relevant biological information. Here we present a study to characterize meagre (Argyrosomus regius) acoustic activity during social contexts in captivity using an automatic pattern-recognition methodology based on the Hidden Markov Model. Calls produced by meagre during the breading season showed a richer repertoire than previously reported. Besides the dense choruses composed by grunts already known for this species, meagre emitted successive series of isolated pulses, audible as ‘knocks’. Grunts with a variable number of pulses were also registered. The overall acoustic activity was concurrent with the number of spawning events. A diel call rhythms exhibit peak of calling activity from 15:00 to midnight. In addition, grunt acoustic parameters varied significantly along the reproduction season. These results open the possibility to use the meagre vocal activity to predict breeding and approaching spawning periods in aquaculture management.

Release calls of Moroccan spadefoot toad, Pelobates varaldii (Anura, Pelobatidae)

Abstract Release calls of Pelobates varaldii Pasteur and Bons (1959) are described quantitatively based on airborne recordings obtained from 4 males and 12 females from a population of the extreme north of its range. The calls are sequences of pulsed notes with a variable number of pulses per note. To the best of our knowledge this is the first report on the acoustic repertoire of this endemic endangered species from Morocco.

Ablation Investigation of Cemented Carbides Using Short-Pulse Laser Beams

As an excellent engineering tool material, cemented carbides are capable to shape and cut metallic materials with high surface finish quality and precision. However, in regard to conventional abrasive methods cemented carbides are difficult-to-machine materials due to their extreme hardness combined with relatively low toughness. In contrast, laser beam machining is an advanced non-contacting cutting method which is therefore suitable for shaping hard materials. In particular, the application of short-pulse laser beams enables the cutting of hard materials meeting high precision requirements. Moreover, it can effectively reduce defects induced by mechanical contacts and thermal reactions. In this paper, a general study of the ablation mechanism of cemented carbides using short-pulse laser is conducted. Special attention is paid to the correlation between the material ablation and machining parameters within the nanosecond regime: pulse number and pulse energy. In doing so, two cemented carbide grades with similar composition but different grain size have been chosen as investigated materials. An experimental set-up equipped with a nanosecond laser and an auto-stage is implemented to produce dimples on the cemented carbide surfaces with variable pulse number and pulse energy. The experimental design and characterization of geometrical features of produced dimples are presented and discussed. The work is complemented with a thorough surface integrity assessment of the shaped materials. It is found that ablation increases proportionally with the pulse number and applied energy. Regarding microstructural effects, ablation is discerned to be more pronounced in the coarse-grained grade as compared to the medium-sized one.

Design and test of component circuits of an integrated quantum voltage noise source for Johnson noise thermometry

We present design and testing of a pseudo-random number generator (PRNG) and a variable pulse number multiplier (VPNM) which are digital circuit subsystems in an integrated quantum voltage noise source for Jonson noise thermometry. Well-defined, calculable pseudo-random patterns of single flux quantum pulses are synthesized with the PRNG and multiplied digitally with the VPNM. The circuit implementation on rapid single flux quantum technology required practical circuit scales and bias currents, 279 junctions and 33mA for the PRNG, and 1677 junctions and 218mA for the VPNM. We confirmed the circuit operation with sufficiently wide margins, 80–120%, with respect to the designed bias currents.

Design and Operation of a 9-bit Single-flux-quantum Pulse-frequency Modulation Digital-to-analog Converter

We designed and operated a 9-bit single-flux-quantum (SFQ) digital-to-analog converter (DAC). SFQ pulse-frequency modulation (PFM) was employed for generation of variable quantum output voltage, where a 9-bit variable pulse number multiplier and a 100-fold voltage multiplier were the key components. Test chips were fabricated using a Nb Josephson integration technology. Arbitrary voltage waveforms were synthesized with the maximum voltage of 2.54mV. For ac voltage standard applications, relationships between the DAC resolution and the synthesized waveform frequency are discussed.

High repetition rate laser ablation for vapor–liquid–solid nanowire growth

A high repetition rate (500 kHz) solid state laser was used for the ablation process in a Pulsed Laser Deposition (PLD)/Vapor–Liquid–Solid (VLS) growing. A ZnO target was ablated with laser powers between 0.6 W and 1.2 W, and a variable number of pulses per train and trains frequencies. ZnO structures were grown on gold patterned and unpatterned substrates surfaces. Enhanced growth of the nanostructures could be noticed on the catalyst patterned surfaces. Better nanowire morphologies were also observed for bigger number of laser pulses per train. The enhancements are more evident for low laser powers. Based on plume expansion investigations, by using a high speed camera and a Particle-In-Cell (PIC) Monte-Carlo based simulations, the nanostructure morphology variations could be understood on the basis of the plume particles diffusion process and thin film versus VLS growing competition.

Demonstration of 6-bit, 0.20-mV<sub>pp</sub> Quasi-Triangle Voltage Waveform Generator Based on Pulse-Frequency Modulation

We present our design and operation of a 6-bit quasi-triangle voltage waveform generator comprising three circuit blocks; an improved variable Pulse Number Multiplier (variable-PNM), a Code Generator (CG), and a Double-Flux-Quantum Amplifier (DFQA). They are integrated into a single chip using a niobium Josephson junction technology. While the multiplication factor of our previous m-bit variable-PNM was limited between 2m-1 and 2m, that of the improved one is extended between 1 and 2m. Correct operations of the 6-bit variable-PNM are confirmed in low-speed testing with respect to the codes from the CG, whereas generation of a 6-bit, 0.20mVpp quasi-triangle voltage waveform is demonstrated with the 10-fold DFQA in high-speed testing.

Performance Analysis of Gradual Multi-pulse Pulse-Position Modulation in Deep-Space Optical Communications

A gradual multi-pulse pulse-position modulation (gradual MPPM) scheme is proposed as a new modulation scheme to improve both the performance and bandwidth-utilization efficiency of the conventional optical multi-pulse pulse-position modulation (MPPM) scheme in deep-space optical communications. Whereas in the conventional MPPM scheme, a fixed number of optical pulses is transmitted in every signal block, a variable number of pulses are transmitted in the proposed scheme. Information is represented by different combinations of the positions of these pulses. The transmission characteristics, bandwidth utilization, and power requirements for the proposed scheme are studied in this paper. Several performance measures are derived and compared with those of the conventional MPPM scheme in deep-space optical communications. Our results reveal that, at the same average power, the proposed gradual MPPM scheme achieves much lower levels of symbol-error rates than those of the ordinary MPPM scheme, whereas, at the same peak power levels, the ordinary MPPM outperforms the gradual scheme. Also, in terms of bandwidth-utilization efficiency, the proposed modulation scheme achieves higher efficiency than the ordinary MPPM by allowing many more symbols to be transmitted per frame.

Advertisement and release calls in Neotropical toads of the Rhinella granulosa group and evidence of natural hybridization between R. bergi and R. major (Anura: Bufonidae)

The Rhinella granulosa group currently includes 12 species distributed eastern to the Andes, from Panama to central Argentina. We studied bioacoustic features of the advertisement calls in seven of these species: Rhinella azarai, R. bergi, R. centralis, R. dorbignyi, R. fernandezae, R. major, and R. merianae. In addition, we analyzed the release calls of R. azarai, R. bergi, R. dorbignyi, and R. fernandezae. The advertisement calls consisted of long trills, composed by notes with a variable pulse number (2–8) that was characteristic of each species. The release calls consisted of a single note, pulsed or not. Both advertisement and release calls clearly varied between species, except for R. dorbignyi and R. fernandezae. The study of specimens sharing exosomatic characters with R. bergi and R. major from a syntopy area, which presented intermediate spectral and temporal call parameters, confirmed natural hybridization between these two species.

Influence of the cumulative effects of multiple laser pulses on laser-induced incandescence signals from soot

The effect of multiple laser pulses reaching soot particles before an actual laser-induced incandescence (LII) measurement is investigated in order to gain some insights on soot morphological and fine structure changes due to rapid laser heating. Soot, extracted from a premixed and a quenched diffusion flames, is flowing through a tubular cell and undergoes a variable number of pulses at different fluence. The response of soot is studied by the two-color LII technique. Transmission electron microscopy (TEM) analysis of laser-modified soot aggregates from the diffusion flame is also presented. The results indicate that even at low laser fluences a permanent soot transformation is induced causing an increase in the absorption function E(m). This is interpreted as an induced graphitization of soot particles by the laser pulse heating. At high fluences the vaporization process and a profound restructuring of soot particles affect the morphology of the aggregates. Soot from diffusion and premixed flames behaves in a similar way although this similarity occurs at different fluence levels indicating a different initial fine structure of soot particles.

Spectral sidebands and multipulse formation in passively mode-locked lasers

Pulse formation in passively mode locked lasers is often accompanied with dispersive waves that form of spectral sidebands due to spatial inhomogoneities in the laser cavity. Here we present an explicit calculation of the amplitude, frequency, and precise shape of the sidebands accompanying a soliton-like pulse. We then extend the study to the global steady state of mode locked laser with a variable number of pulses, and present experimental results in a mode locked fiber laser that confirm the theory. The strong correlation between the temporal width of the sidebands and the measured spacing between the pulses in multipulse operation suggests that the sidebands have an important role in the inter-pulse interaction.

Single Pulse and Pulse Train Modulation of Cutaneous Electrical Stimulation: A Comparison of Methods

: Changing the amplitude of single rectangular pulse stimuli (SP) has the disadvantage of recruiting tactile and nociceptive fibers in a changing, unknown proportion. Keeping the amplitude constant, but applying a varying number of pulses in a train is another way of stimulus variation, keeping the proportion constant. So, pulse trains (PT) with a variable number of pulses but fixed amplitude might be more suitable to study nonperipheral aspects of processing of stimuli. In this study, we compared the effects of PT and SP stimulation on subjective Numeric Rating Scale scores of perceived stimulus strength and evoked potentials (EP). A total of 41 healthy subjects were electrically stimulated at the left forearm or left middle fingertip using SP and PT stimuli. Numeric Rating Scale scores and EPs were averaged from 105 randomized stimuli at 5 stimulus amplitudes or number of pulses for each subject. The relationships between stimulus amplitudes or number of pulses, EP components and Numeric Rating Scale scores differed depending on the stimulation method and stimulus location. Although the repeatedly reported Numeric Rating Scale-EP (N150-P200) correlation was reproduced for SP at the fingertip, no significant correlation was found for SP stimulation at the forearm. For PT this correlation was found for both stimulus locations. These findings demonstrate that SP and PT involve different ways of processing. The two methods result in different Numeric Rating Scale scores and EP components. Furthermore, PT stimulation is less dependent on stimulus location.

About the Formation of a Barrier Discharge in a KrCl Excilamp

the space discharge was observed. With increasing pulse repetition frequency, diffusion channels of small diameter were formed, and at pulse repetition frequencies of ~1 kHz and higher, the discharge represented diffusion microdischarges shaped as two cones with joint apexes. The number of such microdischarges increased when the excitation power increases, for example, due to increased pulse repetition frequency, and they occupied the entire excilamp volume (cone bases covered the entire surface of quartz tubes). In this case, the maximum radiation power was obtained for the discharge consisting of diffusion microdischarges, and the maximum radiation efficiency was recorded at intermediate pulse repetition frequencies (~1 kHz), when the first diffusion cone-shaped microdischarges were formed. The present work studies the dynamics of the formation of the stationary barrier discharge stage for which the average radiation power of KrCl* molecules reaches its maximum. In our experiments, we used a coaxial excilamp described in [1, 2]. It was manufactured from two quartz tubes. The external diameter of the outer tube with walls having a thickness of 2.5 mm was equal to 65 mm, and the external diameter of the inner tube with walls having a thickness of 1.5 mm was equal to 43 mm. The discharge gap was 8.5 mm. The excilamp length was 57 cm. The length of the external grid electrode was 10 cm. The internal electrode was made from an aluminum foil. The inner quartz tube together with the electrode was cooled with running water. Unipolar excitation pulses had amplitudes up to 8 kV, duration of ~1.5 µs, and repetition frequency of 75 kHz. The given excitation pulse repetition frequency ensured comparatively high average radiation power and efficiency of KrCl* molecules (λ ~ 222 nm) equal to 35 mW/cm 2 and 11%, respectively. To study the dynamics of the barrier discharge ignition, excitation pulses were applied in series with variable number of pulses in each train. Pulse trains were applied with a frequency of 1 Hz. The pulse train duration increased continuously from 10 µs to 0.5 s, which allowed us to trace successive changes in the discharge shape after switching on the excilamp. During the experiment, we registered the voltage pulses on the excilamp, the discharge current, and radiation pulses of KrCl* molecules in the UV range of the spectrum. In addition, we took photographs of the discharge glow at various durations of the excitation pulse trains. Before the experiments, we optimized the pressure and composition of the working mixture. The best results were obtained at a pressure of 200 Torr for the Kr : Cl2 mixture in the ratio 200 : (1–0.5). The main results of the experiments were the following. The excilamp started to operate in the stationary mode 1 min after switching on, and four characteristic discharge stages were identified during the first second of its operation. In the first stage (0–0.02 ms), the space discharge was formed in the interelectrode gap. In the second stage (0.02–0.1 ms), filamentary channels were registered against the background of the space glow; then (0.1–400 ms) the filamentary channels were converted into a comparatively small number of bright branching channels whose radiation efficiency was low. In the fourth stationary stage typically formed in ∼1 s, only cone-shaped microdischarges were observed, and the efficiency of

The fabrication of nickel and chromium silicide using an XeCl excimer laser

The formation of nickel and chromium silicides using an XeCl excimer laser has been studied. Both metals are deposited to a thickness of 500 Å by electron beam evaporation on silicon substrates. These layers are then processed using laser fluences ranging from 0.45 to 1.4 J/cm 2, and a variable number of pulses. Rutherford backscattering spectrometry (RBS) and cross-sectional transmission electron microscopy (XTEM) indicate the formation of crystalline NiSi 2 and CrSi 2 at the Ni Si and Cr Si interfaces, respectively.

Advertisement Call Discrimination by Female Cricket Frogs (Acris crepitans)

siderable attention (see Fritzsch et al., 1988). Variation in the advertisement call of the cricket frog, Acris crepitans, has been studied thoroughly (Nevo and Capranica, 1985; Wagner, 1989a; Ryan and Wilczynski, 1991). The male call is a click that is sung in a series known as a call group. Each call is composed of a variable number of pulses that can be partitioned into pulse groups. Typically, call duration increases from the beginning to the end of call groups. We refer to this variation in call duration from beginning to end of a call group as a graded signal. Wagner (1989a, b, c) and Perrill and Shepherd (1989) studied the social correlates associated with the auditory signals of Blanchard's cricket frog. In this study, we used two-choice discrimination tests to measure female preferences for temporal pattern, sound intensity, call rate, and dominant frequency. We demonstrate that females prefer calls of higher sound intensity, higher call rate, and lower dominant frequency. Females do not appear to discriminate among males based on variation in temporal pattern. A series of ponds in a city park in central Indiana served as the study site. Amplexed pairs of Acris crepitans were collected and brought to the lab. Females were separated from males and tested within 12 h of capture. All of the females responded at least once to the stimuli presented and some females gave as many as three responses. Females were not tested with the same stimulus more than once. l i s. colog 72:1225-

Advertisement calls of two anuran amphibians,Rana tigrina andTomopterna breviceps

Rana tigrina andTomopterna breviceps occur as sympatric species at Dharwad, India. Sexually mature males produce advertisement calls. The advertisement call of both the species consist of a number of calls produced in series forming a call group. Each call group ofRana tigrina comprises 10–40 calls, whereas that ofTomopterna breviceps consists 13–141 calls. Each call consists of a pulse group with variable number of pulses which lack pulse interval. Calls of both the species exhibit similarities in (i) call consisting of series of calls with a pulse group in each call, (ii) absence of pulse interval within the pulse group, (iii) the amplitude of the first pulse being always small, and (iv) the frequency spectrum beginning from 200 Hz. Based on the similarities in the spectral features of the calls, it is suggested that the two species may be closely related to each other.

Relative fertility in hybridization experiments using three song types of the held crickets Gryllus integer and Gryllus rubens

Species-specific calling songs of male field crickets attract conspecific females. Each wing closure results in a pulse of sound, and the song is composed of pulses arranged in species-specific patterns of short chirps, long continuous trills, or intermediates between chirps and trills. California Gryllus integer has a song with pulses of sound delivered in groups of two or three to produce a chirp, but in central Texas, the G. integer song has a variable number of pulses delivered in long continuous trills. Gryllus rubens occurs from eastern Texas to Florida and has a trilling song with a slower pulse rate than that of Texas G. integer. Identification of these three groups in the laboratory was confirmed by recording and analyzing songs for California and Texas G. integer and G. rubens males. All possible crosses were performed in the laboratory between conspecifics and heterospecifics. No progeny resulted in California G. integer and Texas G. integer or California G. integer and G. rubens crosses. Hybrids were produced in G. rubens and Texas G. integer crosses. Results suggest that California and Texas G. integer are different species, or at least populations geographically separated enough to result in reproductive incompatibility and different song types. Texas G. integer and G. rubens are apparently closely related species.