An Evaluation of Time-Trial-Based Predictions of V[Combining Dot Above]O2max and Recommended Training Paces for Collegiate and Recreational Runners.

PubMed

Scudamore, Eric M; Barry, Vaughn W; Coons, John M

2018-04-01

Scudamore, EM, Barry, VW, and Coons, JM. An Evaluation of time-trial-based predictions of V[Combining Dot Above]O2max and recommended training paces for collegiate and recreational runners. J Strength Cond Res 32(4): 1137-1143, 2018-The purpose of the current study was to determine the accuracy of Jack Daniels' VDOT Running Calculator for the prediction of V[Combining Dot Above]O2max, and recommendations of interval and training paces (pIN and pTH) in samples of National Collegiate Athletic Association Division 1 track athletes (ATH, n = 11) and recreational runners (REC; n = 9). Predicted variable data were obtained using results from indoor 5-km time-trials. Data from the VDOT Calculator were compared with laboratory-tested V[Combining Dot Above]O2max, pace at V[Combining Dot Above]O2max (V[Combining Dot Above]O2maxpace), and lactate threshold pace (LTpace). Results indicated that VDOT underestimated V[Combining Dot Above]O2max in ATH (t(10) = -6.00, p < 0.001, d = 1.75) and REC (t(8) = -8.96, p < 0.001, d = 3.44). Follow-up between-groups analysis indicated that the difference between VDOT and V[Combining Dot Above]O2max was significantly greater in REC than in ATH (p = 0.0031, d = 1.59). pIN was slower than V[Combining Dot Above]O2maxpace in REC (t(8) = -4.26, p = 0.003, d = 1.76), but not different in ATH (t(10) = 0.52, p = 0.614, d = 0.14). Conversely, pTH was faster than LTpace in ATH (t(8) = -4.17, p = 0.003, d = 1.49), but not different in REC (t(8) = 1.64, p = 0.139, d = 0.57). Practically, pTH can be confidently used for threshold training regardless of the ability level. pIN also seemed to be accurate for ATH, but may be not be optimal for improving V[Combining Dot Above]O2max in REC. Practitioners should interpret VDOT with caution as it may underestimate V[Combining Dot Above]O2max.

Bipolar leads for use with permanently implantable cardiac pacing systems: a review of limitations of traditional and coaxial configurations and the development and testing of new conductor, insulation, and electrode designs.

PubMed

Tyers, G F; Mills, P; Clark, J; Cheesman, M; Yeung-Lai-Wah, J A; Brownlee, R R

1997-01-01

The unacceptable rate of mechanical failures, threshold problems, and recalls experienced with many coaxial bipolar cardiac pacing lead designs are reviewed in detail. To address these problems, redundant insulation coradial atrial and ventricular tined leads (AL and VL, respectively) with iridium oxide electrodes were developed and subjected to extensive accelerated testing. There were no mechanical failures. The new lead body design proved to be much more durable than widely used trifilar MP35N configurations. The data reviewed and early and current test results are strongly supportive of tightly coupled insulation being a major factor in improving lead durability as long as the insulating material is not stressed. In addition to improving flex life, insulation adherence to the conductor may reduce the potential for ionic degradation. Pacing and sensing thresholds in animal studies of the new leads were within the reported range for leads with steroid eluting electrodes. A multicenter Canadian clinical trial was initiated with the first implant in early January 1994. By November 1995, 110 VL and 82 AL had been placed in 124 patients and followed for a mean of 11 +/- 6 months; maximum 21, total 1355. There were 60 males and 64 females with a mean age of 64 +/- 16 years, range 15-88. Primary indications for pacing were AV block in 61 patients, sick sinus syndrome in 53, vasovagal syncope in 4, and congestive heart failure in 7. Many patients had associated or primary tachyarrhythmias, including 111 with supraventricular and 12 with ventricular. Forty-two percent of patients (52/124) had prior cardiac procedures, including 18 open heart surgeries and 20 AV nodal ablations. At implant, 8 lead characteristics were rated good or excellent in 90% (746/829) of evaluations. X-ray visibility was of concern in 10% of patients (12/124). Three perioperative complications occurred, including displacement of one AL (1.2%) and one VL (0.9%). There were no subsequent mechanical (connector, conductor, or insulation) or functional (exit block, micro or macro displacement, or over- or undersensing) problems. Implant pacing thresholds (PT) at 0.45 ms were AL, 0.6 +/- 0.2 (74) and VL 0.4 +/- 0.2 V; impedance (Z) at 3.5 V output AL 373 +/- 77 (82) and VL 497 +/- 117 omega. Sensing thresholds (ST) were AL 3.1 +/- 1.6 (74) and VL 10.3 +/- 4.9 mV. Ventricular lead data were obtained for all patients (N = 110). Atrial lead data are incomplete, because some patients were in atrial fibrillation during implantation. After 12 months, AL PT at 1.5 V output was 0.18 +/- 0.10 ms (21) and at 2.5 V was 0.10 +/- 0.053 (22). Associated AL ST was 3.3 +/- 0.9 mV (21) AL Z 500 +/- 65 omega (25). After 18 months VL PT at 1.5 V was 0.15 +/- 0.10 ms (9) and at 2.5 V output was 0.09 +/- 0.04 ms (9). Associated VL ST was > 7.5 +/- 2.4 mV (9) and VL Z 497 +/- 105 omega (9). Follow-up time discrepancy is due to the VL being available 6 months earlier than the AL. There were no 30-day deaths and only one late death at 10 months in a patient with chronic atrial fibrillation. Death was unrelated to pacer or lead function. At 1 year, 68% AL (15/22) and 62% (24/39) captured at 0.5 V and < or = 1 ms pulse width output. Innovative adherent insulation coradial bipolar lead conductors of the design studied combined with coated iridium oxide electrodes provide for a negligible incidence of mechanical or functional failure with clinical follow-up now approaching 3 years. Excellent acute and chronic sensing and pacing thresholds have been documented. Late thresholds have continued to improve gradually. Long-term clinical pacing at < or = 1.5 V output with a large safety margin is feasible in essentially all patients. This coradial design produces very flexible < 5 French bipolar redundantly insulated lead bodies allowing both AL and VL to simultaneously pass through a single 10 French introducer sheath. (ABSTRACT TRUNCATED)

Autocapture compatibility in patients with the MembraneEX lead and Affinity pulse generators.

PubMed

Schuchert, A; Voitk, J; Liu, B; Kolk, R; Stammwitz, E; Beiras, J

2001-10-01

The first Autocapture generation worked well with all recommended leads. The newer Autocapture generation provides a more sensitive resolution for evoked response testing and its implementation in a dual-chamber device. The purpose of the study was to evaluate the performance of the Affinity SR/DR pacemaker with the new Autocapture algorithm in combination with the small surface area pacing lead MembraneEX in 129 patients. Autocapture ventricular threshold, sensing threshold, lead impedance, evoked response (ER) and polarization signals were determined at implantation and discharge, as well as after 1 and 3 months. Autocapture recommendation rate was based on the ER sensitivity test. The median pacing threshold was 0.38, 0.50, 0.75, 0.75 V at implant, discharge, 1 and 3 months post-implant, respectively. The respective data for median lead impedance were 744, 605, 649 and 691 ohms; median sensing threshold was 12.5 mV at all visits. The median ER amplitude was 9.0, 10.1, 9.9 and 10.1 mV and the median polarization signal 0.39 mV at all visits. The frequency of recommended Autocapture activation was 98.3%, 99.2%, 98.3% and 96.2% of all patients at implant, at discharge, 1 and 3 months post-implant respectively. In conclusion, the studied pulse generator enabled, in combination with this pacing lead, in >95% of all patients activation of Autocapture.

Robotic positioning of standard electrophysiology catheters: a novel approach to catheter robotics.

PubMed

Knight, Bradley; Ayers, Gregory M; Cohen, Todd J

2008-05-01

Robotic systems have been developed to manipulate and position electrophysiology (EP) catheters remotely. One limitation of existing systems is their requirement for specialized catheters or sheaths. We evaluated a system (Catheter Robotics Remote Catheter Manipulation System [RCMS], Catheter Robotics, Inc., Budd Lake, New Jersey) that manipulates conventional EP catheters placed through standard introducer sheaths. The remote controller functions much like the EP catheter handle, and the system permits repeated catheter disengagement for manual manipulation without requiring removal of the catheter from the body. This study tested the hypothesis that the RCMS would be able to safely and effectively position catheters at various intracardiac sites and obtain thresholds and electrograms similar to those obtained with manual catheter manipulation. Two identical 7 Fr catheters (Blazer II; Boston Scientific Corp., Natick, Massachusetts) were inserted into the right femoral veins of 6 mongrel dogs through separate, standard 7 Fr sheaths. The first catheter was manually placed at a right ventricular endocardial site. The second catheter handle was placed in the mating holder of the RCMS and moved to approximately the same site as the first catheter using the Catheter Robotics RCMS. The pacing threshold was determined for each catheter. This sequence was performed at 2 right atrial and 2 right ventricular sites. The distance between the manually and robotically placed catheters tips was measured, and pacing thresholds and His-bundle recordings were compared. The heart was inspected at necropsy for signs of cardiac perforation or injury. Compared to manual positioning, remote catheter placement produced the same pacing threshold at 7/24 sites, a lower threshold at 11/24 sites, and a higher threshold at only 6/24 sites (p > 0.05). The average distance between catheter tips was 0.46 +/- 0.32 cm (median 0.32, range 0.13-1.16 cm). There was no difference between right atrial and right ventricular sites (p > 0.05). His-bundle electrograms were equal in amplitude and timing. Further, the remote navigation catheter was able to be disengaged, manually manipulated, then reengaged in the robot without issue. There was no evidence of perforation. The Catheter Robotics remote catheter manipulation system, which uses conventional EP catheters and introducer sheaths, appears to be safe and effective at directing EP catheters to intracardiac sites and achieving pacing thresholds and electrograms equivalent to manually placed catheters. Further clinical studies are needed to confirm these observations.

The rationale and design of the Micra Transcatheter Pacing Study: safety and efficacy of a novel miniaturized pacemaker.

PubMed

Ritter, Philippe; Duray, Gabor Z; Zhang, Shu; Narasimhan, Calambur; Soejima, Kyoko; Omar, Razali; Laager, Verla; Stromberg, Kurt; Williams, Eric; Reynolds, Dwight

2015-05-01

Recent advances in miniaturization technologies and battery chemistries have made it possible to develop a pacemaker small enough to implant within the heart while still aiming to provide similar battery longevity to conventional pacemakers. The Micra Transcatheter Pacing System is a miniaturized single-chamber pacemaker system that is delivered via catheter through the femoral vein. The pacemaker is implanted directly inside the right ventricle of the heart, eliminating the need for a device pocket and insertion of a pacing lead, thereby potentially avoiding some of the complications associated with traditional pacing systems. The Micra Transcatheter Pacing Study is currently undergoing evaluation in a prospective, multi-site, single-arm study. Approximately 720 patients will be implanted at up to 70 centres around the world. The study is designed to have a continuously growing body of evidence and data analyses are planned at various time points. The primary safety and efficacy objectives at 6-month post-implant are to demonstrate that (i) the percentage of Micra patients free from major complications related to the Micra system or implant procedure is significantly higher than 83% and (ii) the percentage of Micra patients with both low and stable thresholds is significantly higher than 80%. The safety performance benchmark is based on a reference dataset of 977 subjects from 6 recent pacemaker studies. The Micra Transcatheter Pacing Study will assess the safety and efficacy of a miniaturized, totally endocardial pacemaker in patients with an indication for implantation of a single-chamber ventricular pacemaker. NCT02004873. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

Time-Resolved Transposon Insertion Sequencing Reveals Genome-Wide Fitness Dynamics during Infection.

PubMed

Yang, Guanhua; Billings, Gabriel; Hubbard, Troy P; Park, Joseph S; Yin Leung, Ka; Liu, Qin; Davis, Brigid M; Zhang, Yuanxing; Wang, Qiyao; Waldor, Matthew K

2017-10-03

Transposon insertion sequencing (TIS) is a powerful high-throughput genetic technique that is transforming functional genomics in prokaryotes, because it enables genome-wide mapping of the determinants of fitness. However, current approaches for analyzing TIS data assume that selective pressures are constant over time and thus do not yield information regarding changes in the genetic requirements for growth in dynamic environments (e.g., during infection). Here, we describe structured analysis of TIS data collected as a time series, termed pattern analysis of conditional essentiality (PACE). From a temporal series of TIS data, PACE derives a quantitative assessment of each mutant's fitness over the course of an experiment and identifies mutants with related fitness profiles. In so doing, PACE circumvents major limitations of existing methodologies, specifically the need for artificial effect size thresholds and enumeration of bacterial population expansion. We used PACE to analyze TIS samples of Edwardsiella piscicida (a fish pathogen) collected over a 2-week infection period from a natural host (the flatfish turbot). PACE uncovered more genes that affect E. piscicida 's fitness in vivo than were detected using a cutoff at a terminal sampling point, and it identified subpopulations of mutants with distinct fitness profiles, one of which informed the design of new live vaccine candidates. Overall, PACE enables efficient mining of time series TIS data and enhances the power and sensitivity of TIS-based analyses. IMPORTANCE Transposon insertion sequencing (TIS) enables genome-wide mapping of the genetic determinants of fitness, typically based on observations at a single sampling point. Here, we move beyond analysis of endpoint TIS data to create a framework for analysis of time series TIS data, termed pattern analysis of conditional essentiality (PACE). We applied PACE to identify genes that contribute to colonization of a natural host by the fish pathogen Edwardsiella piscicida. PACE uncovered more genes that affect E. piscicida 's fitness in vivo than were detected using a terminal sampling point, and its clustering of mutants with related fitness profiles informed design of new live vaccine candidates. PACE yields insights into patterns of fitness dynamics and circumvents major limitations of existing methodologies. Finally, the PACE method should be applicable to additional "omic" time series data, including screens based on clustered regularly interspaced short palindromic repeats with Cas9 (CRISPR/Cas9). Copyright © 2017 Yang et al.

A feasible approach for direct his-bundle pacing using a new steerable catheter to facilitate precise lead placement.

PubMed

Zanon, Francesco; Baracca, Enrico; Aggio, Silvio; Pastore, Gianni; Boaretto, Graziano; Cardano, Paola; Marotta, Tiziana; Rigatelli, Gianluca; Galasso, Mariapaola; Carraro, Mauro; Zonzin, Pietro

2006-01-01

Much clinical evidence has shown that right ventricular (RV) apical pacing is detrimental to left ventricular function. Preservation of the use of the His-Purkinje (H-P) system may be ideal in heart block that is restricted to the AV node, but may be of no benefit when H-P disease exists. To investigate the feasibility of direct His-bundle pacing (DHBP) using a new system consisting of a steerable catheter and a new 4.1 F screw-in lead. Between May and December 2004, 26 patients (19 male, mean age: 77 +/- 5 years) with a standard pacemaker (PM) indication and preserved His-bundle conduction were enrolled and DHBP was attempted. DHBP was achieved in 24 patients (92%); two patients were paced in the His area, but the paced QRS morphology and duration were different from the native QRS. The mean time for lead positioning was 19 +/- 17 minutes, the mean fluoroscopy time was 11 +/- 8 minutes, and the total procedure time (skin-to-skin including positioning of a quadripolar diagnostic catheter for His recording) was 75 +/- 18 minutes. In DHBP pacing, the acute pacing threshold was 2.3 +/- 1.0 V at a pulse duration of 0.5 msec, and the sensed potentials were 2.9 +/- 2.0 mV. At a 3-month follow-up examination, the same QRS duration and morphology recorded on implantation were observed in all patients. The pacing threshold was 2.8 +/- 1.4 V, and sensed potentials were 2.5 +/- 1.8 mV; the sensing configuration was changed from bipolar to unipolar in 6 patients to resolve undersensing issues. No major complications were observed. This feasibility study shows that DHBP can be accomplished with a new system consisting of a steerable catheter and an active fixation lead in 92% of the patients in whom it was attempted.

Effect of steroid eluting versus conventional electrodes on propafenone induced rise in chronic ventricular pacing threshold.

PubMed

Cornacchia, D; Fabbri, M; Maresta, A; Nigro, P; Sorrentino, F; Puglisi, A; Ricci, R; Peraldo, C; Fazzari, M; Pistis, G

1993-12-01

The aim of this study was to evaluate chronic ventricular pacing threshold increase after oral propafenone therapy. Eighty-three patients affected by advanced atrioventricular block and sick sinus syndrome were studied at least 3 months after pacemaker implantation, before and after oral propafenone therapy (450-900 mg/day based on body weight). The patients were subdivided into three groups according to the type of unipolar electrode that was implanted: group I (41 patients) Medtronic CapSure 4003, group II (30 patients) Medtronic Target Tip 4011, and group III (12 patients) Osypka Vy screw-in lead. In all cases a Medtronic unipolar pacemaker was implanted: 30 Minix, 23 Activitrax, 14 Elite, 12 Legend, and 4 Pasys. Propafenone blood level was measured in 75 patients 3-5 hours after propafenone administration. The pacing autothreshold was measured at 0.8 V, 1.6 V, and 2.5 V by reducing pulse width. At the three different outputs before and after propafenone, threshold increments were significantly lower in group I in comparison with group II and group III (propafenone ranging from < 0.001 to < 0.05). No significant difference was found in pacing impedance or in propafenone plasma concentration in the three groups. Strength-duration curves were drawn for each group at baseline and after propafenone administration. Before propafenone, in group I, the knee was markedly shifted to the left and downward as compared to the classic curve, so that the steep part was predominant; in group II and group III this shift was progressively less evident.(ABSTRACT TRUNCATED AT 250 WORDS)

A randomized trial of the effect of automated ventricular capture on device longevity and threshold measurement in pacemaker patients.

PubMed

Koplan, Bruce A; Gilligan, David M; Nguyen, Luc S; Lau, Theodore K; Thackeray, Lisa M; Berg, Kellie Chase

2008-11-01

An automatic capture (AC) algorithm adjusts ventricular pacing output to capture the ventricle while optimizing output to 0.5 V above threshold. AC maintains this output and confirms capture on a beat-to-beat basis in bipolar and unipolar pacing and sensing. To assess the AC algorithm and its impact on device longevity. Patients implanted with a pacemaker were randomized 1:1 to have the AC feature on or off for 12 months. Two threshold tests were conducted at each visit- automatic threshold and manual threshold. Average ventricular voltage output and projected device longevity were compared between AC on and off using nonparametric tests. Nine hundred ten patients were enrolled and underwent device implantation. Average ventricular voltage output was 1.6 V for the AC on arm (n = 444) and 3.1 V for the AC off arm (n = 446) (P < 0.001). Projected device longevity was 10.3 years for AC on and 8.9 years for AC off (P < 0.0001), or a 16% increase in longevity for AC on. The proportion of patients in whom there was a difference between automatic threshold and manual threshold of

Modeling bipolar stimulation of cardiac tissue

NASA Astrophysics Data System (ADS)

Galappaththige, Suran K.; Gray, Richard A.; Roth, Bradley J.

2017-09-01

Unipolar stimulation of cardiac tissue is often used in the design of cardiac pacemakers because of the low current required to depolarize the surrounding tissue at rest. However, the advantages of unipolar over bipolar stimulation are not obvious at shorter coupling intervals when the tissue near the pacing electrode is relatively refractory. Therefore, this paper analyzes bipolar stimulation of cardiac tissue. The strength-interval relationship for bipolar stimulation is calculated using the bidomain model and a recently developed parsimonious ionic current model. The strength-interval curves obtained using different electrode separations and arrangements (electrodes placed parallel to the fibers versus perpendicular to the fibers) indicate that bipolar stimulation results in more complex activation patterns compared to unipolar stimulation. An unusually low threshold stimulus current is observed when the electrodes are close to each other (a separation of 1 mm) because of break excitation. Unlike for unipolar stimulation, anode make excitation is not present during bipolar stimulation, and an abrupt switch from anode break to cathode make excitation can cause dramatic changes in threshold with very small changes in the interval. These results could impact the design of implantable pacemakers and defibrillators.

'PACE-Gate': When clinical trial evidence meets open data access.

PubMed

Geraghty, Keith J

2017-08-01

Science is not always plain sailing and sometimes the voyage is across an angry sea. A recent clinical trial of treatments for chronic fatigue syndrome (the PACE trial) has whipped up a storm of controversy. Patients claim the lead authors overstated the effectiveness of cognitive behavioural therapy and graded exercise therapy by lowering the thresholds they used to determine improvement. In this extraordinary case, patients discovered that the treatments tested had much lower efficacy after an information tribunal ordered the release of data from the PACE trial to a patient who had requested access using a freedom of information request.

Meta-Analysis of Single-Case Research Design Studies on Instructional Pacing.

PubMed

Tincani, Matt; De Mers, Marilyn

2016-11-01

More than four decades of research on instructional pacing has yielded varying and, in some cases, conflicting findings. The purpose of this meta-analysis was to synthesize single-case research design (SCRD) studies on instructional pacing to determine the relative benefits of brisker or slower pacing. Participants were children and youth with and without disabilities in educational settings, excluding higher education. Tau-U, a non-parametric statistic for analyzing data in SCRD studies, was used to determine effect size estimates. The article extraction yielded 13 instructional pacing studies meeting contemporary standards for high quality SCRD research. Eleven of the 13 studies reported small to large magnitude effects when two or more pacing parameters were compared, suggesting that instructional pacing is a robust instructional variable. Brisker instructional pacing with brief inter-trial interval (ITI) produced small increases in correct responding and medium to large reductions in challenging behavior compared with extended ITI. Slower instructional pacing with extended wait-time produced small increases in correct responding, but also produced small increases in challenging behavior compared with brief wait-time. Neither brief ITI nor extended wait-time meets recently established thresholds for evidence-based practice, highlighting the need for further instructional pacing research. © The Author(s) 2016.

[Loss of capture by myocardial ischemia: A case report].

PubMed

Sonou, A; Adjagba, P M; Hounkponou, M; Codjo, L; Houéhanou-Sonou, C; Assani, S; Yessoufou, T; Sacca, J; Houénassi, M

2017-02-01

We report the case of a patient with pacemaker who presented chest pain during exercise followed by fainting. He has a history of arterial hypertension and diabetes. The initial examination was normal; the ventricular stimulation threshold was 1.125 volts (V) and cardiac enzymes were normal. Stress test has reproduced chest pain followed by loss of pacemaker capture and asystole. Coronary angiography showed a tight stenosis of the proximal anterior interventricular artery dilated by a drug-eluting stent. The control of stress test was normal. A stent thrombosis eight days later led to an acute coronary syndrome with recurrent syncope due to the loss of ventricular capture. The ventricular pacing threshold was then 2.25V. After revascularization and stabilization of the patient's clinical status, this threshold returned to 1.125V. This clinic case has confirmed that coronary artery disease could increase pacing threshold. It also highlights the usefulness of automatic capture algorithms in coronary patients. The stress test cannot only help to detect coronary artery disease but also allows the optimization of programming the pacemaker. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Voltage and pace-capture mapping of linear ablation lesions overestimates chronic ablation gap size.

PubMed

O'Neill, Louisa; Harrison, James; Chubb, Henry; Whitaker, John; Mukherjee, Rahul K; Bloch, Lars Ølgaard; Andersen, Niels Peter; Dam, Høgni; Jensen, Henrik K; Niederer, Steven; Wright, Matthew; O'Neill, Mark; Williams, Steven E

2018-04-26

Conducting gaps in lesion sets are a major reason for failure of ablation procedures. Voltage mapping and pace-capture have been proposed for intra-procedural identification of gaps. We aimed to compare gap size measured acutely and chronically post-ablation to macroscopic gap size in a porcine model. Intercaval linear ablation was performed in eight Göttingen minipigs with a deliberate gap of ∼5 mm left in the ablation line. Gap size was measured by interpolating ablation contact force values between ablation tags and thresholding at a low force cut-off of 5 g. Bipolar voltage mapping and pace-capture mapping along the length of the line were performed immediately, and at 2 months, post-ablation. Animals were euthanized and gap sizes were measured macroscopically. Voltage thresholds to define scar were determined by receiver operating characteristic analysis as <0.56 mV (acutely) and <0.62 mV (chronically). Taking the macroscopic gap size as gold standard, error in gap measurements were determined for voltage, pace-capture, and ablation contact force maps. All modalities overestimated chronic gap size, by 1.4 ± 2.0 mm (ablation contact force map), 5.1 ± 3.4 mm (pace-capture), and 9.5 ± 3.8 mm (voltage mapping). Error on ablation contact force map gap measurements were significantly less than for voltage mapping (P = 0.003, Tukey's multiple comparisons test). Chronically, voltage mapping and pace-capture mapping overestimated macroscopic gap size by 11.9 ± 3.7 and 9.8 ± 3.5 mm, respectively. Bipolar voltage and pace-capture mapping overestimate the size of chronic gap formation in linear ablation lesions. The most accurate estimation of chronic gap size was achieved by analysis of catheter-myocardium contact force during ablation.

Subclavian vein pacing and venous pressure waveform measurement for phrenic nerve monitoring during cryoballoon ablation of atrial fibrillation.

PubMed

Ghosh, Justin; Singarayar, Suresh; Kabunga, Peter; McGuire, Mark A

2015-06-01

The phrenic nerves may be damaged during catheter ablation of atrial fibrillation. Phrenic nerve function is routinely monitored during ablation by stimulating the right phrenic nerve from a site in the superior vena cava (SVC) and manually assessing the strength of diaphragmatic contraction. However the optimal stimulation site, method of assessing diaphragmatic contraction, and techniques for monitoring the left phrenic nerve have not been established. We assessed novel techniques to monitor phrenic nerve function during cryoablation procedures. Pacing threshold and stability of phrenic nerve capture were assessed when pacing from the SVC, left and right subclavian veins. Femoral venous pressure waveforms were used to monitor the strength of diaphragmatic contraction. Stable capture of the left phrenic nerve by stimulation in the left subclavian vein was achieved in 96 of 100 patients, with a median capture threshold of 2.5 mA [inter-quartile range (IQR) 1.4-5.0 mA]. Stimulation of the right phrenic nerve from the subclavian vein was superior to stimulation from the SVC with lower pacing thresholds (1.8 mA IQR 1.4-3.3 vs. 6.0 mA IQR 3.4-8.0, P < 0.001). Venous pressure waveforms were obtained in all patients and attenuation of the waveform was always observed prior to onset of phrenic nerve palsy. The left phrenic nerve can be stimulated from the left subclavian vein. The subclavian veins are the optimal sites for phrenic nerve stimulation. Monitoring the femoral venous pressure waveform is a novel technique for detecting impending phrenic nerve damage. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

Clinical safety of an MRI conditional implantable cardioverter defibrillator system: A prospective Monocenter ICD-Magnetic resonance Imaging feasibility study (MIMI).

PubMed

Kypta, Alexander; Blessberger, Hermann; Hoenig, Simon; Saleh, Karim; Lambert, Thomas; Kammler, Juergen; Fellner, Franz; Lichtenauer, Michael; Steinwender, Clemens

2016-03-01

The aim of this study was to evaluate the safety and efficacy of the Lumax 740(®) Implantable Cardioverter Defibrillator (ICD) system in patients undergoing a defined 1.5 Tesla (T) MRI. Between November 2013 and April 2014, eighteen patients (age range, 41-78 years; mean age, 64 years) implanted with a Lumax 740(®) ICD system for at least 6 weeks before an MRI were enrolled into this single-center feasibility study. The local ethics committee approved the study before patients gave written informed consent. Patients underwent defined MRI 1.5T of the brain and lower lumbar spine with three safety follow-up evaluations obtained during the 3-month study period. Data were analyzed descriptively. Study endpoints were the absence of either MRI and pacing system related serious adverse device effects (SADE), or of a ventricular pacing threshold increase >0.5V, or of an R-wave amplitude attenuation < 50%, or of an R-wave amplitude < 5.0 mV at 1-month follow-up. The assessment of safety and efficacy was supported by recording of all adverse events, changes in pacing threshold, R-wave sensing, pacing impedances and in battery status. Sixteen patients completed the MRI and the follow-up period. As no SADE occurred, the SADE free rate was 100%. Freedom from ventricular pacing threshold increase was 100% (16/16; 95%CI: 82.9%; 100.0%). There were no significant differences between baseline and follow-up measurements of sensing amplitudes (-0.58 ± 2.07 mV, P = 0.239, -0.41 ± 1.04 mV, P = 0.133, and -0.25 ± 1.36 mV, P = 0.724, for immediately after, 1 month and 3 months after MRI scan, respectively) and pacing thresholds (-0.047 ± 0.18 V, P = 0.317, -0.019 ± 0.11 V, P = 0.490, and 0.075 ± 0.19 V, P = 0.070, for immediately after, 1 month and 3 months after MRI scan, respectively). Lead impedances after the MRI scan were significantly lower as compared with baseline values (-22.8 ± 21.69 Ω, P = 0.001, -21.62 ± 39.71 Ω, P = 0.040, and -33.68 ± 57.73 Ω, P = 0.018, for immediately after, 1 month and 3 months after MRI scan, respectively). MRI scans in patients with MRI conditional ICD system (Lumax 740(®) ) are feasible and can be performed safely under defined conditions in a hospital setting. © 2015 Wiley Periodicals, Inc.

Left heart pacing lead implantation using subxiphoid videopericardioscopy.

PubMed

Zenati, Marco A; Bonanomi, Gianluca; Chin, Albert K; Schwartzman, David

2003-09-01

Recent clinical data support the utility of left heart pacing. The transvenous approach for left heart pacing lead implantation is imperfect. A direct epicardial approach may have advantages, but heretofore its utility has been limited because of the requirement for thoracotomy. We sought to examine the feasibility of a method for epicardial lead implantation that did not require thoracotomy. In five large swine, percutaneous access to the epicardium was achieved with subxiphoid videopericardioscopy, using a device that marries endoscopy with a port through which pacing leads could be introduced. In each animal, standard, active fixation pacing leads were implanted onto the left atrium and ventricle. The atrial lead was implanted at the base of the appendage. The ventricular lead was implanted on the anterior, lateral, and inferior walls. Continuous direct visualization of the epicardium provided guidance for lead localization and fixation, including avoidance of complications such as trauma to epicardial coronary vessels. Capture thresholds were uniformly low. Postmortem examination demonstrated anatomically accurate, uncomplicated lead fixation. Using subxiphoid videopericardioscopy, uncomplicated, anatomically accurate left heart epicardial pacing lead implantation can be achieved without thoracotomy.

Complications with the MICRA TPS Pacemaker System: Persistent Complete Heart Block and Late Capture Failure.

PubMed

Holm, Niels; Müller, Andreas; Zbinden, Rainer

2017-04-01

A Medtronic MICRA transcatheter pacing system (Medtronic, Minneapolis, MN, USA) was implanted in an 86-year-old patient with sick sinus syndrome and left bundle branch block after transfemoral aortic valve implantation. During implantation she developed a persistent complete heart block due to manipulation with the large-bore delivery catheter. Two weeks later, acute pacemaker dysfunction occurred due to massive increase of pacing threshold and impedance without obvious pacemaker dislocation or myocardial perforation. Recurrent capture failure was seen with pacing output set at 5 V/1.0 ms. Hence, microdislocation or fixation of the tines in the right ventricular trabeculae has to be assumed. © 2016 Wiley Periodicals, Inc.

Could persistency of current of injury forecast successful active-fixation pacing lead implantation?

PubMed

Shali, Shalaimaiti; Su, Yangang; Qin, Shengmei; Ge, Junbo

2018-05-01

Presence of adequate current of injury (COI) was recognized as a sign of favorable pacemaker lead outcome. Little is known regarding the value of its dynamic behavior. We sought to test whether persistency of COI could predict active-fixation pacing lead performance. COI was monitored up to 10min after right ventricular (RV) pacing electrode fixation. COI persistency was defined as the percentage of COI magnitude relative to its initial measurement. An unacceptable pacing threshold (≥1.0V in acute evaluation or ≥2.0V over 2-year follow-up) with or without lead dislodgement was considered as lead failure. Lead implantation was attempted for 217 times in 174 patients (age 66.3±7.8years, 78 female). Acute lead failures occurred 43 times. Independent predictors of acute lead failure were RV enlargement (odds ratio [OR] 1.23, 95% confidential interval [CI] 1.11-2.04, P=0.033), absence of COI (OR 3.13, 95%CI 2.08-9.09, P=0.027), and COI persistency at 5min (OR 0.32, 95%CI 0.20-0.69, P=0.001) and 10min (OR 0.41, 95%CI 0.13-0.77, P=0.001). The optimal cutoffs were COI 5min persistency ≥50% (sensitivity 81.4%; specificity 81.9%) and COI 10min persistency ≥20% (sensitivity 86%; specificity 88.6%). There were 12 lead failures during 24.0±6.4months of follow-up. Patients with COI 5min persistency ≥50% had higher event-free survival compared to those with COI 5min persistency <50% (hazard ratio 3.54, 95% CI 1.04-12.06, P=0.043). COI persistency appears to be a valuable indicator for both acute and long-term outcome of active-fixation pacemaker leads. A precipitous decline in COI may require more attention to make sure of the lead performance. Copyright © 2018 Elsevier Ireland Ltd. All rights reserved.

Permanent His-bundle pacing: a systematic literature review and meta-analysis.

PubMed

Zanon, Francesco; Ellenbogen, Kenneth A; Dandamudi, Gopi; Sharma, Parikshit S; Huang, Weijian; Lustgarten, Daniel L; Tung, Roderick; Tada, Hiroshi; Koneru, Jayanthi N; Bergemann, Tracy; Fagan, Dedra H; Hudnall, John Harrison; Vijayaraman, Pugazhendhi

2018-04-26

Permanent cardiac pacing of the His-bundle restores and retains normal electrical activation of the ventricles. Data on His-bundle pacing (HBP) are largely limited to small single-centre reports, and clinical benefits and risks have not been systematically examined. We sought to systematically examine published studies of patients undergoing permanent HBP and quantify the benefits and risks of the therapy. PubMed, Embase, and Cochrane Library were searched for full-text articles on permanent HBP. Clinical outcomes of interest included implant success rate, procedural and lead complications, pacing thresholds, QRS duration, and ejection fraction at follow-up, and mortality. Data were extracted and summarized. Where possible, meta-analysis of aggregate data was performed. Out of 2876 articles, 26 met the inclusion criteria representing 1438 patients with an implant attempt. Average age of patients was 73 years and 62.1% were implanted due to atrioventricular block. Overall average implant success rate was 84.8% and was higher with use of catheter-delivered systems (92.1%; P < 0.001). Average pacing thresholds were 1.71 V at implant and 1.79 V at >3 months follow-up; although, pulse widths varied at testing. Average left ventricular ejection fractions (LVEFs) were 42.8% at baseline and 49.5% at follow-up. There were 43 complications observed in 907 patients across the 17 studies that reported safety information. Among 26 articles of permanent HBP, the implant success rate averaged 84.8% and LVEF improved by an average of 5.9% during follow-up. Specific reporting of our clinical outcomes of interest varied widely, highlighting the need for uniform reporting in future HBP trials.

Catheter Ablation of Focal Atrial Tachycardia Using Remote Magnetic Navigation.

PubMed

Webster, Mark; Pasupati, Sanjeevan; Lever, Nigel; Stiles, Martin

2018-05-01

This first-in-human study evaluated the safety and technical feasibility of the Tempo temporary cardiac pacing lead (BioTrace Medical), which includes a novel fixation mechanism and soft tip. Complications of temporary pacing leads include dislodgment, arrhythmias, and ventricular perforation. Temporary pacing applications have increased with transcatheter aortic valve replacement (TAVR) growth, for rapid pacing during balloon valvuloplasty (BAV) and valve deployment, and for periprocedural bradyarrhythmia support. Eligible patients required temporary pacing for TAVR, BAV, or electrophysiology (EP) procedures. Transthoracic echocardiograms were obtained at baseline and 24 hours after lead removal. Safety was defined as freedom from pericardial effusion requiring intervention or evidence of tamponade. Technical feasibility involved successful intracardiac delivery and pace capture. Additional evaluations included pacing threshold (PCT), rapid pacing, dislodgment, or sustained ventricular arrhythmias. Follow-up was to 30 days. Twenty-five patients (60% female; mean age, 64 ± 19 years) underwent 13 TAVRs (7 Sapien 3 valves [Edwards Lifesciences], 4 CoreValves [Medtronic], and 2 Lotus valves [Boston Scientific]), 11 EP procedures, and 1 BAV at two New Zealand centers from January 2016 to June 2016. Safety was met in all patients, with no device-related adverse events. Technical feasibility was achieved in 23 cases (92%); 2 patients had unsuitable anatomy. No patient had lead dislodgment or sustained ventricular arrhythmias, and the final procedural PCT was 0.7 ± 0.5 mA. Rapid pacing was successful in all cases. Five patients had successful postprocedural use up to 5 days. This first-in-human study demonstrates the safety and technical feasibility of the Tempo lead, providing stable periprocedural temporary pacing support.

A Pilot Study on the Effects of Slow Paced Breathing on Current Food Craving.

PubMed

Meule, Adrian; Kübler, Andrea

2017-03-01

Heart rate variability biofeedback (HRV-BF) involves slow paced breathing (approximately six breaths per minute), thereby maximizing low-frequent heart rate oscillations and baroreflex gain. Mounting evidence suggests that HRV-BF promotes symptom reductions in a variety of physical and mental disorders. It may also positively affect eating behavior by reducing food cravings. The aim of the current study was to investigate if slow paced breathing can be useful for attenuating momentary food craving. Female students performed paced breathing either at six breaths per minute (n = 32) or at nine breaths per minute (n = 33) while watching their favorite food on the computer screen. Current food craving decreased during a first resting period, increased during paced breathing, and decreased during a second resting period in both conditions. Although current hunger increased in both conditions during paced breathing as well, it remained elevated after the second resting period in the nine breaths condition only. Thus, breathing rate did not influence specific food craving, but slow paced breathing appeared to have a delayed influence on state hunger. Future avenues are suggested for the study of HRV-BF in the context of eating behavior.

Energy expenditure and influence of physiologic factors during marathon running.

PubMed

Loftin, Mark; Sothern, Melinda; Koss, Cathie; Tuuri, Georgianna; Vanvrancken, Connie; Kontos, Anthony; Bonis, Marc

2007-11-01

This study examined energy expenditure and physiologic determinants for marathon performance in recreational runners. Twenty recreational marathon runners participated (10 males aged 41 +/- 11.3 years, 10 females aged 42.7 +/- 11.7 years). Each subject completed a V(.-)O2max and a 1-hour treadmill run at recent marathon pace, and body composition was indirectly determined via dual energy X-ray absorptiometry. The male runners exhibited higher V(.-)O2max (ml x kg(-1) x min(-1)) values (52.6 +/- 5.5) than their female counterparts (41.9 +/- 6.6), although ventilatory threshold (T-vent) values were similar between groups (males: 76.2 +/- 6.1 % of V(.-)O2max, females: 75.1 +/- 5.1%). The male runners expended more energy (2,792 +/- 235 kcal) for their most recent marathon as calculated from the 1-hour treadmill run at marathon pace than the female runners (2,436 +/- 297 kcal). Body composition parameters correlated moderately to highly (r ranging from 0.50 to 0.87) with marathon run time. Also, V(.-)O2max (r = -0.73) and ventilatory threshold (r = -0.73) moderately correlated with marathon run time. As a group, the participants ran near their ventilatory threshold for their most recent marathon (r = 0.74). These results indicate the influence of body size on marathon run performance. In general, the larger male and female runners ran slower and expended more kilocalories than smaller runners. Regardless of marathon finishing time, the runners maintained a pace near their T-vent, and as T-vent or V(.-)O2max increased, marathon performance time decreased.

Anodal right ventricular capture during left ventricular stimulation in CRT-implantable cardioverter defibrillators.

PubMed

Thibault, Bernard; Roy, Denis; Guerra, Peter G; Macle, Laurent; Dubuc, Marc; Gagné, Pierre; Greiss, Isabelle; Novak, Paul; Furlani, Aldo; Talajic, Mario

2005-07-01

Cardiac resynchronization therapy (CRT) has been shown to improve symptoms of patients with moderate to severe heart failure. Optimal CRT involves biventricular or left ventricular (LV) stimulation alone, atrio-ventricular (AV) delay optimization, and possibly interventricular timing adjustment. Recently, anodal capture of the right ventricle (RV) has been described for patients with CRT-pacemakers. It is unknown whether the same phenomenon exists in CRT systems associated with defibrillators (CRT-ICD). The RV leads used in these systems are different from pacemaker leads: they have a larger diameter and shocking coils, which may affect the occurrence of anodal capture. We looked for anodal RV capture during LV stimulation in 11 consecutive patients who received a CRT-ICD system with RV leads with a true bipolar design. Fifteen patients who had RV leads with an integrated design were used as controls. Anodal RV and LV thresholds were determined at pulse width (pw) durations of 0.2, 0.5, and 1.0 ms. RV anodal capture during LV pacing was found in 11/11 patients at some output with true bipolar RV leads versus 0/15 patients with RV leads with an integrated bipolar design. Anodal RV capture threshold was more affected by changes in pw duration than LV capture threshold. In CRT-ICD systems, RV leads with a true bipolar design with the proximal ring also used as the anode for LV pacing are associated with a high incidence of anodal RV capture during LV pacing. This may affect the clinical response to alternative resynchronization methods using single LV stimulation or interventricular delay programming.

The effect of hyperkalaemia on cardiac rhythm devices.

PubMed

Barold, S Serge; Herweg, Bengt

2014-04-01

In patients with pacemakers, hyperkalaemia causes three important abnormalities that usually become manifest when the K level exceeds 7 mEq/L: (i) widening of the paced QRS complex from delayed intraventricular conduction velocity, (ii) Increased atrial and ventricular pacing thresholds that may cause failure to capture. In this respect, the atria are more susceptible to loss of capture than the ventricles, and (iii) Increased latency (usually with ventricular pacing) manifested by a greater delay of the interval from the pacemaker stimulus to the onset of depolarization. First-degree ventricular pacemaker exit block may progress to second-degree Wenckebach (type I) exit block characterized by gradual prolongation of the interval from the pacemaker stimulus to the onset of the paced QRS complex ultimately resulting in an ineffectual stimulus. The disturbance may then progress to 2 : 1, 3 : 1 pacemaker exit block, etc., and eventually to complete exit block with total lack of capture. Ventricular undersensing is uncommonly observed because of frequent antibradycardia pacing. During managed ventricular pacing, hyperkalaemia-induced marked first-degree atrioventricular block may induce a pacemaker syndrome. With implantable cardioverter-defibrillators (ICDs) oversensing of the paced or spontaneous T-wave may occur. The latter may cause inappropriate shocks. A raised impedance from the right ventricular coil to the superior vena cava coil may become an important sign of hyperkalaemia in the asymptomatic or the minimally symptomatic ICD patient.

Real-time identification of residential appliance events based on power monitoring

NASA Astrophysics Data System (ADS)

Yang, Zhao; Zhu, Zhicheng; Wei, Zhiqiang; Yin, Bo; Wang, Xiuwei

2018-03-01

Energy monitoring for specific home appliances has been regarded as the pre-requisite for reducing residential energy consumption. To enhance the accuracy of identifying operation status of household appliances and to keep pace with the development of smart power grid, this paper puts forward the integration of electric current and power data on the basis of existing algorithm. If average power difference of several adjacent cycles varies from the baseline and goes beyond the pre-assigned threshold value, the event will be flagged. Based on MATLAB platform and domestic appliances simulations, the results of tested data and verified algorithm indicate that the power method has accomplished desired results of appliance identification.

A Leadless Intracardiac Transcatheter Pacing System.

PubMed

Reynolds, Dwight; Duray, Gabor Z; Omar, Razali; Soejima, Kyoko; Neuzil, Petr; Zhang, Shu; Narasimhan, Calambur; Steinwender, Clemens; Brugada, Josep; Lloyd, Michael; Roberts, Paul R; Sagi, Venkata; Hummel, John; Bongiorni, Maria Grazia; Knops, Reinoud E; Ellis, Christopher R; Gornick, Charles C; Bernabei, Matthew A; Laager, Verla; Stromberg, Kurt; Williams, Eric R; Hudnall, J Harrison; Ritter, Philippe

2016-02-11

A leadless intracardiac transcatheter pacing system has been designed to avoid the need for a pacemaker pocket and transvenous lead. In a prospective multicenter study without controls, a transcatheter pacemaker was implanted in patients who had guideline-based indications for ventricular pacing. The analysis of the primary end points began when 300 patients reached 6 months of follow-up. The primary safety end point was freedom from system-related or procedure-related major complications. The primary efficacy end point was the percentage of patients with low and stable pacing capture thresholds at 6 months (≤2.0 V at a pulse width of 0.24 msec and an increase of ≤1.5 V from the time of implantation). The safety and efficacy end points were evaluated against performance goals (based on historical data) of 83% and 80%, respectively. We also performed a post hoc analysis in which the rates of major complications were compared with those in a control cohort of 2667 patients with transvenous pacemakers from six previously published studies. The device was successfully implanted in 719 of 725 patients (99.2%). The Kaplan-Meier estimate of the rate of the primary safety end point was 96.0% (95% confidence interval [CI], 93.9 to 97.3; P<0.001 for the comparison with the safety performance goal of 83%); there were 28 major complications in 25 of 725 patients, and no dislodgements. The rate of the primary efficacy end point was 98.3% (95% CI, 96.1 to 99.5; P<0.001 for the comparison with the efficacy performance goal of 80%) among 292 of 297 patients with paired 6-month data. Although there were 28 major complications in 25 patients, patients with transcatheter pacemakers had significantly fewer major complications than did the control patients (hazard ratio, 0.49; 95% CI, 0.33 to 0.75; P=0.001). In this historical comparison study, the transcatheter pacemaker met the prespecified safety and efficacy goals; it had a safety profile similar to that of a transvenous system while providing low and stable pacing thresholds. (Funded by Medtronic; Micra Transcatheter Pacing Study ClinicalTrials.gov number, NCT02004873.).

Atrial septal pacing in small dogs: a pilot study.

PubMed

Jones, Ashley E; Estrada, Amara H; Pariaut, Romain; Sosa-Samper, Ivan; Shih, Andre C; Mincey, Brandy D; Moïse, N Sydney

2014-09-01

To determine the feasibility of atrial septal pacing via a delivery catheter-guided small non-retracting helix pacing lead. Six healthy beagles (8.3-12.9 kg). Using single plane fluoroscopic guidance, Medtronic(®) 3830 SelectSecure leads were connected to the atrial septum via Medtronic® Attain Select® II standard 90 Left Heart delivery catheter. Pacing threshold and lead impedance were measured at implantation. The Wenckebach point was tested via atrial pacing up to 220 paced pulses per minute (ppm). Thoracic radiographs were performed following implantation to identify the lead position, and repeated at 24 h, 1 month, and 3 months post-operatively. Macro-lead dislodgement occurred in two dogs at 24 h and in three dogs at one-month post-implantation. Lead impedance, measured at the time of implantation, ranged from 583 to 1421 Ω. The Wenckebach point was >220 ppm in four of the six dogs. The remaining two dogs had Wenckebach points of 120 and 190 ppm. This pilot study suggests the selected implantation technique and lead system were inadequate for secure placement in the atrial septum of these dogs. The possible reasons for inadequate stability include unsuitable lead design for this location, inadequate lead slack at the time of implantation and inadequate seating of the lead as evidenced by low impedance at the time of implantation. Other implantation techniques and/or pacing leads should be investigated to determine the optimal way of pacing the atria in small breed dogs that are prone to sinus node dysfunction. Copyright © 2014 Elsevier B.V. All rights reserved.

Application of the predicted heat strain model in development of localized, threshold-based heat stress management guidelines for the construction industry.

PubMed

Rowlinson, Steve; Jia, Yunyan Andrea

2014-04-01

Existing heat stress risk management guidelines recommended by international standards are not practical for the construction industry which needs site supervision staff to make instant managerial decisions to mitigate heat risks. The ability of the predicted heat strain (PHS) model [ISO 7933 (2004). Ergonomics of the thermal environment analytical determination and interpretation of heat stress using calculation of the predicted heat strain. Geneva: International Standard Organisation] to predict maximum allowable exposure time (D lim) has now enabled development of localized, action-triggering and threshold-based guidelines for implementation by lay frontline staff on construction sites. This article presents a protocol for development of two heat stress management tools by applying the PHS model to its full potential. One of the tools is developed to facilitate managerial decisions on an optimized work-rest regimen for paced work. The other tool is developed to enable workers' self-regulation during self-paced work.

An infrared optical pacing system for screening cardiac electrophysiology in human cardiomyocytes.

PubMed

McPheeters, Matthew T; Wang, Yves T; Werdich, Andreas A; Jenkins, Michael W; Laurita, Kenneth R

2017-01-01

Human cardiac myocytes derived from pluripotent stem cells (hCM) have invigorated interest in genetic disease mechanisms and cardiac safety testing; however, the technology to fully assess electrophysiological function in an assay that is amenable to high throughput screening has lagged. We describe a fully contactless system using optical pacing with an infrared (IR) laser and multi-site high fidelity fluorescence imaging to assess multiple electrophysiological parameters from hCM monolayers in a standard 96-well plate. Simultaneous multi-site action potentials (FluoVolt) or Ca2+ transients (Fluo4-AM) were measured, from which high resolution maps of conduction velocity and action potential duration (APD) were obtained in a single well. Energy thresholds for optical pacing were determined for cell plating density, laser spot size, pulse width, and wavelength and found to be within ranges reported previously for reliable pacing. Action potentials measured using FluoVolt and a microelectrode exhibited the same morphology and rate of depolarization. Importantly, we show that this can be achieved accurately with minimal damage to hCM due to optical pacing or fluorescence excitation. Finally, using this assay we demonstrate that hCM exhibit reproducible changes in repolarization and impulse conduction velocity for Flecainide and Quinidine, two well described reference compounds. In conclusion, we demonstrate a high fidelity electrophysiological screening assay that incorporates optical pacing with IR light to control beating rate of hCM monolayers.

Predicting Critical Power in Elite Cyclists: Questioning the Validity of the 3-Minute All-Out Test.

PubMed

Bartram, Jason C; Thewlis, Dominic; Martin, David T; Norton, Kevin I

2017-07-01

New applications of the critical-power concept, such as the modeling of intermittent-work capabilities, are exciting prospects for elite cycling. However, accurate calculation of the required parameters is traditionally time invasive and somewhat impractical. An alternative single-test protocol (3-min all-out) has recently been proposed, but validation in an elite population is lacking. The traditional approach for parameter establishment, but with fewer tests, could also prove an acceptable compromise. Six senior Australian endurance track-cycling representatives completed 6 efforts to exhaustion on 2 separate days over a 3-wk period. These included 1-, 4-, 6-, 8-, and 10-min self-paced efforts, plus the 3-min all-out protocol. Traditional work-vs-time calculations of CP and anaerobic energy contribution (W') using the 5 self-paced efforts were compared with calculations from the 3-min all-out protocol. The impact of using just 2 or 3 self-paced efforts for traditional CP and W' estimation was also explored using thresholds of agreement (8 W, 2.0 kJ, respectively). CP estimated from the 3-min all-out approach was significantly higher than from the traditional approach (402 ± 33, 351 ± 27 W, P < .001), while W' was lower (15.5 ± 3.0, 24.3 ± 4.0 kJ, P = .02). Five different combinations of 2 or 3 self-paced efforts led to CP estimates within the threshold of agreement, with only 1 combination deemed accurate for W'. In elite cyclists the 3-min all-out approach is not suitable to estimate CP when compared with the traditional method. However, reducing the number of tests used in the traditional method lessens testing burden while maintaining appropriate parameter accuracy.

21 CFR 870.3720 - Pacemaker electrode function tester.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker electrode function tester. 870.3720... electrode function tester. (a) Identification. A pacemaker electrode function tester is a device which is... measuring the patient's pacing threshold and intracardiac R-wave potential. (b) Classification. Class II...

A novel method to estimate safety factor of capture by a fetal micropacemaker.

PubMed

Vest, Adriana Nicholson; Zhou, Li; Bar-Cohen, Yaniv; Eli Loeb, Gerald

2016-07-01

We have developed a rechargeable fetal micropacemaker in order to treat severe fetal bradycardia with comorbid hydrops fetalis, a life-threatening condition in pre-term non-viable fetuses for which there are no effective treatment options. The small size and minimally invasive form factor of our design limit the volume available for circuitry and a power source. The device employs a fixed-rate and fixed-amplitude relaxation oscillator and a tiny, rechargeable lithium ion power cell. For both research and clinical applications, it is valuable to monitor the electrode-myocardium interface in order to determine that adequate pacemaker output is being provided. This is typically accomplished by observing the minimal stimulus strength that achieves threshold for pacing capture. The output of our simple micropacemaker cannot be programmatically altered to determine this minimal capture threshold, but a safety factor can be inferred by determining the refractory period for ventricular capture at a given stimulus strength. This is done by measuring the minimal timing between naturally occurring QRS complexes and pacing stimuli that successfully generate a premature ventricular contraction. The method was tested in a pilot study in four fetal sheep and the data demonstrate that a relative measure of threshold is obtainable. This method provides valuable real-time information about the electrode-tissue interface.

Phase-resolved analysis of the susceptibility of pinned spiral waves to far-field pacing in a two-dimensional model of excitable media

PubMed Central

Bittihn, Philip; Squires, Amgad; Luther, Gisa; Bodenschatz, Eberhard; Krinsky, Valentin; Parlitz, Ulrich; Luther, Stefan

2010-01-01

Life-threatening cardiac arrhythmias are associated with the existence of stable and unstable spiral waves. Termination of such complex spatio-temporal patterns by local control is substantially limited by anchoring of spiral waves at natural heterogeneities. Far-field pacing (FFP) is a new local control strategy that has been shown to be capable of unpinning waves from obstacles. In this article, we investigate in detail the FFP unpinning mechanism for a single rotating wave pinned to a heterogeneity. We identify qualitatively different phase regimes of the rotating wave showing that the concept of vulnerability is important but not sufficient to explain the failure of unpinning in all cases. Specifically, we find that a reduced excitation threshold can lead to the failure of unpinning, even inside the vulnerable window. The critical value of the excitation threshold (below which no unpinning is possible) decreases for higher electric field strengths and larger obstacles. In contrast, for a high excitation threshold, the success of unpinning is determined solely by vulnerability, allowing for a convenient estimation of the unpinning success rate. In some cases, we also observe phase resetting in discontinuous phase intervals of the spiral wave. This effect is important for the application of multiple stimuli in experiments. PMID:20368243

A novel method to estimate safety factor of capture by a fetal micropacemaker

PubMed Central

Vest, Adriana Nicholson; Zhou, Li; Bar-Cohen, Yaniv; Loeb, Gerald Eli

2016-01-01

We have developed a rechargeable fetal micropacemaker in order to treat severe fetal bradycardia with comorbid hydrops fetalis, a life-threatening condition in pre-term non-viable fetuses for which there are no effective treatment options. The small size and minimally invasive form factor of our design limit the volume available for circuitry and a power source. The device employs a fixed-rate and fixed-amplitude relaxation oscillator and a tiny, rechargeable lithium ion power cell. For both research and clinical applications, it is valuable to monitor the electrode-myocardium interface in order to determine that adequate pacemaker output is being provided. This is typically accomplished by observing the minimal stimulus strength that achieves threshold for pacing capture. The output of our simple micropacemaker cannot be programmatically altered to determine this minimal capture threshold, but a safety factor can be inferred by determining the refractory period for ventricular capture at a given stimulus strength. This is done by measuring the minimal timing between naturally occurring QRS complexes and pacing stimuli that successfully generate a premature ventricular contraction. The method was tested in a pilot study in 4 fetal sheep and the data demonstrate that a relative measure of threshold is obtainable. This method provides valuable real-time information about the electrode-tissue interface. PMID:27340134

Optimal programming management of ventricular tachycardia storm in ICD patients

PubMed Central

Qian, Zhiyong; Guo, Jianghong; Zhang, Zhiyong; Wang, Yao; Hou, Xiaofeng; Zou, Jiangang

2015-01-01

Abstract Ventricular tachycardia storm (VTS) is defined as a life-threatening syndrome of three or more separate episodes of ventricular tachycardia (VT) leading to implantable cardioverter defibrillator (ICD) therapy within 24 hours. Patients with VTS have poor outcomes and require immediate medical attention. ICD shocks have been shown to be associated with increased mortality in several studies. Optimal programming in minimization of ICD shocks may decrease mortality. Large controlled trials showed that long detection time and high heart rate detection threshold reduced ICD shock burden without an increase in syncope or death. As a fundamental therapy of ICD, antitachycardia pacing (ATP) can terminate most slow VT with a low risk of acceleration. For fast VT, burst pacing is more effective and less likely to result in acceleration than ramp pacing. One algorithm of optimal programming management during a VTS is presented in the review. PMID:25745473

Pacemaker leads: performance and progress.

PubMed

de Voogt, W G

1999-03-11

Pacing leads remain the "weaker link" of the permanent pacing system. Lead failure has been an issue since the beginning of implantable pacemaker therapy. Modern electronics have brought about considerable progress in pacing technology, but lead design has been slower to evolve and problems persist. IS-1 standardization must be considered a significant advance, but some issues regarding IS-1 standardization persist and have been the cause of some compatibility problems. With respect to lead insulation, silicone has proved to offer total reliability for > 30 years. In the search for better handling characteristics, polyurethane 80A was employed for bipolar leads, but it failed to demonstrate satisfactory insulating properties. New insulation materials, such as ethylene-fluoro-ethylene (ETFE), and coated wire technology look promising, having shown 99.32% survival at 5-year follow-up. Reliability is the main objective in lead design, but leads should provide low battery consumption as well. Low coil resistance, with high electrode impedance in steroid-eluting leads, is the standard at present. Low polarization is a desirable property for 2 main reasons: (1) in conjunction with low-threshold leads, it decreases battery consumption; and (2) it allows capture detection and, therefore, safer pacing at low battery consumption. Lead tip design as well as pacing pulse configuration can influence polarization.

Different regions of latest electrical activation during left bundle-branch block and right ventricular pacing in cardiac resynchronization therapy patients determined by coronary venous electro-anatomic mapping.

PubMed

Mafi Rad, Masih; Blaauw, Yuri; Dinh, Trang; Pison, Laurent; Crijns, Harry J; Prinzen, Frits W; Vernooy, Kevin

2014-11-01

Current targeted left ventricular (LV) lead placement strategy is directed at the latest activated region during intrinsic activation. However, cardiac resynchronization therapy (CRT) is most commonly applied by simultaneous LV and right ventricular (RV) pacing without contribution from intrinsic conduction. Therefore, targeting the LV lead to the latest activated region during RV pacing might be more appropriate. We investigated the difference in LV electrical activation sequence between left bundle-branch block (LBBB) and RV apex (RVA) pacing using coronary venous electro-anatomic mapping (EAM). Twenty consecutive CRT candidates with LBBB underwent intra-procedural coronary venous EAM during intrinsic activation and RVA pacing using EnSite NavX. Left ventricular lead placement was aimed at the latest activated region during LBBB according to current recommendations. In all patients, LBBB was associated with a circumferential LV activation pattern, whereas RVA pacing resulted in activation from the apex of the heart to the base. In 10 of 20 patients, RVA pacing shifted the latest activated region relative to LBBB. In 18 of 20 patients, the LV lead was successfully positioned in the latest activated region during LBBB. For the whole study population, LV lead electrical delay, expressed as percentage of QRS duration, was significantly shorter during RVA pacing than during LBBB (72 ± 13 vs. 82 ± 5%, P = 0.035). Right ventricular apex pacing alters LV electrical activation pattern in CRT patients with LBBB, and shifts the latest activated region in a significant proportion of these patients. These findings warrant reconsideration of the current practice of LV lead targeting for CRT. © 2014 The Authors. European Journal of Heart Failure © 2014 European Society of Cardiology.

Electrophysiological determinants of arrhythmic susceptibility upon endocardial and epicardial pacing in guinea-pig heart.

PubMed

Osadchii, O E

2012-08-01

Endocardial pacing instituted to treat symptomatic bradycardia may nevertheless promote tachyarrhythmia in some pacemaker-implanted patients. We sought to determine the contributing electrophysiological mechanisms. Left ventricular (LV) monophasic action potential duration (APD(90)) and effective refractory periods were determined in perfused guinea-pig hearts along with volume-conducted ECG recordings during epicardial and endocardial stimulations. Consistent with electrotonic modulation of repolarization, APD(90) at a given (either epicardial or endocardial) recording site tended to be longer while pacing from the ipsilateral LV site as compared to stimulations applied at the opposite side of ventricular wall. As a result, the intrinsic transmural repolarization gradient was amplified during endocardial pacing while being significantly reduced upon epicardial stimulations. The maximum slope of APD(90) restitution was greater upon endocardial than epicardial pacing. The excitability was found to recur at earlier repolarization time point at endocardium than epicardium, thereby contributing to increased endocardial critical intervals for re-excitation. Premature extrasystolic beats could have been elicited at shorter coupling stimulation intervals and propagated with greater transmural conduction delay upon endocardial than epicardial stimulations. Endocardial site exhibited lower ventricular fibrillation thresholds and greater inducibility of tachyarrhythmia upon extrasystolic stimulations as compared to epicardium. Arrhythmic susceptibility in guinea-pig heart is greater during endocardial than epicardial pacing because of greater transmural APD(90) dispersion, steeper electrical restitution slopes, greater critical intervals for LV re-excitation and slower transmural conduction of the earliest premature ectopic beats. Further studies are warranted to determine whether these effects may contribute to proarrhythmia in paced human patients. © 2012 The Author Acta Physiologica © 2012 Scandinavian Physiological Society.

Additional electrodes on the Quartet™ LV lead provide more programmable pacing options than bipolar and tripolar equivalents.

PubMed

O'Donnell, David; Sperzel, Johannes; Thibault, Bernard; Rinaldi, Christopher A; Pappone, Carlo; Gutleben, Klaus-Jürgen; Leclercq, Christopher; Razavi, Hedi; Ryu, Kyungmoo; Mcspadden, Luke C; Fischer, Avi; Tomassoni, Gery

2017-04-01

The aim of this study was to evaluate any benefits to the number of viable pacing vectors and maximal spatial coverage with quadripolar left ventricular (LV) leads when compared with tripolar and bipolar equivalents in patients receiving cardiac resynchronization therapy (CRT). A meta-analysis of five previously published clinical trials involving the Quartet™ LV lead (St Jude Medical, St Paul, MN, USA) was performed to evaluate the number of viable pacing vectors defined as capture thresholds ≤2.5 V and no phrenic nerve stimulation and maximal spatial coverage of viable vectors in CRT patients at pre-discharge (n = 370) and first follow-up (n = 355). Bipolar and tripolar lead configurations were modelled by systematic elimination of two and one electrode(s), respectively, from the Quartet lead. The Quartet lead with its four pacing electrodes exhibited the greatest number of pacing vectors per patient when compared with the best bipolar and the best tripolar modelled equivalents. Similarly, the Quartet lead provided the highest spatial coverage in terms of the distance between two furthest viable pacing cathodes when compared with the best bipolar and the best tripolar configurations (P < 0.05). Among the three modelled bipolar configurations, the lead configuration with the two most distal electrodes resulted in the highest number of viable pacing vectors. Among the four modelled tripolar configurations, elimination of the second proximal electrode (M3) resulted in the highest number of viable pacing options per patient. There were no significant differences observed between pre-discharge and first follow-up analyses. The Quartet lead with its four electrodes and the capability to pace from four anatomical locations provided the highest number of viable pacing vectors at pre-discharge and first follow-up visits, providing more flexibility in device programming and enabling continuation of CRT in more patients when compared with bipolar and tripolar equivalents. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Pacing: a concept analysis of the chronic pain intervention.

PubMed

Jamieson-Lega, Kathryn; Berry, Robyn; Brown, Cary A

2013-01-01

The intervention of pacing is regularly recommended for chronic pain patients. However, pacing is poorly defined and appears to be interpreted in varying, potentially contradictory manners within the field of chronic pain. This conceptual lack of clarity has implications for effective service delivery and for researchers' ability to conduct rigorous study. An examination of the background literature demonstrates that while pacing is often one part of a multidisciplinary pain management program, outcome research is hindered by a lack of a clear and shared definition of this currently ill-defined construct. To conduct a formal concept analysis of the term 'pacing'. A standardized concept analysis process (including literature scoping to identify all uses of the concept, analysis to determine defining attributes of the concept and identification of model, borderline and contrary cases) was used to determine what the concept of pacing does and does not represent within the current evidence base. A conceptual model including the core attributes of action, time, balance, learning and self-management emerged. From these attributes, an evidence-based definition for pacing was composed and distributed to stakeholders for review. After consideration of stakeholder feedback, the emergent definition of pacing was finalized as follows: "Pacing is an active self-management strategy whereby individuals learn to balance time spent on activity and rest for the purpose of achieving increased function and participation in meaningful activities". The findings of the present concept analysis will help to standardize the use and definition of the term pacing across disciplines for the purposes of both pain management and research.

Short- and long-term performance of a tripolar down-sized single lead for implantable cardioverter defibrillator treatment: a randomized prospective European multicenter study. European Endotak DSP Investigator Group.

PubMed

Sandstedt, B; Kennergren, C; Schaumann, A; Herse, B; Neuzner, J

1998-11-01

A new, thinner (10 Fr) and more flexible, single-pass transvenous endocardial ICD lead, Endotak DSP, was compared with a conventional lead, Endotak C, as a control in a prospective randomized multicenter study in combination with a nonactive can ICD. A total of 123 patients were enrolled, 55 of whom received a down-sized DSP lead. Lead-alone configuration was successfully implanted in 95% of the DSP patients vs 88% in the control group. The mean defibrillation threshold (DFT) was determined by means of a step-down protocol, and was identical in the two groups, 10.5 +/- 4.8 J in the DSP group versus 10.5 +/- 4.8 J in the control group. At implantation, the DSP mean pacing threshold was lower, 0.51 +/- 0.18 V versus 0.62 +/- 0.35 V (p < 0.05) in the control group, and the mean pacing impedance higher, 594 +/- 110 omega vs 523 +/- 135 omega (p < 0.05). During the follow-up period, the statistically significant difference in thresholds disappeared, while the difference in impedance remained. Tachyarrhythmia treatment by shock or antitachycardia pacing (ATP) was delivered in 53% and 41%, respectively, of the patients with a 100% success rate. In the DSP group, all 28 episodes of polymorphic ventricular tachycardia or ventricular fibrillation were converted by the first shock as compared to 57 of 69 episodes (83%) in the control group (p < 0.05). Monomorphic ventricular tachycardias were terminated by ATP alone in 96% versus 94%. Lead related problems were minor and observed in 5% and 7%, respectively. In summary, both leads were safe and efficacious in the detection and treatment of ventricular tachyarrhythmias. There were no differences between the DSP and control groups regarding short- or long-term lead related complications.

Right ventricular septal pacing: the success of stylet-driven active-fixation leads.

PubMed

Rosso, Raphael; Teh, Andrew W; Medi, Caroline; Hung, Thuy To; Balasubramaniam, Richard; Mond, Harry G

2010-01-01

The detrimental effects of right ventricular (RV) apical pacing on left ventricular function has driven interest in alternative pacing sites and in particular the mid RV septum and RV outflow tract (RVOT). RV septal lead positioning can be successfully achieved with a specifically shaped stylet and confirmed by the left anterior oblique (LAO) fluoroscopic projection. Such a projection is neither always used nor available during pacemaker implantation. The aim of this study was to evaluate how effective is the stylet-driven technique in septal lead placement guided only by posterior-anterior (PA) fluoroscopic view. One hundred consecutive patients with an indication for single- or dual-chamber pacing were enrolled. RV septal lead positioning was attempted in the PA projection only and confirmed by the LAO projection at the end of the procedure. The RV lead position was septal in 90% of the patients. This included mid RV in 56 and RVOT in 34 patients. There were no significant differences in the mean stimulation threshold, R-wave sensing, and lead impedance between the two sites.In the RVOT, 97% (34/35) of leads were placed on the septum, whereas in the mid RV the value was 89% (56/63). The study confirms that conventional active-fixation pacing leads can be successfully and safely deployed onto the RV septum using a purposely-shaped stylet guided only by the PA fluoroscopic projection.

Transcatheter leadless pacemaker implantation in a patient with a transvenous dual-chamber pacemaker already in place.

PubMed

Karjalainen, Pasi P; Nammas, Wail; Paana, Tuomas

2016-01-01

An 83-year-old lady had a DDDR pacemaker inserted in 1997 for symptomatic atrioventricular block. She underwent battery replacement in 2008. In 2010, she developed atrial fibrillation; the pacemaker was switched to VVIR mode. During the last 2years, ventricular lead threshold increased progressively. In December 2015, she presented for elective battery replacement. After successful battery replacement, the ventricular lead threshold remained high; therefore, we implanted a leadless transcatheter pacemaker, via femoral vein access, using a dedicated catheter delivery system. Electrical measurements at this stage revealed a pacing threshold of 0.28V at 0.24msec, and an impedance of 650Ω. Copyright © 2016 Elsevier Inc. All rights reserved.

Self-Paced Physics, Segments 28-31.

ERIC Educational Resources Information Center

New York Inst. of Tech., Old Westbury.

Four study segments of the Self-Paced Physics Course materials are presented in this sixth problems and solutions book used as a part of student course work. The subject matter is related to electric currents, current densities, resistances, Ohm's law, voltages, Joule heating, electromotive forces, single loop circuits, series and parallel…

Implantation techniques and chronic lead parameters of biventricular pacing dual-chamber defibrillators.

PubMed

Daoud, Emile G; Kalbfleisch, Steven J; Hummel, John D; Weiss, Raul; Augustini, Ralph S; Duff, Steven B; Polsinelli, Georgia; Castor, John; Meta, Tejas

2002-10-01

The aim of this study is to describe implantation techniques and lead performance for biventricular pacing, dual-chamber implantable cardioverter defibrillators (ICDs). A dual-chamber ICD with biventricular pacing was implanted in 87 patients with congestive heart failure (ejection fraction: 0.21 +/- 0.09), prolonged QRS duration (161 +/- 22 msec), and an indication for ICD therapy. Left ventricular pacing was achieved with a thoracotomy approach (n = 21) or a nonthoracotomy approach (n = 66). With a thoracotomy, biventricular devices were implanted successfully in all patients. During follow-up (17 +/- 11 months), 9 patients died (43%), 2 underwent transplantation, and 2 required left ventricular lead revision. At last follow-up, biventricular sensing and capture threshold were 11 +/- 5 mV and 1.5 +/- 0.8 V, respectively. For nonthoracotomy procedures, two types of coronary sinus (CS) leads were implanted: an over-the-wire lead (n = 45) and a shaped lead (n = 21). The rate of successful implantation (overall: 89%) (over-the-wire 93% vs shaped 81%; P = 0.1) and durations for CS lead placement (66 +/- 50 vs 58 +/- 34 min, P = 0.6) and the procedure (133 +/- 58 vs 129 +/- 33 min, P = 0.8) were not different between the two CS leads. During follow-up (11 +/- 9 months), 9 patients died (14%), and the shaped CS lead dislodged in 3 patients (3 shaped vs 0 over-the-wire, P = 0.01). At last follow-up, biventricular sensing and capture threshold were 10 +/- 4 mV and 1.8 +/- 0.7 V, respectively, and there was no difference between over-the-wire and shaped leads. By multivariate analysis, mortality was associated with absence of spironolactone therapy but not procedural features. Nonthoracotomy CS lead implantation is feasible, with a success rate of about 90% and few adverse events. For the remaining 10%, a thoracotomy approach can be completed safely in these ill patients without increased risk for death.

Clinical evaluation of a thin bipolar pacing lead.

PubMed

Breivik, K; Danilovic, D; Ohm, O J; Guerola, M; Stertman, W A; Suntinger, A

1997-03-01

The main disadvantages of bipolar pacing leads have traditionally been related to their relative thickness and stiffness compared to unipolar leads. In a new "drawn filled tube" plus "coated wire" technology, each conductor strand is composed of MP35N tubing filled with silver core and coated with a thin ETFE polymer insulation material. This and parallel winding of single anode and cathode conductors into a single bifilar coil resulted in a bipolar lead (ThinLine, Intermedics) with a body diameter and flexibility similar to unipolar leads. The lead is tined, polyurethane, with the cathode and the anode made of iridium-oxide-coated titanium (IROX). The slotted 8-mm2 cathode tip is coated with polyethylene glycol, a blood soluble material. We present the clinical evaluation results from four pacemaker clinics, where 47 leads (23 atrial-J model 432-04 and 24 ventricular model 430-10) were implanted in 25 patients and followed for up to 2 years. The lead handling characteristics were found to be very satisfactory. Electrical parameters of the leads were measured at implant and noninvasively on postoperative days 1, 2, 21, 42, and months 3, 6, 12, and 24. Mean chronic pulse width thresholds at 2.5 V were 0.14 +/- 0.05 ms in the atrium and 0.10 +/- 0.02 ms in the ventricle, pacing impedances 443 +/- 104 omega and 520 +/- 241 omega, while median electrogram amplitudes were > or = 3.5 mV and > or = 7 mV, respectively. Pacing impedances and thresholds were found to be slightly but statistically significantly higher in unipolar than in bipolar configuration--the findings are explainable by the lead construction. One of 47 leads failed 3 weeks after implant; the conductors were short circuited due to an error during the manufacturing process. We conclude that the new lead thus far has demonstrated appropriate mechanical and electrical characteristics.

Clinical safety of the ProMRI pacemaker system in patients subjected to thoracic spine and cardiac 1.5-T magnetic resonance imaging scanning conditions.

PubMed

Bailey, William M; Mazur, Alexander; McCotter, Craig; Woodard, Pamela K; Rosenthal, Lawrence; Johnson, Whitney; Mela, Theofanie

2016-02-01

Permanent cardiac pacemakers have historically been considered a contraindication to magnetic resonance imaging (MRI). The purpose of the ProMRI Phase B Study, a multicenter, prospective, single-arm, nonrandomized study, was to evaluate the clinical safety of the Biotronik ProMRI pacemaker system in patients undergoing thoracic spine and cardiac MRI. The ProMRI Phase B study enrolled 245 patients with stable baseline pacing indices implanted with an Entovis pacemaker (DR-T or SR-T) and Setrox 53-cm and/or 60-cm lead(s). Device interrogation was performed at enrollment, pre- and post-MRI scan, and 1 and 3 months post-MRI. End-points were (1) freedom from MRI- and pacing system-related serious adverse device effects through 1 month post-MRI; (2) freedom from atrial and ventricular MRI-induced pacing threshold increase (>0.5 V); and (3) freedom from P- and R-wave amplitude attenuation (<50%), or P wave <1.5 mV, or R wave <5.0 mV at 1 month post-MRI. In total, 216 patients completed the MRI and 1-month post-MRI follow-up. One adverse event possibly related to the implanted system and the MRI procedure occurred, resulting in a serious adverse device effect-free rate of 99.6% (220/221; P < .0001. Freedom from atrial and ventricular pacing threshold increase was 100% (194/194, P < .001) and 100% (206/206, P < .001) respectively. Freedom from P- and R-wave amplitude attenuation was 98.2% (167/170, P < .001) and 100% (188/188, P < .001) respectively. The results of the ProMRI Phase B study demonstrate the clinical safety and efficacy of the ProMRI pacemaker system in patients subjected to thoracic spine and cardiac MRI conditions. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Clinical safety of the ProMRI pacemaker system in patients subjected to head and lower lumbar 1.5-T magnetic resonance imaging scanning conditions.

PubMed

Bailey, William M; Rosenthal, Lawrence; Fananapazir, Lameh; Gleva, Marye; Mazur, Alexander; Rinaldi, C A; Kypta, Alexander; Merkely, Béla; Woodard, Pamela K

2015-06-01

Permanent cardiac pacemakers have historically been considered a contraindication to magnetic resonance imaging (MRI). The purpose of the ProMRI/ProMRI AFFIRM Study, which was a multicenter, prospective, single-arm, nonrandomized study, was to evaluate the clinical safety of the Biotronik ProMRI Pacemaker System under specific MRI conditions. The ProMRI Study (in the United States) and the ProMRI AFFIRM study (outside the United States) with identical design enrolled 272 patients with stable baseline pacing indices implanted with an Entovis or Evia pacemaker (DR-T or SR-T) and Setrox or Safio 53-cm or 60-cm lead. Device interrogation was performed at enrollment, pre-MRI and post-MRI scan, and 1 and 3 months post-MRI. End-points were (1) freedom from MRI- and pacing system-related serious adverse device effects (SADEs) through 1 month post-MRI, (2) freedom from atrial and ventricular MRI-induced pacing threshold increase (>0.5 V), and (3) freedom from P- and R-wave amplitude attenuation (<50%), or P wave <1.5 mV, or R wave <5.0 mV at 1 month post-MRI. Two hundred twenty-six patients completed the MRI and 1-month post-MRI follow-up. No adverse events related to the implanted system and the MRI procedure occurred, resulting in an SADE-free rate of 100.0% (229/229, P <.001). Freedom from atrial and ventricular pacing threshold increase was 99.0% (189/191, P = .003) and 100% (217/217, P <.001), respectively. Freedom from P- and R- wave amplitude attenuation was 99.4% (167/168, P <.001) and 99.5% (193/194, P <.001), respectively. The results of the ProMRI/ProMRI AFFIRM studies demonstrate the clinical safety and efficacy of the ProMRI pacemaker system in patients subjected to head and lower lumbar MRI conditions. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Role of apamin-sensitive small conductance calcium-activated potassium currents in long-term cardiac memory in rabbits.

PubMed

Yin, Dechun; Chen, Mu; Yang, Na; Wu, Adonis Z; Xu, Dongzhu; Tsai, Wei-Chung; Yuan, Yuan; Tian, Zhipeng; Chan, Yi-Hsin; Shen, Changyu; Chen, Zhenhui; Lin, Shien-Fong; Weiss, James N; Chen, Peng-Sheng; Everett, Thomas H

2018-05-01

Apamin-sensitive small conductance calcium-activated K current (I KAS ) is up-regulated during ventricular pacing and masks short-term cardiac memory (CM). The purpose of this study was to determine the role of I KAS in long-term CM. CM was created with 3-5 weeks of ventricular pacing and defined by a flat or inverted T wave off pacing. Epicardial optical mapping was performed in both paced and normal ventricles. Action potential duration (APD 80 ) was determined during right atrial pacing. Ventricular stability was tested before and after I KAS blockade. Four paced hearts and 4 normal hearts were used for western blotting and histology. There were no significant differences in either echocardiographic parameters or fibrosis levels between groups. Apamin induced more APD 80 prolongation in CM than in normal ventricles (mean [95% confidence interval]: 9.6% [8.8%-10.5%] vs 3.1% [1.9%-4.3%]; P <.001). Apamin significantly lengthened APD 80 in the CM model at late activation sites, indicating significant I KAS up-regulation at those sites. The CM model also had altered Ca 2+ handling, with the 50% Ca 2+ transient duration and amplitude increased at distal sites compared to a proximal site (near the pacing site). After apamin, the CM model had increased ventricular fibrillation (VF) inducibility (paced vs control: 33/40 (82.5%) vs 7/20 (35%); P <.001) and longer VF durations (124 vs 26 seconds; P <.001). Chronic ventricular pacing increases Ca 2+ transients at late activation sites, which activates I KAS to maintain repolarization reserve. I KAS blockade increases VF vulnerability in chronically paced rabbit ventricles. Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Pacing: A concept analysis of a chronic pain intervention

PubMed Central

Jamieson-Lega, Kathryn; Berry, Robyn; Brown, Cary A

2013-01-01

BACKGROUND: The intervention of pacing is regularly recommended for chronic pain patients. However, pacing is poorly defined and appears to be interpreted in varying, potentially contradictory manners within the field of chronic pain. This conceptual lack of clarity has implications for effective service delivery and for researchers’ ability to conduct rigorous study. An examination of the background literature demonstrates that while pacing is often one part of a multidisciplinary pain management program, outcome research is hindered by a lack of a clear and shared definition of this currently ill-defined construct. OBJECTIVES: To conduct a formal concept analysis of the term ‘pacing’. METHODS: A standardized concept analysis process (including literature scoping to identify all uses of the concept, analysis to determine defining attributes of the concept and identification of model, borderline and contrary cases) was used to determine what the concept of pacing does and does not represent within the current evidence base. RESULTS: A conceptual model including the core attributes of action, time, balance, learning and self-management emerged. From these attributes, an evidence-based definition for pacing was composed and distributed to stakeholders for review. After consideration of stakeholder feedback, the emergent definition of pacing was finalized as follows: “Pacing is an active self-management strategy whereby individuals learn to balance time spent on activity and rest for the purpose of achieving increased function and participation in meaningful activities”. CONCLUSION: The findings of the present concept analysis will help to standardize the use and definition of the term pacing across disciplines for the purposes of both pain management and research. PMID:23717825

Exercise capacity and N-terminal pro-brain natriuretic peptide levels with biventricular vs. right ventricular pacing for atrioventricular block: results from the PREVENT-HF German Substudy.

PubMed

Stockburger, Martin; de Teresa, Eduardo; Lamas, Gervasio; Desaga, Martin; Koenig, Carsten; Habedank, Dirk; Cobo, Erik; Navarro, Xavier; Wiegand, Uwe

2014-01-01

Previous studies showed unfavourable effects of right ventricular (RV) pacing. Ventricular pacing (VP), however, is required in many patients with atrioventricular (AV) block. The PREVENT-HF study explored left ventricular (LV) remodelling during RV vs. biventricular (BIV) pacing in AV block without advanced heart failure. The pre-specified PREVENT-HF German Substudy examined exercise capacity and N-terminal pro-brain natriuretic peptide (NT-proBNP). Patients with expected VP ≥80% were randomized to RV or BIV pacing. Endpoints were peak oxygen uptake (pVO2), oxygen uptake at the anaerobic threshold (VO2AT), ventilatory efficiency (VE/VCO2), and logNT-proBNP. Considering crossover, intention to treat (ITT), and on-treatment (OT) analyses of covariance (ANCOVA) were performed. For exercise testing 44 (RV: 25, BIV: 19), and for NT-proBNP 53 patients (RV: 29, BIV: 24) were included. The ITT analysis revealed significant differences in pVO2 [ANCOVA effect 2.83 mL/kg/min, confidence interval (CI) 0.83-4.91, P = 0.007], VO2AT (ANCOVA effect 2.14 mL/min/k, CI 0.14-4.15, P = 0.03), and VE/VCO2 (ANCOVA effect -5.46, CI -10.79 to -0.13, P = 0.04) favouring BIV randomization. The significant advantage in pVO2 persisted in OT analysis, while VO2AT and VE/VCO2 showed trends favouring BIV pacing. LogNT-proBNP did not differ between groups. (ITT: ANCOVA effect 0.008, CI -0.40 to +0.41, P = 0.97; OT: ANCOVA effect -0.03, CI -0.44 to 0.30, P = 0.90). Our study suggests that BIV pacing produces better exercise capacity over 1 year compared with RV pacing in patients without advanced heart failure and AV block. In contrast, we observed no significant changes of NT-proBNP. Larger trials will allow appraising the clinical usefulness of BIV pacing in AV block. ClinicalTrials.gov Identifier: NCT00170326.

PACE and the Medicare+Choice risk-adjusted payment model.

PubMed

Temkin-Greener, H; Meiners, M R; Gruenberg, L

2001-01-01

This paper investigates the impact of the Medicare principal inpatient diagnostic cost group (PIP-DCG) payment model on the Program of All-Inclusive Care for the Elderly (PACE). Currently, more than 6,000 Medicare beneficiaries who are nursing home certifiable receive care from PACE, a program poised for expansion under the Balanced Budget Act of 1997. Overall, our analysis suggests that the application of the PIP-DCG model to the PACE program would reduce Medicare payments to PACE, on average, by 38%. The PIP-DCG payment model bases its risk adjustment on inpatient diagnoses and does not capture adequately the risk of caring for a population with functional impairments.

Transvenous versus open chest lead placement for resynchronization therapy in patients with heart failure: comparison of ventricular electromechanical synchronicity.

PubMed

Zhang, Hai-Bo; Meng, Xu; Han, Jie; Li, Yan; Zhang, Ye; Jiang, Teng-Yong; Zhao, Ying-Xin; Zhou, Yu-Jie

2017-04-01

Transvenous lead placement is the standard approach for left ventricular (LV) pacing in cardiac resynchronization therapy (CRT), while the open chest access epicardial lead placement is currently the most frequently used second choice. Our study aimed to compare the ventricular electromechanical synchronicity in patients with heart failure after CRT with these two different LV pacing techniques. We enrolled 33 consecutive patients with refractory heart failure secondly to dilated cardiomyopathy who were eligible for CRT in this study. Nineteen patients received transvenous (TV group) while 14 received open chest (OP group) LV lead pacing. Intra- and inter-ventricular electromechanical synchronicity was assessed by tissue Doppler imaging (TDI) before and one year after CRT procedure. Before CRT procedure, the mean QRS-duration, maximum time difference to systolic peak velocity among 12 left ventricle segments (LV Ts-12), standard deviation of time difference to systolic peak velocity of 12 left ventricle segments (LV Ts-SD), and inter-ventricular mechanical delay (IVMD) in OP and TV group were 166 ± 17 ms and 170 ± 21 ms, 391 ± 42 ms and 397 ± 36 ms, 144 ± 30 ms and 148 ± 22 ms, 58 ± 25 ms and 60 ± 36 ms, respectively (all P > 0.05). At one year after the CRT, the mean QRS-duration, LV Ts-12, LV Ts-SD, and IVMD in TV and OP group were 128 ± 14 ms and 141 ± 22 ms ( P = 0.031), 136 ± 37 ms and 294 ± 119 ms ( P = 0.023), 50 ± 22 ms and 96 ± 34 ms ( P = 0.015), 27 ± 11 ms and 27 ± 26 ms ( P = 0.86), respectively. The LV lead implantation procedure time was 53.4 ± 16.3 min for OP group and 136 ± 35.1 min for TV group ( P = 0.016). The mean LV pacing threshold increased significantly from 1.7 ± 0.6 V/0.5 ms to 2.3 ± 1.6 V/0.5 ms ( P < 0.05) in TV group while it remained stable in the OP group. Compared to conventional endovascular approach, open chest access of LV pacing for CRT leads to better improvement of the intraventricular synchronization.

Prospective evaluation of defibrillation threshold and postshock rhythm in young ICD recipients.

PubMed

Radbill, Andrew E; Triedman, John K; Berul, Charles I; Walsh, Edward P; Alexander, Mark E; Webster, Gregory; Cecchin, Frank

2012-12-01

Adaptation of implantable cardioverter defibrillator (ICD) systems to the needs of pediatric and congenital heart patients is problematic due to constraints of vascular and thoracic anatomy. An improved understanding of the defibrillation energy and postshock pacing requirements in such patients may help direct more tailored ICD therapy. We describe the first prospective evaluation of defibrillation threshold (DFT) and postshock rhythm in this population. We prospectively studied patients ≤ 60 kg at time of ICD intervention. DFTs were obtained using a binary search protocol with three VF inductions. Postshock pacing was programmed using a stepwise protocol, lowering the rate prior to each VF induction. Twenty patients were enrolled: 11 had channelopathy, five congenital heart disease, and four cardiomyopathy. The median age was 16 years, median weight 48 kg. Twelve patients had a transvenous high-voltage coil; eight had pericardial +/- subcutaneous coil(s). Median DFT was 7 J (range 3-31 J); 19/20 patients had DFT ≤ 15 J and all patients <25 kg had DFT ≤ 9 J (n = 6). There was no difference in DFT between patients with transvenous versus pericardial +/- subcutaneous coils (median 7 J vs 6 J, P = 0.59). No patient with normal atrioventricular conduction prior to defibrillation required postshock pacing (n = 16). There were no adverse events. These data suggest that many pediatric ICD patients have low DFTs and adequate postshock escape rhythm. This may help determine appropriate parameters for future design of pediatric-specific ICDs. ©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.

Implantation of active fixation leads in coronary veins for left ventricular stimulation: report of five cases.

PubMed

Hansky, Bert; Vogt, Juergen; Gueldner, Holger; Schulte-Eistrup, Sebastian; Lamp, Barbara; Heintze, Johannes; Horstkotte, Dieter; Koerfer, Reiner

2007-01-01

Securing transvenous left ventricular (LV) pacing leads without an active fixation mechanism in proximal coronary vein (CV) segments is usually challenging and frequently impossible. We investigated how active fixation leads can be safely implanted in this location, how to avoid perforating the free wall of the CV, and how to recognize and respond to perforations. In five patients with no alternative to LV pacing from proximal CV segments, 4 Fr SelectSecure (Medtronic, Minneapolis, MN, USA) leads, which have a fixed helix, were implanted through a modified 6 Fr guide catheter with a pre-shaped tip (Launcher, Medtronic). Active fixation leads were successfully implanted in proximal CVs in five patients. There were no complications. Acute and chronic pacing thresholds were comparable to those of conventional CV leads. The pre-shaped guide catheter tip remains in close proximity to the myocardial aspect of the CV, directing the lead helix toward a safe implantation site. If only proximal CV pacing sites are available, 4 Fr SelectSecure leads can be safely implanted through a modified Launcher guide catheter, avoiding more invasive implantation techniques. Other than venous stenting or implantation of leads with retractable tines, SelectSecure leads are expected to remain extractable.

Occurrence of simultaneous cathodal-anodal capture with left ventricular quadripolar leads for cardiac resynchronization therapy: an electrocardiogram evaluation.

PubMed

Occhetta, Eraldo; Dell'Era, Gabriele; Giubertoni, Ailia; Magnani, Andrea; Rametta, Francesco; Blandino, Alessandro; Magnano, Vincenzo; Malacrida, Maurizio; Marino, Paolo

2017-04-01

The occurrence of left ventricular (LV) anodal activation during pacing with modern multipolar cardiac resynchronization therapy (CRT) systems has never been reported. The aim of our study was to demonstrate, by means of electrocardiogram (ECG) analysis, the occurrence of simultaneous cathodal-anodal LV capture with quadripolar LV leads. We studied 10 first-time recipients of a CRT device equipped with a quadripolar LV lead. During follow-up, standard supine 12-lead ECGs were obtained in available cathode-to-anode LV pacing configurations with a pulse amplitude equal to twice the pacing threshold. The occurrence of simultaneous cathodal-anodal LV capture was defined as the presence of variations in electrocardiographic ventricular activation (EVA) when the distal tip (cathode)-to-device can (anode) pacing configuration was compared with the distal tip (cathode)-to-proximal ring (anode) configuration. In eight patients, we found differences in EVA when different LV sites were paced through the unipolar LV tip and unipolar LV ring configurations. In these patients, a difference in EVA was detected in 61.5% (59 of 96) of the ECG leads (marked difference in 31.3%, slight difference in 30.2%). Changes in EVA between unipolar tip-to-can and bipolar tip-to-ring pacing that were suggestive of cathodal-anodal LV capture were found in six patients. In these patients, a total of 30 (41.7%) ECG leads showed a difference in EVA (marked difference in 20.8%, slight difference in 20.8%). In our experience, additional anodal capture by the proximal LV ring during LV pacing is provable in most recipients of a resynchronization device equipped with a multipolar LV lead. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Estimation of the effects of multipoint pacing on battery longevity in routine clinical practice.

PubMed

Akerström, Finn; Narváez, Irene; Puchol, Alberto; Pachón, Marta; Martín-Sierra, Cristina; Rodríguez-Mañero, Moisés; Rodríguez-Padial, Luis; Arias, Miguel A

2017-09-23

Multipoint pacing (MPP) permits simultaneous multisite pacing of the left ventricle (LV); initial studies suggest haemodynamic and clinical benefits over conventional (single LV site) cardiac resynchronization therapy (CRT). The aim of this study was to estimate the impact of MPP activation on battery longevity in routine clinical practice. Patient (n = 46) and device data were collected from two centres at least 3 months after MPP-CRT device implantation. Multipoint pacing programming was based on the maximal possible anatomical LV1/LV2 separation according to three predefined LV pacing capture threshold (PCT) cut-offs (≤1.5 V; ≤4.0 V; and ≤6.5 V). Estimated battery longevity was calculated using the programmed lower rate limit, lead impedances, outputs, and pacing percentages. Relative to the longevity for conventional CRT using the lowest PCT (8.9 ± 1.2 years), MPP activation significantly shortened battery longevity for all three PCT cut-offs (≤1.5 V, -5.6%; ≤4.0 V, -16.9%; ≤6.5 V, -21.3%; P's <0.001). When compared with conventional CRT based on longest right ventricle-LV delay (8.3 ± 1.3 years), battery longevity was significantly shortened for the MPP ≤ 4.0 V and ≤6.5 V cut-offs (-10.8 and -15.7%, respectively; P's <0.001). Maximal LV1/LV2 spacing was possible in 23.9% (≤1.5 V), 56.5% (≤4.0 V), and 69.6% (≤6.5 V) of patients. Multipoint pacing activation significantly reduces battery longevity compared with that for conventional CRT configuration. When reasonable MPP LV vector PCTs (≤4.0 V) are achieved, the decrease in battery longevity is relatively small which may prompt the clinician to activate MPP. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.

Adjustment of the evoked response sensitivity after hospital discharge in pacemaker patients with automatic ventricular threshold tracking activated.

PubMed

Schuchert, A; Ventura, R; Meinertz, T

2001-02-01

Automatic threshold tracking in cardiac pacemakers allows ventricular capture verification and self-adaptive pacing output regulation. The Autocapture algorithm detects the evoked response (ER) signal immediately after the pacing pulse to verify the efficacy of ventricular pacing. Before hospital delivery, the ER sensitivity must be programmed individually so that the pacemaker detects the ER signal adequately without sensing lead polarization. The aims of the study were to assess the frequency of patients in whom Autocapture could be activated and whether the ER sensitivity had to be adjusted after hospital discharge. The study included 44 patients who received the VVIR pacemaker Regency SR+ (St. Jude Medical) connected to the model 1450 T pacing lead. ER signal, lead polarization, and ER sensitivity were evaluated before hospital discharge and 1, 3, and 6 months after implantation. The system recommended activating Autocapture in 42 of 44 patients. The mean ER signal was 8.4+/-1.2 mV at discharge, 9.0+/-3.9 mV at month 1, 8.9+/-4.9 mV at month 3, and 9.3+/-4.5 mV at month 6. Polarization was 1.0+/-0.1 mV at discharge, 1.1+/-0.5 mV at month 1, 1.1+/-0.2 mV at month 3, and 1.1+/-0.5 mV at month 6. Mean ER sensitivity was 3.7+/-1.8 mV at discharge, 4.0+/-1.8 mV after 1, 4.1+/-2.2 mV after 3, and 4.1+/-1.8 mV after 6 months. ER sensitivity could remain unadjusted in 14 patients. Programming to a less sensitive ER setting from 2.9+/-1.2 mV to 4.3+/-1.5 mV was possible in 21 patients. Programming to a more sensitive ER setting from 4.1+/-1.1 mV to 2.5+/-0.9 mV was required in nine patients because of the decrease of the ER signal. The automatic threshold tracking algorithm Autocapture could be activated in 95% of patients. Programming to more sensitive ER settings was recommended in 21% of the patients after hospital discharge. Therefore, ER signal and polarization must be checked at each follow-up, as a decrease in ER signal amplitude can make reprogramming of the ER sensitivity necessary. There is no risk for the patient if the ER is not sensed, as high voltage backup stimulation is present.

Factors influencing pacing in triathlon

PubMed Central

Wu, Sam SX; Peiffer, Jeremiah J; Brisswalter, Jeanick; Nosaka, Kazunori; Abbiss, Chris R

2014-01-01

Triathlon is a multisport event consisting of sequential swim, cycle, and run disciplines performed over a variety of distances. This complex and unique sport requires athletes to appropriately distribute their speed or energy expenditure (ie, pacing) within each discipline as well as over the entire event. As with most physical activity, the regulation of pacing in triathlon may be influenced by a multitude of intrinsic and extrinsic factors. The majority of current research focuses mainly on the Olympic distance, whilst much less literature is available on other triathlon distances such as the sprint, half-Ironman, and Ironman distances. Furthermore, little is understood regarding the specific physiological, environmental, and interdisciplinary effects on pacing. Therefore, this article discusses the pacing strategies observed in triathlon across different distances, and elucidates the possible factors influencing pacing within the three specific disciplines of a triathlon. PMID:25258562

Preparation of scanning tunneling microscopy tips using pulsed alternating current etching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valencia, Victor A.; Thaker, Avesh A.; Derouin, Jonathan

An electrochemical method using pulsed alternating current etching (PACE) to produce atomically sharp scanning tunneling microscopy (STM) tips is presented. An Arduino Uno microcontroller was used to control the number and duration of the alternating current (AC) pulses, allowing for ready optimization of the procedures for both Pt:Ir and W tips using a single apparatus. W tips prepared using constant and pulsed AC power were compared. Tips fashioned using PACE were sharper than those etched with continuous AC power alone. Pt:Ir tips were prepared with an initial coarse etching stage using continuous AC power followed by fine etching using PACE.more » The number and potential of the finishing AC pulses was varied and scanning electron microscope imaging was used to compare the results. Finally, tip quality using the optimized procedures was verified by UHV-STM imaging. With PACE, at least 70% of the W tips and 80% of the Pt:Ir tips were of sufficiently high quality to obtain atomically resolved images of HOPG or Ni(111)« less

Early Performance and Safety of the Micra Transcatheter Pacemaker in Pigs.

PubMed

Bonner, Matthew; Eggen, Michael; Haddad, Tarek; Sheldon, Todd; Williams, Eric

2015-11-01

The Micra® Transcatheter Pacing System (TPS; Medtronic Inc., Minneapolis, MN, USA) is a miniaturized single-chamber pacemaker system that is delivered via catheter through the femoral vein. In this study, the electrical performance was compared between the TPS and a traditional leaded pacemaker. In addition, the safety profile of the two systems was compared by thorough monitoring for a number of adverse events. The TPS was implanted in the right ventricular apex of 10 Yucatan mini pigs and a Medtronic single-lead pacemaker (SLP) was implanted in the right ventricular apex of another 10 pigs and connected to a traditional pacemaker. The electrical performance of all devices was monitored for 12 weeks. The safety profile of each system was characterized using x-ray, computed tomography, ultrasound, blood work, and necropsy to monitor for a variety of adverse events. At implant the mean pacing thresholds were 0.58 ± 0.17 V @0.24 ms and 0.75 ± 0.29 V @0.21 ms for the TPS and the SLP respectively. After 12 weeks, mean thresholds were 0.94 ± 0.46 V and 1.85 ± 0.75 V (P < 0.0001). There were two pulmonary emboli that were small and past the tertiary branch, and one occurred in each arm. There were also two infections with one in each arm. There were no dislodgements (macro or micro), tissue injury, tamponade, or valve injury. Overall, despite the 10-fold size reduction of the Micra TPS, it appears to perform similarly and have a similar safety profile to a traditional pacemaker system. © 2015 Medtronic PLC. Pacing and Clinical Electrophysiology published by Wiley Periodicals, Inc.

Is right ventricular mid-septal pacing superior to apical pacing in patients with high degree atrio-ventricular block and moderately depressed left ventricular function?

PubMed

Chen, Kang; Mao, Ye; Liu, Shao-hua; Wu, Qiong; Luo, Qing-zhi; Pan, Wen-qi; Jin, Qi; Zhang, Ning; Ling, Tian-you; Chen, Ying; Gu, Gang; Shen, Wei-feng; Wu, Li-qun

2014-06-01

We are aimed to investigate whether right ventricular mid-septal pacing (RVMSP) is superior to conventional right ventricular apical pacing (RVAP) in improving clinical functional capacity and left ventricular ejection fraction (LVEF) for patients with high-degree atrio-ventricular block and moderately depressed left ventricle (LV) function. Ninety-two patients with high-degree atrio-ventricular block and moderately reduced LVEF (ranging from 35% to 50%) were randomly allocated to RVMSP (n=45) and RVAP (n=47). New York Heart Association (NYHA) functional class, echocardiographic LVEF, and distance during a 6-min walk test (6MWT) were determined at 18 months after pacemaker implantation. Serum levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured using an enzyme-linked immunosorbent assay (ELISA) kit. Compared with baseline, NYHA functional class remained unchanged at 18 months, distance during 6MWT (485 m vs. 517 m) and LVEF (36.7% vs. 41.8%) were increased, but BNP levels were reduced (2352 pg/ml vs. 710 pg/ml) in the RVMSP group compared with those in the RVAP group, especially in patients with LVEF 35%-40% (for all comparisons, P<0.05). However, clinical function capacity and LV function measurements were not significantly changed in patients with RVAP, despite the pacing measurements being similar in both groups, such as R-wave amplitude and capture threshold. RVMSP provides a better clinical utility, compared with RVAP, in patients with high-degree atrioventricular block and moderately depressed LV function whose LVEF levels ranged from 35% to 40%.

Surprisingly Low Limits of Selection in Plant Domestication

PubMed Central

Allaby, Robin G.; Kitchen, James L.; Fuller, Dorian Q.

2015-01-01

Current debate concerns the pace at which domesticated plants emerged from cultivated wild populations and how many genes were involved. Using an individual-based model, based on the assumptions of Haldane and Maynard Smith, respectively, we estimate that a surprisingly low number of 50–100 loci are the most that could be under selection in a cultivation regime at the selection strengths observed in the archaeological record. This finding is robust to attempts to rescue populations from extinction through selection from high standing genetic variation, gene flow, and the Maynard Smith-based model of threshold selection. Selective sweeps come at a cost, reducing the capacity of plants to adapt to new environments, which may contribute to the explanation of why selective sweeps have not been detected more frequently and why expansion of the agrarian package during the Neolithic was so frequently associated with collapse. PMID:27081302

Constitutively Active Acetylcholine-Dependent Potassium Current Increases Atrial Defibrillation Threshold by Favoring Post-Shock Re-Initiation

PubMed Central

Bingen, Brian O.; Askar, Saïd F. A.; Neshati, Zeinab; Feola, Iolanda; Panfilov, Alexander V.; de Vries, Antoine A. F.; Pijnappels, Daniël A.

2015-01-01

Electrical cardioversion (ECV), a mainstay in atrial fibrillation (AF) treatment, is unsuccessful in up to 10–20% of patients. An important aspect of the remodeling process caused by AF is the constitutive activition of the atrium-specific acetylcholine-dependent potassium current (IK,ACh → IK,ACh-c), which is associated with ECV failure. This study investigated the role of IK,ACh-c in ECV failure and setting the atrial defibrillation threshold (aDFT) in optically mapped neonatal rat cardiomyocyte monolayers. AF was induced by burst pacing followed by application of biphasic shocks of 25–100 V to determine aDFT. Blocking IK,ACh-c by tertiapin significantly decreased DFT, which correlated with a significant increase in wavelength during reentry. Genetic knockdown experiments, using lentiviral vectors encoding a Kcnj5-specific shRNA to modulate IK,ACh-c, yielded similar results. Mechanistically, failed ECV was attributed to incomplete phase singularity (PS) removal or reemergence of PSs (i.e. re-initiation) through unidirectional propagation of shock-induced action potentials. Re-initiation occurred at significantly higher voltages than incomplete PS-removal and was inhibited by IK,ACh-c blockade. Whole-heart mapping confirmed our findings showing a 60% increase in ECV success rate after IK,ACh-c blockade. This study provides new mechanistic insight into failing ECV of AF and identifies IK,ACh-c as possible atrium-specific target to increase ECV effectiveness, while decreasing its harmfulness. PMID:26487066

Building a Grad Nation: Progress and Challenge in Ending the High School Dropout Epidemic. Annual Update 2014

ERIC Educational Resources Information Center

Balfanz, Robert; Bridgeland, John M.; Fox, Joanna Hornig; DePaoli, Jennifer L.; Ingram, Erin S.; Maushard, Mary

2014-01-01

This fifth annual update on America's high school dropout crisis shows that, for the first time in history, the nation has crossed the 80 percent high school graduation rate threshold and remains on pace, for the second year in a row, to meet the goal of a 90 percent high school graduation rate by the Class of 2020. This report highlights key…

How Much Walking Is Needed to Improve Cardiorespiratory Fitness? An Examination of the 2008 Physical Activity Guidelines for Americans

ERIC Educational Resources Information Center

Anton, Stephen D.; Duncan, Glenn E.; Limacher, Marian C.; Martin, Anthony D.; Perri, Michael G.

2011-01-01

The 2008 Physical Activity Guidelines for Americans (U.S. Department of Health and Human Services, 2008) indicated that two approaches can be used to achieve the activity threshold needed to derive health benefits. Individuals may engage in either 150 min (2 hr 30 min) of moderate intensity activity (e.g., moderate-paced walking), or 75 min (1 hr…

Alternative right ventricular pacing sites.

PubMed

Łuciuk, Dariusz; Łuciuk, Marek; Gajek, Jacek

2015-01-01

The main adverse effect of chronic stimulation is stimulation-induced heart failure in case of ventricular contraction dyssynchrony. Because of this fact, new techniques of stimulation should be considered to optimize electrotherapy. One of these methods is pacing from alternative right ventricular sites. The purpose of this article is to review currently accumulated data about alternative sites of cardiac pacing. Medline and PubMed bases were used to search English and Polish reports published recently. Recent studies report a deleterious effect of long term apical pacing. It is suggested that permanent apical stimulation, by omitting physiological conduction pattern with His-Purkinie network, may lead to electrical and mechanical dyssynchrony of heart muscle contraction. In the long term this pathological situation can lead to severe heart failure and death. Because of this, scientists began to search for some alternative sites of cardiac pacing to reduce the deleterious effect of stimulation. Based on current accumulated data, it is suggested that the right ventricular outflow tract, right ventricular septum, direct His-bundle or biventricular pacing are better alternatives due to more physiological electrical impulse propagation within the heart and the reduction of the dyssynchrony effect. These methods should preserve a better left ventricular function and prevent the development of heart failure in permanent paced patients. As there is still not enough, long-term, randomized, prospective, cross-over and multicenter studies, further research is required to validate the benefits of using this kind of therapy. The article should pay attention to new sites of cardiac stimulation as a better and safer method of treatment.

An Australian Land Force for Conflict in a World Without Precedent (Future Warfare Concept Paper)

DTIC Science & Technology

2009-01-01

Michael B. Ryan, Australian Army Thesis: The current pace of change in the global security environment and information technology demands that, like...information) Wave societies.6 The current pace of change in the global security environment and information technology demands that, like all...Blue, downloaded from www.defence.gov.au/navy; La Franchi , Peter, “High Level Interoperability: Future Development of t Peter, “Development Role

Prevention of atrial fibrillation by inter-atrial septum pacing guided by electrophysiological testing, in patients with delayed interatrial conduction.

PubMed

Manolis, A G; Katsivas, A G; Vassilopoulos, C; Koutsogeorgis, D; Louvros, N E

2002-04-01

Interatrial septum (IAS) pacing seems efficient in synchronizing atrial depolarization in patients (pts) with delayed inter-atrial conduction, but its clinical role in preventing atrial tachyarrhythmias is still debated. This study was conducted in order to evaluate the clinical efficacy of IAS pacing guided by pace mapping of the IAS, as an alternative treatment modality in pts with drug refractory paroxysmal atrial fibrillation (PAF). We evaluated 29 pts (13 male, 16 female, 60 +/- 11 years), with drug refractory PAF, normal sinus node function and prolonged inter-atrial conduction time (P wave 142 +/- 10 ms). Multipolar catheters were inserted and the electrograms from the high right atrium (HRA) and proximal, middle and distal coronary sinus (CS) were recorded. The IAS was paced from multiple sites. The site of IAS where the timing between HRA and distal CS was <20 ms was considered the most suitable for synchronizing the atria. This site was found to be superior to the CS os. near the fossa ovalis in all pts. An active fixation atrial lead was positioned at this site and a standard lead was placed in the right ventricle. During IAS pacing, the P wave duration decreased significantly to 107 +/- 15 ms (P<0.001). At implant, the atrial sensing was 2.3 +/- 0.7 mV, the atrial pacing threshold was 0.95 +/- 0.15 V (0.5 ms) and the impedance was 760 +/- 80 Ohm. We evaluated the pts during four periods of 3 months duration each. The first period (control) was before pacemaker implantation, while the pts were under antiarrhythmic treatment. During the subsequent two periods, we evaluated the clinical efficacy of IAS pacing to prevent PAF recurrences, in AAT (75 bpm) and AAIR (75-140 bpm) mode, with random selection of the order and after discontinuation of antiarrhythmic treatment. During the fourth period, the same AAIR mode was assessed, but antiarrhythmic drugs were also administered. We compared the arrhythmia free interval among the four periods. The proportion of atrial paced beats in AAIR pacing mode plus antiarrhythmics was significantly higher compared with the drug-free period in AAIR mode (57 +/- 9% and 49 +/- 9% respectively, P=0017) and with AAT pacing mode (44 +/- 10%,(, P<0.001). In AAT mode, the arrhythmia free interval was 24.2 +/- 5.1 days, while it was 26.2 +/- 5.7 days in AAIR mode. These intervals did not differ significantly from the pre-implantation period (24.1 +/- 6.3 days). The arrhythmia free interval in AAIR pacing in combination with antiarrhythmic drug therapy was 38.7 +/- 8.1 days and this was significantly longer than the previous periods (P<0.05). Atrial septal pacing in combination with antiarrhythmic drug therapy reduced the incidence of PAF in pts with prolonged inter-atrial conduction times. Pace mapping of the IAS is an attractive technique to assess the shortest atrial activation time between HRA and distal CS. Whether placement of the atrial lead based on the shortest HRA--distal CS time is the best place in the IAS to prevent PAF still remains to be proven.

Influence of internal current and pacing current on pacemaker longevity.

PubMed

Schuchert, A; Kuck, K H

1994-01-01

The effects of lower pulse amplitude on battery current and pacemaker longevity were studied comparing the new, small-sized VVI pacemaker, Minix 8341, with the former model, Pasys 8329. Battery current was telemetrically measured at 0.8, 1.6, 2.5, and 5.0 V pulse amplitude and 0.05, 0.25, 0.5, and 1.0 msec pulse duration. Internal current was assumed to be equal to the battery current at 0.8 V and 0.05 msec. Pacing current was calculated subtracting internal current from battery current. The Minix pacemaker had a significantly lower battery current because of a lower internal current (Minix: 4.1 +/- 0.1 microA; Pasys: 16.1 +/- 0.1 microA); pacing current of both units was similar. At 0.5 msec pulse duration, the programming from 5.0-2.5 V pulse amplitude resulted in a greater relative reduction of battery current in the newer pacemaker (51% vs 25%). Projected longevity of each pacemaker was 7.9 years at 5.0 V and 0.5 msec. The programming from 5.0-2.5 V extended the projected longevity by 2.3 years (Pasys) and by 7.1 years (Minix). The longevity was negligibly longer after programming to 1.6 V. extension of pacemaker longevity can be achieved with the programming to 2.5 V or less if the connected pacemakers need a low internal current for their circuitry.

Changes in left ventricular repolarization and ion channel currents following a transient rate increase superimposed on bradycardia in anesthetized dogs.

PubMed

Rubart, M; Lopshire, J C; Fineberg, N S; Zipes, D P

2000-06-01

We previously demonstrated in dogs that a transient rate increase superimposed on bradycardia causes prolongation of ventricular refractoriness that persists for hours after resumption of bradycardia. In this study, we examined changes in membrane currents that are associated with this phenomenon. The whole cell, patch clamp technique was used to record transmembrane voltages and currents, respectively, in single mid-myocardial left ventricular myocytes from dogs with 1 week of complete AV block; dogs either underwent 1 hour of left ventricular pacing at 120 beats/min or did not undergo pacing. Pacing significantly heightened mean phase 1 and peak plateau amplitudes by approximately 6 and approximately 3 mV, respectively (P < 0.02), and prolonged action potential duration at 90% repolarization from 235+/-8 msec to 278+/-8 msec (1 Hz; P = 0.02). Rapid pacing-induced changes in transmembrane ionic currents included (1) a more pronounced cumulative inactivation of the 4-aminopyridine-sensitive transient outward K+ current, Ito, over the range of physiologic frequencies, resulting from a approximately 30% decrease in the population of quickly reactivating channels; (2) increases in peak density of L-type Ca2+ currents, I(Ca.L), by 15% to 35 % between +10 and +60 mV; and (3) increases in peak density of the Ca2+-activated chloride current, I(Cl.Ca), by 30% to 120% between +30 and +50 mV. Frequency-dependent reduction in Ito combined with enhanced I(Ca.L) causes an increase in net inward current that may be responsible for the observed changes in ventricular repolarization. This augmentation of net cation influx is partially antagonized by an increase in outward I(Ca.Cl).

Assessment of exit block following pulmonary vein isolation: far-field capture masquerading as entrance without exit block.

PubMed

Vijayaraman, Pugazhendhi; Dandamudi, Gopi; Naperkowski, Angela; Oren, Jess; Storm, Randle; Ellenbogen, Kenneth A

2012-10-01

Complete electrical isolation of pulmonary veins (PVs) remains the cornerstone of ablation therapy for atrial fibrillation. Entrance block without exit block has been reported to occur in 40% of the patients. Far-field capture (FFC) can occur during pacing from the superior PVs to assess exit block, and this may appear as persistent conduction from PV to left atrium (LA). To facilitate accurate assessment of exit block. Twenty consecutive patients with symptomatic atrial fibrillation referred for ablation were included in the study. Once PV isolation (entrance block) was confirmed, pacing from all the bipoles on the Lasso catheter was used to assess exit block by using a pacing stimulus of 10 mA at 2 ms. Evidence for PV capture without conduction to LA was necessary to prove exit block. If conduction to LA was noticed, pacing output was decreased until there was PV capture without conduction to LA or no PV capture was noted to assess for far-field capture in both the upper PVs. All 20 patients underwent successful isolation (entrance block) of all 76 (4 left common PV) veins: mean age 58 ± 9 years; paroxysmal atrial fibrillation 40%; hypertension 70%, diabetes mellitus 30%, coronary artery disease 15%; left ventricular ejection fraction 55% ± 10%; LA size 42 ± 11 mm. Despite entrance block, exit block was absent in only 16% of the PVs, suggesting persistent PV to LA conduction. FFC of LA appendage was noted in 38% of the left superior PVs. FFC of the superior vena cava was noted in 30% of the right superior PVs. The mean pacing threshold for FFC was 7 ± 4 mA. Decreasing pacing output until only PV capture (loss of FFC) is noted was essential to confirm true exit block. FFC of LA appendage or superior vena cava can masquerade as persistent PV to LA conduction. A careful assessment for PV capture at decreasing pacing output is essential to exclude FFC. Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

The Positive Effects of Priming Exercise on Oxygen Uptake Kinetics and High-Intensity Exercise Performance Are Not Magnified by a Fast-Start Pacing Strategy in Trained Cyclists

PubMed Central

Caritá, Renato Aparecido Corrêa; Greco, Camila Coelho; Denadai, Benedito Sérgio

2014-01-01

The purpose of this study was to determine both the independent and additive effects of prior heavy-intensity exercise and pacing strategies on the VO2 kinetics and performance during high-intensity exercise. Fourteen endurance cyclists (VO2max  = 62.8±8.5 mL.kg−1.min−1) volunteered to participate in the present study with the following protocols: 1) incremental test to determine lactate threshold and VO2max; 2) four maximal constant-load tests to estimate critical power; 3) six bouts of exercise, using a fast-start (FS), even-start (ES) or slow-start (SS) pacing strategy, with and without a preceding heavy-intensity exercise session (i.e., 90% critical power). In all conditions, the subjects completed an all-out sprint during the final 60 s of the test as a measure of the performance. For the control condition, the mean response time was significantly shorter (p<0.001) for FS (27±4 s) than for ES (32±5 s) and SS (32±6 s). After the prior exercise, the mean response time was not significantly different among the paced conditions (FS = 24±5 s; ES = 25±5 s; SS = 26±5 s). The end-sprint performance (i.e., mean power output) was only improved (∼3.2%, p<0.01) by prior exercise. Thus, in trained endurance cyclists, an FS pacing strategy does not magnify the positive effects of priming exercise on the overall VO2 kinetics and short-term high-intensity performance. PMID:24740278

Lumenless pacing leads: performance and extraction in pediatrics and congenital heart disease.

PubMed

Garnreiter, Jason; Whitaker, Patricia; Pilcher, Thomas; Etheridge, Susan; Saarel, Elizabeth

2015-01-01

Pediatric and congenital heart disease (CHD) patients requiring permanent pacing present unique challenges, including need for long duration of implant, small size, and structural abnormalities. We report 6 years of experience with a novel 4.1-Fr lumenless pacing lead (model 3830, Medtronic Inc., Minneapolis, MN, USA) in this population. Retrospective review of M3830 leads implanted at a pediatric center from 2005 to 2011. Data were compared to a population with a conventional pacing lead (model 1488, St. Jude Medical Inc., St. Paul, MN, USA). A total of 193 patients with 198 model 3830 leads (125 atrial, 73 ventricular) were enrolled. CHD was present in 121 (63%). Age and weight at implant were 16.6 ± 8.5 years and 51.7 ± 23.5 kg, respectively. Length of follow-up was 26 ± 19 months (range 0-73). At implant, mean sensing and capture thresholds were good and remained stable over time. There were no significant differences in electrical performance compared to 101 leads in the comparison group. Implant complications were rare. Follow-up complications occurred in 4% of the M3830 leads and 16% of M1488 leads. Eleven M3830 leads required extraction. All were extracted without complications using only manual traction. There were three deaths in each group. One death in the M1488 group occurred during lead extraction. No other deaths were lead related. During up to 6 years of use in pediatric and CHD patients, the M3830 lead has demonstrated excellent efficacy, a low rate of complications, and straightforward extractability relative to traditional pacing leads. ©2014 Wiley Periodicals, Inc.

Interatrial septum pacing guided by three-dimensional intracardiac echocardiography.

PubMed

Szili-Torok, Tamas; Kimman, Geert Jan P; Scholten, Marcoen F; Ligthart, Jurgen; Bruining, Nico; Theuns, Dominic A M J; Klootwijk, Peter J; Roelandt, Jos R T C; Jordaens, Luc J

2002-12-18

Currently, the interatrial septum (IAS) pacing site is indirectly selected by fluoroscopy and P-wave analysis. The aim of the present study was to develop a novel approach for IAS pacing using intracardiac echocardiography (ICE). Interatrial septum pacing may be beneficial for the prevention of paroxysmal atrial fibrillation. Cross-sectional images are acquired during a pull-back of the ICE transducer from the superior vena cava into the inferior vena cava by an electrocardiogram- and respiration-gated technique. Both atria are then reconstructed using three-dimensional (3D) imaging. Using an "en face" view of the IAS, the desired pacing site is selected. Following lead placement and electrical testing, another 3D reconstruction is performed to verify the final lead position. Twelve patients were included in this study. The IAS pacing was achieved in all patients including six suprafossal (SF) and six infrafossal (IF) lead locations all confirmed by 3D imaging. The mean duration times of atrial lead implantation and fluoroscopy were 70 +/- 48.9 min and 23.7 +/- 20.6 min, respectively. The IAS pacing resulted in a significant reduction of the P-wave duration as compared to sinus rhythm (98.9 +/- 19.3 ms vs. 141.3 +/- 8.6 ms; p < 0.002). The SF pacing showed a greater reduction of the P-wave duration than IF pacing (59.4 +/- 6.6 ms vs. 30.2 +/- 13.6 ms; p < 0.004). Three-dimensional ICE is a feasible tool for guiding IAS pacing.

Self-Paced Physics, Segments 37-40.

ERIC Educational Resources Information Center

New York Inst. of Tech., Old Westbury.

Four study segments of the Self-Paced Physics Course materials are presented in this eighth problems and solutions book used as a part of course assignments. The content is related to magnetic induction, Faraday's law, induced currents, Lenz's law, induced electromotive forces, time-varying magnetic fields, self-inductance, inductors,…

Keeping Pace

ERIC Educational Resources Information Center

Henderson, Nancy

2008-01-01

This article describes the struggles of two tough moms who team up to start their own company. Fed up with a lack of stylish, properly-fitting shoes for their children with cerebral palsy, they established "Keeping Pace" which currently offers a selection of stylish girls' and boys' athletic sneakers and casual dress shoes for boys, all sold…

Self-Paced Physics, Segments 32-36.

ERIC Educational Resources Information Center

New York Inst. of Tech., Old Westbury.

Five study segments of the Self-Paced Physics Course materials are presented in this seventh problems and solutions book used as a part of student course work. The content is related to magnetic fields, magnetic moments, forces on charged particles in magnetic fields, electron volts, cyclotron, electronic charge to mass ratio, current-carrying…

Influence of verapamil on tachycardia-induced alterations of PP1 and PP2A in rabbit atrium

PubMed Central

Laszlo, Roman; Winkler, Christoph; Wöhrl, Stefan; Laszlo, Sara; Eick, Christian; Schreieck, Jürgen; Bosch, Ralph F

2007-01-01

BACKGROUND Long-term atrial fibrillation changes in many regulatory and structural processes may result in stabilization of the arrhythmia. There is evidence that decreased amplitude of L-type Ca2+ current – probably a key mechanism of atrial remodelling –resulting from changes in expression of regulatory proteins is at least jointly responsible. OBJECTIVES To assess the expressions of protein phosphatases PP1 and PP2A, as well as the effect of verapamil pretreatment (VPT), in the early phases of atrial fibrillation in a rabbit model. METHODS Four groups, each consisting of six animals, were studied: ‘not paced, no drug’ group; ‘paced, no drug’ group (rapid atrial pacing [RAP] 600 beats/min for 24 h); ‘not paced, verapamil’ (NPV) group (duration of VPT was seven days, verapamil 7.5 mg/kg was administered every 12 h); and ‘paced, verapamil’ (PV) group (pacemaker stimulation after VPT). Protein expression was evaluated by Western blot analysis. RESULTS RAP resulted in an augmented (32%) PP1 expression (not paced, no drug group versus paced, no drug group). The increase in PP1 expression was prevented with VPT (NPV group versus PV group). Expression of PP2A was not influenced by RAP. However, VPT led to an increase of PP2A expression (16%) after RAP (NPV group versus PV group). CONCLUSIONS Fortified expression of protein phosphatases might be – besides transcriptional downregulation of channel subunits – another important cause of reduced L-type Ca2+ current after RAP. Blocking L-type Ca2+ channels with verapamil to prevent tachycardia-induced changes of PP1 expression might be expedient. PMID:18651001

Hysteresis effect implicates calcium cycling as a mechanism of repolarization alternans.

PubMed

Walker, Mariah L; Wan, Xiaoping; Kirsch, Glenn E; Rosenbaum, David S

2003-11-25

T-wave alternans is due to alternation of membrane repolarization at the cellular level and is a risk factor for sudden cardiac death. Recently, a hysteresis effect has been reported in patients whereby T-wave alternans, once induced by rapid heart rate, persists even when heart rate is subsequently slowed. We hypothesized that alternans hysteresis is an intrinsic property of cardiac myocytes, directly related to an underlying mechanism for repolarization alternans that involves intracellular calcium cycling. Stepwise pacing was used to induce alternans in Langendorff-perfused guinea pig hearts from which optical action potentials were recorded simultaneously at 256 ventricular sites with voltage-sensitive dyes and in whole-cell patch-clamped cardiac myocytes treated with or without BAPTA-AM (1,2-bis[2-aminophenoxy]ethane-N,N,N',N'-tetraacetic acid tetrakis [acetoxymethyl ester]). Alternans hysteresis was observed in every isolated heart: threshold heart rate for alternans was 280+/-12 bpm, but during subsequent deceleration of pacing, alternans persisted to significantly slower heart rates (238+/-5 bpm, P<0.05). Optical mapping showed that this effect also applied to the threshold for spatially discordant alternans (313+/-2.2 bpm during acceleration versus 250+/-6.6 bpm during deceleration, P<0.05). Alternans hysteresis was also observed in isolated cardiac myocytes. Moreover, calcium chelation by BAPTA-AM raised the threshold for alternans and inhibited hysteresis in a dose-dependent manner with no effect on baseline action potential duration. Alternans hysteresis is an intrinsic property of cardiac myocytes that can lead to persistence of arrhythmogenic discordant alternans even after heart rate is slowed. These results also support an important underlying role of calcium cycling in the mechanism of alternans.

Mechanism linking T-wave alternans to the genesis of cardiac fibrillation.

PubMed

Pastore, J M; Girouard, S D; Laurita, K R; Akar, F G; Rosenbaum, D S

1999-03-16

Although T-wave alternans has been closely associated with vulnerability to ventricular arrhythmias, the cellular processes underlying T-wave alternans and their role, if any, in the mechanism of reentry remain unclear. -T-wave alternans on the surface ECG was elicited in 8 Langendorff-perfused guinea pig hearts during fixed-rate pacing while action potentials were recorded simultaneously from 128 epicardial sites with voltage-sensitive dyes. Alternans of the repolarization phase of the action potential was observed above a critical threshold heart rate (HR) (209+/-46 bpm) that was significantly lower (by 57+/-36 bpm) than the HR threshold for alternation of action potential depolarization. The magnitude (range, 2.7 to 47.0 mV) and HR threshold (range, 171 to 272 bpm) of repolarization alternans varied substantially between cells across the epicardial surface. T-wave alternans on the surface ECG was explained primarily by beat-to-beat alternation in the time course of cellular repolarization. Above a critical HR, membrane repolarization alternated with the opposite phase between neighboring cells (ie, discordant alternans), creating large spatial gradients of repolarization. In the presence of discordant alternans, a small acceleration of pacing cycle length produced a characteristic sequence of events: (1) unidirectional block of an impulse propagating against steep gradients of repolarization, (2) reentrant propagation, and (3) the initiation of ventricular fibrillation. Repolarization alternans at the level of the single cell accounts for T-wave alternans on the surface ECG. Discordant alternans produces spatial gradients of repolarization of sufficient magnitude to cause unidirectional block and reentrant ventricular fibrillation. These data establish a mechanism linking T-wave alternans of the ECG to the pathogenesis of sudden cardiac death.

Optogenetic pacing in Drosophila melanogaster

PubMed Central

Alex, Aneesh; Li, Airong; Tanzi, Rudolph E.; Zhou, Chao

2015-01-01

Electrical stimulation is currently the gold standard for cardiac pacing. However, it is invasive and nonspecific for cardiac tissues. We recently developed a noninvasive cardiac pacing technique using optogenetic tools, which are widely used in neuroscience. Optogenetic pacing of the heart provides high spatial and temporal precisions, is specific for cardiac tissues, avoids artifacts associated with electrical stimulation, and therefore promises to be a powerful tool in basic cardiac research. We demonstrated optogenetic control of heart rhythm in a well-established model organism, Drosophila melanogaster. We developed transgenic flies expressing a light-gated cation channel, channelrhodopsin-2 (ChR2), specifically in their hearts and demonstrated successful optogenetic pacing of ChR2-expressing Drosophila at different developmental stages, including the larva, pupa, and adult stages. A high-speed and ultrahigh-resolution optical coherence microscopy imaging system that is capable of providing images at a rate of 130 frames/s with axial and transverse resolutions of 1.5 and 3.9 μm, respectively, was used to noninvasively monitor Drosophila cardiac function and its response to pacing stimulation. The development of a noninvasive integrated optical pacing and imaging system provides a novel platform for performing research studies in developmental cardiology. PMID:26601299

Baseline tests of the EVA change-of-pace coupe electric passenger vehicle

NASA Technical Reports Server (NTRS)

Bozek, J. M.; Maslowski, E. A.; Dustin, M. O.

1977-01-01

The EVA Change-of-Pace Coupe, is an electric passenger vehicle, to characterize the state-of-the-art of electric vehicles. The EVA Change-of-Pace Coupe is a four passenger sedan that has been coverted to an electric vehicle. It is powered by twenty 6 volt traction batteries through a silicon controlled rectifier chopper controller actuated by a foot throttle to change the voltage applied to the series wound, direct current motor. Braking is accomplished with a vacuum assist hydraulic braking system. Regenerative braking is also provided.

Safety of Magnetic Resonance Imaging in Patients with Cardiac Devices.

PubMed

Nazarian, Saman; Hansford, Rozann; Rahsepar, Amir A; Weltin, Valeria; McVeigh, Diana; Gucuk Ipek, Esra; Kwan, Alan; Berger, Ronald D; Calkins, Hugh; Lardo, Albert C; Kraut, Michael A; Kamel, Ihab R; Zimmerman, Stefan L; Halperin, Henry R

2017-12-28

Patients who have pacemakers or defibrillators are often denied the opportunity to undergo magnetic resonance imaging (MRI) because of safety concerns, unless the devices meet certain criteria specified by the Food and Drug Administration (termed "MRI-conditional" devices). We performed a prospective, nonrandomized study to assess the safety of MRI at a magnetic field strength of 1.5 Tesla in 1509 patients who had a pacemaker (58%) or an implantable cardioverter-defibrillator (42%) that was not considered to be MRI-conditional (termed a "legacy" device). Overall, the patients underwent 2103 thoracic and nonthoracic MRI examinations that were deemed to be clinically necessary. The pacing mode was changed to asynchronous mode for pacing-dependent patients and to demand mode for other patients. Tachyarrhythmia functions were disabled. Outcome assessments included adverse events and changes in the variables that indicate lead and generator function and interaction with surrounding tissue (device parameters). No long-term clinically significant adverse events were reported. In nine MRI examinations (0.4%; 95% confidence interval, 0.2 to 0.7), the patient's device reset to a backup mode. The reset was transient in eight of the nine examinations. In one case, a pacemaker with less than 1 month left of battery life reset to ventricular inhibited pacing and could not be reprogrammed; the device was subsequently replaced. The most common notable change in device parameters (>50% change from baseline) immediately after MRI was a decrease in P-wave amplitude, which occurred in 1% of the patients. At long-term follow-up (results of which were available for 63% of the patients), the most common notable changes from baseline were decreases in P-wave amplitude (in 4% of the patients), increases in atrial capture threshold (4%), increases in right ventricular capture threshold (4%), and increases in left ventricular capture threshold (3%). The observed changes in lead parameters were not clinically significant and did not require device revision or reprogramming. We evaluated the safety of MRI, performed with the use of a prespecified safety protocol, in 1509 patients who had a legacy pacemaker or a legacy implantable cardioverter-defibrillator system. No long-term clinically significant adverse events were reported. (Funded by Johns Hopkins University and the National Institutes of Health; ClinicalTrials.gov number, NCT01130896 .).

A Process for Technology Prioritization in a Competitive Environment

NASA Technical Reports Server (NTRS)

Stephens, Karen; Herman, Melody; Griffin, Brand

2006-01-01

This slide presentation reviews NASA's process for prioritizing technology requirements where there is a competitive environment. The In-Space Propulsion Technology (ISPT) project is used to exemplify the process. The ISPT project focuses on the mid level Technology Readiness Level (TRL) for development. These are TRL's 4 through 6, (i.e. Technology Development and Technology Demonstration. The objective of the planning activity is to identify the current most likely date each technology is needed and create ISPT technology development schedules based on these dates. There is a minimum of 4 years between flight and pacing mission. The ISPT Project needed to identify the "pacing mission" for each technology in order to provide funding for each area. Graphic representations show the development of the process. A matrix shows which missions are currently receiving pull from the both the Solar System Exploration and the Sun-Solar System Connection Roadmaps. The timeframes of the pacing missions technologies are shown for various types of propulsion. A pacing mission that was in the near future serves to increase the priority for funding. Adaptations were made when budget reductions precluded the total implementation of the plan.

Risk Stratification of Future Left Ventricular Dysfunction for Patients with Indications for Right Ventricular Pacing due to Bradycardia.

PubMed

Ooka, Junichi; Tanaka, Hidekazu; Hatani, Yutaka; Hatazawa, Keiko; Matsuzoe, Hiroki; Shimoura, Hiroyuki; Sano, Hiroyuki; Sawa, Takuma; Motoji, Yoshiki; Mochizuki, Yasuhide; Ryo-Koriyama, Keiko; Matsumoto, Kensuke; Fukuzawa, Koji; Hirata, Ken-Ichi

2017-10-21

Although right ventricular (RV) pacing is the only effective treatment for patients with symptomatic bradycardia, it creates left ventricular (LV) dyssynchrony, which can induce LV dysfunction and heart failure. The current criterion for consideration of cardiac resynchronization therapy (CRT) is LV ejection fraction (LVEF) ≤ 35%, but indication for CRT in patients required for RV pacing with LVEF > 35% remains unclear.We studied 40 patients, all LVEF ≥ 35%, who had undergone implantable cardioverter-defibrillator implantation with RV pacing < 5%. Echocardiography was performed at baseline and during RV pacing. LV dyssynchrony was defined as anteroseptal-to-posterior wall delay from the mid-LV short-axis view using two-dimensional speckle-tracking radial strain (significant: ≥ 130 ms). Patients were divided into two groups based on baseline LVEF: normal LVEF ( ≥ 50%; n = 20) and mildly reduced LVEF (35-50%; n = 20).LVEF and LV dyssynchrony in patients with mildly reduced LVEF deteriorated significantly during RV pacing compared to those in patients with normal LVEF. Moreover, changes in LV dyssynchrony during RV pacing significantly correlated with changes in LVEF (r = -0.44, P < 0.01). Multivariate logistic regression analysis showed that baseline LVEF was the only independent predictor and baseline LVEF < 48% predictive of significant LV dyssynchrony during RV pacing.The extent of RV pacing-induced LV dysfunction may be associated with baseline LV function. These adverse effects on patients with mildly reduced LVEF of 35-50% and indications for RV pacing due to bradycardia can thus be prevented by CRT.

Reduction of the pace polarization artefact for capture detection applications by a tri-phasic stimulation pulse.

PubMed

Sutton, R; Fröhlig, G; de Voogt, W G; Goethals, M; Hintringer, F; Kennergren, C; Scanu, P; Guilleman, D; Treese, N; Hartung, W M; Stammwitz, E; Muetstege, A

2004-11-01

This study investigated the ability to minimize pace polarization artefacts (PPA) by adjusting the post-stimulus pulse duration of a tri-phasic stimulation pulse. Adjustment of the stimulation pulse was enabled by downloading special study software into an already implanted pacemaker. Tests were performed in a total of 296 atrial leads and 311 ventricular leads. Both chronic and acute leads were included in the study. Statistically significant differences were found in the initial PPA (without any adjustment of the stimulus pulse) between atrial and ventricular leads. In addition, significant differences were observed among various lead models with respect to changes over time in the initial ventricular PPA. Successful PPA reduction was defined as a reduction of the PPA below 0.5 mV for atrial leads and below 1 mV for ventricular leads. Results show a success rate for ventricular and atrial PPA reduction of 97.8% and 98.7%, respectively. Threshold tests showed that after reduction of the PPA loss of ventricular capture can be reliably detected. However, atrial threshold tests showed many false positive evoked response detections. In addition, unexpectedly high evoked response amplitudes were observed in the atrium after reduction of the PPA. Results from additional measurements suggest that these high atrial evoked response amplitudes come from the influence of the input filter of the pacemaker.

Rhythm production at school entry as a predictor of poor reading and spelling at the end of first grade.

PubMed

Lundetræ, Kjersti; Thomson, Jenny M

2018-01-01

Rhythm plays an organisational role in the prosody and phonology of language, and children with literacy difficulties have been found to demonstrate poor rhythmic perception. This study explored whether students' performance on a simple rhythm task at school entry could serve as a predictor of whether they would face difficulties in word reading and spelling at the end of grade 1. The participants were 479 Norwegian 6-year-old first graders randomized as controls in the longitudinal RCT on track (n = 1171). Rhythmic timing and pre-reading skills were tested individually at school entry on a digital tablet. On the rhythm task, the students were told to tap a drum appearing on the screen to two different rhythms (2 Hz paced and 1.5 Hz paced). Children's responses were recorded as they tapped on the screen with their index finger. Significant group differences were found in rhythm tapping ability measured at school entry, when groups were defined upon whether children went on to score above or below the 20th percentile reading and spelling thresholds in national assessment tests at the end of grade one. Inclusion of the school-entry rhythmic tapping measure into a model of classification accuracy for above or below threshold reading and spelling improved accuracy of classification by 6.2 and 9.2% respectively.

Non-invasive red light optogenetic pacing and optical coherence microscopy (OCM) imaging for drosophila melanogaster (Conference Presentation)

NASA Astrophysics Data System (ADS)

Men, Jing; Li, Airong; Jerwick, Jason; Tanzi, Rudolph E.; Zhou, Chao

2017-02-01

Cardiac pacing could be a powerful tool for investigating mammalian cardiac electrical conduction systems as well as for treatment of certain cardiac pathologies. However, traditional electrical pacing using pacemaker requires an invasive surgical procedure. Electrical currents from the implanted electrodes can also cause damage to heart tissue, further restricting its utility. Optogenetic pacing has been developed as a promising, non-invasive alternative to electrical stimulation for controlling animal heart rhythms. It induces heart contractions by shining pulsed light on transgene-generated microbial opsins, which in turn activate the light gated ion channels in animal hearts. However, commonly used opsins in optogenetic pacing, such as channelrhodopsin-2 (ChR2), require short light wavelength stimulation (475 nm), which is strongly absorbed and scattered by tissue. Here, we performed optogenetic pacing by expression of recently engineered red-shifted microbial opsins, ReaChR and CsChrimson, in a well-established animal model, Drosophila melanogaster, using the 617 nm stimulation light pulses. The OCM technique enables non-invasive optical imaging of animal hearts with high speed and ultrahigh axial and transverse resolutions. We integrated a customized OCM system with the optical stimulation system to monitor the optogenetic pacing noninvasively. The use of red-sifted opsins enabled deeper penetration of simulating light at lower power, which is promising for applications of optogenetic pacing in mammalian cardiac pathology studies or clinical treatments in the future.

Is there a right place to pace the right ventricle? Evaluation of apical and septal positions in a pacemaker population: study protocol for a prospective intervention-control trial.

PubMed

Muto, Carmine; Calvi, Valeria; Botto, Giovanni Luca; Pecora, Domenico; Ciaramitaro, Gianfranco; Valsecchi, Sergio; Malacrida, Maurizio; Maglia, Giampiero

2014-11-01

The main objective of research in pacemaker therapy has been to provide the best physiologic way to pace the heart. Despite the good results provided by right ventricular pacing minimization and by biventricular pacing in specific subsets of heart failure patients, these options present many limitations for standard pacemaker recipients. In these patients, pacing the right ventricle at alternative sites could result in a lower degree of left intraventricular dyssynchrony. Despite the lack of strong evidence and the difficulty in placing and accurately classifying the final lead position, pacing at alternative right ventricular sites seems to have become a standard procedure at many implanting centers. The RIGHT PACE study is a multi-center, prospective, single-blind, double-arm, intervention-control trial comparing right ventricular pacing from the apex and from the septal site in terms of left intraventricular dyssynchrony. A total of 408 patients with indications for cardiac pacing but without indications for ICD and/or CRT will be enrolled. Investigators will be divided on the basis of their prior experience of selective site pacing lead implantation and patients will be treated according to the clinical practice of the centers. After device implantation, they will be followed up for 24 months through evaluation of clinical, echocardiographic and safety/system-performance variables. This study might provide important information about the impact of the right ventricular pacing on the left ventricular dyssynchrony, and about acute and chronic responses to selective site pacing, as adopted in current clinical practice. This trial is registered at ClinicalTrials.gov (ID:NCT01647490). Right Ventricular Lead Placement in a Pacemaker Population: Evaluation of apical and alternative position. ClinicalTrials.gov: NCT01647490. Copyright © 2014 Elsevier Inc. All rights reserved.

Electrical cardioversion

PubMed Central

Sucu, Murat; Davutoglu, Vedat; Ozer, Orhan

2009-01-01

External electrical cardioversion was first performed in the 1950s. Urgent or elective cardioversions have specific advantages, such as termination of atrial and ventricular tachycardia and recovery of sinus rhythm. Electrical cardioversion is life-saving when applied in urgent circumstances. The succcess rate is increased by accurate tachycardia diagnosis, careful patient selection, adequate electrode (paddles) application, determination of the optimal energy and anesthesia levels, prevention of embolic events and arrythmia recurrence and airway conservation while minimizing possible complications. Potential complications include ventricular fibrillation due to general anesthesia or lack of synchronization between the direct current (DC) shock and the QRS complex, thromboembolus due to insufficient anticoagulant therapy, non-sustained VT, atrial arrhythmia, heart block, bradycardia, transient left bundle branch block, myocardial necrosis, myocardial dysfunction, transient hypotension, pulmonary edema and skin burn. Electrical cardioversion performed in patients with a pacemaker or an incompatible cardioverter defibrillator may lead to dysfunction, namely acute or chronic changes in the pacing or sensitivity threshold. Although this procedure appears fairly simple, serious consequences might occur if inappropriately performed. PMID:19448376

Step Detection Robust against the Dynamics of Smartphones

PubMed Central

Lee, Hwan-hee; Choi, Suji; Lee, Myeong-jin

2015-01-01

A novel algorithm is proposed for robust step detection irrespective of step mode and device pose in smartphone usage environments. The dynamics of smartphones are decoupled into a peak-valley relationship with adaptive magnitude and temporal thresholds. For extracted peaks and valleys in the magnitude of acceleration, a step is defined as consisting of a peak and its adjacent valley. Adaptive magnitude thresholds consisting of step average and step deviation are applied to suppress pseudo peaks or valleys that mostly occur during the transition among step modes or device poses. Adaptive temporal thresholds are applied to time intervals between peaks or valleys to consider the time-varying pace of human walking or running for the correct selection of peaks or valleys. From the experimental results, it can be seen that the proposed step detection algorithm shows more than 98.6% average accuracy for any combination of step mode and device pose and outperforms state-of-the-art algorithms. PMID:26516857

Feasibility of Leadless Cardiac Pacing Using Injectable Magnetic Microparticles

PubMed Central

Rotenberg, Menahem Y.; Gabay, Hovav; Etzion, Yoram; Cohen, Smadar

2016-01-01

A noninvasive, effective approach for immediate and painless heart pacing would have invaluable implications in several clinical scenarios. Here we present a novel strategy that utilizes the well-known mechano-electric feedback of the heart to evoke cardiac pacing, while relying on magnetic microparticles as leadless mechanical stimulators. We demonstrate that after localizing intravenously-injected magnetic microparticles in the right ventricular cavity using an external electromagnet, the application of magnetic pulses generates mechanical stimulation that provokes ventricular overdrive pacing in the rat heart. This temporary pacing consistently managed to revert drug-induced bradycardia, but could only last up to several seconds in the rat model, most likely due to escape of the particles between the applied pulses using our current experimental setting. In a pig model with open chest, MEF-based pacing was induced by banging magnetic particles and has lasted for a longer time. Due to overheating of the electromagnet, we intentionally terminated the experiments after 2 min. Our results demonstrate for the first time the feasibility of external leadless temporary pacing, using injectable magnetic microparticles that are manipulated by an external electromagnet. This new approach can have important utilities in clinical settings in which immediate and painless control of cardiac rhythm is required. PMID:27091192

An infrared optical pacing system for high-throughput screening of cardiac electrophysiology in human cardiomyocytes (Conference Presentation)

NASA Astrophysics Data System (ADS)

McPheeters, Matt T.; Wang, Yves T.; Laurita, Kenneth R.; Jenkins, Michael W.

2017-02-01

Cardiomyocytes derived from human induced pluripotent stem cells (hiPS-HCM) have the potential to provide individualized therapies for patients and to test drug candidates for cardiac toxicity. In order for hiPS-CM to be useful for such applications, there is a need for high-throughput technology to rapidly assess cardiac electrophysiology parameters. Here, we designed and tested a fully contactless optical mapping (OM) and optical pacing (OP) system capable of imaging and point stimulation of hiPS-CM in small wells. OM allowed us to characterize cardiac electrophysiological parameters (conduction velocity, action potential duration, etc.) using voltage-sensitive dyes with high temporal and spatial resolution over the entire well. To improve OM signal-to-noise ratio, we tested a new voltage-sensitive dye (Fluovolt) for accuracy and phototoxicity. Stimulation is essential because most electrophysiological parameters are rate dependent; however, traditional methods utilizing electrical stimulation is difficult in small wells. To overcome this limitation, we utilized OP (λ = 1464 nm) to precisely control heart rate with spatial precision without the addition of exogenous agents. We optimized OP parameters (e.g., well size, pulse width, spot size) to achieve robust pacing and minimize the threshold radiant exposure. Finally, we tested system sensitivity using Flecainide, a drug with well described action on multiple electrophysiological properties.

Effect of intermodular connection on fast sparse synchronization in clustered small-world neural networks

NASA Astrophysics Data System (ADS)

Kim, Sang-Yoon; Lim, Woochang

2015-11-01

We consider a clustered network with small-world subnetworks of inhibitory fast spiking interneurons and investigate the effect of intermodular connection on the emergence of fast sparsely synchronized rhythms by varying both the intermodular coupling strength Jinter and the average number of intermodular links per interneuron Msyn(inter ). In contrast to the case of nonclustered networks, two kinds of sparsely synchronized states such as modular and global synchronization are found. For the case of modular sparse synchronization, the population behavior reveals the modular structure, because the intramodular dynamics of subnetworks make some mismatching. On the other hand, in the case of global sparse synchronization, the population behavior is globally identical, independently of the cluster structure, because the intramodular dynamics of subnetworks make perfect matching. We introduce a realistic cross-correlation modularity measure, representing the matching degree between the instantaneous subpopulation spike rates of the subnetworks, and examine whether the sparse synchronization is global or modular. Depending on its magnitude, the intermodular coupling strength Jinter seems to play "dual" roles for the pacing between spikes in each subnetwork. For large Jinter, due to strong inhibition it plays a destructive role to "spoil" the pacing between spikes, while for small Jinter it plays a constructive role to "favor" the pacing between spikes. Through competition between the constructive and the destructive roles of Jinter, there exists an intermediate optimal Jinter at which the pacing degree between spikes becomes maximal. In contrast, the average number of intermodular links per interneuron Msyn(inter ) seems to play a role just to favor the pacing between spikes. With increasing Msyn(inter ), the pacing degree between spikes increases monotonically thanks to the increase in the degree of effectiveness of global communication between spikes. Furthermore, we employ the realistic sub- and whole-population order parameters, based on the instantaneous sub- and whole-population spike rates, to determine the threshold values for the synchronization-unsynchronization transition in the sub- and whole populations, and the degrees of global and modular sparse synchronization are also measured in terms of the realistic sub- and whole-population statistical-mechanical spiking measures defined by considering both the occupation and the pacing degrees of spikes. It is expected that our results could have implications for the role of the brain plasticity in some functional behaviors associated with population synchronization.

Corticosterone and pace of life in two life-history ecotypes of the garter snake Thamnophis elegans.

PubMed

Palacios, Maria G; Sparkman, Amanda M; Bronikowski, Anne M

2012-02-01

Glucocorticoids are main candidates for mediating life-history trade-offs by regulating the balance between current reproduction and survival. It has been proposed that slow-living organisms should show higher stress-induced glucocorticoid levels that favor self-maintenance rather than current reproduction when compared to fast-living organisms. We tested this hypothesis in replicate populations of two ecotypes of the garter snake (Thamnophis elegans) that exhibit slow and fast pace of life strategies. We subjected free-ranging snakes to a capture-restraint protocol and compared the stress-induced corticosterone levels between slow- and fast-living snakes. We also used a five-year dataset to assess whether baseline corticosterone levels followed the same pattern as stress-induced levels in relation to pace of life. In accordance with the hypothesis, slow-living snakes showed higher stress-induced corticosterone levels than fast-living snakes. Baseline corticosterone levels showed a similar pattern with ecotype, although differences depended on the year of study. Overall, however, levels of glucocorticoids are higher in slow-living than fast-living snakes, which should favor self-maintenance and survival at the expense of current reproduction. The results of the present study are the first to relate glucocorticoid levels and pace of life in a reptilian system and contribute to our understanding of the physiological mechanisms involved in life-history evolution. Copyright © 2011 Elsevier Inc. All rights reserved.

The impact of weight classification on safety: timing steps to adapt to external constraints

PubMed Central

Gill, S.V.

2015-01-01

Objectives: The purpose of the current study was to evaluate how weight classification influences safety by examining adults’ ability to meet a timing constraint: walking to the pace of an audio metronome. Methods: With a cross-sectional design, walking parameters were collected as 55 adults with normal (n=30) and overweight (n=25) body mass index scores walked to slow, normal, and fast audio metronome paces. Results: Between group comparisons showed that at the fast pace, those with overweight body mass index (BMI) had longer double limb support and stance times and slower cadences than the normal weight group (all ps<0.05). Examinations of participants’ ability to meet the metronome paces revealed that participants who were overweight had higher cadences at the slow and fast paces (all ps<0.05). Conclusions: Findings suggest that those with overweight BMI alter their gait to maintain biomechanical stability. Understanding how excess weight influences gait adaptation can inform interventions to improve safety for individuals with obesity. PMID:25730658

Optogenetic pacing in Drosophila melanogaster (Conference Presentation)

NASA Astrophysics Data System (ADS)

Alex, Aneesh; Li, Airong; Men, Jing; Jerwick, Jason; Tanzi, Rudolph E.; Zhou, Chao

2016-03-01

A non-invasive, contact-less cardiac pacing technology can be a powerful tool in basic cardiac research and in clinics. Currently, electrical pacing is the gold standard for cardiac pacing. Although highly effective in controlling the cardiac function, the invasive nature, non-specificity to cardiac tissues and possible tissue damage limits its capabilities. Optical pacing of heart is a promising alternative, which is non-invasive and more specific, has high spatial and temporal precision, and avoids shortcomings in electrical stimulation. Optical coherence tomography has been proved to be an effective technique in non-invasive imaging in vivo with ultrahigh resolution and imaging speed. In the last several years, non-invasive specific optical pacing in animal hearts has been reported in quail, zebrafish, and rabbit models. However， Drosophila Melanogaster, which is a significant model with orthologs of 75% of human disease genes, has rarely been studied concerning their optical pacing in heart. Here, we combined optogenetic control of Drosophila heartbeat with optical coherence microscopy (OCM) technique for the first time. The light-gated cation channel, channelrhodopsin-2 (ChR2) was specifically expressed by transgene as a pacemaker in drosophila heart. By stimulating the pacemaker with 472 nm pulsed laser light at different frequencies, we achieved non-invasive and more specific optical control of the Drosophila heart rhythm, which demonstrates the wide potential of optical pacing for studying cardiac dynamics and development. Imaging capability of our customized OCM system was also involved to observe the pacing effect visually. No tissue damage was found after long exposure to laser pulses, which proved the safety of optogenetic control of Drosophila heart.

Cardiac optogenetic pacing in drosophila melanogaster using red-shifted opsins (Conference Presentation)

NASA Astrophysics Data System (ADS)

Men, Jing; Li, Airong; Jerwick, Jason; Tanzi, Rudolph E.; Zhou, Chao

2017-02-01

Electrical pacing is the current gold standard for investigation of mammalian cardiac electrical conduction systems as well as for treatment of certain cardiac pathologies. However, this method requires an invasive surgical procedure to implant the pacing electrodes. Recently, optogenetic pacing has been developed as an alternative, non-invasive method for heartbeat pacing in animals. It induces heartbeats by shining pulsed light on transgene-generated microbial opsins which in turn activate light gated ion channels in animal hearts. However, commonly used opsins, such as channelrhodopsin-2 (ChR2), require short light wavelength stimulation (475 nm), which is strongly absorbed and scattered by tissue. Here, we expressed recently engineered red-shifted opsins, ReaChR and CsChrimson, in the heart of a well-developed animal model, Drosophila melanogaster, for the first time. Optogenetic pacing was successfully conducted in both ReaChR and CsChrimson flies at their larval, pupal, and adult stages using 617 nm excitation light pulse, enabling a much deeper tissue penetration compared to blue stimulation light. A customized high speed and ultrahigh resolution OCM system was used to non-invasively monitor the heartbeat pacing in Drosophila. Compared to previous studies on optogenetic pacing of Drosophila, higher penetration depth of optogenetic excitation light was achieved in opaque late pupal flies. Lower stimulating power density is needed for excitation at each developmental stage of both groups, which improves the safety of this technique for heart rhythm studies.

Short-term action potential memory and electrical restitution: A cellular computational study on the stability of cardiac repolarization under dynamic pacing

PubMed Central

2018-01-01

Electrical restitution (ER) is a major determinant of repolarization stability and, under fast pacing rate, it reveals memory properties of the cardiac action potential (AP), whose dynamics have never been fully elucidated, nor their ionic mechanisms. Previous studies have looked at ER mainly in terms of changes in AP duration (APD) when the preceding diastolic interval (DI) changes and described dynamic conditions where this relationship shows hysteresis which, in turn, has been proposed as a marker of short-term AP memory and repolarization stability. By means of numerical simulations of a non-propagated human ventricular AP, we show here that measuring ER as APD versus the preceding cycle length (CL) provides additional information on repolarization dynamics which is not contained in the companion formulation. We focus particularly on fast pacing rate conditions with a beat-to-beat variable CL, where memory properties emerge from APD vs CL and not from APD vs DI and should thus be stored in APD and not in DI. We provide an ion-currents characterization of such conditions under periodic and random CL variability, and show that the memory stored in APD plays a stabilizing role on AP repolarization under pacing rate perturbations. The gating kinetics of L-type calcium current seems to be the main determinant of this safety mechanism. We also show that, at fast pacing rate and under otherwise identical pacing conditions, a periodically beat-to-beat changing CL is more effective than a random one in stabilizing repolarization. In summary, we propose a novel view of short-term AP memory, differentially stored between systole and diastole, which opens a number of methodological and theoretical implications for the understanding of arrhythmia development. PMID:29494628

Evaluation of Safety and Efficacy of Qinming8631 DR Implantable Cardiac Pacemaker in Chinese Patients: A Prospective, Multicenter, Randomized Controlled Trial of the First Domestically Developed Pacemaker of China.

PubMed

Xiang, Mei-Xiang; Wang, Dong-Qi; Xu, Jing; Zhang, Zheng; Hu, Jian-Xin; Wang, Dong-Mei; Gu, Xiang; Liu, He-Ping; Guo, Tao; Yang, Xiang-Jun; Ling, Feng; Lin, Jia-Feng; Cai, Shang-Lang; Zhu, Guo-Bin; Wang, Jian-An

2016-11-20

High cost of imported pacemakers is a main obstacle for Chinese patients suffering from bradyarrhythmia, and a domestically developed pacemaker will help lower the burden. This study aimed to evaluate the safety and efficacy of Qinming8631 DR (Qinming Medical, Baoji, China), the first domestically developed dual-chamber pacemaker of China, compared with a commercially available pacemaker Talos DR (Biotronik, Berlin, Germany) in Chinese patients. A prospective randomized trial was conducted at 14 centers in China. Participants were randomized into trial (Qinming8631 DR) and control (Talos DR) groups. Parameters of the pacing systems were collected immediately after device implantation and during follow-ups. The effective pacing rate at 6-month follow-up was recorded as the primary end point. Electrical properties, magnet response, single- and double-pole polarity conversion, rate response function, and adverse events of the pacing system were analyzed. The Cochran-Mantel-Haenszel Chi-square test, paired t-test, and Wilcoxon signed-rank test were used for measuring primary qualitative outcomes and comparing normally and abnormally distributed measurement data. A total of 225 patients with a diagnosis of bradyarrhythmia and eligible for this study were randomly enrolled into the trial (n = 113) and control (n = 112) groups. They underwent successful pacemaker implantation with acceptable postoperative pacing threshold and sensitivity. Effective pacing rates of trial and control groups were comparable both in the full analysis set and the per protocol set (81.4% vs. 79.5%, P = 0.712 and 95.4% vs. 89.5%, P = 0.143, respectively). In both data sets, noninferiority of the trial group was above the predefined noninferiority limit(-9.5%). This study established the noninferiority of Qinming8631 DR to Talos DR. The safety and efficacy of Qinming8631 DR pacemaker were comparable to those of Talos DR in treating patients with cardiac bradyarrhythmia.

Spatial resolution of pace mapping of idiopathic ventricular tachycardia/ectopy originating in the right ventricular outflow tract.

PubMed

Bogun, Frank; Taj, Majid; Ting, Michael; Kim, Hyungjin Myra; Reich, Stephen; Good, Eric; Jongnarangsin, Krit; Chugh, Aman; Pelosi, Frank; Oral, Hakan; Morady, Fred

2008-03-01

Pace mapping has been used to identify the site of origin of focal ventricular arrhythmias. The spatial resolution of pace mapping has not been adequately quantified using currently available three-dimensional mapping systems. The purpose of this study was to determine the spatial resolution of pace mapping in patients with idiopathic ventricular tachycardia or premature ventricular contractions originating in the right ventricular outflow tract. In 16 patients with idiopathic ventricular tachycardia/ectopy from the right ventricular outflow tract, comparisons and classifications of pace maps were performed by two observers (good pace map: match >10/12 leads; inadequate pace map: match < or =10/12 leads) and a customized MATLAB 6.0 program (assessing correlation coefficient and normalized root mean square of the difference (nRMSd) between test and template signals). With an electroanatomic mapping system, the correlation coefficient of each pace map was correlated with the distance between the pacing site and the effective ablation site. The endocardial area within the 10-ms activation isochrone was measured. The ablation procedure was effective in all patients. Sites with good pace maps had a higher correlation coefficient and lower nRMSd than sites with inadequate pace maps (correlation coefficient: 0.96 +/- 0.03 vs 0.76 +/- 0.18, P <.0001; nRMSd: 0.41 +/- 0.16 vs 0.89 +/- 0.39, P <.0001). Using receiver operating characteristic curves, appropriate cutoff values were >0.94 for correlation coefficient (sensitivity 81%, specificity 89%) and < or =0.54 for nRMSd (sensitivity 76%, specificity 80%). Good pace maps were located a mean of 7.3 +/- 5.0 mm from the effective ablation site and had a mean activation time of -24 +/- 7 ms. However, in 3 (18%) of 16 patients, the best pace map was inadequate at the effective ablation site, with an endocardial activation time at these sites of -25 +/- 12 ms. Pace maps with correlation coefficient > or =0.94 were confined to an area of 1.8 +/- 0.6 cm2. The 10-ms isochrone measured 1.2 +/- 0.7 cm2. The spatial resolution of a good pace map for targeting ventricular tachycardia/ectopy is 1.8 cm2 in the right ventricular outflow tract and therefore is inferior to the spatial resolution of activation mapping as assessed by isochronal activation. In approximately 20% of patients, pace mapping is unreliable in identifying the site of origin, possibly due a deeper site of origin and preferential conduction via fibers connecting the focus to the endocardial surface.

Overview of recent and current research on the TCV tokamak

NASA Astrophysics Data System (ADS)

S. Codathe TCV Team

2013-10-01

Through a diverse research programme, the Tokamak à Configuration Variable (TCV) addresses physics issues and develops tools for ITER and for the longer term goals of nuclear fusion, relying especially on its extreme plasma shaping and electron cyclotron resonance heating (ECRH) launching flexibility and preparing for an ECRH and NBI power upgrade. Localized edge heating was unexpectedly found to decrease the period and relative energy loss of edge localized modes (ELMs). Successful ELM pacing has been demonstrated by following individual ELM detection with an ECRH power cut before turning the power back up to trigger the next ELM, the duration of the cut determining the ELM period. Negative triangularity was also seen to reduce the ELM energy release. H-mode studies have focused on the L-H threshold dependence on the main ion species and on the divertor leg length. Both L- and H-modes have been explored in the snowflake configuration with emphasis on edge measurements, revealing that the heat flux to the strike points on the secondary separatrix increases as the X-points approach each other, well before they coalesce. In L-mode, a systematic scan of the auxiliary power deposition profile, with no effect on confinement, has ruled it out as the cause of confinement degradation. An ECRH power absorption observer based on transmitted stray radiation was validated for eventual polarization control. A new profile control methodology was introduced, relying on real-time modelling to supplement diagnostic information; the RAPTOR current transport code in particular has been employed for joint control of the internal inductance and central temperature. An internal inductance controller using the ohmic transformer has also been demonstrated. Fundamental investigations of neoclassical tearing mode (NTM) seed island formation by sawtooth crashes and of NTM destabilization in the absence of a sawtooth trigger were carried out. Both stabilizing and destabilizing agents (electron cyclotron current drive on or inside the q = 1 surface, respectively) were used to pace sawtooth oscillations, permitting precise control of their period. Locking of the sawtooth period to a pre-defined ECRH modulation period was also demonstrated. Sawtooth control has permitted nearly failsafe NTM prevention when combined with backup NTM stabilization by ECRH.

Division of labour between Myc and G1 cyclins in cell cycle commitment and pace control.

PubMed

Dong, Peng; Maddali, Manoj V; Srimani, Jaydeep K; Thélot, François; Nevins, Joseph R; Mathey-Prevot, Bernard; You, Lingchong

2014-09-01

A body of evidence has shown that the control of E2F transcription factor activity is critical for determining cell cycle entry and cell proliferation. However, an understanding of the precise determinants of this control, including the role of other cell-cycle regulatory activities, has not been clearly defined. Here, recognizing that the contributions of individual regulatory components could be masked by heterogeneity in populations of cells, we model the potential roles of individual components together with the use of an integrated system to follow E2F dynamics at the single-cell level and in real time. These analyses reveal that crossing a threshold amplitude of E2F accumulation determines cell cycle commitment. Importantly, we find that Myc is critical in modulating the amplitude, whereas cyclin D/E activities have little effect on amplitude but do contribute to the modulation of duration of E2F activation, thereby affecting the pace of cell cycle progression.

Separation of the pace-maker and plateau components of delayed rectification in cardiac Purkinje fibres

PubMed Central

Hauswirth, O.; Noble, D.; Tsien, R. W.

1972-01-01

1. Experiments on sheep Purkinje fibres were designed to determine whether the current mechanisms responsible for delayed rectification at the pace-maker (negative to -50 mV) and plateau (positive to -50 mV) ranges of potential are kinetically separable and independent. 2. Hyperpolarizations from the plateau range were shown to produce decay of a single component of outward current within the plateau range, but two components were evident when the hyperpolarizations entered the pace-maker range. 3. The time courses of recovery of the two components were too similar at -25 mV to allow temporal resolution at this potential. Clear temporal resolution was, however, possible at potentials between -55 and -95 mV. An indirect method of resolving the two components at -25 mV was used. 4. The kinetic properties of the two components correspond to those previously described for the pace-maker potassium current, iK2, and the outward plateau current, ix1 (Noble & Tsien, 1968, 1969a). 5. The instantaneous (fully activated) current—voltage relation for iK2 was reconstructed from the analysed current records. It was found that this relation shows a negative slope conductance at all potentials positive to -75 mV and that the current tends towards zero at zero membrane potential. 6. The results are compared with those predicted by two reaction models of the iK2 and ix1 mechanisms. It is concluded that iK2 and ix1 are kinetically separable but that it is not possible with present techniques to decide whether they are controlled by the same or completely independent membrane structures. It is also shown that the instantaneous current—voltage relation calculated for iK2 does not depend on whether the controlling mechanisms are assumed to be independent or linked. PMID:4679715

Paradigm shift in lead design.

PubMed

Irnich, W

1999-09-01

During the past 30 years there has been a tremendous development in electrode technology from bulky (90 mm2) to pin-sized (1.0 mm2) electrodes. Simultaneously, impedance has increased from 110 Ohms to >1 kOhms, which has been termed a "paradigm shift" in lead design. If current is responsible for stimulation, why is its impedance a key factor in saving energy? Further, what mechanism is behind this development based on experimental findings and what conclusion can be drawn from it to optimize electrode size? If it is assumed that there is always a layer of nonexcitable tissue between the electrode surface and excitable myocardium and that the electric field (potential gradient) produced by the electrode at this boundary is reaching threshold level, then a formula can be derived for the voltage threshold that completely describes the electrophysiology and electrophysics of a hemispherical electrode. Assuming that the mean chronic threshold for porous steroid-eluting electrodes is 0.6 V with 0.5-ms pulse duration, thickness of nonexcitable tissue can be estimated to be 1.5 mm. Taking into account this measure and the relationship between chronaxie and electrode area, voltage threshold, impedance, and energy as a function of surface area can be calculated. The lowest voltage for 0.5-ms pulse duration is reached with r(o) = 0.5 d, yielding a surface area of 4 mm2 and a voltage threshold of 0.62 V, an impedance of 1 kOhms, and an energy level of 197 nJ. It can be deduced from our findings that a further reduction of surface areas below 1.6 mm2 will not diminish energy threshold substantially, if pulse duration remains at 0.5 ms. Lowest energy is reached with t = chronaxie, yielding an energy level <100 nJ with surface areas < or =1.5 mm2. It is striking to see how well the theoretically derived results correspond to the experimental findings. It is also surprising that the hemispheric model so accurately approximates experimental results with differently shaped electrodes that it can be concluded that electrode shape seems to play a minor role in electrode efficiency. Further energy reduction can only be achieved by reducing the pulse duration to chronaxie. A real paradigm shift will occur only if the fundamentals of electrostimulation in combination with electrophysics are accepted by the pacing community.

Sympathetic Nervous Regulation of Calcium and Action Potential Alternans in the Intact Heart.

PubMed

Winter, James; Bishop, Martin J; Wilder, Catherine D E; O'Shea, Christopher; Pavlovic, Davor; Shattock, Michael J

2018-01-01

Rationale: Arrhythmogenic cardiac alternans are thought to be an important determinant for the initiation of ventricular fibrillation. There is limited information on the effects of sympathetic nerve stimulation (SNS) on alternans in the intact heart and the conclusions of existing studies, focused on investigating electrical alternans, are conflicted. Meanwhile, several lines of evidence implicate instabilities in Ca handling, not electrical restitution, as the primary mechanism underpinning alternans. Despite this, there have been no studies on Ca alternans and SNS in the intact heart. The present study sought to address this, by application of voltage and Ca optical mapping for the simultaneous study of APD and Ca alternans in the intact guinea pig heart during direct SNS. Objective : To determine the effects of SNS on APD and Ca alternans in the intact guinea pig heart and to examine the mechanism(s) by which the effects of SNS are mediated. Methods and Results : Studies utilized simultaneous voltage and Ca optical mapping in isolated guinea pig hearts with intact innervation. Alternans were induced using a rapid dynamic pacing protocol. SNS was associated with rate-independent shortening of action potential duration (APD) and the suppression of APD and Ca alternans, as indicated by a shift in the alternans threshold to faster pacing rates. Qualitatively similar results were observed with exogenous noradrenaline perfusion. In contrast with previous reports, both SNS and noradrenaline acted to flatten the slope of the electrical restitution curve. Pharmacological block of the slow delayed rectifying potassium current (I Ks ), sufficient to abolish I Ks -mediated APD-adaptation, partially reversed the effects of SNS on pacing-induced alternans. Treatment with cyclopiazonic acid, an inhibitor of the sarco(endo)plasmic reticulum ATPase, had opposite effects to that of SNS, acting to increase susceptibility to alternans, and suggesting that accelerated Ca reuptake into the sarcoplasmic reticulum is a major mechanism by which SNS suppresses alternans in the guinea pig heart. Conclusions : SNS suppresses calcium and action potential alternans in the intact guinea pig heart by an action mediated through accelerated Ca handling and via increased I Ks .

Increased cardiac output elicits higher V̇O2max in response to self-paced exercise.

PubMed

Astorino, Todd Anthony; McMillan, David William; Edmunds, Ross Montgomery; Sanchez, Eduardo

2015-03-01

Recently, a self-paced protocol demonstrated higher maximal oxygen uptake versus the traditional ramp protocol. The primary aim of the current study was to further explore potential differences in maximal oxygen uptake between the ramp and self-paced protocols using simultaneous measurement of cardiac output. Active men and women of various fitness levels (N = 30, mean age = 26.0 ± 5.0 years) completed 3 graded exercise tests separated by a minimum of 48 h. Participants initially completed progressive ramp exercise to exhaustion to determine maximal oxygen uptake followed by a verification test to confirm maximal oxygen uptake attainment. Over the next 2 sessions, they performed a self-paced and an additional ramp protocol. During exercise, gas exchange data were obtained using indirect calorimetry, and thoracic impedance was utilized to estimate hemodynamic function (stroke volume and cardiac output). One-way ANOVA with repeated measures was used to determine differences in maximal oxygen uptake and cardiac output between ramp and self-paced testing. Results demonstrated lower (p < 0.001) maximal oxygen uptake via the ramp (47.2 ± 10.2 mL·kg(-1)·min(-1)) versus the self-paced (50.2 ± 9.6 mL·kg(-1)·min(-1)) protocol, with no interaction (p = 0.06) seen for fitness level. Maximal heart rate and cardiac output (p = 0.02) were higher in the self-paced protocol versus ramp exercise. In conclusion, data show that the traditional ramp protocol may underestimate maximal oxygen uptake compared with a newly developed self-paced protocol, with a greater cardiac output potentially responsible for this outcome.

To pace or not to pace: a pilot study of four- and five-gaited Icelandic horses homozygous for the DMRT3 'Gait Keeper' mutation.

PubMed

Jäderkvist Fegraeus, K; Hirschberg, I; Árnason, T; Andersson, L; Velie, B D; Andersson, L S; Lindgren, G

2017-12-01

The Icelandic horse is a breed known mainly for its ability to perform the ambling four-beat gait 'tölt' and the lateral two-beat gait pace. The natural ability of the breed to perform these alternative gaits is highly desired by breeders. Therefore, the discovery that a nonsense mutation (C>A) in the DMRT3 gene was the main genetic factor for horses' ability to perform gaits in addition to walk, trot and canter was of great interest. Although several studies have demonstrated that homozygosity for the DMRT3 mutation is important for the ability to pace, only about 70% of the homozygous mutant (AA) Icelandic horses are reported to pace. The aim of the study was to genetically compare four- and five-gaited (i.e. horses with and without the ability to pace) AA Icelandic horses by performing a genome-wide association (GWA) analysis. All horses (n = 55) were genotyped on the 670K Axiom Equine Genotyping Array, and a GWA analysis was performed using the genabel package in r. No SNP demonstrated genome-wide significance, implying that the ability to pace goes beyond the presence of a single gene variant. Despite its limitations, the current study provides additional information regarding the genetic complexity of pacing ability in horses. However, to fully understand the genetic differences between four- and five-gaited AA horses, additional studies with larger sample materials and consistent phenotyping are needed. © 2017 Stichting International Foundation for Animal Genetics.

The impact of breathing rate on the cardiac autonomic dynamics among children with cerebral palsy compared to typically developed controls.

PubMed

Amichai, Taly; Eylon, Sharon; Berger, Itai; Katz-Leurer, Michal

2018-02-06

To describe the immediate effect of breathing rate on heart rate (HR) and heart rate variability (HRV) in children with cerebral palsy (CP) and a control group of typically developed (TD) age and gender-matched children. Twenty children with CP at gross motor function classification system levels I-III and 20 TD children aged 6-11 participated in the study. HR was monitored at rest and during paced breathing with biofeedback. Respiratory measures were assessed by KoKo spirometry. Children with CP have lower spirometry and HRV values at rest compared to TD children. The mean reduction of breathing rate during paced breathing among children with CP was significantly smaller. Nonetheless, while practicing paced breathing, both groups reduced their breathing rate and increased their HRV. The results of the current work present the immediate effect of paced breathing on HRV parameters in CP and TD children. Further studies are needed to investigate the effect of long-term treatment focusing on paced breathing for children with CP.

Lack of endogenous pain inhibition during exercise in people with chronic whiplash associated disorders: an experimental study.

PubMed

Van Oosterwijck, Jessica; Nijs, Jo; Meeus, Mira; Van Loo, Michel; Paul, Lorna

2012-03-01

A controlled experimental study was performed to examine the efficacy of the endogenous pain inhibitory systems and whether this (mal)functioning is associated with symptom increases following exercise in patients with chronic whiplash-associated disorders (WAD). In addition, 2 types of exercise were compared. Twenty-two women with chronic WAD and 22 healthy controls performed a submaximal and a self-paced, physiologically limited exercise test on a cycle ergometer with cardiorespiratory monitoring on 2 separate occasions. Pain pressure thresholds (PPT), health status, and activity levels were assessed in response to the 2 exercise bouts. In chronic WAD, PPT decreased following submaximal exercise, whereas they increased in healthy subjects. The same effect was established in response to the self-paced, physiologically limited exercise, with exception of the PPT at the calf which increased. A worsening of the chronic WAD symptom complex was reported post-exercise. Fewer symptoms were reported in response to the self-paced, physiologically limited exercise. These observations suggest abnormal central pain processing during exercise in patients with chronic WAD. Submaximal exercise triggers post-exertional malaise, while a self-paced and physiologically limited exercise will trigger less severe symptoms, and therefore seems more appropriate for chronic WAD patients. The results from this exercise study suggest impaired endogenous pain inhibition during exercise in people with chronic WAD. This finding highlights the fact that one should be cautious when evaluating and recommending exercise in people with chronic WAD, and that the use of more individual, targeted exercise therapies is recommended. Copyright © 2012 American Pain Society. Published by Elsevier Inc. All rights reserved.

Effects of renal sympathetic denervation on the atrial electrophysiology in dogs with pacing-induced heart failure.

PubMed

Wang, Xiaozhan; Zhao, Qingyan; Deng, Hongping; Wang, Xule; Guo, Zongwen; Dai, Zixuan; Xiao, Jinping; Wan, Peixing; Huang, Congxin

2014-10-01

Heart failure (HF) and atrial fibrillation (AF) are associated with sympathetic activation. Renal sympathetic denervation (RSD) can suppress AF vulnerability. The impact of RSD on atrial electrophysiology in experimental HF is unclear. Twenty-two beagles were randomized into control, HF, and HF + RSD groups. Control dogs were implanted cardiac pacemakers without pacing. Dogs in the HF group underwent right ventricular pacing for 3 weeks at 240 beats/min to induce HF. The dogs in the HF + RSD group received RSD and underwent the same HF-inducing procedure. The P-wave dispersion was higher in HF dogs than in the control and HF + RSD dogs (19 ± 3.1 ms vs 13 ± 2.3 ms, 15 ± 2.9 ms, P = 0.04). Conduction time within the interatrium was significantly longer in the HF dogs than that in the control and HF + RSD dogs (39 ± 4 ms vs 31 ± 3 ms, 33 ± 4 ms; P = 0.03). Window of vulnerability (WOV) of AF was widened in the HF dogs than in the HF + RSD dogs (37 ± 5 ms vs 14 ± 3 ms; P < 0.01), while AF could not be induced (WOV = 0) in the control dogs during S1 S2 stimulation. The voltage in the threshold for AF inducibility was lower during ganglionated plexi stimulation in the HF dogs than in the control and HF + RSD dogs (1.8 ± 0.6 V vs 2.5 ± 0.6 V, 2.4 ± 0.4 V; P = 0.04). RSD could reverse the atrial electrical remodeling and decrease AF inducibility in dogs with pacing-induced HF. ©2014 Wiley Periodicals, Inc.

Low Energy Multi-Stage Atrial Defibrillation Therapy Terminates Atrial Fibrillation with Less Energy than a Single Shock

PubMed Central

Li, Wenwen; Janardhan, Ajit H.; Fedorov, Vadim V.; Sha, Qun; Schuessler, Richard B.; Efimov, Igor R.

2011-01-01

Background Implantable device therapy of atrial fibrillation (AF) is limited by pain from high-energy shocks. We developed a low-energy multi-stage defibrillation therapy and tested it in a canine model of AF. Methods and Results AF was induced by burst pacing during vagus nerve stimulation. Our novel defibrillation therapy consisted of three stages: ST1 (1-4 low energy biphasic shocks), ST2 (6-10 ultra-low energy monophasic shocks), and ST3 (anti-tachycardia pacing). Firstly, ST1 testing compared single or multiple monophasic (MP) and biphasic (BP) shocks. Secondly, several multi-stage therapies were tested: ST1 versus ST1+ST3 versus ST1+ST2+ST3. Thirdly, three shock vectors were compared: superior vena cava to distal coronary sinus (SVC>CSd), proximal coronary sinus to left atrial appendage (CSp>LAA) and right atrial appendage to left atrial appendage (RAA>LAA). The atrial defibrillation threshold (DFT) of 1BP shock was less than 1MP shock (0.55 ± 0.1 versus 1.38 ± 0.31 J; p =0.003). 2-3 BP shocks terminated AF with lower peak voltage than 1BP or 1MP shock and with lower atrial DFT than 4 BP shocks. Compared to ST1 therapy alone, ST1+ST3 lowered the atrial DFT moderately (0.51 ± 0.46 versus 0.95 ± 0.32 J; p = 0.036) while a three-stage therapy, ST1+ST2+ST3, dramatically lowered the atrial DFT (0.19 ± 0.12 J versus 0.95 ± 0.32 J for ST1 alone, p=0.0012). Finally, the three-stage therapy ST1+ST2+ST3 was equally effective for all studied vectors. Conclusions Three-stage electrotherapy significantly reduces the AF defibrillation threshold and opens the door to low energy atrial defibrillation at or below the pain threshold. PMID:21980076

Electrophysiological determinants of hypokalaemia-induced arrhythmogenicity in the guinea-pig heart.

PubMed

Osadchii, O E; Olesen, S P

2009-12-01

Hypokalaemia is an independent risk factor contributing to arrhythmic death in cardiac patients. In the present study, we explored the mechanisms of hypokalaemia-induced tachyarrhythmias by measuring ventricular refractoriness, spatial repolarization gradients, and ventricular conduction time in isolated, perfused guinea-pig heart preparations. Epicardial and endocardial monophasic action potentials from distinct left ventricular (LV) and right ventricular (RV) recording sites were monitored simultaneously with volume-conducted electrocardiogram (ECG) during steady-state pacing and following a premature extrastimulus application at progressively reducing coupling stimulation intervals in normokalaemic and hypokalaemic conditions. Hypokalaemic perfusion (2.5 mm K(+) for 30 min) markedly increased the inducibility of tachyarrhythmias by programmed ventricular stimulation and rapid pacing, prolonged ventricular repolarization and shortened LV epicardial and endocardial effective refractory periods, thereby increasing the critical interval for LV re-excitation. Hypokalaemia increased the RV-to-LV transepicardial repolarization gradients but had no effect on transmural dispersion of APD(90) and refractoriness across the LV wall. As determined by local activation time recordings, the LV-to-RV transepicardial conduction and the LV transmural (epicardial-to-endocardial) conduction were slowed in hypokalaemic heart preparations. This change was attributed to depressed diastolic excitability as evidenced by increased ventricular pacing thresholds. These findings suggest that hypokalaemia-induced arrhythmogenicity is attributed to shortened LV refractoriness, increased critical intervals for LV re-excitation, amplified RV-to-LV transepicardial repolarization gradients and slowed ventricular conduction in the guinea-pig heart.

Experimental Psychological Stress on Quantitative Sensory Testing Response in Patients with Temporomandibular Disorders.

PubMed

Araújo Oliveira Ferreira, Dyna Mara; Costa, Yuri Martins; de Quevedo, Henrique Müller; Bonjardim, Leonardo Rigoldi; Rodrigues Conti, Paulo César

2018-05-15

To assess the modulatory effects of experimental psychological stress on the somatosensory evaluation of myofascial temporomandibular disorder (TMD) patients. A total of 20 women with myofascial TMD and 20 age-matched healthy women were assessed by means of a standardized battery of quantitative sensory testing. Cold detection threshold (CDT), warm detection threshold (WDT), cold pain threshold (CPT), heat pain threshold (HPT), mechanical pain threshold (MPT), wind-up ratio (WUR), and pressure pain threshold (PPT) were performed on the facial skin overlying the masseter muscle. The variables were measured in three sessions: before (baseline) and immediately after the Paced Auditory Serial Addition Task (PASAT) (stress) and then after a washout period of 20 to 30 minutes (poststress). Mixed analysis of variance (ANOVA) was applied to the data, and the significance level was set at P = .050. A significant main effect of the experimental session on all thermal tests was found (ANOVA: F > 4.10, P < .017), where detection tests presented an increase in thresholds in the poststress session compared to baseline (CDT, P = .012; WDT, P = .040) and pain thresholds were reduced in the stress (CPT, P < .001; HPT, P = .001) and poststress sessions (CPT, P = .005; HPT, P = .006) compared to baseline. In addition, a significant main effect of the study group on all mechanical tests (MPT, WUR, and PPT) was found (ANOVA: F > 4.65, P < .037), where TMD patients were more sensitive than healthy volunteers. Acute mental stress conditioning can modulate thermal sensitivity of the skin overlying the masseter in myofascial TMD patients and healthy volunteers. Therefore, psychological stress should be considered in order to perform an unbiased somatosensory assessment of TMD patients.

Investigating the pace of temperature change and its implications over the twenty-first century

NASA Astrophysics Data System (ADS)

Chavaillaz, Y.; Joussaume, S.; Braconnot, P.; Vautard, R.

2015-12-01

In most studies, climate change is approached by focusing on the evolution between a fixed current baseline and the future, emphasizing stronger warming as we move further from the current climate. Under climate conditions that are continuously evolving, human systems might have to constantly adapt to a changing target. We propose here an alternative approach, and consider indicators of the pace of temperature change and its effects on temperature distributions estimated from projections of an ensemble of 18 General Circulation Models. The pace is represented by a rate defined by the difference between two subsequent 20-year periods. Under the strongest emission pathway (RCP 8.5), the warming rate strongly increases over the twenty-first century, with a maximum reached before 2080. Whilst northern high-latitudes witness the highest temperature rise, all other latitudes highlight at least a doubling in the warming rate compared to the current period. The spatial extent of significant shifts in annual temperature distributions between two subsequent 20-year periods is projected to be at least four times larger than in the current period. They are mainly located in tropical areas, such as West Africa and South-East Asia. The fraction of the world population exposed to these shifts grows from 8% to 60% from around 2060 onwards, i.e. reaching 6 billions people. In contrast, low mitigation measures (RCP 6.0) are sufficient to keep the warming rate similar to current values. Under the medium mitigation pathway (RCP 4.5), population exposure to significant shifts drops to negligible values by the end of the century. Strong mitigation measures (RCP 2.6) are the only option that generates a global return to historical conditions regarding our indicators. Considering the pace of change can bring an alternative way to interact with climate impacts and adaptation communities.

Effects of Reduced Strength on Self-Selected Pacing for Long-Duration Activities

NASA Technical Reports Server (NTRS)

Buxton, Roxanne E.; Ryder, Jeffrey W.; English, Kirk E.; Guined, Jamie R.; Ploutz-Snyder, Lori L.

2015-01-01

Strength and aerobic capacity are predictors of astronaut performance for extravehicular activities (EVA) during exploration missions. It is expected that astronauts will self-select a pace below their ventilatory threshold (VT). PURPOSE: To determine the percentage of VT that subjects self-select for prolonged occupational tasks. METHODS: Maximal aerobic capacity and a variety of lower-body strength and power variables were assessed in 17 subjects who climbed 480 rungs on a ladder ergometer and then completed 10 km on a treadmill as quickly as possible using a self-selected pace. The tasks were performed on 4 days, with a weighted suit providing 0% (suit fabric only), 40%, 60%, and 80% of additional bodyweight (BW), thereby altering the strength to BW ratio. Oxygen consumption and heart rate were continuously measured. Repeated measures ANOVA and post-hoc comparisons were performed on the percent of VT values under each suited condition. RESULTS: Subjects consistently self-paced at or below VT for both tasks and the pace was related to suit weight. At the midpoint for the ladder climb the 80% BW condition elicited the lowest metabolic cost (-19+/-14% below VT), significantly different than the 0% BW (-3+/-16%, P=0.002) and the 40% BW conditions (-5+/-22%, P=0.023). The 60% BW condition (-13+/-19%) was different than the 40% BW condition (P=0.034). Upon completion of the ladder task there were no differences among the conditions (0%BW: 3+/-18%; 40%BW: 3+/-21%; 60%BW: - 8+/-25%; 80%BW: -10+/-18%). All subjects failed to complete 5km at 80%BW. At the midpoint of the treadmill test the three remaining conditions were all significantly different (0%BW: -20+/-15%; 40%BW: - 33+/-15%; 60%BW: -41+/-19%). Upon completion of the treadmill test the 60% BW condition (-38+/-12%) was significantly different than the 40% BW (-28+/-15%, P=0.024). CONCLUSIONS: Decreasing relative strength results in progressive and disproportionate decreases (relative to VT) in self-selected pacing during long-duration activities. Thus, during prolonged, endurance-type activities, large reductions in strength cause notable performance decrements despite no changes in aerobic capacity. These data highlight the importance of both aerobic capacity and muscle strength to the performance of prolonged EVA in exploration mission scenarios.

Bachmann bundle pacing reduces atrial electromechanical delay in type 1 myotonic dystrophy patients.

PubMed

Russo, Vincenzo; Rago, Anna; Papa, Andrea Antonio; Arena, Giulia; Politano, Luisa; Nigro, Gerardo

2018-04-01

Atrial electromechanical delay (AEMD) is an echocardiographic parameter correlated with the onset of supraventricular arrhythmias in several clinical conditions. Inter-atrial septal pacing in the region of Bachmann's bundle (BB) has been shown to be safe and feasible in myotonic dystrophy type 1 (DM1) patients, with a low rate of sensing and pacing defects. The aim of this study was to assess the impact of temporary BB pacing compared with right atrial appendage (RAA) pacing on AEMD in DM1 patients undergoing pacemaker (PM) implantation for cardiac rhythm abnormalities. The study enrolled 70 consecutive DM1 patients undergoing PM implantation for cardiac rhythm abnormalities in accordance with the current guidelines. Seventy age- and sex-matched non-DM1 patients undergoing dual-chamber PM implantation for cardiac rhythm abnormalities were used as controls. The atrial pacing lead was temporarily positioned in the RAA and on the right side of the inter-atrial septum in the region of Bachmann's bundle. For each site (BB and RAA), temporary atrial pacing in the AAI mode was established at 10 beats per minute above the sinus rate and a detailed trans-thoracic echocardiogram with tissue Doppler (TDI) analysis was recorded after at least 10 min of atrial pacing to evaluate AEMD. Temporary RAA pacing did not show statistically significant differences in inter-AEMD (48.2 ± 17.8 vs 50.5 ± 16.5 ms; P = 0.8), intra-left AEMD (43.3 ± 15.5 vs 44.6 ± 15.8 ms; P = 0.1), or intra-right-AEMD (14.1 ± 4.2 vs 15.4 ± 5.8 ms; P = 0.9), in comparison with sinus rhythm. Temporary BB pacing determined a significantly lower inter-AEMD (36.1 ± 17.1 vs 50.5 ± 16.5 ms; P = 0.001) and intra-left AEMD (32.5 ± 15.2 vs 44.6 ± 15.8 ms; P = 0.001) values in comparison with temporary RAA pacing. No statistically significant difference was found in intra-right AEMD (12.2 ± 4.6 vs 15.4 ± 5.8 ms; P = 0.2). In the control group, neither temporary RAA pacing nor temporary BB pacing showed statistically significant differences in inter-AEMD, intra-left AEMD, or intra-right AEMD values in comparison with sinus rhythm. In DM1 patients undergoing dual-chamber PM implantation, atrial pacing in the Bachmann bundle region is associated with significantly lower echocardiographic indices of atrial electromechanical delay (inter-AEMD and intra-left AEMD) in comparison with RAA pacing.

The interference of electronic implants in low frequency electromagnetic fields.

PubMed

Silny, J

2003-04-01

Electronic implants such as cardiac pacemakers or nerve stimulators can be impaired in different ways by amplitude-modulated and even continuous electric or magnetic fields of strong field intensities. For the implant bearer, possible consequences of a temporary electromagnetic interference may range from a harmless impairment of his well-being to a perilous predicament. Electromagnetic interferences in all types of implants cannot be covered here due to their various locations in the body and their different sensing systems. Therefore, this presentation focuses exemplarily on the most frequently used implant, the cardiac pacemaker. In case of an electromagnetic interference the cardiac pacemaker reacts by switching to inhibition mode or to fast asynchronous pacing. At a higher disturbance voltage on the input of the pacemaker, a regular asynchronous pacing is likely to arise. In particular, the first-named interference could be highly dangerous for the pacemaker patient. The interference threshold of cardiac pacemakers depends in a complex way on a number of different factors such as: electromagnetic immunity and adjustment of the pacemaker, the composition of the applied low-frequency fields (only electric or magnetic fields or combinations of both), their frequencies and modulations, the type of pacemaker system (bipolar, unipolar) and its location in the body, as well as the body size and orientation in the field, and last but not least, certain physiological conditions of the patient (e.g. inhalation, exhalation). In extensive laboratory studies we have investigated the interference mechanisms in more than 100 cardiac pacemakers (older types as well as current models) and the resulting worst-case conditions for pacemaker patients in low-frequency electric and magnetic fields. The verification of these results in different practical everyday-life situations, e.g. in the fields of high-voltage overhead lines or those of electronic article surveillance systems is currently in progress. In case of the vertically-oriented electric 50 Hz fields preliminary results show that per 1 kV/m unimpaired electrical field strength (rms) an interference voltage of about 400 microVpp as worst-case could occur at the input of a unipolar ventricularly controlled, left-pectorally implanted cardiac pacemaker. Thus, already a field strength above ca. 5 kV/m could cause an interference with an implanted pacemaker. The magnetic fields induces an electric disturbance voltage at the input of the pacemaker. The body and the pacemaker system compose several induction loops, whose induced voltages rates add or subtract. The effective area of one representing inductive loop ranges from 100 to 221 cm2. For the unfavourable left-pectorally implantated and atrially-controlled pacemaker with a low interference threshold, the interference threshold ranges between 552 and 16 microT (rms) for magnetic fields at frequencies between 10 and 250 Hz. On this basis the occurrence of interferences with implanted pacemakers is possible in everyday-life situations. But experiments demonstrate a low probability of interference of cardiac pacemakers in practical situations. This apparent contradiction can be explained by a very small band of inhibition in most pacemakers and, in comparison with the worst-case, deviating conditions.

β-Adrenergic stimulation increases the intra-sarcoplasmic reticulum Ca2+ threshold for Ca2+ wave generation

PubMed Central

Domeier, Timothy L; Maxwell, Joshua T; Blatter, Lothar A

2012-01-01

β-Adrenergic signalling induces positive inotropic effects on the heart that associate with pro-arrhythmic spontaneous Ca2+ waves. A threshold level of sarcoplasmic reticulum (SR) Ca2+ ([Ca2+]SR) is necessary to trigger Ca2+ waves, and whether the increased incidence of Ca2+ waves during β-adrenergic stimulation is due to an alteration in this threshold remains controversial. Using the low-affinity Ca2+ indicator fluo-5N entrapped within the SR of rabbit ventricular myocytes, we addressed this controversy by directly monitoring [Ca2+]SR and Ca2+ waves during β-adrenergic stimulation. Electrical pacing in elevated extracellular Ca2+ ([Ca2+]o= 7 mm) was used to increase [Ca2+]SR to the threshold where Ca2+ waves were consistently observed. The β-adrenergic agonist isoproterenol (ISO; 1 μm) increased [Ca2+]SR well above the control threshold and consistently triggered Ca2+ waves. However, when [Ca2+]SR was subsequently lowered in the presence of ISO (by lowering [Ca2+]o to 1 mm and partially inhibiting sarcoplasmic/endoplasmic reticulum calcium ATPase with cyclopiazonic acid or thapsigargin), Ca2+ waves ceased to occur at a [Ca2+]SR that was higher than the control threshold. Furthermore, for a set [Ca2+]SR level the refractoriness of wave occurrence (Ca2+ wave latency) was prolonged during β-adrenergic stimulation, and was highly dependent on the extent that [Ca]SR exceeded the wave threshold. These data show that acute β-adrenergic stimulation increases the [Ca2+]SR threshold for Ca2+ waves, and therefore the primary cause of Ca2+ waves is the robust increase in [Ca2+]SR above this higher threshold level. Elevation of the [Ca2+]SR wave threshold and prolongation of wave latency represent potentially protective mechanisms against pro-arrhythmogenic Ca2+ release during β-adrenergic stimulation. PMID:22988136

Finite size effects in epidemic spreading: the problem of overpopulated systems

NASA Astrophysics Data System (ADS)

Ganczarek, Wojciech

2013-12-01

In this paper we analyze the impact of network size on the dynamics of epidemic spreading. In particular, we investigate the pace of infection in overpopulated systems. In order to do that, we design a model for epidemic spreading on a finite complex network with a restriction to at most one contamination per time step, which can serve as a model for sexually transmitted diseases spreading in some student communes. Because of the highly discrete character of the process, the analysis cannot use the continuous approximation widely exploited for most models. Using a discrete approach, we investigate the epidemic threshold and the quasi-stationary distribution. The main results are two theorems about the mixing time for the process: it scales like the logarithm of the network size and it is proportional to the inverse of the distance from the epidemic threshold.

Effect of 1. 5 tesla nuclear magnetic resonance imaging scanner on implanted permanent pacemakers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayes, D.L.; Holmes, D.R. Jr.; Gray, J.E.

1987-10-01

Patients with a permanent pacemaker are currently restricted from diagnostic nuclear magnetic resonance (NMR) imaging because of potential adverse effects on the pacemaker by the magnet. Previous work has shown that NMR imaging will result in asynchronous pacing of the pulse generator within a given distance of the magnet. The radiofrequency signal generated by the system may also result in rapid cardiac pacing, which may have deleterious effects. This study utilized a 1.5 tesla unit in an in vivo laboratory animal to evaluate the unit's effects on eight different pulse generators from two manufacturers. All pacemakers functioned in an asynchronousmore » mode when placed within a certain distance of the magnet. In addition, transient reed switch inhibition was observed. Seven of the eight pulse generators paced rapidly when exposed to the radiofrequency signal and there was a dramatic decrease in arterial blood pressure. Whether effective rapid cardiac pacing would occur could not be predicted before exposure to the magnetic resonance unit. Nuclear magnetic resonance imaging with high magnetic fields in patients with a pacemaker should continue to be avoided until the mechanism of the rapid cardiac pacing can be further delineated and either predicted or prevented.« less

PACE: Pharmacists use the power of communication in paediatric asthma.

PubMed

Elaro, Amanda; Shah, Smita; Pomare, Luca N; L Armour, Carol; Z Bosnic-Anticevich, Sinthia

2014-10-01

Paediatric asthma is a public health burden in Australia despite the availability of national asthma guidelines. Community pharmacy interventions focusing on paediatric asthma are scarce. Practitioner Asthma Communication and Education (PACE) is an evidence-based program, developed in the USA for general practice physicians, aimed at addressing the issues of poor clinician-patient communication in the management of paediatric asthma. This program has been shown to improve paediatric asthma management practices of general practitioners in the USA and Australia. The development of a PACE program for community pharmacists will fill a void in the current armamentarium for pharmacist-patient care. To adapt the educational program, PACE, to the community pharmacy setting. To test the feasibility of the new program for pharmacy and to explore its potential impact on pharmacists' communication skills and asthma related practices. Community pharmacies located within the Sydney metropolitan. The PACE framework was reviewed by the research team and amended in order to ensure its relevance within the pharmacy context, thereby developing PACE for Pharmacy. Forty-four pharmacists were recruited and trained in small groups in the PACE for Pharmacy workshops. Pharmacists' satisfaction and acceptability of the workshops, confidence in using communication strategies pre- and post-workshop and self-reported behaviour change post workshop were evaluated. Pharmacist self-reported changes in communication and teaching behaviours during a paediatric asthma consultation. All 44 pharmacists attended both workshops, completed pre- and post-workshop questionnaires and provided feedback on the workshops (100 % retention). The participants reported a high level of satisfaction and valued the interactive nature of the workshops. Following the PACE for Pharmacy program, pharmacists reported significantly higher levels in using the communication strategies, confidence in their application and their helpfulness. Pharmacists checked for written asthma self-management plan possession and inhaler device technique more regularly, and provided verbal instructions more frequently to paediatric asthma patients/carers at the initiation of a new medication. This study provides preliminary evidence that the PACE program can be translated into community pharmacy. PACE for Pharmacy positively affected self-reported communication and education behaviours of pharmacists. The high response rate shows that pharmacists are eager to expand on their clinical role in primary healthcare.

[Permanent cardiac pacing for chronic symptomatic atrioventricular block in uremic hemodialysed patients. A prospective study].

PubMed

Arsenescu, Cătălina; Georgescu, G I M; Covic, A; Briotă, Laura

2002-01-01

Though sudden cardiac death accounts for as much as 15% of all cause mortality in uremia, reports concerning advanced A-V block, requiring permanent cardiac pacing in end-stage renal disease (ESRD) hemodialysed (HD) patients are very few. This is the first long term prospective study reporting on systematic permanent pacemaker implantation, in a cohort of ESRD patients from a single HD unit. Between 01/06/1997 and 30/12/2001, 396 pacemakers were inserted for advanced, symptomatic A-V block in our institution, including 5 in ESRD, HD patients (M/F--4/1, age 47-73, M +/- SD--61 +/- 12 years) from a single dialysis center, treating 137 patients during the study period. Thus, the incidence and prevalence of A-V defects treated by permanent pacing in uremic patients was 0.81% and 3.65% respectively. Conversely, the incidence and prevalence of ESRD treated by hemodialysis, among patients with advanced A-V conduction disturbances, requiring permanent pacing were 0.28% and 1.26%. Mitral valve calcifications were present in all patients; 3 subjects also had extensive aortic valve calcifications. Left ventricular hypertrophy (echocardiographic Framingham criteria) was present in 4 patients, but the systolic function (ejection fraction and fractional shortening index) was normal in all cases, although a clinical picture of chronic heart failure was seen in 3 subjects preoperatively. A-V conduction defects were attributed to extensive metastatic calcifications, involving the cardiac squeleton, consecutive to severe hyperparathyroidism and inadvertent use of calcitriol and calcium carbonate as phosphate binders. No technical difficulties, short or long-term complications related to pacemaker implantation (4 VVI and 1 VVD devices) were encountered. Acute threshold and sensing values were similar with those of non-uremic patients. During follow-up, one patients died from a non cardiac death. If optimal hemodialysis is provided, benefits of permanent pacing are equal in uremic or non uremic patients and pacemaker implantation should be instituted as a prompt life-saving method in all dialysis patients with chronic symptomatic advanced A-V blocks.

The Italian subcutaneous implantable cardioverter-defibrillator survey: S-ICD, why not?

PubMed

Botto, Giovanni Luca; Forleo, Giovanni B; Capucci, Alessandro; Solimene, Francesco; Vado, Antonello; Bertero, Giovanni; Palmisano, Pietro; Pisanò, Ennio; Rapacciuolo, Antonio; Infusino, Tommaso; Vicentini, Alessandro; Viscusi, Miguel; Ferrari, Paola; Talarico, Antonello; Russo, Giovanni; Boriani, Giuseppe; Padeletti, Luigi; Lovecchio, Mariolina; Valsecchi, Sergio; D'Onofrio, Antonio

2017-11-01

A recommendation for a subcutaneous-implantable cardioverter-defibrillator (S-ICD) has been added to recent European Society of Cardiology Guidelines. However, the S-ICD is not ideally suitable for patients who need pacing. The aim of this survey was to analyse the current practice of ICD implantation and to evaluate the actual suitability of S-ICD. The survey 'S-ICD Why Not?' was an independent initiative taken by the Italian Heart Rhythm Society (AIAC). Clinical characteristics, selection criteria, and factors guiding the choice of ICD type were collected in consecutive patients who underwent ICD implantation in 33 Italian centres from September to December 2015. A cardiac resynchronization therapy (CRT) device was implanted in 39% (369 of 947) of patients undergoing de novo ICD implantation. An S-ICD was implanted in 12% of patients with no CRT indication (62 of 510 with available data). S-ICD patients were younger than patients who received transvenous ICD, more often had channelopathies, and more frequently received their device for secondary prevention of sudden death. More frequently, the clinical reason for preferring a transvenous ICD over an S-ICD was the need for pacing (45%) or for antitachycardia pacing (36%). Nonetheless, only 7% of patients fulfilled conditions for recommending permanent pacing, and 4% of patients had a history of monomorphic ventricular tachycardia that might have been treatable with antitachycardia pacing. The vast majority of patients needing ICD therapy are suitable candidates for S-ICD implantation. Nevertheless, it currently seems to be preferentially adopted for secondary prevention of sudden death in young patients with channelopathies. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Cardiology.

Effect of monopolar radiofrequency energy on pacemaker function.

PubMed

Govekar, Henry R; Robinson, Thomas N; Varosy, Paul D; Girard, Guillaume; Montero, Paul N; Dunn, Christina L; Jones, Edward L; Stiegmann, Greg V

2012-10-01

This study aimed to quantify the clinical parameters of mono- and bipolar instruments that inhibit pacemaker function. The specific aims were to quantify pacer inhibition resulting from the monopolar instrument by altering the generator power setting, the generator mode, the distance between the active electrode and the pacemaker, and the location of the dispersive electrode. A transvenous ventricular lead pacemaker overdrive paced the native heart rate of an anesthetized pig. The primary outcome variable was pacer inhibition quantified as the number of beats dropped by the pacemaker during 5 s of monopolar active electrode activation. Lowering the generator power setting from 60 to 30 W decreased the number of dropped paced events (2.3 ± 1.2 vs 1.6 ± 0.8 beats; p = 0.045). At 30 W of power, use of the cut mode decreased the number of dropped paced beats compared with the coagulation mode (0.6 ± 0.5 vs 1.6 ± 0.8; p = 0.015). At 30 W coagulation, firing the active electrode at different distances from the pacemaker generator (3.75, 7.5, 15, and 30 cm) did not change the number of dropped paced beats (p = 0.314, analysis of variance [ANOVA]). The dispersive electrode was placed in four locations (right/left gluteus, right/left shoulder). More paced beats were dropped when the current vector traveled through the pacemaker/leads than when it did not (1.5 ± 1.0 vs 0.2 ± 0.4; p < 0.001). Clinical parameters that reduce the inhibition of a pacemaker by monopolar instruments include lowering the generator power setting, using cut (vs coagulation) mode, and locating the dispersive electrode so the current vector does not traverse the pacemaker generator or leads.

Study protocol for improving asthma outcomes through cross-cultural communication training for physicians: a randomized trial of physician training.

PubMed

Patel, Minal R; Thomas, Lara J; Hafeez, Kausar; Shankin, Matthew; Wilkin, Margaret; Brown, Randall W

2014-06-16

Massive resources are expended every year on cross-cultural communication training for physicians. Such training is a focus of continuing medical education nationwide and is part of the curriculum of virtually every medical school in America. There is a pressing need for evidence regarding the effects on patients of cross-cultural communication training for physicians. There is a need to understand the added benefit of such training compared to more general communication. We know of no rigorous study that has assessed whether cross-cultural communication training for physicians results in better health outcomes for their patients. The current study aims to answer this question by enhancing the Physician Asthma Care Education (PACE) program to cross cultural communication (PACE Plus), and comparing the effect of the enhanced program to PACE on the health outcomes of African American and Latino/Hispanic children with asthma. A three-arm randomized control trial is used to compare PACE Plus, PACE, and usual care. Both PACE and PACE Plus are delivered in two, two-hour sessions over a period of two weeks to 5-10 primary care physicians who treat African American and Latino/Hispanic children with asthma. One hundred twelve physicians and 1060 of their pediatric patients were recruited who self-identify as African American or Latino/Hispanic and experience persistent asthma. Physicians were randomized into receiving either the PACE Plus or PACE intervention or into the control group. The comparative effectiveness of PACE and PACE Plus on clinician's therapeutic and communication practices with the family/patient, children's urgent care use for asthma, asthma control, and quality of life, and parent/caretaker satisfaction with physician performance will be assessed. Data are collected via telephone survey and medical record review at baseline, 9 months following the intervention, and 21 months following the intervention. This study aims to reduce disparities in asthma outcomes among African American and Latino/Hispanic children through cross-cultural communication training of their physicians and assessing the added value of this training compared to general communication. The results of this study will provide important information about the value of cross-cultural training in helping to address persistent racial disparities in outcomes. ClinicalTrials.gov: NCT01251523 December 1, 2010.

Characteristics of elite open-water swimmers.

PubMed

VanHeest, Jaci L; Mahoney, Carrie E; Herr, Larry

2004-05-01

Open-water swimming (5, 10, and 25 km) has many unique challenges that separate it from other endurance sports, like marathon running and cycling. The characteristics of a successful open-water swimmer are unclear. The purpose of this study was to determine the physical and metabolic characteristics of a group of elite-level open-water swimmers. The open-water swimmers were participating in a 1-week training camp. Anthropometric, metabolic, and blood chemistry assessments were performed on the athletes. The swimmers had a VO(2)peak of 5.51 +/- 0.96 and 5.06 +/- 0.57 ml.kg(-1).min(-1) for males and females, respectively. Their lactate threshold (LT) occurred at a pace equal to 88.75% of peak pace for males and 93.75% for females. These elite open-water swimmers were smaller and lighter than competitive pool swimmers. They possess aerobic metabolic alterations that resulted in enhanced performance in distance swimming. Trainers and coaches should develop dry-land programs that will improve the athlete's muscular endurance. Furthermore, programs should be designed to increase the LT velocity as a percentage of peak swimming velocity.

Differential modulation of late sodium current by protein kinase A in R1623Q mutant of LQT3

PubMed Central

Tsurugi, Takuo; Nagatomo, Toshihisa; Abe, Haruhiko; Oginosawa, Yasushi; Takemasa, Hiroko; Kohno, Ritsuko; Makita, Naomasa; Makielski, Jonathan C.; Otsuji, Yutaka

2009-01-01

Aims In the type 3 long QT syndrome (LQT3), shortening of the QT interval by overdrive pacing is used to prevent life-threatening arrhythmias. However, it is unclear whether accelerated heart rate induced by β-adrenergic agents produces similar effects on the late sodium current (INa) to those by overdrive pacing therapy. We analyzed the β-adrenergic-like effects of protein kinase A and fluoride on INa in R1623Q mutant channels. Main methods cDNA encoding either wild-type (WT) or R1623Q mutant of hNav1.5 was stably transfected into HEK293 cells. INa was recorded using a whole-cell patch-clamp technique at 23 °C. Key findings In R1623Q channels, 2 mM pCPT-AMP and 120 mM fluoride significantly delayed macroscopic current decay and increased relative amplitude of the late INa in a time-dependent manner. Modulations of peak INa gating kinetics (activation, inactivation, recovery from inactivation) by fluoride were similar in WT and R1623Q channels. The effects of fluoride were almost completely abolished by concomitant dialysis with a protein kinase inhibitor. We also compared the effect of pacing with that of β-adrenergic stimulation by analyzing the frequency-dependence of the late INa. Fluoride augmented frequency-dependent reduction of the late INa, which was due to preferential delay of recovery of late INa. However, the increase in late INa by fluoride at steady-state was more potent than the frequency-dependent reduction of late INa. Significance Different basic mechanisms participate in the QT interval shortening by pacing and β-adrenergic stimulation in the LQT3. PMID:19167409

High ventricular lead impedance of a DDD pacemaker after cranial magnetic resonance imaging.

PubMed

Baser, Kazim; Guray, Umit; Durukan, Mine; Demirkan, Burcu

2012-09-01

Management of electromagnetic interference in the form of magnetic resonance imaging (MRI) in patients with pacemakers (PMs) may be challenging. Serious consequences, especially in PM-dependent patients, may be encountered. Changes in device programming, asynchronous pacing, heating of the lead tip(s), and increased thresholds or even device dislocation may be experienced. We report of a patient with a DDD PM who underwent an emergent MRI, after which there was an increase in ventricular impedance as well as increased cardiac biomarkers. ©2011, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.

Application synergies between the NASA Pre- Aerosol Cloud and ocean Ecosystem (PACE) and Hyperspectral Infrared Imager (HyspIRI) missions

NASA Astrophysics Data System (ADS)

Lee, C. M.; Omar, A. H.; Hook, S. J.; Tzortziou, M.; Luvall, J. C.; Turner, W. W.

2016-02-01

Observations from the Pre-Aerosol Cloud and ocean Ecosystem (PACE) and Hyperspectral InfraRed Imager (HyspIRI) satellite missions are highly complementary and have the potential to significantly advance understanding of various science and applications challenges in the ocean sciences and water quality communities. Scheduled for launch in the 2022 timeframe, PACE is designed to make climate-quality global measurements essential for understanding ocean biology, biogeochemistry and ecology, and determining the role of the ocean in global biogeochemical cycling and ocean ecology, and how it affects and is affected by climate change. PACE will provide high signal-to-noise, hyperspectral observations over an extended spectral range (UV to SWIR) and will have global coverage every 1-2 days, at approximately 1 km spatial resolution; furthermore, PACE is currently designed to include a polarimeter, which will vastly improve atmospheric correction algorithms over water bodies. The PACE mission will enable advances in applications across a range of areas, including oceans, climate, water resources, ecological forecasting, disasters, human health and air quality. HyspIRI, with contiguous measurements in VSWIR, and multispectral measurements in TIR, will be able to provide detailed spectral observations and higher spatial resolution (30 to 60-m) over aquatic systems, but at a temporal resolution that is approximately 5-16 days. HyspIRI would enable improved, detailed studies of aquatic ecosystems, including benthic communities, algal blooms, coral reefs, and wetland species distribution as well as studies of water quality indicators or pollutants such as oil spills, suspended sediment, and colored dissolved organic matter. Together, PACE and HyspIRI will be able to address numerous applications and science priorities, including improving and extending climate data records, and studies of inland, coastal and ocean environments.

Contributions of adaptation currents to dynamic spike threshold on slow timescales: Biophysical insights from conductance-based models

NASA Astrophysics Data System (ADS)

Yi, Guosheng; Wang, Jiang; Wei, Xile; Deng, Bin; Li, Huiyan; Che, Yanqiu

2017-06-01

Spike-frequency adaptation (SFA) mediated by various adaptation currents, such as voltage-gated K+ current (IM), Ca2+-gated K+ current (IAHP), or Na+-activated K+ current (IKNa), exists in many types of neurons, which has been shown to effectively shape their information transmission properties on slow timescales. Here we use conductance-based models to investigate how the activation of three adaptation currents regulates the threshold voltage for action potential (AP) initiation during the course of SFA. It is observed that the spike threshold gets depolarized and the rate of membrane depolarization (dV/dt) preceding AP is reduced as adaptation currents reduce firing rate. It is indicated that the presence of inhibitory adaptation currents enables the neuron to generate a dynamic threshold inversely correlated with preceding dV/dt on slower timescales than fast dynamics of AP generation. By analyzing the interactions of ionic currents at subthreshold potentials, we find that the activation of adaptation currents increase the outward level of net membrane current prior to AP initiation, which antagonizes inward Na+ to result in a depolarized threshold and lower dV/dt from one AP to the next. Our simulations demonstrate that the threshold dynamics on slow timescales is a secondary effect caused by the activation of adaptation currents. These findings have provided a biophysical interpretation of the relationship between adaptation currents and spike threshold.

Multistage electrotherapy delivered through chronically-implanted leads terminates atrial fibrillation with lower energy than a single biphasic shock.

PubMed

Janardhan, Ajit H; Gutbrod, Sarah R; Li, Wenwen; Lang, Di; Schuessler, Richard B; Efimov, Igor R

The goal of this study was to develop a low-energy, implantable device-based multistage electrotherapy (MSE) to terminate atrial fibrillation (AF). Previous attempts to perform cardioversion of AF by using an implantable device were limited by the pain caused by use of a high-energy single biphasic shock (BPS). Transvenous leads were implanted into the right atrium (RA), coronary sinus, and left pulmonary artery of 14 dogs. Self-sustaining AF was induced by 6 ± 2 weeks of high-rate RA pacing. Atrial defibrillation thresholds of standard versus experimental electrotherapies were measured in vivo and studied by using optical imaging in vitro. The mean AF cycle length (CL) in vivo was 112 ± 21 ms (534 beats/min). The impedances of the RA-left pulmonary artery and RA-coronary sinus shock vectors were similar (121 ± 11 Ω vs. 126 ± 9 Ω; p = 0.27). BPS required 1.48 ± 0.91 J (165 ± 34 V) to terminate AF. In contrast, MSE terminated AF with significantly less energy (0.16 ± 0.16 J; p < 0.001) and significantly lower peak voltage (31.1 ± 19.3 V; p < 0.001). In vitro optical imaging studies found that AF was maintained by localized foci originating from pulmonary vein-left atrium interfaces. MSE Stage 1 shocks temporarily disrupted localized foci; MSE Stage 2 entrainment shocks continued to silence the localized foci driving AF; and MSE Stage 3 pacing stimuli enabled consistent RA-left atrium activation until sinus rhythm was restored. Low-energy MSE significantly reduced the atrial defibrillation thresholds compared with BPS in a canine model of AF. MSE may enable painless, device-based AF therapy. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Multistage Electrotherapy Delivered Through Chronically-Implanted Leads Terminates Atrial Fibrillation With Lower Energy Than a Single Biphasic Shock

PubMed Central

Janardhan, Ajit H.; Gutbrod, Sarah R.; Li, Wenwen; Lang, Di; Schuessler, Richard B.; Efimov, Igor R.

2014-01-01

Objectives The goal of this study was to develop a low-energy, implantable device–based multistage electrotherapy (MSE) to terminate atrial fibrillation (AF). Background Previous attempts to perform cardioversion of AF by using an implantable device were limited by the pain caused by use of a high-energy single biphasic shock (BPS). Methods Transvenous leads were implanted into the right atrium (RA), coronary sinus, and left pulmonary artery of 14 dogs. Self-sustaining AF was induced by 6 ± 2 weeks of high-rate RA pacing. Atrial defibrillation thresholds of standard versus experimental electrotherapies were measured in vivo and studied by using optical imaging in vitro. Results The mean AF cycle length (CL) in vivo was 112 ± 21 ms (534 beats/min). The impedances of the RA–left pulmonary artery and RA–coronary sinus shock vectors were similar (121 ± 11 Ω vs. 126 ± 9 Ω; p = 0.27). BPS required 1.48 ± 0.91 J (165 ± 34 V) to terminate AF. In contrast, MSE terminated AF with significantly less energy (0.16 ± 0.16 J; p < 0.001) and significantly lower peak voltage (31.1 ± 19.3 V; p < 0.001). In vitro optical imaging studies found that AF was maintained by localized foci originating from pulmonary vein–left atrium interfaces. MSE Stage 1 shocks temporarily disrupted localized foci; MSE Stage 2 entrainment shocks continued to silence the localized foci driving AF; and MSE Stage 3 pacing stimuli enabled consistent RA–left atrium activation until sinus rhythm was restored. Conclusions Low-energy MSE significantly reduced the atrial defibrillation thresholds compared with BPS in a canine model of AF. MSE may enable painless, device-based AF therapy. PMID:24076284

Effects of premature stimulation on HERG K+ channels

PubMed Central

Lu, Yu; Mahaut-Smith, Martyn P; Varghese, Anthony; Huang, Christopher L-H; Kemp, Paul R; Vandenberg, Jamie I

2001-01-01

The unusual kinetics of human ether-à-go-go-related gene (HERG) K+ channels are consistent with a role in the suppression of arrhythmias initiated by premature beats. Action potential clamp protocols were used to investigate the effect of premature stimulation on HERG K+ channels, transfected in Chinese hamster ovary cells, at 37 °C. HERG K+ channel currents peaked during the terminal repolarization phase of normally paced action potential waveforms. However, the magnitude of the current and the time point at which conductance was maximal depended on the type of action potential waveform used (epicardial, endocardial, Purkinje fibre or atrial). HERG K+ channel currents recorded during premature action potentials consisted of an early transient outward current followed by a sustained outward current. The magnitude of the transient current component showed a biphasic dependence on the coupling interval between the normally paced and premature action potentials and was maximal at a coupling interval equivalent to 90% repolarization (APD90) for ventricular action potentials. The largest transient current response occurred at shorter coupling intervals for Purkinje fibre (APD90– 20 ms) and atrial (APD90– 30 ms) action potentials. The magnitude of the sustained current response following premature stimulation was similar to that recorded during the first action potential for ventricular action potential waveforms. However, for Purkinje and atrial action potentials the sustained current response was significantly larger during the premature action potential than during the normally paced action potential. A Markov model that included three closed states, one open and one inactivated state with transitions permitted between the pre-open closed state and the inactivated state, successfully reproduced our results for the effects of premature stimuli, both during square pulse and action potential clamp waveforms. These properties of HERG K+ channels may help to suppress arrhythmias initiated by early afterdepolarizations and premature beats in the ventricles, Purkinje fibres or atria. PMID:11744759

Leadless Pacing: Current State and Future Direction.

PubMed

Merkel, Matthias; Grotherr, Philipp; Radzewitz, Andrea; Schmitt, Claus

2017-12-01

Leadless pacing is now an established alternative to conventional pacing with subcutaneous pocket and transvenous lead for patients with class I or II single-chamber pacing indication. Available 12-month follow-up data shows a 48% fewer major complication rate in patients with Micra™ compared to a historical control group in a nonrandomized study [1]. There is one system with Food and Drug Administration (FDA) approval and two with the Communauté Européenne (CE) mark. The OPS code for the implantation is 8-83d.3 and the procedure has recently been rated as a "new Examination and Treatment Method (NUB)" in the German DRG system, meaning adequate reimbursement is negotiable with health insurance providers. The systems offer similar generator longevity and programming possibilities as conventional pacemaker systems, including rate response, remote monitoring, and MRI safety. The biggest downsides to date are limitations to single-chamber stimulation, lack of long-time data, and concerns of handling of the system at the end of its life span. However, implant procedure complication rates and procedure times do not exceed conventional pacemaker operations, and proper training and patient selection is provided.

Self-Paced Prioritized Curriculum Learning With Coverage Penalty in Deep Reinforcement Learning.

PubMed

Ren, Zhipeng; Dong, Daoyi; Li, Huaxiong; Chen, Chunlin; Zhipeng Ren; Daoyi Dong; Huaxiong Li; Chunlin Chen; Dong, Daoyi; Li, Huaxiong; Chen, Chunlin; Ren, Zhipeng

2018-06-01

In this paper, a new training paradigm is proposed for deep reinforcement learning using self-paced prioritized curriculum learning with coverage penalty. The proposed deep curriculum reinforcement learning (DCRL) takes the most advantage of experience replay by adaptively selecting appropriate transitions from replay memory based on the complexity of each transition. The criteria of complexity in DCRL consist of self-paced priority as well as coverage penalty. The self-paced priority reflects the relationship between the temporal-difference error and the difficulty of the current curriculum for sample efficiency. The coverage penalty is taken into account for sample diversity. With comparison to deep Q network (DQN) and prioritized experience replay (PER) methods, the DCRL algorithm is evaluated on Atari 2600 games, and the experimental results show that DCRL outperforms DQN and PER on most of these games. More results further show that the proposed curriculum training paradigm of DCRL is also applicable and effective for other memory-based deep reinforcement learning approaches, such as double DQN and dueling network. All the experimental results demonstrate that DCRL can achieve improved training efficiency and robustness for deep reinforcement learning.

Person-Centered Care for Older Adults With Serious Mental Illness and Substance Misuse Within a Program of All-Inclusive Care for the Elderly.

PubMed

Cacchione, Pamela Z; Eible, Lisa; Gill, Le'Roi L; Huege, Steven F

2016-05-01

Providing person-centered care (PCC) to older adults with dual diagnosis, co-occurring serious mental illness (SMI), and substance misuse is complex and requires an interprofessional team. Older adults, who qualify for both Medicaid and Medicare (i.e., dual-eligibles) are overrepresented in the population of older adults with SMI and substance misuse. Programs of All-Inclusive Care for the Elderly (PACE) exist to support community living needs of nursing home-eligible older adults and are increasingly in a position to serve older adults with SMI and substance misuse issues. PACE programs provide integrated person-centered mental health care to address the serious medical, social, and emotional complications posed by having SMI and substance misuse disorders. The case study presented illustrates PCC provided to a dual-diagnosis PACE participant, illustrating the impact of recent and past trauma on current psychopathology and substance misuse. Finally, recommendations for addressing PCC of dual diagnosis within the PACE model are provided. [Journal of Gerontological Nursing, 42(5), 11-17.]. Copyright 2016, SLACK Incorporated.

Advanced decision modeling for real time variable tolling : development and testing of a data collection platform.

DOT National Transportation Integrated Search

2012-06-01

Our current ability to forecast demand on tolled facilities has not kept pace with advances in decision sciences and : technological innovation. The current forecasting methods suffer from lack of descriptive power of actual behavior because : of the...

AREA RADIATION MONITOR

DOEpatents

Manning, F.W.; Groothuis, S.E.; Lykins, J.H.; Papke, D.M.

1962-06-12

S>An improved area radiation dose monitor is designed which is adapted to compensate continuously for background radiation below a threshold dose rate and to give warning when the dose integral of the dose rate of an above-threshold radiation excursion exceeds a selected value. This is accomplished by providing means for continuously charging an ionization chamber. The chamber provides a first current proportional to the incident radiation dose rate. Means are provided for generating a second current including means for nulling out the first current with the second current at all values of the first current corresponding to dose rates below a selected threshold dose rate value. The second current has a maximum value corresponding to that of the first current at the threshold dose rate. The excess of the first current over the second current, which occurs above the threshold, is integrated and an alarm is given at a selected integrated value of the excess corresponding to a selected radiation dose. (AEC)

Arrhythmogenic epilepsy and pacing need: A matter of controversy

PubMed Central

Kepez, Alper; Erdogan, Okan

2015-01-01

There is increasing awareness among the cardiology community regarding ictal bradyarrhythmias as a cause of loss of consciousness. A high degree of suspicion is necessary when diagnosing ictal bradyarrhythmias, and delay in diagnosing this condition may lead to morbidity associated with falls and trauma. Ictal bradyarrhythmias have also been suggested to be associated with sudden unexplained death in epilepsy, although evidence related to this association is limited. There is no guideline-directed therapy for symptomatic ictal bradyarrhythmias due to a lack of randomized, controlled trials. Cardiac pacemaker therapy is commonly used for these patients; however, currently, there is no universal agreement on the pacing indications for these patients. In this review, we focus on the pathophysiology and clinical presentation of ictal bradyarrhythmias and then discuss the pacing need based on the available literature data. PMID:26488022

Marked attenuation of shock burden by the use of antitachycardia pacing therapy in a patient with an implanted cardioverter-defibrillator.

PubMed

Ganjehei, Leila; Nazeri, Alireza; Massumi, Ali; Razavi, Mehdi

2012-01-01

A 76-year-old man was admitted to our institution for elective exchange of his implanted cardioverter-defibrillator generator. Nine years earlier, he had been diagnosed with nonischemic cardiomyopathy and nonsustainable ventricular tachycardia. At that time, he had received a single-chamber implanted cardioverter-defibrillator, which was upgraded to a dual-chamber implanted cardioverter-defibrillator 3 years later. In the course of the current admission, routine device interrogation during exchange of the patient's implanted cardioverter-defibrillator generator revealed 150 episodes of ventricular tachycardia in the preceding 7 months, 137 of which had been successfully treated by antitachycardia pacing therapy without shock. These findings show the remarkable effectiveness of antitachycardia pacing in terminating ventricular tachycardia while preventing the delivery of shocks, minimizing patient discomfort, and avoiding implanted cardioverter-defibrillator battery depletion.

Molecular Validation of PACE4 as a Target in Prostate Cancer12

PubMed Central

D'Anjou, François; Routhier, Sophie; Perreault, Jean-Pierre; Latil, Alain; Bonnel, David; Fournier, Isabelle; Salzet, Michel; Day, Robert

2011-01-01

Prostate cancer remains the single most prevalent cancer in men. Standard therapies are still limited and include androgen ablation that initially causes tumor regression. However, tumor cells eventually relapse and develop into a hormone-refractory prostate cancer. One of the current challenges in this disease is to define new therapeutic targets, which have been virtually unchanged in the past 30 years. Recent studies have suggested that the family of enzymes known as the proprotein convertases (PCs) is involved in various types of cancers and their progression. The present study examined PC expression in prostate cancer and validates one PC, namely PACE4, as a target. The evidence includes the observed high expression of PACE4 in all different clinical stages of human prostate tumor tissues. Gene silencing studies targeting PACE4 in the DU145 prostate cancer cell line produced cells (cell line 4-2) with slower proliferation rates, reduced clonogenic activity, and inability to grow as xenografts in nude mice. Gene expression and proteomic profiling of the 4-2 cell line reveals an increased expression of known cancer-related genes (e.g., GJA1, CD44, IGFBP6) that are downregulated in prostate cancer. Similarly, cancer genes whose expression is decreased in the 4-2 cell line were upregulated in prostate cancer (e.g., MUC1, IL6). The direct role of PACE4 in prostate cancer is most likely through the upregulated processing of growth factors or through the aberrant processing of growth factors leading to sustained cancer progression, suggesting that PACE4 holds a central role in prostate cancer. PMID:21633671

Biophysical Insights into How Spike Threshold Depends on the Rate of Membrane Potential Depolarization in Type I and Type II Neurons

PubMed Central

Yi, Guo-Sheng; Wang, Jiang; Tsang, Kai-Ming; Wei, Xi-Le; Deng, Bin

2015-01-01

Dynamic spike threshold plays a critical role in neuronal input-output relations. In many neurons, the threshold potential depends on the rate of membrane potential depolarization (dV/dt) preceding a spike. There are two basic classes of neural excitability, i.e., Type I and Type II, according to input-output properties. Although the dynamical and biophysical basis of their spike initiation has been established, the spike threshold dynamic for each cell type has not been well described. Here, we use a biophysical model to investigate how spike threshold depends on dV/dt in two types of neuron. It is observed that Type II spike threshold is more depolarized and more sensitive to dV/dt than Type I. With phase plane analysis, we show that each threshold dynamic arises from the different separatrix and K+ current kinetics. By analyzing subthreshold properties of membrane currents, we find the activation of hyperpolarizing current prior to spike initiation is a major factor that regulates the threshold dynamics. The outward K+ current in Type I neuron does not activate at the perithresholds, which makes its spike threshold insensitive to dV/dt. The Type II K+ current activates prior to spike initiation and there is a large net hyperpolarizing current at the perithresholds, which results in a depolarized threshold as well as a pronounced threshold dynamic. These predictions are further attested in several other functionally equivalent cases of neural excitability. Our study provides a fundamental description about how intrinsic biophysical properties contribute to the threshold dynamics in Type I and Type II neurons, which could decipher their significant functions in neural coding. PMID:26083350

The PACE evaluation: initial findings.

PubMed

Branch, L G; Coulam, R F; Zimmerman, Y A

1995-06-01

As of mid-1994 there were nine replications of the On Lok model operating under dual capitation payments as sites in the Program of All-inclusive Care for the Elderly (PACE). A tenth site had begun operating under capitation, but was unable to remain viable. The present descriptive study documents the growth and development of the first seven of these sites, all that had been operating under capitation during 1992. Comparisons among these sites and with On Lok are presented in the areas of organizational structure, client characteristics, approaches to case management, service delivery options, and financing. There is considerable variability in the implementation of the PACE model. Combined Medicare and Medicaid capitation monthly payments range from $2,147 to $5,973. These seven PACE sites (excluding On Lok) served a total of 888 current clients at the end of 1992, after a cumulative 136 months of experience under capitation. The very slow enrollment rates may imply that the target clients are less enthusiastic about this model than are its architects. The client selection process may suggest niche-marketing or skimming, but not the full representation of the nursing home population in their states. Given both the slow enrollment and the niche-marketing (the benevolent term) or skimming (the pejorative term) that has occurred, caution about the long-term viability of the PACE model may be warranted.

The Role Of Orbital Forcing On Polar Ice Volume And Global Sea-Level During The Late Pliocene (3.3-.2.6 Ma)

NASA Astrophysics Data System (ADS)

Naish, T.; Grant, G.; Dunbar, G. B.; Patterson, M. O.; Kominz, M. A.; Stocchi, P.

2017-12-01

Challenges remain concerning the potentially intractable problem of constraining the absolute magnitude of Pliocene eustatic sea-level change, and the role of orbital forcing on the frequency of ice volume/sea-level change is widely debated. Here, we present three new high-resolution geological archives for the MPWP: (i) ice-berg rafted debris (IBRD) mass accumulation rates from deep ocean sediment core (IODP U1361) off the Wilkes Margin of Antarctica recording fluctuations in the East Antarctic ice sheet; (ii) a continuous shallow-marine record of sea-level change from the Wanganui Basin, New Zealand; and (iii) a record sea-level-controlled terrigenous sedimentation (IODP 1124) to the deep ocean on Hikurangi margin of New Zealand. All three records are dominated by precession-paced cyclicity ( 20ka) in-phase with high-latitude southern hemisphere insolation between 3.3M-2.9Ma, and provide insights into orbital-forcing of ice volume and sea-level independent of the benthic oxygen isotope records. Moreover, we have back-stripped the Wanganui record to reveal glacial-interglacial sea-level changes of 20±10m amplitude. We conclude that during this interval, precession-paced Antarctic ice volume changes largely drove global glacial-interglacial sea-level fluctuations, in the absence of a significant northern hemisphere ice volume contribution. Prior to 3.3Ma, proxy data from IODP U1361 and ANDRILL 1-A records extending back to 5Ma, show that the Antarctic margin experienced warmer ocean temperatures, a lack of perennial sea-ice, and fluctuations in ice extent paced by obliquity. The emergence of precession at 3.3Ma coincident with the M2 glaciation in the benthic d18O record, also coincides with continent-wide cooling, ice expansion and the development of extensive seasonal sea-ice around Antarctica. We argue that a melt threshold response to orbital forcing was crossed, whereby Antarctic ice sheet melt was restricted to peak austral summer insolation (precession), rather than a longer summer melt-season controlled by mean annual insolation (obliquity). An obliquity-paced signal re-emerges in the New Zealand sea-level records after 2.9Ma, while the EAIS IBRD record continues to be paced by precession, implying an increasingly dominant influence of northern hemisphere ice sheets.

Waning and aging of cellular immunity to Bordetella pertussis.

PubMed

van Twillert, Inonge; Han, Wanda G H; van Els, Cécile A C M

2015-11-01

While it is clear that the maintenance of Bordetella pertussis-specific immunity evoked both after vaccination and infection is insufficient, it is unknown at which pace waning occurs and which threshold levels of sustained functional memory B and T cells are required to provide long-term protection. Longevity of human cellular immunity to B. pertussis has been studied less extensively than serology, but is suggested to be key for the observed differences between the duration of protection induced by acellular vaccination and whole cell vaccination or infection. The induction and maintenance of levels of protective memory B and T cells may alter with age, associated with changes of the immune system throughout life and with accumulating exposures to circulating B. pertussis or vaccine doses. This is relevant since pertussis affects all age groups. This review summarizes current knowledge on the waning patterns of human cellular immune responses to B. pertussis as addressed in diverse vaccination and infection settings and in various age groups. Knowledge on the effectiveness and flaws in human B. pertussis-specific cellular immunity ultimately will advance the improvement of pertussis vaccination strategies. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Massive digoxin ingestion. Report of a case and review of currently available therapies.

PubMed Central

Bremner, W F; Third, J L; Lawrie, T D

1977-01-01

Recent reports of treatment of massive digoxin overdosage have emphasized the success of medical therapy. This report describes a fatal outcome to this problem despite aggressive medical management, including pervenous cardiac pacing and draws attention to deficiencies in current treatment of a serious problem. PMID:328024

Optimizing α for better statistical decisions: a case study involving the pace-of-life syndrome hypothesis: optimal α levels set to minimize Type I and II errors frequently result in different conclusions from those using α = 0.05.

PubMed

Mudge, Joseph F; Penny, Faith M; Houlahan, Jeff E

2012-12-01

Setting optimal significance levels that minimize Type I and Type II errors allows for more transparent and well-considered statistical decision making compared to the traditional α = 0.05 significance level. We use the optimal α approach to re-assess conclusions reached by three recently published tests of the pace-of-life syndrome hypothesis, which attempts to unify occurrences of different physiological, behavioral, and life history characteristics under one theory, over different scales of biological organization. While some of the conclusions reached using optimal α were consistent to those previously reported using the traditional α = 0.05 threshold, opposing conclusions were also frequently reached. The optimal α approach reduced probabilities of Type I and Type II errors, and ensured statistical significance was associated with biological relevance. Biologists should seriously consider their choice of α when conducting null hypothesis significance tests, as there are serious disadvantages with consistent reliance on the traditional but arbitrary α = 0.05 significance level. Copyright © 2012 WILEY Periodicals, Inc.

A Prospective Evaluation of a Protocol for Magnetic Resonance Imaging of Patients With Implanted Cardiac Devices

PubMed Central

Nazarian, Saman; Hansford, Rozann; Roguin, Ariel; Goldsher, Dorith; Zviman, Menekhem M.; Lardo, Albert C.; Caffo, Brian S.; Frick, Kevin D.; Kraut, Michael A.; Kamel, Ihab R.; Calkins, Hugh; Berger, Ronald D.; Bluemke, David A.; Halperin, Henry R.

2015-01-01

Background Magnetic resonance imaging (MRI) is avoided in most patients with implanted cardiac devices because of safety concerns. Objective To define the safety of a protocol for MRI at the commonly used magnetic strength of 1.5 T in patients with implanted cardiac devices. Design Prospective nonrandomized trial. (ClinicalTrials.gov registration number: NCT01130896) Setting One center in the United States (94% of examinations) and one in Israel. Patients 438 patients with devices (54% with pacemakers and 46% with defibrillators) who underwent 555 MRI studies. Intervention Pacing mode was changed to asynchronous for pacemaker-dependent patients and to demand for others. Tachy-arrhythmia functions were disabled. Blood pressure, electrocardiography, oximetry, and symptoms were monitored by a nurse with experience in cardiac life support and device programming who had immediate backup from an electrophysiologist. Measurements Activation or inhibition of pacing, symptoms, and device variables. Results In 3 patients (0.7% [95% CI, 0% to 1.5%]), the device reverted to a transient back-up programming mode without long-term effects. Right ventricular (RV) sensing (median change, 0 mV [interquartile range {IQR}, −0.7 to 0 V]) and atrial and right and left ventricular lead impedances (median change, −2 Ω[IQR, −13 to 0 Ω], −4 Ω [IQR, −16 to 0 Ω], and −11 Ω [IQR, −40 to 0 Ω], respectively) were reduced immediately after MRI. At long-term follow-up (61% of patients), decreased RV sensing (median, 0 mV, [IQR, −1.1 to 0.3 mV]), decreased RV lead impedance (median, −3 Ω, [IQR, −29 to 15 Ω]), increased RV capture threshold (median, 0 V, IQR, [0 to 0.2 Ω]), and decreased battery voltage (median, −0.01 V, IQR, −0.04 to 0 V) were noted. The observed changes did not require device revision or reprogramming. Limitations Not all available cardiac devices have been tested. Long-term in-person or telephone follow-up was unavailable in 43 patients (10%), and some data were missing. Those with missing long-term capture threshold data had higher baseline right atrial and right ventricular capture thresholds and were more likely to have undergone thoracic imaging. Defibrillation threshold testing and random assignment to a control group were not performed. Conclusion With appropriate precautions, MRI can be done safely in patients with selected cardiac devices. Because changes in device variables and programming may occur, electrophysiologic monitoring during MRI is essential. Primary Funding Source National Institutes of Health. PMID:21969340

Visual aided pacing in respiratory maneuvers

NASA Astrophysics Data System (ADS)

Rambaudi, L. R.; Rossi, E.; Mántaras, M. C.; Perrone, M. S.; Siri, L. Nicola

2007-11-01

A visual aid to pace self-controlled respiratory cycles in humans is presented. Respiratory manoeuvres need to be accomplished in several clinic and research procedures, among others, the studies on Heart Rate Variability. Free running respiration turns to be difficult to correlate with other physiologic variables. Because of this fact, voluntary self-control is asked from the individuals under study. Currently, an acoustic metronome is used to pace respiratory frequency, its main limitation being the impossibility to induce predetermined timing in the stages within the respiratory cycle. In the present work, visual driven self-control was provided, with separate timing for the four stages of a normal respiratory cycle. This visual metronome (ViMet) was based on a microcontroller which power-ON and -OFF an eight-LED bar, in a four-stage respiratory cycle time series handset by the operator. The precise timing is also exhibited on an alphanumeric display.

Comparing maximum rate and sustainability of pacing by mechanical vs. electrical stimulation in the Langendorff-perfused rabbit heart.

PubMed

Quinn, T Alexander; Kohl, Peter

2016-12-01

Mechanical stimulation (MS) represents a readily available, non-invasive means of pacing the asystolic or bradycardic heart in patients, but benefits of MS at higher heart rates are unclear. Our aim was to assess the maximum rate and sustainability of excitation by MS vs. electrical stimulation (ES) in the isolated heart under normal physiological conditions. Trains of local MS or ES at rates exceeding intrinsic sinus rhythm (overdrive pacing; lowest pacing rates 2.5±0.5 Hz) were applied to the same mid-left ventricular free-wall site on the epicardium of Langendorff-perfused rabbit hearts. Stimulation rates were progressively increased, with a recovery period of normal sinus rhythm between each stimulation period. Trains of MS caused repeated focal ventricular excitation from the site of stimulation. The maximum rate at which MS achieved 1:1 capture was lower than during ES (4.2±0.2 vs. 5.9±0.2 Hz, respectively). At all overdrive pacing rates for which repetitive MS was possible, 1:1 capture was reversibly lost after a finite number of cycles, even though same-site capture by ES remained possible. The number of MS cycles until loss of capture decreased with rising stimulation rate. If interspersed with ES, the number of MS to failure of capture was lower than for MS only. In this study, we demonstrate that the maximum pacing rate at which MS can be sustained is lower than that for same-site ES in isolated heart, and that, in contrast to ES, the sustainability of successful 1:1 capture by MS is limited. The mechanism(s) of differences in MS vs. ES pacing ability, potentially important for emergency heart rhythm management, are currently unknown, thus warranting further investigation. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Cardiology.

Comparing maximum rate and sustainability of pacing by mechanical vs. electrical stimulation in the Langendorff-perfused rabbit heart

PubMed Central

Quinn, T. Alexander; Kohl, Peter

2016-01-01

Aims Mechanical stimulation (MS) represents a readily available, non-invasive means of pacing the asystolic or bradycardic heart in patients, but benefits of MS at higher heart rates are unclear. Our aim was to assess the maximum rate and sustainability of excitation by MS vs. electrical stimulation (ES) in the isolated heart under normal physiological conditions. Methods and results Trains of local MS or ES at rates exceeding intrinsic sinus rhythm (overdrive pacing; lowest pacing rates 2.5±0.5 Hz) were applied to the same mid-left ventricular free-wall site on the epicardium of Langendorff-perfused rabbit hearts. Stimulation rates were progressively increased, with a recovery period of normal sinus rhythm between each stimulation period. Trains of MS caused repeated focal ventricular excitation from the site of stimulation. The maximum rate at which MS achieved 1:1 capture was lower than during ES (4.2±0.2 vs. 5.9±0.2 Hz, respectively). At all overdrive pacing rates for which repetitive MS was possible, 1:1 capture was reversibly lost after a finite number of cycles, even though same-site capture by ES remained possible. The number of MS cycles until loss of capture decreased with rising stimulation rate. If interspersed with ES, the number of MS to failure of capture was lower than for MS only. Conclusion In this study, we demonstrate that the maximum pacing rate at which MS can be sustained is lower than that for same-site ES in isolated heart, and that, in contrast to ES, the sustainability of successful 1:1 capture by MS is limited. The mechanism(s) of differences in MS vs. ES pacing ability, potentially important for emergency heart rhythm management, are currently unknown, thus warranting further investigation. PMID:28011835

Input-output relation and energy efficiency in the neuron with different spike threshold dynamics.

PubMed

Yi, Guo-Sheng; Wang, Jiang; Tsang, Kai-Ming; Wei, Xi-Le; Deng, Bin

2015-01-01

Neuron encodes and transmits information through generating sequences of output spikes, which is a high energy-consuming process. The spike is initiated when membrane depolarization reaches a threshold voltage. In many neurons, threshold is dynamic and depends on the rate of membrane depolarization (dV/dt) preceding a spike. Identifying the metabolic energy involved in neural coding and their relationship to threshold dynamic is critical to understanding neuronal function and evolution. Here, we use a modified Morris-Lecar model to investigate neuronal input-output property and energy efficiency associated with different spike threshold dynamics. We find that the neurons with dynamic threshold sensitive to dV/dt generate discontinuous frequency-current curve and type II phase response curve (PRC) through Hopf bifurcation, and weak noise could prohibit spiking when bifurcation just occurs. The threshold that is insensitive to dV/dt, instead, results in a continuous frequency-current curve, a type I PRC and a saddle-node on invariant circle bifurcation, and simultaneously weak noise cannot inhibit spiking. It is also shown that the bifurcation, frequency-current curve and PRC type associated with different threshold dynamics arise from the distinct subthreshold interactions of membrane currents. Further, we observe that the energy consumption of the neuron is related to its firing characteristics. The depolarization of spike threshold improves neuronal energy efficiency by reducing the overlap of Na(+) and K(+) currents during an action potential. The high energy efficiency is achieved at more depolarized spike threshold and high stimulus current. These results provide a fundamental biophysical connection that links spike threshold dynamics, input-output relation, energetics and spike initiation, which could contribute to uncover neural encoding mechanism.

Input-output relation and energy efficiency in the neuron with different spike threshold dynamics

PubMed Central

Yi, Guo-Sheng; Wang, Jiang; Tsang, Kai-Ming; Wei, Xi-Le; Deng, Bin

2015-01-01

Neuron encodes and transmits information through generating sequences of output spikes, which is a high energy-consuming process. The spike is initiated when membrane depolarization reaches a threshold voltage. In many neurons, threshold is dynamic and depends on the rate of membrane depolarization (dV/dt) preceding a spike. Identifying the metabolic energy involved in neural coding and their relationship to threshold dynamic is critical to understanding neuronal function and evolution. Here, we use a modified Morris-Lecar model to investigate neuronal input-output property and energy efficiency associated with different spike threshold dynamics. We find that the neurons with dynamic threshold sensitive to dV/dt generate discontinuous frequency-current curve and type II phase response curve (PRC) through Hopf bifurcation, and weak noise could prohibit spiking when bifurcation just occurs. The threshold that is insensitive to dV/dt, instead, results in a continuous frequency-current curve, a type I PRC and a saddle-node on invariant circle bifurcation, and simultaneously weak noise cannot inhibit spiking. It is also shown that the bifurcation, frequency-current curve and PRC type associated with different threshold dynamics arise from the distinct subthreshold interactions of membrane currents. Further, we observe that the energy consumption of the neuron is related to its firing characteristics. The depolarization of spike threshold improves neuronal energy efficiency by reducing the overlap of Na+ and K+ currents during an action potential. The high energy efficiency is achieved at more depolarized spike threshold and high stimulus current. These results provide a fundamental biophysical connection that links spike threshold dynamics, input-output relation, energetics and spike initiation, which could contribute to uncover neural encoding mechanism. PMID:26074810

Perception of Self-Motion and Regulation of Walking Speed in Young-Old Adults.

PubMed

Lalonde-Parsi, Marie-Jasmine; Lamontagne, Anouk

2015-07-01

Whether a reduced perception of self-motion contributes to poor walking speed adaptations in older adults is unknown. In this study, speed discrimination thresholds (perceptual task) and walking speed adaptations (walking task) were compared between young (19-27 years) and young-old individuals (63-74 years), and the relationship between the performance on the two tasks was examined. Participants were evaluated while viewing a virtual corridor in a helmet-mounted display. Speed discrimination thresholds were determined using a staircase procedure. Walking speed modulation was assessed on a self-paced treadmill while exposed to different self-motion speeds ranging from 0.25 to 2 times the participants' comfortable speed. For each speed, participants were instructed to match the self-motion speed described by the moving corridor. On the walking task, participants displayed smaller walking speed errors at comfortable walking speeds compared with slower of faster speeds. The young-old adults presented larger speed discrimination thresholds (perceptual experiment) and larger walking speed errors (walking experiment) compared with young adults. Larger walking speed errors were associated with higher discrimination thresholds. The enhanced performance on the walking task at comfortable speed suggests that intersensory calibration processes are influenced by experience, hence optimized for frequently encountered conditions. The altered performance of the young-old adults on the perceptual and walking tasks, as well as the relationship observed between the two tasks, suggest that a poor perception of visual motion information may contribute to the poor walking speed adaptations that arise with aging.

Social Media Policy in Social Work Education: A Review and Recommendations

ERIC Educational Resources Information Center

Karpman, Hannah E.; Drisko, James

2016-01-01

Although social media use has grown dramatically, program policies have not kept pace. Some programs now state that student social media activities have led to professional conduct reviews and may violate ethical standards. This article reviews current social media policies and conceptualizes their key elements. A review of current social media…

The Development of Geo-KOMPSAT-2A (GK-2A) Convective Initiation Algorithm over the Korea peninsular

NASA Astrophysics Data System (ADS)

Kim, H. S.; Chung, S. R.; Lee, B. I.; Baek, S.; Jeon, E.

2016-12-01

The rapid development of convection can bring heavy rainfall that suffers a great deal of damages to society as well as threatens human life. The high accurate forecast of the strong convection is essentially demanded to prevent those disasters from the severe weather. Since a geostationary satellite is the most suitable instrument for monitoring the single cloud's lifecycle from its formation to extinction, it has been attempted to capture the precursor signals of convection clouds by satellite. Keeping pace with the launch of Geo-KOMPSAT-2A (GK-2A) in 2018, we planned to produce convective initiation (CI) defined as the indicator of potential cloud objects to bring heavy precipitation within two hours. The CI algorithm for GK-2A is composed of four stages. The beginning is to subtract mature cloud pixels, a sort of convective cloud mask by visible (VIS) albedo and infrared (IR) brightness temperature thresholds. Then, the remained immature cloud pixels are clustered as a cloud object by watershed techniques. Each clustering object is undergone 'Interest Fields' tests for IR data that reflect cloud microphysical properties at the current and their temporal changes; the cloud depth, updraft strength and production of glaciations. All thresholds of 'Interest fields' were optimized for Korean-type convective clouds. Based on scores from tests, it is decided whether the cloud object would develop as a convective cell or not. Here we show the result of case study in this summer over the Korea peninsular by using Himawari-8 VIS and IR data. Radar echo and data were used for validation. This study suggests that CI products of GK-2A would contribute to enhance accuracy of the very short range forecast over the Korea peninsular.

Management of climatic heat stress risk in construction: a review of practices, methodologies, and future research.

PubMed

Rowlinson, Steve; Yunyanjia, Andrea; Li, Baizhan; Chuanjingju, Carrie

2014-05-01

Climatic heat stress leads to accidents on construction sites brought about by a range of human factors emanating from heat induced illness, and fatigue leading to impaired capability, physical and mental. It is an occupational characteristic of construction work in many climates and the authors take the approach of re-engineering the whole safety management system rather than focusing on incremental improvement, which is current management practice in the construction industry. From a scientific viewpoint, climatic heat stress is determined by six key factors: (1) air temperature, (2) humidity, (3) radiant heat, and (4) wind speed indicating the environment, (5) metabolic heat generated by physical activities, and (6) "clothing effect" that moderates the heat exchange between the body and the environment. By making use of existing heat stress indices and heat stress management processes, heat stress risk on construction sites can be managed in three ways: (1) control of environmental heat stress exposure through use of an action-triggering threshold system, (2) control of continuous work time (CWT, referred by maximum allowable exposure duration) with mandatory work-rest regimens, and (3) enabling self-paced working through empowerment of employees. Existing heat stress practices and methodologies are critically reviewed and the authors propose a three-level methodology for an action-triggering, localized, simplified threshold system to facilitate effective decisions by frontline supervisors. The authors point out the need for "regional based" heat stress management practices that reflect unique climatic conditions, working practices and acclimatization propensity by local workers indifferent geographic regions. The authors set out the case for regional, rather than international, standards that account for this uniqueness and which are derived from site-based rather than laboratory-based research. Copyright © 2013 Elsevier Ltd. All rights reserved.

Optimal pacing modes after cardiac transplantation: is synchronisation of recipient and donor atria beneficial?

PubMed Central

Parry, Gareth; Malbut, Katie; Dark, John H; Bexton, Rodney S

1992-01-01

Objective—To investigate the response of the transplanted heart to different pacing modes and to synchronisation of the recipient and donor atria in terms of cardiac output at rest. Design—Doppler derived cardiac output measurements at three pacing rates (90/min, 110/min and 130/min) in five pacing modes: right ventricular pacing, donor atrial pacing, recipient-donor synchronous pacing, donor atrial-ventricular sequential pacing, and synchronous recipient-donor atrial-ventricular sequential pacing. Patients—11 healthy cardiac transplant recipients with three pairs of epicardial leads inserted at transplantation. Results—Donor atrial pacing (+11% overall) and donor atrial-ventricular sequential pacing (+8% overall) were significantly better than right ventricular pacing (p < 0·001) at all pacing rates. Synchronised pacing of recipient and donor atrial segments did not confer additional benefit in either atrial or atrial-ventricular sequential modes of pacing in terms of cardiac output at rest at these fixed rates. Conclusions—Atrial pacing or atrial-ventricular sequential pacing appear to be appropriate modes in cardiac transplant recipients. Synchronisation of recipient and donor atrial segments in this study produced no additional benefit. Chronotropic competence in these patients may, however, result in improved exercise capacity and deserves further investigation. PMID:1389737

Hydrodynamic sensory threshold in harbour seals (Phoca vitulina) for artificial flatfish breathing currents.

PubMed

Niesterok, Benedikt; Dehnhardt, Guido; Hanke, Wolf

2017-07-01

Harbour seals have the ability to detect benthic fish such as flatfish using the water currents these fish emit through their gills (breathing currents). We investigated the sensory threshold in harbour seals for this specific hydrodynamic stimulus under conditions which are realistic for seals hunting in the wild. We used an experimental platform where an artificial breathing current was emitted through one of eight different nozzles. Two seals were trained to search for the active nozzle. Each experimental session consisted of eight test trials of a particular stimulus intensity and 16 supra-threshold trials of high stimulus intensity. Test trials were conducted with the animals blindfolded. To determine the threshold, a series of breathing currents differing in intensity was used. For each intensity, three sessions were run. The threshold in terms of maximum water velocity within the breathing current was 4.2 cm s -1 for one seal and 3.7 cm s -1 for the other. We measured background flow velocities from 1.8 to 3.4 cm s -1 Typical swimming speeds for both animals were around 0.5 m s -1 Swimming speed differed between successful and unsuccessful trials. It appears that swimming speed is restricted for the successful detection of a breathing current close to the threshold. Our study is the first to assess a sensory threshold of the vibrissal system for a moving harbour seal under near-natural conditions. Furthermore, this threshold was defined for a natural type of stimulus differing from classical dipole stimuli which have been widely used in threshold determination so far. © 2017. Published by The Company of Biologists Ltd.

IVHS Denver Metro Area, Master Plan

DOT National Transportation Integrated Search

1994-02-01

THE DENVER METROPOLITAN AREA CURRENTLY FACES A NUMBER OF CHALLENGES IN PROVIDING AN ADEQUATE TRANSPORTATION SYSTEM. THE AREA IS EXPERIENCING NEAR-RECORD POPULATION GROWTH, BUT THE AVAILABLE FUNDING FOR INFRASTRUCTURE IS NOT KEEPING PACE. DENVER IS A ...

Less efficient oculomotor performance is associated with increased incidence of head impacts in high school ice hockey.

PubMed

Kiefer, Adam W; DiCesare, Christopher; Nalepka, Patrick; Foss, Kim Barber; Thomas, Staci; Myer, Gregory D

2018-01-01

To evaluate associations between pre-season oculomotor performance on visual tracking tasks and in-season head impact incidence during high school boys ice hockey. Prospective observational study design. Fifteen healthy high school aged male hockey athletes (M=16.50±1.17years) performed two 30s blocks each of a prosaccade and self-paced saccade task, and two trials each of a slow, medium, and fast smooth pursuit task (90°s -1 ; 180°s -1 ; 360°s -1 ) during the pre-season. Regular season in-game collision data were collected via helmet-mounted accelerometers. Simple linear regressions were used to examine relations between oculomotor performance measures and collision incidence at various impact thresholds. The variability of prosaccade latency was positively related to total collisions for the 20g force cutoff (p=0.046, adjusted R 2 =0.28). The average self-paced saccade velocity (p=0.020, adjusted R 2 =0.37) and variability of smooth pursuit gaze velocity (p=0.012, adjusted R 2 =0.47) were also positively associated with total collisions for the 50g force cutoff. These results provide preliminary evidence that less efficient oculomotor performance on three different oculomotor tasks is associated with increased incidence of head impacts during a competitive ice hockey season. The variability of prosaccade latency, the average self-paced saccade velocity and the variability of gaze velocity during predictable smooth pursuit all related to increased head impacts. Future work is needed to further understand player initiated collisions, but this is an important first step toward understanding strategies to reduce incidence of injury risk in ice hockey, and potentially contact sports more generally. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Safety and feasibility of leadless pacemaker in patients undergoing atrioventricular node ablation for atrial fibrillation.

PubMed

Yarlagadda, Bharath; Turagam, Mohit K; Dar, Tawseef; Jangam, Pragna; Veerapaneni, Vaishnavi; Atkins, Donita; Bommana, Sudharani; Friedman, Paul; Deshmukh, Abhishek J; Doshi, Rahul; Reddy, Vivek Y; Dukkipati, Srinivas R; Natale, Andrea; Lakkireddy, Dhanunjaya

2018-03-01

Atrioventricular node (AVN) ablation and permanent pacing is an established strategy for rate control in the management of symptomatic atrial fibrillation (AF). Leadless pacemakers (LPs) can overcome some of the short-term and long-term limitations of conventional transvenous pacemakers (CTPs). The purpose of this study was to compare the feasibility and safety of LP with those of single-chamber CTP in patients with AF undergoing AVN ablation. We conducted a multicenter observational study of patients undergoing AVN ablation and pacemaker implantation (LP vs single-chamber CTP) between February 2014 and November 2016. The primary efficacy end points were acceptable sensing (R wave ≥5.0 mV) and pacing thresholds (≤2.0 V at 0.4 ms) at follow-up. Safety end points included device-related major and minor (early ≤1 month, late >1 month) adverse events. A total of 127 patients with LP (n = 60) and CTP (n = 67) were studied. The median follow-up was 12 months (interquartile range 12-18 months). Ninety-five percent of the LP group and 97% of the CTP group met the primary efficacy end point at follow-up (57 of 60 vs 65 of 67; P = .66). There was 1 major adverse event (loss of pacing and sensing) in the LP group and 2 (lead dislodgement) in the CTP group (1 of 60 vs 2 of 67; P = 1.00). There were 6 minor adverse events (5 early and 1 late) in the LP group and 3 (early) in the CTP group (6 of 60 vs 3 of 67; P = .30). Our results demonstrate the feasibility and safety of LP compared with CTP in patients undergoing AVN ablation for AF. Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Prescribing 6-weeks of running training using parameters from a self-paced maximal oxygen uptake protocol.

PubMed

Hogg, James S; Hopker, James G; Coakley, Sarah L; Mauger, Alexis R

2018-05-01

The self-paced maximal oxygen uptake test (SPV) may offer effective training prescription metrics for athletes. This study aimed to examine whether SPV-derived data could be used for training prescription. Twenty-four recreationally active male and female runners were randomly assigned between two training groups: (1) Standardised (STND) and (2) Self-Paced (S-P). Participants completed 4 running sessions a week using a global positioning system-enabled (GPS) watch: 2 × interval sessions; 1 × recovery run; and 1 × tempo run. STND had training prescribed via graded exercise test (GXT) data, whereas S-P had training prescribed via SPV data. In STND, intervals were prescribed as 6 × 60% of the time that velocity at [Formula: see text] ([Formula: see text]) could be maintained (T max ). In S-P, intervals were prescribed as 7 × 120 s at the mean velocity of rating of perceived exertion 20 ( v RPE20). Both groups used 1:2 work:recovery ratio. Maximal oxygen uptake ([Formula: see text]), [Formula: see text], T max, v RPE20, critical speed (CS), and lactate threshold (LT) were determined before and after the 6-week training. STND and S-P training significantly improved [Formula: see text] by 4 ± 8 and 6 ± 6%, CS by 7 ± 7 and 3 ± 3%; LT by 5 ± 4% and 7 ± 8%, respectively (all P < .05), with no differences observed between groups. Novel metrics obtained from the SPV can offer similar training prescription and improvement in [Formula: see text], CS and LT compared to training derived from a traditional GXT.

Biophysical mechanism of spike threshold dependence on the rate of rise of the membrane potential by sodium channel inactivation or subthreshold axonal potassium current

PubMed Central

Wester, Jason C.

2013-01-01

Spike threshold filters incoming inputs and thus gates activity flow through neuronal networks. Threshold is variable, and in many types of neurons there is a relationship between the threshold voltage and the rate of rise of the membrane potential (dVm/dt) leading to the spike. In primary sensory cortex this relationship enhances the sensitivity of neurons to a particular stimulus feature. While Na+ channel inactivation may contribute to this relationship, recent evidence indicates that K+ currents located in the spike initiation zone are crucial. Here we used a simple Hodgkin-Huxley biophysical model to systematically investigate the role of K+ and Na+ current parameters (activation voltages and kinetics) in regulating spike threshold as a function of dVm/dt. Threshold was determined empirically and not estimated from the shape of the Vm prior to a spike. This allowed us to investigate intrinsic currents and values of gating variables at the precise voltage threshold. We found that Na+ inactivation is sufficient to produce the relationship provided it occurs at hyperpolarized voltages combined with slow kinetics. Alternatively, hyperpolarization of the K+ current activation voltage, even in the absence of Na+ inactivation, is also sufficient to produce the relationship. This hyperpolarized shift of K+ activation allows an outward current prior to spike initiation to antagonize the Na+ inward current such that it becomes self-sustaining at a more depolarized voltage. Our simulations demonstrate parameter constraints on Na+ inactivation and the biophysical mechanism by which an outward current regulates spike threshold as a function of dVm/dt. PMID:23344915

Very low threshold-current temperature sensitivity in constricted double-heterojunction AlGaAs lasers

NASA Technical Reports Server (NTRS)

Botez, D.; Connolly, J. C.; Gilbert, D. B.; Ettenberg, M.

1981-01-01

The temperature dependence of threshold currents in constricted double-heterojunction diode lasers with strong lateral mode confinement is found to be significantly milder than for other types of lasers. The threshold-current relative variations with ambient temperature are typically two to three times less than for other devices of CW-operation capability. Over the interval 10-70 C the threshold currents fit the empirical exponential law exp/(T2-T1)/T0/ with T0 values in the 240-375 C range in pulsed operation, and in the 200-310 C range in CW operation. The external differential quantum efficiency and the mode far-field pattern near threshold are virtually invariant with temperature. The possible causes of high-T0 behavior are analyzed, and a new phenomenon - temperature-dependent current focusing - is presented to explain the results.

Presentation Time Concerning System-Paced Multimedia Instructions and the Superiority of Learner Pacing

ERIC Educational Resources Information Center

Stiller, Klaus D.; Petzold, Kirstin; Zinnbauer, Peter

2011-01-01

The superiority of learner-paced over system-paced instructions was demonstrated in multiple experiments. In these experiments, the system-paced presentations were highly speeded, causing cognitive overload, while the learner-paced instructions allowed adjustments of the presentational flow to the learner's needs by pacing facilities, mostly…

Impact of ethnicity, gender, and dehydration on the urinary excretion of inhaled salbutamol with respect to doping control.

PubMed

Dickinson, John; Hu, Jie; Chester, Neil; Loosemore, Mike; Whyte, Greg

2014-11-01

To examine the impact of dehydration, ethnicity, and gender on urinary concentrations of salbutamol in relation to the threshold stipulated by the World Anti-Doping Agency (WADA). Repeated measures open-label. Eighteen male and 14 female athletes (9 white males, 9 white females, 2 Afro-Caribbean males, 2 Afro-Caribbean females, 6 Asian [Indian subcontinent] males, and 4 Asian females) were recruited. All participants were nonasthmatic. After inhalation of 800 μg or 1600 μg of salbutamol, athletes exercised in a hot controlled environment (35°C, 40% relative humidity) at a self-selected pace until a target weight loss (2% or 5%) was achieved. Urine concentration of free salbutamol. After inhalation of 1600 μg salbutamol, 20 participants presented with a urine salbutamol concentrations above the current WADA limit (1000 ng/mL) and decision limit (1200 ng/mL) resulting in an adverse analytical finding. There were no differences according to gender or ethnic origin. Dehydration equivalent to a body mass loss greater than 2% concomitant to the acute inhalation of 1600 μg of salbutamol may result in a urine concentration above the current WADA limit and decision limit leading to a positive test finding independent of gender or ethnic origin. Asthmatic athletes using salbutamol should receive clear dosing advise and education to minimize the risk of inhaling doses of salbutamol that may produce urine concentrations of salbutamol above 1200 ng/mL.

Investigating possible ethnicity and sex bias in clinical examiners: an analysis of data from the MRCP(UK) PACES and nPACES examinations.

PubMed

McManus, I C; Elder, Andrew T; Dacre, Jane

2013-07-30

Bias of clinical examiners against some types of candidate, based on characteristics such as sex or ethnicity, would represent a threat to the validity of an examination, since sex or ethnicity are 'construct-irrelevant' characteristics. In this paper we report a novel method for assessing sex and ethnic bias in over 2000 examiners who had taken part in the PACES and nPACES (new PACES) examinations of the MRCP(UK). PACES and nPACES are clinical skills examinations that have two examiners at each station who mark candidates independently. Differences between examiners cannot be due to differences in performance of a candidate because that is the same for the two examiners, and hence may result from bias or unreliability on the part of the examiners. By comparing each examiner against a 'basket' of all of their co-examiners, it is possible to identify examiners whose behaviour is anomalous. The method assessed hawkishness-doveishness, sex bias, ethnic bias and, as a control condition to assess the statistical method, 'even-number bias' (i.e. treating candidates with odd and even exam numbers differently). Significance levels were Bonferroni corrected because of the large number of examiners being considered. The results of 26 diets of PACES and six diets of nPACES were examined statistically to assess the extent of hawkishness, as well as sex bias and ethnicity bias in individual examiners. The control (odd-number) condition suggested that about 5% of examiners were significant at an (uncorrected) 5% level, and that the method therefore worked as expected. As in a previous study (BMC Medical Education, 2006, 6:42), some examiners were hawkish or doveish relative to their peers. No examiners showed significant sex bias, and only a single examiner showed evidence consistent with ethnic bias. A re-analysis of the data considering only one examiner per station, as would be the case for many clinical examinations, showed that analysis with a single examiner runs a serious risk of false positive identifications probably due to differences in case-mix and content-specificity. In examinations where there are two independent examiners at a station, our method can assess the extent of bias against candidates with particular characteristics. The method would be far less sensitive in examinations with only a single examiner per station as examiner variance would be confounded with candidate performance variance. The method however works well when there is more than one examiner at a station and in the case of the current MRCP(UK) clinical examination, nPACES, found possible sex bias in no examiners and possible ethnic bias in only one.

Influence of emission threshold of explosive emission cathodes on current waveform in foilless diodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, P.; Liu, G. Z.; Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024

The emission threshold of explosive emission cathodes (EECs) is an important factor for beam quality. It can affect the explosive emission delay time, the plasma expansion process on the cathode surface, and even the current amplitude when the current is not fully space-charge-limited. This paper researches the influence of the emission threshold of an annular EEC on the current waveform in a foilless diode when the current is measured by a Rogowski coil. The particle-in-cell simulation which is performed under some tolerable and necessary simplifications shows that the long explosive emission delay time of high-threshold cathodes may leave an apparentmore » peak of displacement current on the rise edge of the current waveform, and this will occur only when the electron emission starts after this peak. The experimental researches, which are performed under a diode voltage of 1 MV and a repetitive frequency of 20 Hz, demonstrate that the graphite cathode has a lower emission threshold and a longer lifetime than the stainless steel cathode according to the variation of the peak of displacement current on the rise edge of the current waveform.« less

Intergenerational groups and emerging science: How can museums facilitate learning?

NASA Astrophysics Data System (ADS)

Holm, Jessica

New research in science and technology is emerging today at a faster pace than ever, and staying informed can be challenging for the public, especially families with younger children. Museums are already a resource to promote science literacy, and museum educators are trained to make all kinds of scientific ideas accessible to a variety of audiences. Unfortunately, because emerging science is fast-paced and ever-changing, many museums -- especially smaller institutions -- do not have the staff or budgetary resources to present this research to a wide audience. This study surveyed current literature in museum education and science learning, and current museum professionals from a range of institutions, to create a gallery guide that is flexible and easy to update for a museum, and that provides a fun and educational tool for family visitors. The study also includes a protocol to assist museum educators in collaborating with the researchers providing the science content.

Temperature dependence of threshold current in GaAs/AlGaAs quantum well lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blood, P.; Colak, S.; Kucharska, A.I.

1988-02-22

We have calculated the threshold current and its temperature (T) dependence in the range 200--400 K for AlGaAs quantum well lasers with 25-A-wide GaAs wells using a model which includes lifetime broadening of the transitions and broadening of the density of states function by fluctuations in the well width. The threshold current varies approximately linearly with T and the principal effect of broadening is to increase the threshold current causing a reduction in the fractional change of current with temperature. The apparent value of the parameter T/sub 0/ is increased to approx. =400 K, compared with approx. =320 K withoutmore » broadening. The calculations are compared with experimental data.« less

Pacing and awareness: brain regulation of physical activity.

PubMed

Edwards, A M; Polman, R C J

2013-11-01

The aim of this current opinion article is to provide a contemporary perspective on the role of brain regulatory control of paced performances in response to exercise challenges. There has been considerable recent conjecture as to the role of the brain during exercise, and it is now broadly accepted that fatigue does not occur without brain involvement and that all voluntary activity is likely to be paced at some level by the brain according to individualised priorities and knowledge of personal capabilities. This article examines the role of pacing in managing and distributing effort to successfully accomplish physical tasks, while extending existing theories on the role of the brain as a central controller of performance. The opinion proposed in this article is that a central regulator operates to control exercise performance but achieves this without the requirement of an intelligent central governor located in the subconscious brain. It seems likely that brain regulation operates at different levels of awareness, such that minor homeostatic challenges are addressed automatically without conscious awareness, while larger metabolic disturbances attract conscious awareness and evoke a behavioural response. This supports the view that the brain regulates exercise performance but that the interpretation of the mechanisms underlying this effect have not yet been fully elucidated.

Permanent Leadless Cardiac Pacemaker Therapy: A Comprehensive Review.

PubMed

Tjong, Fleur V Y; Reddy, Vivek Y

2017-04-11

A new technology, leadless pacemaker therapy, was recently introduced clinically to address lead- and pocket-related complications in conventional transvenous pacemaker therapy. These leadless devices are self-contained right ventricular single-chamber pacemakers implanted by using a femoral percutaneous approach. In this review of available clinical data on leadless pacemakers, early results with leadless devices are compared with historical results with conventional single-chamber pacing. Both presently manufactured leadless pacemakers show similar complications, which are mostly related to the implant procedure: cardiac perforation, device dislocation, and femoral vascular access site complications. In comparison with conventional transvenous single-chamber pacemakers, slightly higher short-term complication rates have been observed: 4.8% for leadless pacemakers versus 4.1% for conventional pacemakers. The complication rate of the leadless pacemakers is influenced by the implanter learning curve for this new procedure. No long-term outcome data are yet available for the leadless pacemakers. Larger leadless pacing trials, with long-term follow-up and direct randomized comparison with conventional pacing systems, will be required to define the proper clinical role of these leadless systems. Although current leadless pacemakers are limited to right ventricular pacing, future advanced, communicating, multicomponent systems are expected to expand the potential benefits of leadless therapy to a larger patient population. © 2017 American Heart Association, Inc.

The influence of stripe width on the threshold current of double-heterojunction lasers

NASA Technical Reports Server (NTRS)

Ladany, I.

1977-01-01

Experimental measurements of the threshold current of oxide-isolated stripe laser as a function of stripe width and p-layer resistivity are presented. A calculation of the influence of carrier outdiffusion has been made, including the effect of current leakage beyond the stripe edges. The calculated threshold increase is in substantial agreement with experiment for stripe widths down to about 10 microns. The data also yield an effective diffusion length of about 7 microns for the lasers studied. Deviations between experimental and calculated thresholds occurring at stripe widths of 4-6 microns are represented by an empirical curve which is compared with previously published calculations of threshold gain.

[Subcutaneous implantable cardioverter-defibrillator in prevention of sudden cardiac death in Poland - opinion paper endorsed by the Polish Cardiac Society Working Group on Heart Rhythm].

PubMed

Ptaszyński, Paweł; Grabowski, Marcin; Kowalski, Oskar; Kempa, Maciej; Mitkowski, Przemysław; Przybylski, Andrzej; Sterliński, Maciej

2017-01-01

In the past years, cardiovascular mortality has decreased but despite these cardiovascular diseases are responsible for millions of deaths every year in the world and approximately 25% of which are sudden cardiac death (SCD). Implantable defibrillators (ICD) is proven therapy used in primary and secondary SCD prevention. Currently majority of devices use transvenous leads inserted predominantly into the right heart for both pacing and defibrillation. On the other hand, ICD may cause complica-tions, including inappropriate shocks, device-related infection and lead failure. Problems with transvenous leads prompted the development of a subcutaneous defibrillator (S-ICD) with an electrode system that is placed entirely subcutaneously, outside the thoracic cavity. The device may be useful when venous access is difficult, in young patients and in patients at particular risk of infection. S-ICD is not suitable for patients with indications for bradycardia pacing, cardiac resynchronisation therapy and in cases with tachyarrhythmia easily terminated by antitachycardia pacing.

Temporary atrial epicardial pacing as prophylaxis against atrial fibrillation after heart surgery: a meta-analysis.

PubMed

Daoud, Emile G; Snow, Rick; Hummel, John D; Kalbfleisch, Steven J; Weiss, Raul; Augostini, Ralph

2003-02-01

Recent studies have reported the use of temporary epicardial atrial pacing as prophylaxis for postoperative atrial fibrillation (AF). The aim of this study was to assess the effect of pacing therapies for prevention of postoperative AF using meta-analysis. Using a computerized MEDLINE search, eight pacing prophylaxis trials with 776 patients were included in the meta-analysis. Trials compared control patients to patients randomized to right atrial, left atrial, or biatrial pacing used in conjunction with either fixed high-rate pacing or overdrive pacing. Overdrive biatrial pacing (OR 2.6, CI 1.4-4.8), overdrive right atrial pacing (OR 1.8, CI 1.1-2.7), and fixed high-rate biatrial pacing (OR 2.5, CI 1.3-5.1) demonstrated a significant antiarrhythmic effect for prevention of AF after open heart surgery. Furthermore, studies investigating overdrive left atrial pacing and fixed high-rate right atrial pacing have been underpowered to assess efficacy. Biatrial overdrive and fixed high-rate pacing and right atrial fixed high-rate pacing reduced the risk of new-onset AF after open heart surgery, and the relative risk reduction is approximately 2.5-fold. These results imply that various pacing algorithms are useful as a nonpharmacologic method to prevent postoperative AF.

The effect of cardiac electric anisotropy on epicardial potential fields during ventricular repolarization.

PubMed

Spaggiari, S; Baruffi, S; Macchi, E; Traversa, M; Arisi, G; Taccardi, B

1986-11-01

We tried to establish whether some of the manifestations of electrical anisotropy previously observed on the canine ventricular epicardium during the spread of excitation were also present during repolarization, with the appropriate polarity. To this end we determined the potential distribution on the ventricular surface of exposed dog hearts during ventricular excitation and repolarization. The ventricles were paced by means of epicardial or intramural electrodes. During the early stages of ventricular excitation following epicardial pacing we observed typical, previously described potential patterns, with negative, elliptical equipotential lines surrounding the pacing site, and two maxima aligned along the direction of subepicardial fibers. Intramural pacing gave rise to similar patterns. The axis joining the maxima, however, was oriented along the direction of intramural fibers. The repolarization potential pattern relating to epicardial excitation exhibited some features similar to those observed during the spread of excitation, namely the presence of families of elliptical equipotential lines around the pacing site, with pairs of potential extrema along the major or minor axes of the ellipses or both. The location of the extrema and the distribution of the epicardial potential gradients during repolarization suggested the presence of anisotropic current generators mainly oriented along the direction of deep myocardial fibers, with some contribution from more superficial sources which were oriented along the direction of subepicardial fibers. Deep stimulation elicited more complicated epicardial patterns whose interpretation is still obscure. We conclude that the electrical anisotropy of the heart affects the distribution of repolarization potentials and probably the strength of electrical generators during ventricular repolarization.

On the Raman threshold of passive large mode area fibers

NASA Astrophysics Data System (ADS)

Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas

2011-02-01

The output power of fiber optic laser systems has been exponentially increasing in the last years. However, non-linear effects, and in particular stimulated Raman scattering (SRS), are threatening to seriously limit the development pace in the near future. SRS can take place anywhere along the laser system, however it is actually the passive delivery fiber at the end of the system, the section where SRS is most likely to occur. The common way to combat this problem is to use the so-called Large Mode Area (LMA) fibers. However, these fibers are expensive and have a multimode nature that will either reduce the beam quality of the laser output or require a careful excitation of the fundamental mode. Furthermore, the larger the core area, the more complicated it will be to sustain single-mode operation. Therefore, it is becoming increasingly important to be able to determine which is the minimum core area required in the delivery fiber to avoid SRS. This calculation is usually carried out using the conventional formula for the Raman Threshold published by R.G. Smith in 1972: Pth =16Aeff gRLeff . In this work we demonstrate that this formula and the conclusions derived from it are inaccurate for short (several meters long) LMA fibers. For example, one widely spread belief (obtained from this expression) is that there is no dependence of the Raman intensity threshold (Ith=Pth/Aeff) on the mode area. However, our calculations show otherwise. Additionally, we have obtained an improved Raman threshold formula valid for short LMA fibers.

42 CFR 460.60 - PACE organizational structure.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 4 2011-10-01 2011-10-01 false PACE organizational structure. 460.60 Section 460.60 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES... ELDERLY (PACE) PACE Administrative Requirements § 460.60 PACE organizational structure. (a) A PACE...

Cognitive Constraints and Island Effects

PubMed Central

Hofmeister, Philip; Sag, Ivan A.

2012-01-01

Competence-based theories of island effects play a central role in generative grammar, yet the graded nature of many syntactic islands has never been properly accounted for. Categorical syntactic accounts of island effects have persisted in spite of a wealth of data suggesting that island effects are not categorical in nature and that non-structural manipulations that leave island structures intact can radically alter judgments of island violations. We argue here, building on work by Deane, Kluender, and others, that processing factors have the potential to account for this otherwise unexplained variation in acceptability judgments. We report the results of self-paced reading experiments and controlled acceptability studies which explore the relationship between processing costs and judgments of acceptability. In each of the three self-paced reading studies, the data indicate that the processing cost of different types of island violations can be significantly reduced to a degree comparable to that of non-island filler-gap constructions by manipulating a single non-structural factor. Moreover, this reduction in processing cost is accompanied by significant improvements in acceptability. This evidence favors the hypothesis that island-violating constructions involve numerous processing pressures that aggregate to drive processing difficulty above a threshold so that a perception of unacceptability ensues. We examine the implications of these findings for the grammar of filler-gap dependencies.* PMID:22661792

Preliminary findings on the safety of 1.5 and 3 Tesla magnetic resonance imaging in cardiac pacemaker patients.

PubMed

van Dijk, Vincent F; Delnoy, Peter Paul H M; Smit, Jaap Jan J; Ramdat Misier, R Anand; Elvan, Arif; van Es, H Wouter; Rensing, Benno J W M; Raciti, Giovanni; Boersma, Lucas V A

2017-07-01

Modern pacemakers are designed to allow patients to undergo magnetic resonance imaging (MRI) under a set of specific conditions. Aim of this study is to provide confirmatory evidence of safety and performance of a new pacing system (ImageReady™, Boston Scientific) in patients undergoing 1.5 and 3T MRI. Two prospective, nonrandomized, single-arm studies were designed to provide confirmatory data of no impact of MRI on device function, lead parameters, and patient conditions in subjects implanted with the system undergoing a clinically non-indicated 1.5T and 3T MRI, respectively. Device measurements were done within 1 hour before and after the scan and at 1 month follow-up. Thirty-two subjects underwent MRI visit (17 subjects with 1.5T MRI and 15 subjects with 3T MRI). There were no unanticipated adverse effects related to the pacemaker. Device measurements taken pre- and post-MRI scan did not show any clinical relevant change that could indicate an effect of the MRI on the device or at the lead-tissue interface (RV threshold change: 0.01 ± 0.13 V, P = 0.60; RA threshold change: 0.01 ± 0.11 V, P = 0.53; R wave change: -0.44 ± 1.73 mV, P = 0.36; R wave change: 0.12 ± 1.67 mV, P = 0.73), with data confirmed at 1-month follow-up visit. The study documented safety of the pacing system in the 1.5T and 3T MRI environment by showing no adverse events related to device or MRI scan. Additional data are required to cover the more complex scenarios involving different diagnostic needs, conditions of use, clinical conditions, and new emerging technologies. © 2017 Wiley Periodicals, Inc.

Maximizing the Prospects for Progress Against Cancer

Cancer.gov

The 2018 American Society of Clinical Oncology annual meeting featured numerous, potentially practice changing research findings, according to NCI Director Dr. Norman Sharpless. In this Cancer Currents post, Dr. Sharpless discusses the rapid pace of progress in cancer research.

Thresholds for activation of rabbit retinal ganglion cells with an ultrafine, extracellular microelectrode.

PubMed

Jensen, Ralph J; Rizzo, Joseph F; Ziv, Ofer R; Grumet, Andrew; Wyatt, John

2003-08-01

To determine electrical thresholds required for extracellular activation of retinal ganglion cells as part of a project to develop an epiretinal prosthesis. Retinal ganglion cells were recorded extracellularly in retinas isolated from adult New Zealand White rabbits. Electrical current pulses of 100- micro s duration were delivered to the inner surface of the retina from a 5- micro m long electrode. In about half of the cells, the point of lowest threshold was found by searching with anodal current pulses; in the other cells, cathodal current pulses were used. Threshold measurements were obtained near the cell bodies of 20 ganglion cells and near the axons of 19 ganglion cells. Both cathodal and anodal stimuli evoked a neural response in the ganglion cells that consisted of a single action potential of near-constant latency that persisted when retinal synaptic transmission was blocked with cadmium chloride. For cell bodies, but not axons, thresholds for both cathodal and anodal stimulation were dependent on the search method used to find the point of lowest threshold. With search and stimulation of matching polarity, cathodal stimuli evoked a ganglion cell response at lower currents (approximately one seventh to one tenth axonal threshold) than did anodal stimuli for both cell bodies and axons. With cathodal search and stimulation, cell body median thresholds were somewhat lower (approximately one half) than the axonal median thresholds. With anodal search and stimulation, cell body median thresholds were approximately the same as axonal median thresholds. The results suggest that cathodal stimulation should produce lower thresholds, more localized stimulation, and somewhat better selectivity for cell bodies over axons than would anodal stimulation.

Physiologic pacing: new modalities and pacing sites.

PubMed

Padeletti, Luigi; Lieberman, Randy; Valsecchi, Sergio; Hettrick, Douglas A

2006-12-01

Right ventricular (RV) apical pacing impairs left ventricular function by inducing dys-synchronous contraction and relaxation. Chronic RV apical pacing is associated with an increased risk of atrial fibrillation, morbidity, and even mortality. These observations have raised questions regarding the appropriate pacing mode and site, leading to the introduction of algorithms and new pacing modes to reduce the ventricular pacing burden in dual chamber devices, and a shift of the pacing site away from the RV apex. However, further investigations are required to assess the long-term results of pacing from alternative sites in the right ventricle, because long-term results so far are equivocal. The potential benefit of prophylactic biventricular, mono-chamber left ventricular, and bifocal RV pacing should be explored in selected patients with a narrow QRS complex, especially those with impaired left ventricular function. His bundle pacing is a promising and evolving technique that requires improvements in lead technology.

42 CFR 460.6 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Basis... enrolled in a PACE program. PACE stands for programs of all-inclusive care for the elderly. PACE center is... care for the elderly that is operated by an approved PACE organization and that provides comprehensive...

42 CFR 460.6 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Basis... enrolled in a PACE program. PACE stands for programs of all-inclusive care for the elderly. PACE center is... care for the elderly that is operated by an approved PACE organization and that provides comprehensive...

42 CFR 460.180 - Medicare payment to PACE organizations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 4 2010-10-01 2010-10-01 false Medicare payment to PACE organizations. 460.180... FOR THE ELDERLY (PACE) Payment § 460.180 Medicare payment to PACE organizations. (a) Principle of payment. Under a PACE program agreement, CMS makes a prospective monthly payment to the PACE organization...

Synchronization modulation of Na/K pumps on Xenopus oocytes

NASA Astrophysics Data System (ADS)

Liang, Pengfei; Mast, Jason; Chen, Wei

We developed a new technique named synchronization modulation to electrically synchronize and modulate the Na/K pump molecules by a specially designed oscillating electric field. This technique is based on the theory of energy-trap in quantum physics as well as the concept of electronic synchrotron accelerator. As a result, the Na-transports are all entrapped into the positive half-cycle of the applied electric field and consequently, all of the K-transports are entrapped into the negative half cycle of the field. To demonstrate the process of the pump synchronization and modulation, we use Xenopus oocytes as a platform and introduce two-electrode whole-cell voltage clamp in measurement of pump current. Practically, we first synchronize the pump molecules running at the same pace (rate and phase) by a specially designed oscillation electric field. Then, we carefully maintain the pump synchronization status and gradually change the field frequency (decrease and increase) to modulate the pump molecules to newer pumping rate. The result shows a separation of the inward K current from the outward Na current, and about 10 time increase of the total (inward plus outward) pump current from the net outward current from the random paced pump molecules. Also, the ratio of the modulated total pump current with synchronized total pump current is consistent with the ratio of their field frequencies.

The 800 Pound Gorilla: The Threat and Taming of Global Climate Change

ERIC Educational Resources Information Center

Hansen, Jim

2008-01-01

This article provides two case studies that examine the current and future consequences of continued global warming at the current business-as-usual pace and at a decreased (new alternative forms of energy) level. Cause and effect relationships, such as the varying levels of CO[subscript 2] (carbon dioxide) emissions and the effect it has on…

Line length dependence of threshold current density and driving force in eutectic SnPb and SnAgCu solder electromigration

NASA Astrophysics Data System (ADS)

Yoon, Min-Seung; Ko, Min-Ku; Kim, Bit-Na; Kim, Byung-Joon; Park, Yong-Bae; Joo, Young-Chang

2008-04-01

The relationship between the threshold current density and the critical line length in eutectic SnPb and SnAgCu electromigrations were examined using solder lines with the various lengths ranging from 100to1000μm. When the electron wind-force was balanced by the back-stress gradient force, the net flux of electromigration is zero, at which the current density and line length are defined as the threshold current density and the critical length, respectively. It was found that in SnAgCu electromigration, the 1/L dependence on the threshold current density showed good agreement, whereas the threshold current densities of the eutectic SnPb deviated from the 1/L dependence. The balance between the electron wind-force and the back-stress gradient force was the main factor determining the threshold product of SnAgCu electromigration. On the other hand, in the case of eutectic SnPb, the chemical driving force is contributed as a back-flux force in addition to the back-stress gradient force. The existence of the chemical driving force was caused by the nonequilibrium Pb concentration inside the Pb-rich phases between the cathode and anode during the electromigration procedure.

Protocol for diaphragm pacing in patients with respiratory muscle weakness due to motor neurone disease (DiPALS): a randomised controlled trial

PubMed Central

2012-01-01

Background Motor neurone disease (MND) is a devastating illness which leads to muscle weakness and death, usually within 2-3 years of symptom onset. Respiratory insufficiency is a common cause of morbidity, particularly in later stages of MND and respiratory complications are the leading cause of mortality in MND patients. Non Invasive Ventilation (NIV) is the current standard therapy to manage respiratory insufficiency. Some MND patients however do not tolerate NIV due to a number of issues including mask interface problems and claustrophobia. In those that do tolerate NIV, eventually respiratory muscle weakness will progress to a point at which intermittent/overnight NIV is ineffective. The NeuRx RA/4 Diaphragm Pacing System was originally developed for patients with respiratory insufficiency and diaphragm paralysis secondary to stable high spinal cord injuries. The DiPALS study will assess the effect of diaphragm pacing (DP) when used to treat patients with MND and respiratory insufficiency. Method/Design 108 patients will be recruited to the study at 5 sites in the UK. Patients will be randomised to either receive NIV (current standard care) or receive DP in addition to NIV. Study participants will be required to complete outcome measures at 5 follow up time points (2, 3, 6, 9 and 12 months) plus an additional surgery and 1 week post operative visit for those in the DP group. 12 patients (and their carers) from the DP group will also be asked to complete 2 qualitative interviews. Discussion The primary objective of this trial will be to evaluate the effect of Diaphragm Pacing (DP) on survival over the study duration in patients with MND with respiratory muscle weakness. The project is funded by the National Institute for Health Research, Health Technology Assessment (HTA) Programme (project number 09/55/33) and the Motor Neurone Disease Association and the Henry Smith Charity. Trial Registration: Current controlled trials ISRCTN53817913. The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the HTA programme, NIHR, NHS or the Department of Health. PMID:22897892

International Utilization at the Threshold of "Assembly Complete"- Science Returns from the International Space Station

NASA Technical Reports Server (NTRS)

Robinson, Julie A.

2009-01-01

The European Columbus and Japanese Kibo laboratories are now fully operational on the International Space Station (ISS), bringing decades of international planning to fruition. NASA is now completing launch and activation of major research facilities that will be housed in the Destiny U.S. Laboratory, Columbus, and Kibo. These facilities include major physical sciences capabilities for combustion, fluid physics, and materials science, as well as additional multipurpose and supporting infrastructure. Expansion of the laboratory space and expansion to a 6-person crew (planned for May 2009), is already leading to significant increases in research throughput even before assembly is completed. International research on the ISS includes exchanges of results, sharing of facilities, collaboration on experiments, and joint publication and communication of accomplishments. Significant and ongoing increases in research activity on ISS have occurred over the past year. Although research results lag behind on-orbit operations by 2-5 years, the surge of early research activities following Space Shuttle return to flight in 2005 is now producing an accompanying surge in scientific publications. Evidence of scientific productivity from early utilization opportunities combined with the current pace of research activity in orbit are both important parts of the evidence base for evaluating the potential future achievements of a complete and active ISS.

Direct His bundle pacing post AVN ablation.

PubMed

Lakshmanadoss, Umashankar; Aggarwal, Ashim; Huang, David T; Daubert, James P; Shah, Abrar

2009-08-01

Atrioventricular nodal (AVN) ablation with concomitant pacemaker implantation is one of the strategies that reduce symptoms in patients with atrial fibrillation (AF). However, the long-term adverse effects of right ventricular (RV) apical pacing have led to the search for alternating sites of pacing. Biventricular pacing produces a significant improvement in functional capacity over RV pacing in patients undergoing AVN ablation. Another alternative site for pacing is direct His bundle to reduce the adverse outcome of RV pacing. Here, we present a case of direct His bundle pacing using steerable lead delivery system in a patient with symptomatic paroxysmal AF with concurrent AVN ablation.

42 CFR 460.34 - Duration of PACE program agreement.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Program Agreement § 460.34 Duration of PACE program agreement. An agreement is...

42 CFR 460.34 - Duration of PACE program agreement.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Program Agreement § 460.34 Duration of PACE program agreement. An agreement is...

Spontaneous recombination current in InGaAs/GaAs quantum well lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blood, P.; Fletcher, E.D.; Woodbridge, K.

1990-10-08

We have studied the intrinsic factors which determine the threshold current and its temperature dependence in 160-A-wide In{sub 0.2}Ga{sub 0.8}As single well quantum lasers with GaAs barriers, grown by molecular beam epitaxy on GaAs substrates. By measuring the relative temperature dependence of the spontaneous emission intensity at threshold we show that radiative transitions between higher order ({ital n}=2,3) electron and heavy hole subbands make a significant contribution to the threshold current and its temperature sensitivity, even in devices where the laser transitions are between {ital n}=1 subbands. These higher transitions will also influence the dependence of threshold current and itsmore » temperature sensitivity on well width.« less

Canine left ventricle electromechanical behavior under different pacing modes.

PubMed

Vo Thang, Thanh-Thuy; Thibault, Bernard; Finnerty, Vincent; Pelletier-Galarneau, Matthieu; Khairy, Paul; Grégoire, Jean; Harel, François

2012-10-01

Cardiac resynchronization therapy may improve survival and quality of life in patients suffering from heart failure with left ventricular (LV) contraction dyssynchrony. While several studies have investigated electrical or mechanical determinants of synchronous contraction, few have focused on activation contraction coupling at a macroscopic level. The objective of the study was to characterize LV electromechanical behavior and response to pacing in a heart failure model. We analyzed data from 3D electroanatomic non-contact mapping and blood pool SPECT for 12 dogs with right ventricular (RV) tachycardia pacing-induced dilated cardiomyopathy. Surfaces generated by the two modalities were registered. Electrical signals were analyzed, and endocardial wall displacement curves were portrayed. Rapid pacing decreased the mean LV ejection fraction (LVEF) to 20.9 % and prolonged the QRS duration to 79 ± 10 ms (normal range: 40-50 ms). QRS duration remained unchanged with biventricular pacing (88.5 ms), while single site pacing further prolonged the QRS duration (113.3 ms for RV pacing and 111.6 ms for LV pacing). No trend was observed in LV systolic function. Activation duration time was significantly increased with all pacing modes compared to baseline. Finally, electromechanical delay, as defined by the delay between electrical activation and mechanical response, was increased by single site pacing (172.9 ms for RV pacing and 174.6 ms for LV pacing) but not by biventricular pacing (162.4 ms). Combined temporal and spatial coregistration electroanatomic maps and baseline gated blood pool SPECT imaging allowed us to quantify activation duration time, electromechanical delay, and LVEF for different pacing modes. Even if pacing modes did not significantly modify LVEF or activation duration, they produced alterations in electromechanical delay, with biventricular pacing significantly decreasing the electromechanical delay as measured by surface tracings and endocardial non-contact mapping.

Bachmann's Bundle Pacing not Only Improves Interatrial Conduction but Also Reduces the Need for Ventricular Pacing.

PubMed

Sławuta, Agnieszka; Kliś, Magdalena; Skoczyński, Przemysław; Bańkowski, Tomasz; Moszczyńska-Stulin, Joanna; Gajek, Jacek

2016-01-01

Patients treated for sick sinus syndrome may have interatrial conduction disorder leading to atrial fibrillation. This study was aimed to assess the influence of the atrial pacing site on interatrial and atrioventricular conduction as well as the percentage of ventricular pacing in patients with sick sinus syndrome implanted with atrioventricular pacemaker. The study population: 96 patients (58 females, 38 males) aged 74.1 ± 11.8 years were divided in two groups: Group 1 (n = 44) with right atrial appendage pacing and group 2 (n = 52) with Bachmann's area pacing. We assessed the differences in atrioventricular conduction in sinus rhythm and atrial 60 and 90 bpm pacing, P-wave duration and percentage of ventricular pacing. No differences in baseline P-wave duration in sinus rhythm between the groups (102.4 ± 17 ms vs. 104.1 ± 26 ms, p = ns.) were noted. Atrial pacing 60 bpm resulted in longer P-wave in group 1 vs. group 2 (138.3 ± 21 vs. 106.1 ± 15 ms, p < 0.01). The differences between atrioventricular conduction time during sinus rhythm and atrial pacing at 60 and 90 bpm were significantly longer in patients with right atrial appendage vs. Bachmann's pacing (44.1 ± 17 vs. 9.2 ± 7 ms p < 0.01 and 69.2 ± 31 vs. 21.4 ± 12 ms p < 0.05, respectively). The percentage of ventricular pacing was higher in group 1 (21 vs. 4%, p < 0.01). Bachmann's bundle pacing decreases interatrial and atrioventricular conduction delay. Moreover, the frequency-dependent atrioventricular conduction lengthening is much less pronounced during Bachmann's bundle pacing. Right atrial appendage pacing in sick sinus syndrome patients promotes a higher percentage of ventricular pacing.

42 CFR 460.32 - Content and terms of PACE program agreement.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Program Agreement § 460.32 Content and terms of PACE program agreement. (a...

42 CFR 460.90 - PACE benefits under Medicare and Medicaid.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Services § 460.90 PACE benefits under Medicare and Medicaid. If a Medicare...

Multi-Leu PACE4 Inhibitor Retention within Cells Is PACE4 Dependent and a Prerequisite for Antiproliferative Activity

PubMed Central

Ly, Kévin; Levesque, Christine; Kwiatkowska, Anna; Ait-Mohand, Samia; Desjardins, Roxane; Guérin, Brigitte; Day, Robert

2015-01-01

The overexpression as well as the critical implication of the proprotein convertase PACE4 in prostate cancer progression has been previously reported and supported the development of peptide inhibitors. The multi-Leu peptide, a PACE4-specific inhibitor, was further generated and its capability to be uptaken by tumor xenograft was demonstrated with regard to its PACE4 expression status. To investigate whether the uptake of this inhibitor was directly dependent of PACE4 levels, uptake and efflux from cancer cells were evaluated and correlations were established with PACE4 contents on both wild type and PACE4-knockdown cell lines. PACE4-knockdown associated growth deficiencies were established on the knockdown HepG2, Huh7, and HT1080 cells as well as the antiproliferative effects of the multi-Leu peptide supporting the growth capabilities of PACE4 in cancer cells. PMID:26114115

The heart and cardiac pacing in Steinert disease.

PubMed

Nigro, Gerardo; Papa, Andrea Antonio; Politano, Luisa

2012-10-01

Myotonic dystrophy (Dystrophia Myotonica, DM) is the most frequently inherited neuromuscular disease of adult life. It is a multisystemic disease with major cardiac involvement. Core features of myotonic dystrophy are myotonia, muscle weakness, cataract, respiratory failure and cardiac conduction abnormalities. Classical DM, first described by Steinert and called Steinert's disease or DM1 (Dystrophia Myotonica type 1) has been identified as an autosomal dominant disorder associated with the presence of an abnormal expansion of a CTG trinucleotide repeat in the 3' untranslated region of DMPK gene on chromosome 19. This review will mainly focus on the various aspects of cardiac involvement in DM1 patients and the current role of cardiac pacing in their treatment.

Influence of automatic frequent pace-timing adjustments on effective left ventricular pacing during cardiac resynchronization therapy.

PubMed

Varma, Niraj; Stadler, Robert W; Ghosh, Subham; Kloppe, Axel

2017-05-01

Cardiac resynchronization therapy (CRT) requires effective left ventricular (LV) pacing (i.e. sufficient energy and appropriate timing to capture). The AdaptivCRT™ (aCRT) algorithm serves to maintain ventricular fusion during LV or biventricular pacing. This function was tested by comparing the morphological consistency of ventricular depolarizations and percentage effective LV pacing in CRT patients randomized to aCRT vs. echo-optimization. Continuous recordings (≥20 h) of unipolar LV electrograms from aCRT (n = 38) and echo-optimized patients (n = 22) were analysed. Morphological consistency was determined by the correlation coefficient between each beat and a template beat. Effective LV pacing of paced beats was assessed by algorithmic analysis of negative initial EGM deflection in each evoked response. The %CRT pacing delivered, %effective LV pacing (i.e. % of paced beats with effective LV pacing), and overall %effective CRT (i.e. product of %CRT pacing and %effective LV pacing) were compared between aCRT and echo-optimized patients. Demographics were similar between groups. The mean correlation coefficient between individual beats and template was greater for aCRT (0.96 ± 0.03 vs. 0.91 ± 0.13, P = 0.07). Although %CRT pacing was similar for aCRT and echo-optimized (median 97.4 vs. 98.6%, P = 0.14), %effective LV pacing was larger for aCRT [99.6%, (99.1%, 99.9%) vs. 94.3%, (24.3%, 99.8%), P=0.03]. For aCRT vs. echo-optimized groups, the proportions of patients with ≥90% effective LV pacing was 92 vs. 55% (P = 0.002), and with ≥90% effective CRT was 79 vs. 45%, respectively (P = 0.018). AdaptivCRT™ significantly increased effective LV pacing over echo-optimized CRT. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Japanese Flagship Universities at a Crossroads

ERIC Educational Resources Information Center

Yonezawa, Akiyoshi

2007-01-01

The increasing pace and scope of global structural change has left Japanese flagship universities at a crossroads. Reflecting upon historical trends, current policy changes and respective institutional strategies for global marketing among Japanese top research universities, the author discusses possible future directions for these institutions…

Changes in 42K efflux produced by alterations in transmembrane calcium movements in turtle cardiac pace-maker tissue.

PubMed Central

Fleming, B P; Giles, W

1981-01-01

1. 42K efflux has been measured from small strips of turtle sinus venosus which were electrically paced. Three different procedures for altering transmembrane calcium influx have been utilized to test whether changes in 42K efflux may be modulated by changes in intracellular calcium levels. 2. No significant changes in the 42K fractional escape rate (FER) were observed when external calcium was reduced to O mM or increased to 4 x normal (10 mM). In these experiments extracellular divalent cation concentration was held constant by adding or removing magnesium ions. 3. Application of 10 mM-Ba2+ also failed to alter 42K FER consistently. In red blood cells and snail neurones addition of barium ions has been shown to reduce significantly the calcium-mediated potassium current. 4. A tenfold increase in pacing rate (0.5-5 Hz) resulted in an augmented 42K FER, but repetition of this rate change in O mM-Ca2+ indicated that this increase in 42K FER was not strongly dependent on the amount of calcium entry. 5. Attempts to load the pace-maker cells with calcium by using the ionophore A23187 (10 micrograms ml . -1 of 2.0 x 10(-5) M) consistently resulted in very large increases in 42K FER. However, this effect (i) was blocked by atropine and (ii) was markedly reduced by pretreating the tissues with hemicholinium, indicating that A23187-induced release of acetylcholine from the endogenous nerve terminals was responsible for the observed increase in 42K FER. 6. In summary, three different experimental tests indicate that the majority of the 42K efflux is not tightly linked to transmembrane calcium movement in sinus venosus pace-maker tissue. PMID:6796675

Stimulus rate increases lateralisation in linguistic and non-linguistic tasks measured by functional transcranial Doppler sonography

PubMed Central

Payne, Heather; Gutierrez-Sigut, Eva; Subik, Joanna; Woll, Bencie; MacSweeney, Mairéad

2016-01-01

Studies to date that have used fTCD to examine language lateralisation have predominantly used word or sentence generation tasks. Here we sought to further assess the sensitivity of fTCD to language lateralisation by using a metalinguistic task which does not involve novel speech generation: rhyme judgement in response to written words. Line array judgement was included as a non-linguistic visuospatial task to examine the relative strength of left and right hemisphere lateralisation within the same individuals when output requirements of the tasks are matched. These externally paced tasks allowed us to manipulate the number of stimuli presented to participants and thus assess the influence of pace on the strength of lateralisation. In Experiment 1, 28 right-handed adults participated in rhyme and line array judgement tasks and showed reliable left and right lateralisation at the group level for each task, respectively. In Experiment 2 we increased the pace of the tasks, presenting more stimuli per trial. We measured laterality indices (LIs) from 18 participants who performed both linguistic and non-linguistic judgement tasks during the original ‘slow’ presentation rate (5 judgements per trial) and a fast presentation rate (10 judgements per trial). The increase in pace led to increased strength of lateralisation in both the rhyme and line conditions. Our results demonstrate for the first time that fTCD is sensitive to the left lateralised processes involved in metalinguistic judgements. Our data also suggest that changes in the strength of language lateralisation, as measured by fTCD, are not driven by articulatory demands alone. The current results suggest that at least one aspect of task difficulty, the pace of stimulus presentation, influences the strength of lateralisation during both linguistic and non-linguistic tasks. PMID:25908491

The immediate effects of lidocaine iontophoresis using interferential current on pressure sense threshold and tactile sensation.

PubMed

Yoosefinejad, Amin Kordi; Motealleh, Alireza; Abbasnia, Keramatollah

2016-01-01

Iontophoresis is the noninvasive delivery of ions using direct current. The direct current has some disadvantages such as skin burning. Interferential current is a kind of alternating current without limitations of direct current; so the purpose of this study is to investigate and compare the effects of lidocaine, interferential current and lidocaine iontophoresis using interferential current. 30 healthy women aged 20-24 years participated in this randomized clinical trial study. Pressure, tactile and pain thresholds were evaluated before and after the application of treatment methods. Pressure, tactile and pain sensitivity increased significantly after the application of lidocaine alone (p < 0.005) and lidocaine iontophoresis using interferential current (p < 0.0001). Lidocaine iontophoresis using interferential current can increase perception threshold of pain, tactile stimulus and pressure sense more significantly than lidocaine and interferential current alone.

Synthesis of polymer nanostructures with conductance switching properties

DOEpatents

Su, Kai; Nuraje, Nurxat; Zhang, Lingzhi; Matsui, Hiroshi; Yang, Nan Loh

2015-03-03

The present invention is directed to crystalline organic polymer nanoparticles comprising a conductive organic polymer; wherein the crystalline organic polymer nanoparticles have a size of from 10 nm to 200 nm and exhibits two current-voltage states: (1) a high resistance current-voltage state, and (2) a low resistance current-voltage state, wherein when a first positive threshold voltage (V.sub.th1) or higher positive voltage, or a second negative threshold voltage (V.sub.th2) or higher negative voltage is applied to the nanoparticle, the nanoparticle exhibits the low-resistance current-voltage state, and when a voltage less positive than the first positive threshold voltage or a voltage less negative than the second negative threshold voltage is applied to the nanoparticle, the nanoparticle exhibits the high-resistance current-voltage state. The present invention is also directed methods of manufacturing the nanoparticles using novel interfacial oxidative polymerization techniques.

Investigating the effect of freeway congestion thresholds on decision-making inputs.

DOT National Transportation Integrated Search

2010-05-01

Congestion threshold is embedded in the congestion definition. Two basic approaches exist in : current practice for setting the congestion threshold. One common approach uses the free-flow or : unimpeded conditions as the congestion threshold. ...

Influence of Pacing by Periodic Auditory Stimuli on Movement Continuation: Comparison with Self-regulated Periodic Movement

PubMed Central

Ito, Masanori; Kado, Naoki; Suzuki, Toshiaki; Ando, Hiroshi

2013-01-01

[Purpose] The purpose of this study was to investigate the influence of external pacing with periodic auditory stimuli on the control of periodic movement. [Subjects and Methods] Eighteen healthy subjects performed self-paced, synchronization-continuation, and syncopation-continuation tapping. Inter-onset intervals were 1,000, 2,000 and 5,000 ms. The variability of inter-tap intervals was compared between the different pacing conditions and between self-paced tapping and each continuation phase. [Results] There were no significant differences in the mean and standard deviation of the inter-tap interval between pacing conditions. For the 1,000 and 5,000 ms tasks, there were significant differences in the mean inter-tap interval following auditory pacing compared with self-pacing. For the 2,000 ms syncopation condition and 5,000 ms task, there were significant differences from self-pacing in the standard deviation of the inter-tap interval following auditory pacing. [Conclusion] These results suggest that the accuracy of periodic movement with intervals of 1,000 and 5,000 ms can be improved by the use of auditory pacing. However, the consistency of periodic movement is mainly dependent on the inherent skill of the individual; thus, improvement of consistency based on pacing is unlikely. PMID:24259932

Indications for permanent pacing and pacing mode prescription from 1989 to 2006. Experience of a single academic centre in Northern Greece.

PubMed

Styliadis, Ioannis H; Mantziari, Aggeliki P; Gouzoumas, Nikolaos I; Vassilikos, Vasilios P; Paraskevaidis, Stelios A; Mochlas, Sotirios T; Boufidou, Amalia I; Parcharidis, Georgios E

2008-01-01

Indications for pacing and pacing mode prescription have changed in the past decades following advances in pacemaker technology. The aim of the present study was to evaluate changes in indications for pacing and pacing modes during the years 1989-2006 in a single academic pacemaker centre in Northern Greece. Archives of permanent pacemaker implantation procedures were studied retrospectively and data from all implants, first or replacements, were retrieved. Data from 2078 procedures were found, 78.7% of which were first implantations. Patients were 54% male with mean age 72.5 years. Main indications for pacing were atrioventricular block (AVB, 45.7%), sick sinus syndrome (SSS, 32.8%), and atrial fibrillation (12.1%). Almost half (48.9%) of the AVB cases were complete AVB, while the most common types of SSS were tachy-brady syndrome (44.1%) and asystole (27.1%). Rare indications for pacing were carotid sinus syndrome (5.0%), heart failure (3.3%) and hypertrophic obstructive cardiomyopathy (1.0%). The two most frequently used pacing modes were VVI (38.5%) and DDD (25.8%). However, pacing modes have changed greatly over the years, with a marked increase in dual-chamber pacing after 1997 and a preference for rate responsive units after 2002. Biventricular systems were also used in selected patients with heart failure from 2002 on. Indications for pacing and pacing mode prescription in our centre are similar to other pacemaker registries and reflect the global trend in pacing for mimicking the physiological activity of the heart and for addressing problems other than symptomatic bradycardia.

Axonal Dysfunction Precedes Motor Neuronal Death in Amyotrophic Lateral Sclerosis

PubMed Central

Iwai, Yuta; Shibuya, Kazumoto; Misawa, Sonoko; Sekiguchi, Yukari; Watanabe, Keisuke; Amino, Hiroshi; Kuwabara, Satoshi

2016-01-01

Wide-spread fasciculations are a characteristic feature in amyotrophic lateral sclerosis (ALS), suggesting motor axonal hyperexcitability. Previous excitability studies have shown increased nodal persistent sodium conductances and decreased potassium currents in motor axons of ALS patients, both of the changes inducing hyperexcitability. Altered axonal excitability potentially contributes to motor neuron death in ALS, but the relationship of the extent of motor neuronal death and abnormal excitability has not been fully elucidated. We performed multiple nerve excitability measurements in the median nerve at the wrist of 140 ALS patients and analyzed the relationship of compound muscle action potential (CMAP) amplitude (index of motor neuronal loss) and excitability indices, such as strength-duration time constant, threshold electrotonus, recovery cycle and current-threshold relationships. Compared to age-matched normal controls (n = 44), ALS patients (n = 140) had longer strength-duration time constant (SDTC: a measure of nodal persistent sodium current; p < 0.05), greater threshold changes in depolarizing threshold electrotonus (p < 0.05) and depolarizing current threshold relationship (i.e. less accommodation; (p < 0.05), greater superexcitability (a measure of fast potassium current; p < 0.05) and reduced late subexcitability (a measure of slow potassium current; p < 0.05), suggesting increased persistent sodium currents and decreased potassium currents. The reduced potassium currents were found even in the patient subgroups with normal CMAP (> 5mV). Regression analyses showed that SDTC (R = -0.22) and depolarizing threshold electrotonus (R = -0.22) increased with CMAP decline. These findings suggest that motor nerve hyperexcitability occurs in the early stage of the disease, and precedes motor neuronal loss in ALS. Modulation of altered ion channel function could be a treatment option for ALS. PMID:27383069

Functional characteristics of left ventricular synchronization via right ventricular outflow-tract pacing detected by two-dimensional strain echocardiography.

PubMed

Hirayama, Yasutaka; Kawamura, Yuichiro; Sato, Nobuyuki; Saito, Tatsuya; Tanaka, Hideichi; Saijo, Yasuaki; Kikuchi, Kenjiro; Ohori, Katsumi; Hasebe, Naoyuki

2017-02-01

Recently, due to the detrimental effects on the ventricular function associated with right ventricular apical (RVA) pacing, right ventricular septal (RVS) pacing has become the preferred pacing method. However, the term RVS pacing refers to both right ventricular outflow-tract (RVOT) and mid-septal (RVMS) pacing, leading to a misinterpretation of the results of clinical studies. The purpose of this study, therefore, was to elucidate the functional differences of RVA, RVOT, and RVMS pacing in patients with atrioventricular block. We compared the QRS duration, global longitudinal strain (GLS), and left ventricular (LV) synchronization parameters at the three pacing sites in 47 patients. The peak systolic strain (PSS) time delay between the earliest and latest segments among the 18 LV segments and standard deviation (SD) of the time to the PSS were also calculated for the 18 LV segments at each pacing site using two-dimensional (2D) strain echocardiography. RVMS pacing was associated with a significantly shorter QRS duration compared with RVA and RVOT pacing (154.4±21.4 vs 186.5±19.9 and 171.1±21.5 ms, P <0.001). In contrast, RVOT pacing revealed a greater GLS (-14.69±4.92 vs -13.12±4.76 and -13.51±4.81%, P <0.001), shorter PSS time delay between the earliest and latest segments (236.0±87.9 vs 271.3±102.9 and 281.9±126.6%, P =0.007), and shorter SD of the time to the PSS (70.8±23.8 vs 82.7±30.8 and 81.5±33.7 ms, P =0.002) compared with RVA and RVMS pacing. These results suggest that the functional characteristics of RVOT pacing may be a more optimal pacing site than RVMS, regardless of the pacing QRS duration, in patients with atrioventricular conduction disorders.

Assessing parental empathy: a role for empathy in child attachment.

PubMed

Stern, Jessica A; Borelli, Jessica L; Smiley, Patricia A

2015-01-01

Although empathy has been associated with helping behavior and relationship quality, little research has evaluated the role of parental empathy in the development of parent-child relationships. The current study (1) establishes preliminary validity of the Parental Affective and Cognitive Empathy Scale (PACES), a method for coding empathy from parents' narrative responses to the Parent Development Interview - Revised for School-Aged Children (PDI-R-SC), and (2) tests a theoretical model of empathy and attachment. Sixty caregivers and their children completed a battery of questionnaire and interview measures, including the PDI-R-SC and the Child Attachment Interview (CAI). Caregivers' interview narratives were scored for empathy using PACES. PACES showed good interrater reliability and good convergent validity with a self-report empathy measure. Parent empathy was positively related to child attachment security (using a continuous score for narrative coherence) and emotional openness on the CAI, as well as to child perceptions of parental warmth. Moreover, parent empathy mediated the relation between parents' self-reported attachment style and their children's attachment security. Implications for attachment theory and future directions for establishing scale validity are discussed.

Dependence of threshold current on the number of wells in AlGaAs-GaAs quantum well lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blood, P.; Fletcher, E.D.; Woodbridge, K.

1985-08-01

GaAs-AlGaAs multiple quantum well injection lasers have been grown by molecular beam epitaxy with different numbers (N) of uncoupled GaAs wells 25 A wide symmetrically disposed about the center of a 4000-A-wide waveguide. The devices emit at about 770 nm and for N = 4 the broad area threshold current density is 1.1 kA cm/sup -2/. The threshold current increases with increasing N (2

Weigh stations' capacity enhancement alternatives : a comparison of mainline electronic screening and physical expansion

DOT National Transportation Integrated Search

1998-08-19

A number of weigh stations are unable to keep pace with current truck traffic levels. In response, state enforcement agencies are compelled to seek capacity enhancements for the weigh stations. One response is to increase physical capacity by adding ...

A Data Envelopment Analysis Approach to Prioritize Renewable Energy Technologies

USDA-ARS?s Scientific Manuscript database

Due to growing financial and environmental concerns, governmental rules, regulations and incentives alternative energy sources will soon grow at a much faster pace than conventional sources of energy. However, the current body of research providing comparative decision making models that either rank...

Modifying Ventricular Fibrillation by Targeted Rotor Substrate Ablation: Proof-of-Concept from Experimental Studies to Clinical VF

PubMed Central

KRUMMEN, DAVID E.; HAYASE, JUSTIN; VAMPOLA, STEPHEN P.; HO, GORDON; SCHRICKER, AMIR A.; LALANI, GAUTAM G.; BAYKANER, TINA; COE, TAYLOR M.; CLOPTON, PAUL; RAPPEL, WOUTER-JAN; OMENS, JEFFREY H.; NARAYAN, SANJIV M.

2016-01-01

Introduction Recent work has suggested a role for organized sources in sustaining ventricular fibrillation (VF). We assessed whether ablation of rotor substrate could modulate VF inducibility in canines, and used this proof-of-concept as a foundation to suppress antiarrhythmic drug-refractory clinical VF in a patient with structural heart disease. Methods and Results In 9 dogs, we introduced 64-electrode basket catheters into one or both ventricles, used rapid pacing at a recorded induction threshold to initiate VF, and then defibrillated after 18±8 seconds. Endocardial rotor sites were identified from basket recordings using phase mapping, and ablation was performed at nonrotor (sham) locations (7 ± 2 minutes) and then at rotor sites (8 ± 2 minutes, P = 0.10 vs. sham); the induction threshold was remeasured after each. Sham ablation did not alter canine VF induction threshold (preablation 150 ± 16 milliseconds, postablation 144 ± 16 milliseconds, P = 0.54). However, rotor site ablation rendered VF noninducible in 6/9 animals (P = 0.041), and increased VF induction threshold in the remaining 3. Clinical proof-of-concept was performed in a patient with repetitive ICD shocks due to VF refractory to antiarrhythmic drugs. Following biventricular basket insertion, VF was induced and then defibrillated. Mapping identified 4 rotors localized at borderzone tissue, and rotor site ablation (6.3 ± 1.5 minutes/site) rendered VF noninducible. The VF burden fell from 7 ICD shocks in 8 months preablation to zero ICD therapies at 1 year, without antiarrhythmic medications. Conclusions Targeted rotor substrate ablation suppressed VF in an experimental model and a patient with refractory VF. Further studies are warranted on the efficacy of VF source modulation. PMID:26179310

A comparative analysis of the effectiveness of active versus passive atrial lead fixation in Chinese patients with cardiac implantable electrical devices: a long term, retrospective, observational, single-center study.

PubMed

Hao, Yinglu; Li, Yanping; Liao, Derong; Yang, Ling; Liu, Fangyan

2017-03-01

Data comparing active atrial lead fixation with passive atrial lead fixation in Chinese patients with cardiovascular implantable electronic devices (CIEDs) for atrial pacing is limited. Our study evaluated the effectiveness of active fixation versus passive fixation of atrial leads by observing the lead performance parameters. This retrospective, long-term, single-center study included a cohort of Chinese patients who underwent CIED implantation at the Department of Cardiology of People's Hospital of Yuxi City, China, from 1 March 2010 to 1 March 2015. Efficacy was determined by comparing implantation time, threshold values, incidence of lead dislocation/failure, and lead-related complications between the two groups. Of the 1217 patients, active and passive atrial lead fixation were performed in 530 (mean age, 69.37 ± 11.44 years) and 497 (mean age, 68.33 ± 10.96 years). The active fixation group reported significantly lower mean atrial implantation times (P = .0001) and threshold values (P = .044) compared with the passive atrial lead fixation group. In addition, threshold values in the active atrial lead fixation group were stable throughout the observation period. No instances of myocardial perforation, cardiac tamponade, implantation failure, or electrode dislocation/re-fixation were reported in the active atrial lead fixation group. A favorable decrease in patient comfort parameters such as bed rest time (P = .027) and duration of hospital stay (P = .038) were also observed in the active lead fixation group. Active atrial lead fixation demonstrated greater stability, steady long-term thresholds and minimal lead-related complications compared to passive lead fixation in Chinese patients with CIEDs.

Right versus left atrial pacing in patients with sick sinus syndrome and paroxysmal atrial fibrillation (Riverleft study): study protocol for randomized controlled trial.

PubMed

Ramdjan, Tanwier T T K; van der Does, Lisette J M E; Knops, Paul; Res, Jan C J; de Groot, Natasja M S

2014-11-17

The incidence of sick sinus syndrome will increase due to population ageing. Consequently, this will result in an increase in the number of pacemaker implantations. The atrial lead is usually implanted in the right atrial appendage, but this position may be ineffective for prevention of atrial fibrillation. It has been suggested that pacing distally in the coronary sinus might be more successful in preventing atrial fibrillation episodes. The aim of this trial is to study the efficacy of distal coronary sinus versus right atrial appendage pacing in preventing atrial fibrillation episodes in patients with sick sinus syndrome. This study is designed as a multicenter, randomized controlled trial. Patients with sick sinus syndrome and at least one atrial fibrillation episode of 30 seconds or more in the six months before recruitment will be eligible for participation in this study.All participants will be randomized between pacing distally in the coronary sinus and right atrial appendage. Randomization is stratified for all participating centers. Conventional dual-chamber pacemakers with advanced home monitoring functionality will be implanted. The ventricular lead will be implanted in the right ventricular apex. The first three months of the 36-month follow-up period are considered as run-in time. During the pre-randomization visit and follow-up, an interview, electrocardiogram and pacemaker assessment will be performed, prescribed antiarrhythmic medication will be reviewed and patients will be asked to complete an SF-36 questionnaire. An echocardiographic examination will be conducted in the pre-randomization phase and at the end of each follow-up year. Home monitoring will be used to send daily reports in case of atrial fibrillation episodes. This randomized controlled trial is the first in which home monitoring will be used to compare atrial fibrillation recurrences between pacing in the distal coronary sinus or right atrial appendage. Home monitoring gives the opportunity to accurately detect atrial fibrillation episodes and to study characteristics of atrial fibrillation episodes. Should distal coronary sinus pacing significantly diminish atrial fibrillation recurrences, this study will redefine the preferential location of an atrial lead for preventive pacing. Current Controlled Trials ISRCTN65911661, registered on 8 July 2013.

Exposure of U.S. National Parks to land use and climate change 1900-2100.

PubMed

Hansen, Andrew J; Piekielek, Nathan; Davis, Cory; Haas, Jessica; Theobald, David M; Gross, John E; Monahan, William B; Olliff, Tom; Running, Steven W

2014-04-01

Many protected areas may not be adequately safeguarding biodiversity from human activities on surrounding lands and global change. The magnitude of such change agents and the sensitivity of ecosystems to these agents vary among protected areas. Thus, there is a need to assess vulnerability across networks of protected areas to determine those most at risk and to lay the basis for developing effective adaptation strategies. We conducted an assessment of exposure of U.S. National Parks to climate and land use change and consequences for vegetation communities. We first defined park protected-area centered ecosystems (PACEs) based on ecological principles. We then drew on existing land use, invasive species, climate, and biome data sets and models to quantify exposure of PACEs from 1900 through 2100. Most PACEs experienced substantial change over the 20th century (> 740% average increase in housing density since 1940, 13% of vascular plants are presently nonnative, temperature increase of 1 degree C/100 yr since 1895 in 80% of PACEs), and projections suggest that many of these trends will continue at similar or increasingly greater rates (255% increase in housing density by 2100, temperature increase of 2.5 degrees-4.5 degrees C/100 yr, 30% of PACE areas may lose their current biomes by 2030). In the coming century, housing densities are projected to increase in PACEs at about 82% of the rate of since 1940. The rate of climate warming in the coming century is projected to be 2.5-5.8 times higher than that measured in the past century. Underlying these averages, exposure of individual park PACEs to change agents differ in important ways. For example, parks such as Great Smoky Mountains exhibit high land use and low climate exposure, others such as Great Sand Dunes exhibit low land use and high climate exposure, and a few such as Point Reyes exhibit high exposure on both axes. The cumulative and synergistic effects of such changes in land use, invasives, and climate are expected to dramatically impact ecosystem function and biodiversity in national parks. These results are foundational to developing effective adaptation strategies and suggest policies to better safeguard parks under broad-scale environmental change.

Electrophysiological performance of a bipolar membrane-coated titanium nitride electrode: a randomized comparison of steroid and nonsteroid lead designs.

PubMed

Wiegand, U K; Zhdanov, A; Stammwitz, E; Crozier, I; Claessens, R J; Meier, J; Bos, R J; Bode, F; Potratz, J

1999-06-01

The aim of this multicenter study was to investigate the performance of a new cardiac pacemaker lead with a titanium nitride cathode coated with a copolymer membrane. In particular, the electrophysiological effect of steroid dissolved in this ion-exchange membrane was evaluated by randomized comparison. Ninety-five patients were randomized either to the 1450 T (n = 51) or the 1451 T ventricular lead (n = 45) and received telemeteral VVI(R) pacemakers with identical diagnostic features. Both leads were bipolar, were passively affixed, and had a porous titanium nitride tip with a surface area of 3.5 mm2. The only difference between the two electrodes was 13 micrograms of dexamethasone added to the 1450 Ts membrane coating. Voltage thresholds (VTH) at pulse durations of 0.25, 0.37, and 0.5 ms, lead impedance, and sensing thresholds were measured at discharge, 2 weeks, 1 month, 3 months, and 6 months after implantation. Mean amplitude and the slew rate from three telemetered intracardiac electrograms, chronaxie-rheobase product, and minimum energy consumption were calculated. After a 6-month follow-up, mean voltage thresholds of 0.65 +/- 0.20 V and 0.63 +/- 0.34 were achieved for the 1450 T lead and 1451 T lead, respectively. As a result, a VTH < 1.0 V was obtained in all patients with 1450 T electrodes and in 97.7% of patients with 1451 T leads after 6 months follow-up. In both electrodes, stable VTH was reached 2 weeks after implantation, and no transient rise in threshold was observed. No differences were observed between the steroid and the nonsteroid group in respect to VTH, chronaxie-rheobase product, minimum energy consumption, and potential amplitude and slew rate. In conclusion, safe and efficient pacing at low pulse amplitudes were achieved with both leads. The tip design, independently of the steroid additive, prevented any energy-consuming increases in the voltage threshold.

Effect of laryngotracheal topical anesthesia on recurrent laryngeal nerve monitoring during thyroid Surgery.

PubMed

Pachuski, Justin; Vaida, Sonia; Donahue, Kathleen; Roberts, John; Kunselman, Allen; Oberman, Benjamin; Patel, Hetal; Goldenberg, David

2016-03-01

Intraoperative neuromonitoring of the recurrent laryngeal nerve (RLN) is often used as an adjunct for RLN identification and preservation during thyroidectomies. Laryngotracheal anesthesia (LTA) with topical lidocaine reduces coughing upon emergence from anesthesia and in the immediate postoperative period; however, its use is prohibited with concerns that it could decrease the sensitivity of the intraoperative neuromonitoring. We hypothesize that there is no difference in measurements of nerve conduction made before and after LTA administration. An observational study in which all patients were subjected to LTA administration was conducted. Recurrent laryngeal nerve threshold currents were measured before and after the intervention. Tertiary medical center operating room. Eighteen patients (total of 25 nerves at risk) with American Society of Anesthesiologists classes 1 to 3 undergoing thyroid surgery. After the thyroid was removed and threshold currents at the RLN were obtained, LTA with endotracheal lidocaine was applied on the left and right side of the in situ endotracheal tube (2 cc of 4% lidocaine per side). Threshold currents were reassessed at 5 and 10 minutes after LTA administration. Threshold currents (minimum stimulus current applied to the RLN required to generate a discernible electromyographic response at the vocal cords) were recorded along the RLN for a baseline at 5 and 10 mm from the insertion point of the RLN into the larynx. Threshold currents were reassessed at the same 2 positions on the RLN at 5 and 10 minutes after LTA administration. Differences in mean values, between threshold currents recorded at the 3 different times, at 2 positions on the RLN, were used to compare effects of LTA on nerve conduction. There were no statistically significant differences when comparing threshold currents before and after LTA administration. Laryngotracheal anesthesia had no significant effect on RLN nerve conduction in the period assessed. Copyright © 2016 Elsevier Inc. All rights reserved.

[Role of cyclic adenosine monophosphate response element binding protein in ventricular pacing induced cardiac electrical remodeling in a canine model].

PubMed

Chen, Xuesi; Chen, Xingxing; Cheng, Junhua; Hong, Jun; Zheng, Cheng; Zhao, Jinglin; Li, Jin; Lin, Jiafeng

2015-04-01

This project is designed to explore the potential role of cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) in cardiac electrical remodeling induced by pacing at different ventricular positions in dogs. An animal model by implanting the pacemakers in beagles was established. According to the different pacing positions, the animals were divided into 4 groups:conditional control group (n=6), left ventricle pacing group (n=6), right ventricle pacing group (n=6) and bi-ventricle pacing group (n=6). Cardiac and electrical remodeling were observed by echocardiography, electrocardiogram and plasma BNP. Myocardial pathology and protein expression of extracellular regulated protein kinases1/2 (ERK1/2), P38 mitogen activated protein kinases (P38 MAPK) and CREB were examined at 4 weeks post pacing. Cardiac structure and plasma BNP level were similar among 4 groups (all P>0.05). Electrocardiogram derived Tp-Te interval was significantly prolonged post pacing (92±11, 91±10, and 79±13 ms vs. 60±12 ms), and the Tp-Te interval in bi-ventricle pacing group was shorter than in left or right ventricle pacing group (P < 0.05). Western blot results showed that the expression of p-ERK1/2 in left ventricular myocardium of left ventricle pacing group, right ventricular myocardium of right ventricle pacing group and bi-ventricular myocardium of bi-ventricle pacing group was 2.7±0.4, 2.4±0.2, 1.7±0.1 and 1.9±0.2, respectively, the expression of p-P38 MAPK was 1.9±0.3, 1.7±0.2, 0.8±0.1 and 1.1±0.1, respectively, and the expression of p-CREB was 2.1±0.2, 2.0±0.2, 2.7±0.4 and 2.6±0.3, respectively. The p-ERK1/2 and p-P38 MAPK expression of bi-ventricle pacing group was lower,but the p-CREB expression was higher compared to the other pacing groups (P < 0.05). Ventricular pacing could induce electrical remodeling evidenced by prolonged Tp-Te interval and increased phosphorylation of ERK1/2 and p38 MAPK and reduced phosphorylation of CREB. Compared with single ventricle pacing, bi-ventricle pacing could attenuate electrical remodeling in this model.

Altering Pace Control and Pace Regulation: Attentional Focus Effects during Running.

PubMed

Brick, Noel E; Campbell, Mark J; Metcalfe, Richard S; Mair, Jacqueline L; Macintyre, Tadhg E

2016-05-01

To date, there are no published studies directly comparing self-controlled (SC) and externally controlled (EC) pace endurance tasks. However, previous research suggests pace control may impact on cognitive strategy use and effort perceptions. The primary aim of this study was to investigate the effects of manipulating perception of pace control on attentional focus, physiological, and psychological outcomes during running. The secondary aim was to determine the reproducibility of self-paced running performance when regulated by effort perceptions. Twenty experienced endurance runners completed four 3-km time trials on a treadmill. Subjects completed two SC pace trials, one perceived exertion clamped (PE) trial, and one EC pace time trial. PE and EC were completed in a counterbalanced order. Pacing strategy for EC and perceived exertion instructions for PE replicated the subjects' fastest SC time trial. Subjects reported a greater focus on cognitive strategies such as relaxing and optimizing running action during EC than during SC. The mean HR was 2% lower during EC than that during SC despite an identical pacing strategy. Perceived exertion did not differ between the three conditions. However, increased internal sensory monitoring coincided with elevated effort perceptions in some subjects during EC and a 10% slower completion time for PE (13.0 ± 1.6 min) than that for SC (11.8 ± 1.2 min). Altering pace control and pace regulation impacted on attentional focus. External control over pacing may facilitate performance, particularly when runners engage attentional strategies conducive to improved running efficiency. However, regulating pace based on effort perceptions alone may result in excessive monitoring of bodily sensations and a slower running speed. Accordingly, attentional focus interventions may prove beneficial for some athletes to adopt task-appropriate attentional strategies to optimize performance.

Accelerated graft dysfunction in heart transplant patients with persistent atrioventricular conduction block.

PubMed

Lee, William; Tay, Andre; Walker, Bruce D; Kuchar, Dennis L; Hayward, Christopher S; Spratt, Phillip; Subbiah, Rajesh N

2016-12-01

Bradyarrhythmia following heart transplantation is common-∼7.5-24% of patients require permanent pacemaker (PPM) implantation. While overall mortality is similar to their non-paced counterparts, the effects of chronic right ventricular pacing (CRVP) in heart transplant patients have not been studied. We aim to examine the effects of CRVP on heart failure and mortality in heart transplant patients. Records of heart transplant recipients requiring PPM at St Vincent's Hospital, Sydney, Australia between January 1990 and January 2015 were examined. Patient's without a right ventricular (RV) pacing lead or a follow-up time of <1 year were excluded. Patients with pre-existing abnormal left ventricular function (<50%) were analysed separately. Patients were grouped by pacing dependence (100% pacing dependent vs. non-pacing dependent). The primary endpoint was clinical or echocardiographic heart failure (<35%) in the first 5 years post-PPM. Thirty-three of 709 heart transplant recipients were studied. Two patients had complete RV pacing dependence, and the remaining 31 patients had varying degrees of pacing requirement, with an underlying ventricular escape rhythm. The primary endpoint occurred significantly more in the pacing-dependent group; 2 (100%) compared with 2 (6%) of the non pacing dependent group (P < 0.0001 by log-rank analysis, HR = 24.58). Non-pacing-dependent patients had reversible causes for heart failure, unrelated to pacing. In comparison, there was no other cause of heart failure in the pacing-dependent group. Permanent atrioventricular block is rare in the heart transplant population. We have demonstrated CRVP as a potential cause of accelerated graft failure in pacing-dependent heart transplant patients. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Prospective randomized study to assess the efficacy of site and rate of atrial pacing on long-term progression of atrial fibrillation in sick sinus syndrome: Septal Pacing for Atrial Fibrillation Suppression Evaluation (SAFE) Study.

PubMed

Lau, Chu-Pak; Tachapong, Ngarmukos; Wang, Chun-Chieh; Wang, Jing-Feng; Abe, Haruhiko; Kong, Chi-Woon; Liew, Reginald; Shin, Dong-Gu; Padeletti, Luigi; Kim, You-Ho; Omar, Razali; Jirarojanakorn, Kreingkrai; Kim, Yoon-Nyun; Chen, Mien-Cheng; Sriratanasathavorn, Charn; Munawar, Muhammad; Kam, Ruth; Chen, Jan-Yow; Cho, Yong-Keun; Li, Yi-Gang; Wu, Shu-Lin; Bailleul, Christophe; Tse, Hung-Fat

2013-08-13

Atrial-based pacing is associated with lower risk of atrial fibrillation (AF) in sick sinus syndrome compared with ventricular pacing; nevertheless, the impact of site and rate of atrial pacing on progression of AF remains unclear. We evaluated whether long-term atrial pacing at the right atrial (RA) appendage versus the low RA septum with (ON) or without (OFF) a continuous atrial overdrive pacing algorithm can prevent the development of persistent AF. We randomized 385 patients with paroxysmal AF and sick sinus syndrome in whom a pacemaker was indicated to pacing at RA appendage ON (n=98), RA appendage OFF (n=99), RA septum ON (n=92), or RA septum OFF (n=96). The primary outcome was the occurrence of persistent AF (AF documented at least 7 days apart or need for cardioversion). Demographic data were homogeneous across both pacing site (RA appendage/RA septum) and atrial overdrive pacing (ON/OFF). After a mean follow-up of 3.1 years, persistent AF occurred in 99 patients (25.8%; annual rate of persistent AF, 8.3%). Alternative site pacing at the RA septum versus conventional RA appendage (hazard ratio=1.18; 95% confidence interval, 0.79-1.75; P=0.65) or continuous atrial overdrive pacing ON versus OFF (hazard ratio=1.17; 95% confidence interval, 0.79-1.74; P=0.69) did not prevent the development of persistent AF. In patients with paroxysmal AF and sick sinus syndrome requiring pacemaker implantation, an alternative atrial pacing site at the RA septum or continuous atrial overdrive pacing did not prevent the development of persistent AF. URL: http://www.clinicaltrials.gov. UNIQUE IDENTIFIER: NCT00419640.

Constant DI pacing suppresses cardiac alternans formation in numerical cable models

NASA Astrophysics Data System (ADS)

Zlochiver, S.; Johnson, C.; Tolkacheva, E. G.

2017-09-01

Cardiac repolarization alternans describe the sequential alternation of the action potential duration (APD) and can develop during rapid pacing. In the ventricles, such alternans may rapidly turn into life risking arrhythmias under conditions of spatial heterogeneity. Thus, suppression of alternans by artificial pacing protocols, or alternans control, has been the subject of numerous theoretical, numerical, and experimental studies. Yet, previous attempts that were inspired by chaos control theories were successful only for a short spatial extent (<2 cm) from the pacing electrode. Previously, we demonstrated in a single cell model that pacing with a constant diastolic interval (DI) can suppress the formation of alternans at high rates of activation. We attributed this effect to the elimination of feedback between the pacing cycle length and the last APD, effectively preventing restitution-dependent alternans from developing. Here, we extend this idea into cable models to study the extent by which constant DI pacing can control alternans during wave propagation conditions. Constant DI pacing was applied to ventricular cable models of up to 5 cm, using human kinetics. Our results show that constant DI pacing significantly shifts the onset of both cardiac alternans and conduction blocks to higher pacing rates in comparison to pacing with constant cycle length. We also demonstrate that constant DI pacing reduces the propensity of spatially discordant alternans, a precursor of wavebreaks. We finally found that the protective effect of constant DI pacing is stronger for increased electrotonic coupling along the fiber in the sense that the onset of alternans is further shifted to higher activation rates. Overall, these results support the potential clinical applicability of such type of pacing in improving protocols of implanted pacemakers, in order to reduce the risk of life-threatening arrhythmias. Future research should be conducted in order to experimentally validate these promising results.

Current-Controlled Electrical Point-Source Stimulation of Embryonic Stem Cells

PubMed Central

Chen, Michael Q.; Xie, Xiaoyan; Wilson, Kitchener D.; Sun, Ning; Wu, Joseph C.; Giovangrandi, Laurent; Kovacs, Gregory T. A.

2010-01-01

Stem cell therapy is emerging as a promising clinical approach for myocardial repair. However, the interactions between the graft and host, resulting in inconsistent levels of integration, remain largely unknown. In particular, the influence of electrical activity of the surrounding host tissue on graft differentiation and integration is poorly understood. In order to study this influence under controlled conditions, an in vitro system was developed. Electrical pacing of differentiating murine embryonic stem (ES) cells was performed at physiologically relevant levels through direct contact with microelectrodes, simulating the local activation resulting from contact with surrounding electroactive tissue. Cells stimulated with a charged balanced voltage-controlled current source for up to 4 days were analyzed for cardiac and ES cell gene expression using real-time PCR, immunofluorescent imaging, and genome microarray analysis. Results varied between ES cells from three progressive differentiation stages and stimulation amplitudes (nine conditions), indicating a high sensitivity to electrical pacing. Conditions that maximally encouraged cardiomyocyte differentiation were found with Day 7 EBs stimulated at 30 µA. The resulting gene expression included a sixfold increase in troponin-T and a twofold increase in β-MHCwithout increasing ES cell proliferation marker Nanog. Subsequent genome microarray analysis revealed broad transcriptome changes after pacing. Concurrent to upregulation of mature gene programs including cardiovascular, neurological, and musculoskeletal systems is the apparent downregulation of important self-renewal and pluripotency genes. Overall, a robust system capable of long-term stimulation of ES cells is demonstrated, and specific conditions are outlined that most encourage cardiomyocyte differentiation. PMID:20652088

42 CFR 460.90 - PACE benefits under Medicare and Medicaid.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 4 2010-10-01 2010-10-01 false PACE benefits under Medicare and Medicaid. 460.90 Section 460.90 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN... FOR THE ELDERLY (PACE) PACE Services § 460.90 PACE benefits under Medicare and Medicaid. If a Medicare...

Effects of electrolysis by low-amperage electric current on the chlorophyll fluorescence characteristics of Microcystis aeruginosa.

PubMed

Lin, Li; Feng, Cong; Li, Qingyun; Wu, Min; Zhao, Liangyuan

2015-10-01

Effects of electrolysis by low-amperage electric current on the chlorophyll fluorescence characteristics of Microcystis aeruginosa were investigated in order to reveal the mechanisms of electrolytic inhibition of algae. Threshold of current density was found under a certain initial no. of algae cell. When current density was equal to or higher than the threshold (fixed electrolysis time), growth of algae was inhibited completely and the algae lost the ability to survive. Effect of algal solution volume on algal inhibition was insignificant. Thresholds of current density were 8, 10, 14, 20, and 22 mA cm(-2) at 2.5 × 10(7), 5 × 10(7), 1 × 10(8), 2.5 × 10(8), and 5 × 10(8) cells mL(-1) initial no. of algae cell, respectively. Correlativity between threshold of current and initial no. of algae cells was established for scale-up and determining operating conditions. Changes of chlorophyll fluorescence parameters demonstrated that photosystem (PS) II of algae was damaged by electrolysis but still maintained relatively high activity when algal solution was treated by current densities lower than the threshold. The activity of algae recovered completely after 6 days of cultivation. On the contrary, when current density was higher than the threshold, connection of phycobilisome (PBS) and PS II core complexes was destroyed, PS II system of algae was damaged irreversibly, and algae could not survive thoroughly. The inactivation of M. aeruginosa by electrolysis can be attributed to irreversible separation of PBS from PS II core complexes and the damage of PS II of M. aeruginosa.

Safety of the Wearable Cardioverter Defibrillator (WCD) in Patients with Implanted Pacemakers.

PubMed

Schmitt, Joern; Abaci, Guezine; Johnson, Victoria; Erkapic, Damir; Gemein, Christopher; Chasan, Ritvan; Weipert, Kay; Hamm, Christian W; Klein, Helmut U

2017-03-01

The wearable cardioverter defibrillator (WCD) is an important approach for better risk stratification, applied to patients considered to be at high risk of sudden arrhythmic death. Patients with implanted pacemakers may also become candidates for use of the WCD. However, there is a potential risk that pacemaker signals may mislead the WCD detection algorithm and cause inappropriate WCD shock delivery. The aim of the study was to test the impact of different types of pacing, various right ventricular (RV) lead positions, and pacing modes for potential misleading of the WCD detection algorithm. Sixty patients with implanted pacemakers received the WCD for a short time and each pacing mode (AAI, VVI, and DDD) was tested for at least 30 seconds in unipolar and bipolar pacing configuration. In case of triggering the WCD detection algorithm and starting the sequence of arrhythmia alarms, shock delivery was prevented by pushing of the response buttons. In six of 60 patients (10%), continuous unipolar pacing in DDD mode triggered the WCD detection algorithm. In no patient, triggering occurred with bipolar DDD pacing, unipolar and bipolar AAI, and VVI pacing. Triggering was independent of pacing amplitude, RV pacing lead position, and pulse generator implantation site. Unipolar DDD pacing bears a high risk of false triggering of the WCD detection algorithm. Other types of unipolar pacing and all bipolar pacing modes do not seem to mislead the WCD detection algorithm. Therefore, patients with no reprogrammable unipolar DDD pacing should not become candidates for the WCD. © 2016 Wiley Periodicals, Inc.

Medicare program; prohibition of midyear benefit enhancements for Medicare Advantage organizations. Final rule.

PubMed

2008-07-28

This final rule prohibits Medicare Advantage (MA) organizations, including organizations offering MA plans to employer and union group health plan sponsors, from making midyear changes to nonprescription drug benefits, premiums, and cost-sharing submitted in their approved bids for a given contract year. This final rule also clarifies that MA organizations offering certain kinds of plans restricted to employer and union group health plan sponsors and not open to general enrollment may continue to offer benefit enhancements as they do currently, through means other than midyear benefit enhancements (MYBEs). Programs of all-inclusive care for elderly (PACE) are not subject to the provisions of this final rule and may continue to offer enhanced benefits as specified in our guidance for PACE plans.

Interactive Video-Based Industrial Training in Basic Electronics.

ERIC Educational Resources Information Center

Mirkin, Barry

The Wisconsin Foundation for Vocational, Technical, and Adult Education is currently involved in the development, implementation, and distribution of a sophisticated interactive computer and video learning system. Designed to offer trainees an open entry and open exit opportunity to pace themselves through a comprehensive competency-based,…

A low-power bidirectional telemetry device with a near-field charging feature for a cardiac microstimulator.

PubMed

Shuenn-Yuh Lee; Chih-Jen Cheng; Ming-Chun Liang

2011-08-01

In this paper, wireless telemetry using the near-field coupling technique with round-wire coils for an implanted cardiac microstimulator is presented. The proposed system possesses an external powering amplifier and an internal bidirectional microstimulator. The energy of the microstimulator is provided by a rectifier that can efficiently charge a rechargeable device. A fully integrated regulator and a charge pump circuit are included to generate a stable, low-voltage, and high-potential supply voltage, respectively. A miniature digital processor includes a phase-shift-keying (PSK) demodulator to decode the transmission data and a self-protective system controller to operate the entire system. To acquire the cardiac signal, a low-voltage and low-power monitoring analog front end (MAFE) performs immediate threshold detection and data conversion. In addition, the pacing circuit, which consists of a pulse generator (PG) and its digital-to-analog (D/A) controller, is responsible for stimulating heart tissue. The chip was fabricated by Taiwan Semiconductor Manufacturing Company (TSMC) with 0.35-μm complementary metal-oxide semiconductor technology to perform the monitoring and pacing functions with inductively powered communication. Using a model with lead and heart tissue on measurement, a -5-V pulse at a stimulating frequency of 60 beats per minute (bpm) is delivered while only consuming 31.5 μW of power.

Variables affecting the manifestation of and intensity of pacing behavior: A preliminary case study in zoo-housed polar bears.

PubMed

Cless, Isabelle T; Lukas, Kristen E

2017-09-01

High-speed video analysis was used to quantify two aspects of gait in 10 zoo-housed polar bears. These two variables were then examined as to how they differed in the conditions of pacing versus locomoting for each bear. Percent difference calculations measured the difference between pacing and locomoting data for each bear. We inferred that the higher the percent difference between pacing and locomoting in a given subject, the more intense the pacing may be. The percent difference values were analyzed alongside caregiver survey data defining the locations, frequency, and anticipatory nature of pacing in each bear, as well as each bear's age and sex, to determine whether any variables were correlated. The frequency and intensity of pacing behavior were not correlated. However, location of pacing was significantly correlated both with the subjects' age and whether or not the subject was classified as an anticipatory pacer. Bears appeared to select specific spots within their exhibits to pace, and the location therefore seemed tied to underlying motivation for the behavior. Additionally, bears that were classified in the survey as pacing anticipatorily displayed significantly more intense pacing behavior as quantified by gait analysis. © 2017 Wiley Periodicals, Inc.

Carbon deposition thresholds on nickel-based solid oxide fuel cell anodes II. Steam:carbon ratio and current density

NASA Astrophysics Data System (ADS)

Kuhn, J.; Kesler, O.

2015-03-01

For the second part of a two part publication, coking thresholds with respect to molar steam:carbon ratio (SC) and current density in nickel-based solid oxide fuel cells were determined. Anode-supported button cell samples were exposed to 2-component and 5-component gas mixtures with 1 ≤ SC ≤ 2 and zero fuel utilization for 10 h, followed by measurement of the resulting carbon mass. The effect of current density was explored by measuring carbon mass under conditions known to be prone to coking while increasing the current density until the cell was carbon-free. The SC coking thresholds were measured to be ∼1.04 and ∼1.18 at 600 and 700 °C, respectively. Current density experiments validated the thresholds measured with respect to fuel utilization and steam:carbon ratio. Coking thresholds at 600 °C could be predicted with thermodynamic equilibrium calculations when the Gibbs free energy of carbon was appropriately modified. Here, the Gibbs free energy of carbon on nickel-based anode support cermets was measured to be -6.91 ± 0.08 kJ mol-1. The results of this two part publication show that thermodynamic equilibrium calculations with appropriate modification to the Gibbs free energy of solid-phase carbon can be used to predict coking thresholds on nickel-based anodes at 600-700 °C.

The Pace of Perceivable Extreme Climate Change

NASA Astrophysics Data System (ADS)

Tan, X.; Gan, T. Y.

2015-12-01

When will the signal of obvious changes in extreme climate emerge over climate variability (Time of Emergence, ToE) is a key question for planning and implementing measures to mitigate the potential impact of climate change to natural and human systems that are generally adapted to potential changes from current variability. We estimated ToEs for the magnitude, duration and frequency of global extreme climate represented by 24 extreme climate indices (16 for temperature and 8 for precipitation) with different thresholds of the signal-to-noise (S/N) ratio based on projections of CMIP5 global climate models under RCP8.5 and RCP4.5 for the 21st century. The uncertainty of ToE is assessed by using 3 different methods to calculate S/N for each extreme index. Results show that ToEs of the projected extreme climate indices based on the RCP4.5 climate scenarios are generally projected to happen about 20 years later than that for the RCP8.5 climate scenarios. Under RCP8.5, the projected magnitude, duration and frequency of extreme temperature on Earth will all exceed 2 standard deviations by 2100, and the empirical 50th percentile of the global ToE for the frequency and magnitude of hot (cold) extreme are about 2040 and 2054 (2064 and 2054) for S/N > 2, respectively. The 50th percentile of global ToE for the intensity of extreme precipitation is about 2030 and 2058 for S/N >0.5 and S/N >1, respectively. We further evaluated the exposure of ecosystems and human societies to the pace of extreme climate change by determining the year of ToE for various extreme climate indices projected to occur over terrestrial biomes, marine realms and major urban areas with large populations. This was done by overlaying terrestrial, ecoregions and population maps with maps of ToE derived, to extract ToEs for these regions. Possible relationships between GDP per person and ToE are also investigated by relating the mean ToE for each country and its average value of GDP per person.

Do implantable cardioverter defibrillators improve survival in patients with severe left ventricular systolic dysfunction after coronary artery bypass graft surgery?

PubMed

Fazal, Iftikhar A; Bates, Matthew G D; Matthews, Iain G; Turley, Andrew J

2011-06-01

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether implantable cardioverter defibrillators (ICD) improve survival in patients with severe left ventricular systolic dysfunction (LVSD) after coronary artery bypass graft (CABG) surgery. ICDs are designed to terminate potentially fatal cardiac tachyarrhythmias. A right ventricular lead is mandatory for detection, pacing and defibrillation capabilities. Dual chamber ICDs have an additional right atrial lead and are used for patients with conventional atrioventricular pacing indications. More sophisticated, biventricular devices exist to provide cardiac resynchronisation therapy (CRT) in addition to defibrillation (CRT-D). ICDs have been extensively investigated in patients with LVSD post myocardial infarction and in patients with non-ischaemic cardiomyopathy for both secondary prevention (history of ventricular arrhythmias) and primary prevention (deemed high risk for ventricular arrhythmias). This best evidence topic aims to review the evidence and its applicability to patients post CABG. Nine hundred and sixteen papers were identified using the search method outlined. Eight randomised controlled trials, two meta-analyses, and one non-randomised trial, in addition to international guidelines presented the best evidence to answer the clinical question. The current evidence base and guidelines suggest that ICDs should be considered for all patients with LVSD [ejection fraction (EF) ≤30-40%] receiving optimal pharmacological management, who are ≥40 days post MI [four weeks for National Institute for Health and Clinical Excellence (NICE)] and in New York Heart Association (NYHA) class I-III. UK NICE guidelines require in addition; non-sustained ventricular tachycardia (NSVT) on a Holter monitor and inducible ventricular tachycardia at electrophysiological study for EF between 30 and 35%; or a QRS >120 ms if EF <30%. The North American guidelines recommend EF <30% as a threshold for those with NYHA class I symptoms. The evidence is applicable to patients post CABG, provided all the other criteria are met. European Society of Cardiology (ESC) guidelines recommend waiting at least three months (consensus opinion) after revascularisation prior to assessment for an ICD, to allow time for potential recovery of ventricular function.

[Determination of the anaerobic threshold by the rate of ventilation and cardio interval variability].

PubMed

Seluianov, V N; Kalinin, E M; Pak, G D; Maevskaia, V I; Konrad, A H

2011-01-01

The aim of this work is to develop methods for determining the anaerobic threshold according to the rate of ventilation and cardio interval variability during the test with stepwise increases load on the cycle ergometer and treadmill. In the first phase developed the method for determining the anaerobic threshold for lung ventilation. 49 highly skilled skiers took part in the experiment. They performed a treadmill ski-walking test with sticks with gradually increasing slope from 0 to 25 degrees, the slope increased by one degree every minute. In the second phase we developed a method for determining the anaerobic threshold according dynamics ofcardio interval variability during the test. The study included 86 athletes of different sports specialties who performed pedaling on the cycle ergometer "Monarch" in advance. Initial output was 25 W, power increased by 25 W every 2 min. The pace was steady--75 rev/min. Measurement of pulmonary ventilation and oxygen and carbon dioxide content was performed using gas analyzer COSMED K4. Sampling of arterial blood was carried from the ear lobe or finger, blood lactate concentration was determined using an "Akusport" instrument. RR-intervals registration was performed using heart rate monitor Polar s810i. As a result, it was shown that the graphical method for determining the onset of anaerobic threshold ventilation (VAnP) coincides with the accumulation of blood lactate 3.8 +/- 0.1 mmol/l when testing on a treadmill and 4.1 +/- 0.6 mmol/1 on the cycle ergometer. The connection between the measure of oxygen consumption at VAnP and the dispersion of cardio intervals (SD1), derived regression equation: VO2AnT = 0.35 + 0.01SD1W + 0.0016SD1HR + + 0.106SD1(ms), l/min; (R = 0.98, error evaluation function 0.26 L/min, p < 0.001), where W (W)--Power, HR--heart rate (beats/min), SD1--cardio intervals dispersion (ms) at the moment of registration of cardio interval threshold.

42 CFR 460.122 - PACE organization's appeals process.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Participant Rights § 460.122 PACE organization's appeals process. For purposes...

42 CFR 460.122 - PACE organization's appeals process.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Participant Rights § 460.122 PACE organization's appeals process. For purposes...

42 CFR 460.170 - Reinstatement in PACE.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Participant Enrollment and Disenrollment § 460.170 Reinstatement in PACE. (a) A previously...

42 CFR 460.170 - Reinstatement in PACE.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Participant Enrollment and Disenrollment § 460.170 Reinstatement in PACE. (a) A previously...

Effects of pacing magnitudes and forms on bistability width in a modeled ventricular tissue

NASA Astrophysics Data System (ADS)

Huang, Xiaodong; Liu, Xuemei; Zheng, Lixian; Mi, Yuanyuan; Qian, Yu

2013-07-01

Bistability in periodically paced cardiac tissue is relevant to cardiac arrhythmias and its control. In the present paper, one-dimensional tissue of the phase I Luo-Rudy model is numerically investigated. The effects of various parameters of pacing signals on bistability width are studied. The following conclusions are obtained: (i) Pacing can be classified into two types: pulsatile and sinusoidal types. Pulsatile pacing reduces bistability width as its magnitude is increased. Sinusoidal pacing increases the width as its amplitude is increased. (ii) In a pacing period the hyperpolarizing part plays a more important role than the depolarizing part. Variations of the hyperpolarizing ratio in a period evidently change the width of bistability and its variation tendency. (iii) A dynamical mechanism is proposed to qualitatively explain the phenomena, which reveals the reason for the different effects of pulsatile and sinusoidal pacing on bistability. The methods for changing bistability width by external pacing may help control arrhythmias in cardiology.

Acute cardiorespiratory, perceptual and enjoyment responses to high-intensity interval exercise in adolescents.

PubMed

Malik, Adam A; Williams, Craig A; Bond, Bert; Weston, Kathryn L; Barker, Alan R

2017-11-01

This study aimed to examine adolescents' acute cardiorespiratory and perceptual responses during high-intensity interval exercise (HIIE) and enjoyment responses following HIIE and work-matched continuous moderate intensity exercise (CMIE). Fifty-four 12- to 15-year olds (27 boys) completed 8 × 1-min cycling at 90% peak power with 75-s recovery (HIIE) and at 90% of the gas exchange threshold (CMIE). Absolute oxygen uptake ([Formula: see text]), percentage of maximal [Formula: see text] (%[Formula: see text]), heart rate (HR), percentage of maximal HR (%HR max ) and ratings of perceived exertion (RPE) were collected during HIIE. Enjoyment was measured using the physical activity enjoyment scale (PACES) following HIIE and CMIE. Boys elicited higher absolute [Formula: see text] during HIIE work (p < .01, effect size (ES) > 1.22) and recovery (p < .02, ES > 0.51) intervals but lower %[Formula: see text] during HIIE recovery intervals compared to girls (p < .01, ES > 0.67). No sex differences in HR and %HR max were evident during HIIE and 48 participants attained ≥90% HR max . Boys produced higher RPE at intervals 6 (p = .004, ES = 1.00) and 8 (p = .003, ES = 1.00) during HIIE. PACES was higher after HIIE compared with CMIE (p = .003, ES = 0.58). Items from PACES "I got something out of it", "It's very exciting" and "It gives me a strong feeling of success" were higher after HIIE (all p < .01, ES > 0.32). The items "I feel bored" and "It's not at all interesting" were higher after CMIE (all p < .01, ES > 0.46). HIIE elicits a maximal cardiorespiratory response in most adolescents. Greater enjoyment after HIIE was due to elevated feelings of reward, excitement and success and may serve as a strategy to promote health in youth.

Predictors of temporary epicardial pacing wires use after valve surgery

PubMed Central

2014-01-01

Background Although temporary cardiac pacing is infrequently needed, temporary epicardial pacing wires are routinely inserted after valve surgery. As they are associated with infrequent, but life threatening complications, and the decreased need for postoperative pacing in a group of low risk patients; this study aims to identify the predictors of temporary cardiac pacing after valve surgery. Methods A retrospective analysis of data collected prospectively on 400 consecutive valve surgery patients between May 2002 and December 2012 was performed. Patients were grouped according to avoidance or insertion of temporary pacing wires, and were further subdivided according to temporary cardiac pacing need. Multiple logistic regression was used to determine the predictors of temporary cardiac pacing. Results 170 (42.5%) patients did not have insertion of temporary pacing wires and none of them needed temporary pacing. 230 (57.5%) patients had insertion of temporary pacing wires and among these, only 55 (23.9%) required temporary pacing who were compared with the remaining 175 (76.1%) patients in the main analysis. The determinants of temporary cardiac pacing (adjusted odds ratios; 95% confidence interval) were as follows: increased age (1.1; 1.1, 1.3, p = 0.002), New York Heart Association class III- IV (5.6; 1.6, 20.2, p = 0.008) , pulmonary artery pressure ≥ 50 mmHg (22.0; 3.4, 142.7, p = 0.01), digoxin use (8.0; 1.3, 48.8, p = 0.024), multiple valve surgery (13.5; 1.5, 124.0, p = 0.021), aorta cross clamp time ≥ 60 minutes (7.8; 1.6, 37.2, p = 0.010), and valve annulus calcification (7.9; 2.0, 31.7, p = 0.003). Conclusion Although limited by sample size, the present results suggest that routine use of temporary epicardial pacing wires after valve surgery is only necessary for high risk patients. Preoperative identification and aggressive management of predictors of temporary cardiac pacing and the possible modulation of intraoperative techniques can decrease the need of temporary cardiac pacing. Prospective randomized controlled studies on a larger number of patients are necessary to draw solid conclusions regarding the selective use of temporary epicardial pacing wires in valve surgery. PMID:24521215

42 CFR 460.30 - Program agreement requirement.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Program Agreement § 460.30 Program agreement requirement. (a) A PACE organization must...

42 CFR 460.30 - Program agreement requirement.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Program Agreement § 460.30 Program agreement requirement. (a) A PACE organization must...

42 CFR 460.50 - Termination of PACE program agreement.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Sanctions, Enforcement Actions, and Termination § 460.50 Termination of PACE...

42 CFR 460.50 - Termination of PACE program agreement.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Sanctions, Enforcement Actions, and Termination § 460.50 Termination of PACE...

42 CFR 460.180 - Medicare payment to PACE organizations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Payment § 460.180 Medicare payment to PACE organizations. (a) Principle of...

Congenital and childhood atrioventricular blocks: pathophysiology and contemporary management.

PubMed

Baruteau, Alban-Elouen; Pass, Robert H; Thambo, Jean-Benoit; Behaghel, Albin; Le Pennec, Solène; Perdreau, Elodie; Combes, Nicolas; Liberman, Leonardo; McLeod, Christopher J

2016-09-01

Atrioventricular block is classified as congenital if diagnosed in utero, at birth, or within the first month of life. The pathophysiological process is believed to be due to immune-mediated injury of the conduction system, which occurs as a result of transplacental passage of maternal anti-SSA/Ro-SSB/La antibodies. Childhood atrioventricular block is therefore diagnosed between the first month and the 18th year of life. Genetic variants in multiple genes have been described to date in the pathogenesis of inherited progressive cardiac conduction disorders. Indications and techniques of cardiac pacing have also evolved to allow safe permanent cardiac pacing in almost all patients, including those with structural heart abnormalities. Early diagnosis and appropriate management are critical in many cases in order to prevent sudden death, and this review critically assesses our current understanding of the pathogenetic mechanisms, clinical course, and optimal management of congenital and childhood AV block. • Prevalence of congenital heart block of 1 per 15,000 to 20,000 live births. AV block is defined as congenital if diagnosed in utero, at birth, or within the first month of life, whereas childhood AV block is diagnosed between the first month and the 18th year of life. As a result of several different etiologies, congenital and childhood atrioventricular block may occur in an entirely structurally normal heart or in association with concomitant congenital heart disease. Cardiac pacing is indicated in symptomatic patients and has several prophylactic indications in asymptomatic patients to prevent sudden death. • Autoimmune, congenital AV block is associated with a high neonatal mortality rate and development of dilated cardiomyopathy in 5 to 30 % cases. What is New: • Several genes including SCN5A have been implicated in autosomal dominant forms of familial progressive cardiac conduction disorders. • Leadless pacemaker technology and gene therapy for biological pacing are promising research fields. In utero percutaneous pacing appears to be at high risk and needs further development before it can be adopted into routine clinical practice. Cardiac resynchronization therapy is of proven value in case of pacing-induced cardiomyopathy.

INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Injection lasers based on the AlGaAsSb system emitting at 1.6 μm

NASA Astrophysics Data System (ADS)

Virro, A. L.; Eliseev, P. G.; Lyuk, P. A.; Fridental, Ya K.; Khaller, Yu E.

1988-11-01

An experimental dependence of the threshold current density jth on the thickness of the active region was used to find the reduced threshold current density for AlGaAsSb (λ = 1.59μm, T = 295K) lasers: this density was 8 kA·cm-2·μm-1. The minimum threshold current was jth = 1.8 kA/cm2. Wide-contact lasers exhibited cw operation down to 175 K.

Threshold current for fireball generation

NASA Astrophysics Data System (ADS)

Dijkhuis, Geert C.

1982-05-01

Fireball generation from a high-intensity circuit breaker arc is interpreted here as a quantum-mechanical phenomenon caused by severe cooling of electrode material evaporating from contact surfaces. According to the proposed mechanism, quantum effects appear in the arc plasma when the radius of one magnetic flux quantum inside solid electrode material has shrunk to one London penetration length. A formula derived for the threshold discharge current preceding fireball generation is found compatible with data reported by Silberg. This formula predicts linear scaling of the threshold current with the circuit breaker's electrode radius and concentration of conduction electrons.

DefenseLink Special: Travels with Pace, March 2006

Science.gov Websites

Us Travels with Pace Chairman of the Joint Chiefs of Staff Marine Gen. Peter Pace U.S. Marine Gen . Peter Pace, chairman of the Joint Chiefs of Staff, speaks to students attending the Turkish War College U.S. Air Force Staff Sgt. D. Myles Cullen Hi-Res Pace Wraps Up Visit to Allied Nations WASHINGTON

A Clinical Feasibility Study of Atrial and Ventricular Electromechanical Wave Imaging

PubMed Central

Provost, Jean; Gambhir, Alok; Vest, John; Garan, Hasan; Konofagou, Elisa E.

2014-01-01

Background Cardiac Resynchronization Therapy (CRT) and atrial ablation currently lack a noninvasive imaging modality for reliable treatment planning and monitoring. Electromechanical Wave Imaging (EWI) is an ultrasound-based method that has previously been shown to be capable of noninvasively and transmurally mapping the activation sequence of the heart in animal studies by estimating and imaging the electromechanical wave, i.e., the transient strains occurring in response to the electrical activation, at both very high temporal and spatial resolution. Objective Demonstrate the feasibility of noninvasive transthoracic EWI for mapping the activation sequence during different cardiac rhythms in humans. Methods EWI was performed in CRT patients with a left bundle-branch block (LBBB), during sinus rhythm, left-ventricular pacing, and right-ventricular pacing and in atrial flutter (AFL) patients before intervention and correlated with results from invasive intracardiac electrical mapping studies during intervention. Additionally, the feasibility of single-heartbeat EWI at 2000 frames/s, is demonstrated in humans for the first time in a subject with both AFL and right bundle-branch-block. Results The electromechanical activation maps demonstrated the capability of EWI to localize the pacing sites and characterize the LBBB activation sequence transmurally in CRT patients. In AFL patients, the propagation patterns obtained with EWI were in agreement with results obtained from invasive intracardiac mapping studies. Conclusion Our findings demonstrate the potential capability of EWI to aid in monitoring and follow-up of patients undergoing CRT pacing therapy and atrial ablation with preliminary validation in vivo. PMID:23454060

Effect of short-term rapid ventricular pacing followed by pacing interruption on arterial blood pressure in healthy pigs and pigs with tachycardiomyopathy.

PubMed

Skrzypczak, P; Zyśko, D; Pasławska, U; Noszczyk-Nowak, A; Janiszewski, A; Gajek, J; Nicpoń, J; Kiczak, L; Bania, J; Zacharski, M; Tomaszek, A; Jankowska, E A; Ponikowski, P; Witkiewicz, W

2014-01-01

Ventricular tachycardia may lead to haemodynamic deterioration and, in the case of long term persistence, is associated with the development of tachycardiomyopathy. The effect of ventricular tachycardia on haemodynamics in individuals with tachycardiomyopathy, but being in sinus rhythm has not been studied. Rapid ventricular pacing is a model of ventricular tachycardia. The aim of this study was to determine the effect of rapid ventricular pacing on blood pressure in healthy animals and those with tachycardiomyopathy. A total of 66 animals were studied: 32 in the control group and 34 in the study group. The results of two groups of examinations were compared: the first performed in healthy animals (133 examinations) and the second performed in animals paced for at least one month (77 examinations). Blood pressure measurements were taken during chronic pacing--20 min after onset of general anaesthesia, in baseline conditions (20 min after pacing cessation or 20 min after onset of general anaesthesia in healthy animals) and immediately after short-term rapid pacing. In baseline conditions significantly higher systolic and diastolic blood pressure was found in healthy animals than in those with tachycardiomyopathy. During an event of rapid ventricular pacing, a significant decrease in systolic and diastolic blood pressure was found in both groups of animals. In the group of chronically paced animals the blood pressure was lower just after restarting ventricular pacing than during chronic pacing. Cardiovascular adaptation to ventricular tachycardia develops with the length of its duration. Relapse of ventricular tachycardia leads to a blood pressure decrease more pronounced than during chronic ventricular pacing.

High efficiency low threshold current 1.3 μm InAs quantum dot lasers on on-axis (001) GaP/Si

NASA Astrophysics Data System (ADS)

Jung, Daehwan; Norman, Justin; Kennedy, M. J.; Shang, Chen; Shin, Bongki; Wan, Yating; Gossard, Arthur C.; Bowers, John E.

2017-09-01

We demonstrate highly efficient, low threshold InAs quantum dot lasers epitaxially grown on on-axis (001) GaP/Si substrates using molecular beam epitaxy. Electron channeling contrast imaging measurements show a threading dislocation density of 7.3 × 106 cm-2 from an optimized GaAs template grown on GaP/Si. The high-quality GaAs templates enable as-cleaved quantum dot lasers to achieve a room-temperature continuous-wave (CW) threshold current of 9.5 mA, a threshold current density as low as 132 A/cm2, a single-side output power of 175 mW, and a wall-plug-efficiency of 38.4% at room temperature. As-cleaved QD lasers show ground-state CW lasing up to 80 °C. The application of a 95% high-reflectivity coating on one laser facet results in a CW threshold current of 6.7 mA, which is a record-low value for any kind of Fabry-Perot laser grown on Si.

Anatomical approach to permanent His bundle pacing: Optimizing His bundle capture.

PubMed

Vijayaraman, Pugazhendhi; Dandamudi, Gopi

2016-01-01

Permanent His bundle pacing is a physiological alternative to right ventricular pacing. In this article we describe our approach to His bundle pacing in patients with AV nodal and intra-Hisian conduction disease. It is essential for the implanters to understand the anatomic variations of the His bundle course and its effect on the type of His bundle pacing achieved. We describe several case examples to illustrate our anatomical approach to permanent His bundle pacing in this article. Copyright © 2016 Elsevier Inc. All rights reserved.

InAs-based interband-cascade-lasers emitting around 7 μm with threshold current densities below 1 kA/cm{sup 2} at room temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dallner, Matthias; Hau, Florian; Kamp, Martin

2015-01-26

Interband cascade lasers (ICLs) grown on InAs substrates with threshold current densities below 1 kA/cm{sup 2} are presented. Two cascade designs with different lengths of the electron injector were investigated. Using a cascade design with 3 InAs quantum wells (QWs) in the electron injector, a device incorporating 22 stages in the active region exhibited a threshold current density of 940 A/cm{sup 2} at a record wavelength of 7 μm for ICLs operating in pulsed mode at room temperature. By investigating the influence of the number of stages on the device performance for a cascade design with 2 QWs in the electron injector, amore » further reduction of the threshold current density to 800 A/cm{sup 2} was achieved for a 30 stage device.« less

Ultralow threshold graded-index separate-confinement heterostructure single quantum well (Al, Ga) As lasers

NASA Technical Reports Server (NTRS)

Derry, P. L.; Chen, H. Z.; Morkoc, H.; Yariv, A.; Lau, K. Y.

1988-01-01

Broad area graded-index separate-confinement heterostructure single quantum well lasers grown by molecular-beam epitaxy (MBE) with threshold current density as low as 93 A/sq cm (520 microns long) have been fabricated. Buried lasers formed from similarly structured MBE material with liquid phase epitaxy regrowth had threshold currents at submilliampere levels when high reflectivity coatings were applied to the end facets. A CW threshold current of 0.55 mA was obtained for a laser with facet reflectivities of about 80 percent, a cavity length of 120 micron, and an active region stripe width of 1 micron. These devices driven directly with logic level signals have switch-on delays less than 50 ps without any current prebias. Such lasers permit fully on-off switching while at the same time obviating the need for bias monitoring and feedback control.

Empowering Workplace Students: A Practitioner's Challenge.

ERIC Educational Resources Information Center

Lessard, Richard

For the past 4 years, Alpena Community College, in Michigan, has participated in the Workplace Partnership Project (WPP), a federally funded grant program designed to provide literacy skills to individuals currently employed but lacking the background to keep pace with the changes of the modern workplace. The process for establishing classes at a…

Convenience Store Operations.

ERIC Educational Resources Information Center

Luter, Robert R.

This self-paced, individualized instructional guide is designed for use by those who are currently working in a convenience store or by those who wish to learn the basics of convenience store marketing and operations. Addressed in the individual units of the guide are the following topics: today's convenience store, regular duties and…

Cost of anaesthesia.

PubMed Central

Astley, B A; Walker, J S

1982-01-01

The major contributory factor to the cost of anesthesia today are the increases in medical salaries that have kept pace with inflation, commanding 68% of the total expenditure. The current position has been compared with that of 20 years ago. This outline could be used as a framework for departmental budgeting. PMID:6807406

The Characterization of Brain Behavior Relationships via Cognitive Neuroinformatic Approaches

ERIC Educational Resources Information Center

Kalar, Donald James, II

2009-01-01

The scope, breadth, and volume of data characterizing our current understanding of how the brain functions is growing at an increasingly rapid pace. What is more, theories are becoming increasing complex and nuanced, integrating knowledge from multiple previously independent sources of scientific inquiry. The research described within this…

A data envelopment analysis approach to compare the environmental efficiency of energy technologies and countries

USDA-ARS?s Scientific Manuscript database

Due to increasing financial and environmental concerns, governmental rules, regulations and incentives alternative energy sources are soon expected to grow at a much faster pace than conventional sources of energy. However, the current body of research providing comparative decision making models fo...

Supporting Wellness in Adult Online Education

ERIC Educational Resources Information Center

Thompson, Jacklyn J.; Porto, Stella C. S.

2014-01-01

Online education cannot continue to grow at the current pace while ignoring a crucial component of campus support, wellness for adult online learners. This paper brings awareness to the concept of wellness as an important student support service in adult online education. It includes a summarized review of relevant literature and identifies…

Is Your LPN Program Keeping P.A.C.E.?

ERIC Educational Resources Information Center

Miller, George; Schill, William John

High demand for admission to Licensed Practical Nursing (LPN) programs and limited state resource allocations for LPN training programs in Washington, have forced North Seattle Community College (NSCC) to utilize a selective admissions policy for its LPN program. Currently, prospective LPN students are required to obtain satisfactory scores on…

PCT funding. Beggars belief.

PubMed

Hacking, John

2003-04-10

At the pace of change set for implementing the new PCT funding formula over the next three years, it will take more than 20 years to achieve equity. If the minimum increases were set lower it would largely be achieved within five years. The current state of affairs perpetuates the north-south health divide.

Intraorganizational Career Advancement and Voluntary Turnover in a Multinational Bank in Taiwan

ERIC Educational Resources Information Center

Zhao, Wei; Zhou, Xueguang

2008-01-01

Purpose: This study aims to investigate how various aspects of intraorganizational career advancement--current career attainments, recent pace of upward mobility, and future prospect of career advancement--affect voluntary turnover, drawing empirical evidence from a multinational corporation (MNC) in Taiwan's cultural and labor market environment.…

Higher sympathetic nerve activity during ventricular (VVI) than during dual-chamber (DDD) pacing

NASA Technical Reports Server (NTRS)

Taylor, J. A.; Morillo, C. A.; Eckberg, D. L.; Ellenbogen, K. A.

1996-01-01

OBJECTIVES: We determined the short-term effects of single-chamber ventricular pacing and dual-chamber atrioventricular (AV) pacing on directly measured sympathetic nerve activity. BACKGROUND: Dual-chamber AV cardiac pacing results in greater cardiac output and lower systemic vascular resistance than does single-chamber ventricular pacing. However, it is unclear whether these hemodynamic advantages result in less sympathetic nervous system outflow. METHODS: In 13 patients with a dual-chamber pacemaker, we recorded the electrocardiogram, noninvasive arterial pressure (Finapres), respiration and muscle sympathetic nerve activity (microneurography) during 3 min of underlying basal heart rate and 3 min of ventricular and AV pacing at rates of 60 and 100 beats/min. RESULTS: Arterial pressure was lowest and muscle sympathetic nerve activity was highest at the underlying basal heart rate. Arterial pressure increased with cardiac pacing and was greater with AV than with ventricular pacing (change in mean blood pressure +/- SE: 10 +/- 3 vs. 2 +/- 2 mm Hg at 60 beats/min; 21 +/- 5 vs. 14 +/- 2 mm Hg at 100 beats/min; p < 0.05). Sympathetic nerve activity decreased with cardiac pacing and the decline was greater with AV than with ventricular pacing (60 beats/min -40 +/- 11% vs. -17 +/- 7%; 100 beats/min -60 +/- 9% vs. -48 +/- 10%; p < 0.05). Although most patients showed a strong inverse relation between arterial pressure and muscle sympathetic nerve activity, three patients with severe left ventricular dysfunction (ejection fraction < or = 30%) showed no relation between arterial pressure and sympathetic activity. CONCLUSIONS: Short-term AV pacing results in lower sympathetic nerve activity and higher arterial pressure than does ventricular pacing, indicating that cardiac pacing mode may influence sympathetic outflow simply through arterial baroreflex mechanisms. We speculate that the greater incidence of adverse outcomes in patients treated with single-chamber ventricular rather than dual-chamber pacing may be due in part to increased sympathetic nervous outflow.

Optimizing local capture of atrial fibrillation by rapid pacing: study of the influence of tissue dynamics.

PubMed

Uldry, Laurent; Virag, Nathalie; Jacquemet, Vincent; Vesin, Jean-Marc; Kappenberger, Lukas

2010-12-01

While successful termination by pacing of organized atrial tachycardias has been observed in patients, rapid pacing of AF can induce a local capture of the atrial tissue but in general no termination. The purpose of this study was to perform a systematic evaluation of the ability to capture AF by rapid pacing in a biophysical model of the atria with different dynamics in terms of conduction velocity (CV) and action potential duration (APD). Rapid pacing was applied during 30 s at five locations on the atria, for pacing cycle lengths in the range 60-110% of the mean AF cycle length (AFCL(mean)). Local AF capture could be achieved using rapid pacing at pacing sites located distal to major anatomical obstacles. Optimal pacing cycle lengths were found in the range 74-80% AFCL(mean) (capture window width: 14.6 ± 3% AFCL(mean)). An increase/decrease in CV or APD led to a significant shrinking/stretching of the capture window. Capture did not depend on AFCL, but did depend on the atrial substrate as characterized by an estimate of its wavelength, a better capture being achieved at shorter wavelengths. This model-based study suggests that a proper selection of the pacing site and cycle length can influence local capture results and that atrial tissue properties (CV and APD) are determinants of the response to rapid pacing.

Right Ventricular Outflow Tract Septal Pacing Is Superior to Right Ventricular Apical Pacing

PubMed Central

Zou, Cao; Song, Jianping; Li, Hui; Huang, Xingmei; Liu, Yuping; Zhao, Caiming; Shi, Xin; Yang, Xiangjun

2015-01-01

Background The effects of right ventricular apical pacing (RVAP) and right ventricular outflow tract (RVOT) septal pacing on atrial and ventricular electrophysiology have not been thoroughly compared. Methods and Results To identify a more favorable pacing strategy with fewer adverse effects, 80 patients who had complete atrioventricular block with normal cardiac function and who were treated with either RVAP (n=42) or RVOT septal pacing (n=38) were recruited after an average of 2 years of follow‐up. The data from electrocardiography and echocardiography performed before pacemaker implantation and at the end of follow‐up were collected. The patients in the RVOT septal pacing and RVAP groups showed similar demographic and clinical characteristics before pacing treatments. After a mean follow‐up of 2 years, the final maximum P‐wave duration; P‐wave dispersion; Q‐, R‐, and S‐wave complex duration; left atrial volume index; left ventricular end‐systolic diameter; ratio of transmitral early diastolic filling velocity to mitral annular early diastolic velocity; and interventricular mechanical delay in the RVOT septal pacing group were significantly less than those in the RVAP group (P<0.05). The final left ventricular ejection fraction of the RVOT septal pacing group was significantly higher than that of the RVAP group (P<0.05). Conclusions Compared with RVAP, RVOT septal pacing has fewer adverse effects regarding atrial electrical activity and structure in patients with normal cardiac function. PMID:25896891

42 CFR 460.24 - Limit on number of PACE program agreements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Organization Application and Waiver Process § 460.24 Limit on number of...

42 CFR 460.24 - Limit on number of PACE program agreements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Organization Application and Waiver Process § 460.24 Limit on number of...

Distribution and protection of climatic refugia in North America.

PubMed

Michalak, Julia L; Lawler, Joshua J; Roberts, David R; Carroll, Carlos

2018-05-10

As evidenced by past climatic refugia, locations projected to harbor remnants of present day climates may serve as critical refugia for current biodiversity in the face of modern climate change. Here, we map potential future climatic refugia across North America, defined as locations with increasingly rare climatic conditions. We identified these locations by tracking projected changes in the size and distribution of climate analogs over time. We used biologically-derived thresholds to define analogs and tested the impacts of dispersal limitation using four distances to limit analog searches. We identified at most 12% of North America as potential climatic refugia. Refugia extent varied depending on the analog threshold, dispersal distance, and climate projection. However, in all cases refugia were concentrated at high elevations and in topographically complex regions. Refugia identified using different climate projections were largely nested, suggesting that identified refugia were relatively robust to climate projection selection. Existing conservation areas cover approximately 10% of North America and yet protected up to 25% of identified refugia, indicating that protected areas disproportionately include refugia. Refugia located at lower latitudes (≤ 40°N) and slightly lower elevations (∼2500 m) were more likely to be unprotected. Based on our results, a 23% expansion of the protected areas network would be sufficient to protect the refugia that were present under all three of the climate projections that we explored. We propose that these refugia are high conservation priorities, due to their potential to harbor rare species in the future. However, these locations are simultaneously highly vulnerable to climate change over the long-term. We found that these refugia contracted substantially between the 2050s and the 2080s, emphasizing that the pace of climate change will strongly determine the availability and effectiveness of refugia for protecting today's biodiversity. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Active-Matrix Organic Light Emission Diode Pixel Circuit for Suppressing and Compensating for the Threshold Voltage Degradation of Hydrogenated Amorphous Silicon Thin Film Transistors

NASA Astrophysics Data System (ADS)

Shin, Hee-Sun; Lee, Won-Kyu; Park, Sang-Guen; Kuk, Seung-Hee; Han, Min-Koo

2009-03-01

A new hydrogenated amorphous silicon (a-Si:H) thin film transistor (TFT) pixel circuit for active-matrix organic light emission diodes (AM-OLEDs), which significantly compensates the OLED current degradation by memorizing the threshold voltage of driving TFT and suppresses the threshold voltage shift of a-Si:H TFTs by negative bias annealing, is proposed and fabricated. During the first half of each frame, the driving TFT of the proposed pixel circuit supplies current to the OLED, which is determined by modified data voltage in the compensation scheme. The proposed pixel circuit was able to compensate the threshold voltage shift of the driving TFT as well as the OLED. During the remaining half of each frame, the proposed pixel circuit induces the recovery of the threshold voltage degradation of a-Si:H TFTs owing to the negative bias annealing. The experimental results show that the proposed pixel circuit was able to successfully compensate for the OLED current degradation and suppress the threshold voltage degradation of the driving TFT.

Effect of Right Ventricular versus Biventricular Pacing on Electrical Remodeling in the Normal Heart

PubMed Central

Saba, Samir; Mehdi, Haider; Mathier, Michael A.; Islam, M. Zahadul; Salama, Guy; London, Barry

2010-01-01

Background Biventricular (BIV) pacing can improve cardiac function in heart failure by altering the mechanical and electrical substrates. We investigated the effect of BIV versus right ventricular (RV) pacing on the normal heart. Methods and Results Male New Zealand White rabbits (n=33) were divided into 3 groups: sham-operated (control), RV pacing, and BIV pacing groups. Four weeks after surgery, the native QT (p=0.004) interval was significantly shorter in the BIV group compared to the RV or sham-operated groups. Also, compared to rabbits in the RV group, rabbits in the BIV group had shorter RV ventricular effective refractory period (VERP) at all cycle lengths, and shorter LV paced QT interval during the drive train of stimuli and close to refractoriness (p<0.001 for all comparisons). Protein expression of the KVLQT1 was significantly increased in the BIV group compared to the RV and control groups, while protein expression of SCN5A and connexin43 was significantly decreased in the RV compared to the other study groups. Erg protein expression was significantly increased in both pacing groups compared to the controls. Conclusions In this rabbit model, we demonstrate a direct effect of BIV but not RV pacing on shortening the native QT interval as well as the paced QT interval during burst pacing and close to the VERP. These findings underscore the fact that the effect of BIV pacing is partially mediated through direct electrical remodeling and may have implications as to the effect of BIV pacing on arrhythmia incidence and burden. PMID:20042767

Interatrial septum versus right atrial appendage pacing for prevention of atrial fibrillation : A meta-analysis of randomized controlled trials.

PubMed

Zhang, L; Jiang, H; Wang, W; Bai, J; Liang, Y; Su, Y; Ge, J

2017-07-28

Interatrial septum (IAS) pacing seems to be a promising strategy for the prevention of atrial fibrillation (AF); however, studies have yielded conflicting results. This meta-analysis was to compare IAS with right atrial appendage (RAA) pacing on the prevention of postpacing AF occurrence. Pubmed, MEDLINE, EMBASE and Web of Science databases were searched through October 2016 for randomized controlled trials comparing IAS with RAA pacing on the prevention of AF. Data concerning study design, patient characteristics and outcomes were extracted. Risk ratio (RR), weighted mean differences (WMD) or standardized mean differences (SMD) were calculated using fixed or random effects models. A total of 12 trials involving 1146 patients with dual-chamber pacing were included. Although IAS was superior to RAA pacing in terms of reducing the number of AF episodes (SMD = -0.29, P = 0.05), AF burden (SMD = -0.41, P = 0.008) and P -wave duration (WMD = -34.45 ms, P < 0.0001), neither permanent AF occurrence (RR = 0.94, P = 0.58) nor recurrences of AF (RR = 0.88, P = 0.36) were reduced by IAS pacing. Nevertheless, no differences were observed concerning all-cause death (RR = 1.04, P = 0.88), procedure-related events (RR = 1.17, P = 0.69) and pacing parameters between IAS and RAA pacing in the follow-up period. IAS pacing is safe and as well tolerated as RAA pacing. Although IAS pacing may fail to prevent permanent AF occurrence and recurrences of AF, it is able to not only improve interatrial conduction, but also reduce AF burden.

Effects of septal pacing on P wave characteristics: the value of three-dimensional echocardiography.

PubMed

Szili-Torok, Tamas; Bruining, Nico; Scholten, Marcoen; Kimman, Geert-Jan; Roelandt, Jos; Jordaens, Luc

2003-01-01

Interatrial septum (IAS) pacing has been proposed for the prevention of paroxysmal atrial fibrillation. IAS pacing is usually guided by fluoroscopy and P wave analysis. The authors have developed a new approach for IAS pacing using intracardiac echocardiography (ICE), and examined its effects on P wave characteristics. Cross-sectional images are acquired during pullback of the ICE transducer from the superior vena cava into the inferior vena cava by an electrocardiogram- and respiration-gated technique. The right atrium and IAS are then three-dimensionally reconstructed, and the desired pacing site is selected. After lead placement and electrical testing, another three-dimensional reconstruction is performed to verify the final lead position. The study included 14 patients. IAS pacing was achieved at seven suprafossal (SF) and seven infrafossal (IF) lead locations, all confirmed by three-dimensional imaging. IAS pacing resulted in a significant reduction of P wave duration as compared to sinus rhythm (99.7 +/- 18.7 vs 140.4 +/- 8.8 ms; P < 0.01). SF pacing was associated with a greater reduction of P wave duration than IF pacing (56.1 +/- 9.9 vs 30.2 +/- 13.6 ms; P < 0.01). P wave dispersion remained unchanged during septal pacing as compared to sinus rhythm (21.4 +/- 16.1 vs 13.5 +/- 13.9 ms; NS). Three-dimensional intracardiac echocardiography can be used to guide IAS pacing. SF pacing was associated with a greater decrease in P wave duration, suggesting that it is a preferable location to decrease interatrial conduction delay.

Evaluation and comparison of 50 Hz current threshold of electrocutaneous sensations using different methods

PubMed Central

Lindenblatt, G.; Silny, J.

2006-01-01

Leakage currents, tiny currents flowing from an everyday-life appliance through the body to the ground, can cause a non-adequate perception (called electrocutaneous sensation, ECS) or even pain and should be avoided. Safety standards for low-frequency range are based on experimental results of current thresholds of electrocutaneous sensations, which however show a wide range between about 50 μA (rms) and 1000 μA (rms). In order to be able to explain these differences, the perception threshold was measured repeatedly in experiments with test persons under identical experimental setup, but by means of different methods (measuring strategies), namely: direct adjustment, classical threshold as amperage of 50% perception probability, and confidence rating procedure of signal detection theory. The current is injected using a 1 cm2 electrode at the highly touch sensitive part of the index fingertip. These investigations show for the first time that the threshold of electrocutaneous sensations is influenced both by adaptation to the non-adequate stimulus and individual, emotional factors. Therefore, classical methods, on which the majority of the safety investigations are based, cannot be used to determine a leakage current threshold. The confidence rating procedure of the modern signal detection theory yields a value of 179.5 μA (rms) at 50 Hz power supply net frequency as the lower end of the 95% confidence range considering the variance in the investigated group. This value is expected to be free of adaptation influences, and is distinctly lower than the European limits and supports the stricter regulations of Canada and USA. PMID:17111461

Mouse current vocalization threshold measured with a neurospecific nociception assay: The effect of sex, morphine, and isoflurane

PubMed Central

Spornick, Nicholas; Guptill, Virginia; Koziol, Deloris; Wesley, Robert; Finkel, Julia; Quezado, Zenaide M.N.

2012-01-01

Sine-wave electrical stimulation at frequencies 2000, 250, and 5 Hz to respectively evaluate Aβ, Aδ, and C sensory neurons has recently been added to the armamentarium used to evaluate sensory neurons. We developed an automated nociception assay using sine-wave stimulation methodology to determine current vocalization threshold in response to 2000, 250, and 5 Hz and examine the effects of sex, analgesics, and anesthetics in mice. At baseline, males had significantly higher mean current vocalization thresholds compared with female mice at 2000, 250, and 5 Hz (p ≤ 0.019). By 1 h after intrathecal injections of morphine there were significant increases in current vocalization threshold percent changes from baseline that varied with doses (p = 0.0001) and frequency used (p < 0.0001). Specifically, with increasing doses of morphine, there were significantly greater increases in current vocalization threshold percent changes from baseline in response to 5 Hz compared with 250 and 2000 Hz stimulation in a significantly ordered pattern: 5 Hz > 250 Hz (p < 0.0001) and 250 Hz > 2000 Hz (p = 0.0002). Forty-five minutes after exposure, there were no effects of isoflurane on current vocalization thresholds at any frequency. Therefore, our findings suggest that this automated nociception assay using sine-wave stimulation in mice, can be valuable for measurements of the effects of sex, opioids, and anesthetics on the response to electrical stimuli that preferentially stimulate Aβ, Aδ, and C-sensory fibers in vivo. This investigation suggests the validation of this assay and supports its use to examine mechanisms of nociception in mice. PMID:21864576

Pacing a data transfer operation between compute nodes on a parallel computer

DOEpatents

Blocksome, Michael A [Rochester, MN

2011-09-13

Methods, systems, and products are disclosed for pacing a data transfer between compute nodes on a parallel computer that include: transferring, by an origin compute node, a chunk of an application message to a target compute node; sending, by the origin compute node, a pacing request to a target direct memory access (`DMA`) engine on the target compute node using a remote get DMA operation; determining, by the origin compute node, whether a pacing response to the pacing request has been received from the target DMA engine; and transferring, by the origin compute node, a next chunk of the application message if the pacing response to the pacing request has been received from the target DMA engine.

Broad-based visual benefits from training with an integrated perceptual-learning video game.

PubMed

Deveau, Jenni; Lovcik, Gary; Seitz, Aaron R

2014-06-01

Perception is the window through which we understand all information about our environment, and therefore deficits in perception due to disease, injury, stroke or aging can have significant negative impacts on individuals' lives. Research in the field of perceptual learning has demonstrated that vision can be improved in both normally seeing and visually impaired individuals, however, a limitation of most perceptual learning approaches is their emphasis on isolating particular mechanisms. In the current study, we adopted an integrative approach where the goal is not to achieve highly specific learning but instead to achieve general improvements to vision. We combined multiple perceptual learning approaches that have individually contributed to increasing the speed, magnitude and generality of learning into a perceptual-learning based video-game. Our results demonstrate broad-based benefits of vision in a healthy adult population. Transfer from the game includes; improvements in acuity (measured with self-paced standard eye-charts), improvement along the full contrast sensitivity function, and improvements in peripheral acuity and contrast thresholds. The use of this type of this custom video game framework built up from psychophysical approaches takes advantage of the benefits found from video game training while maintaining a tight link to psychophysical designs that enable understanding of mechanisms of perceptual learning and has great potential both as a scientific tool and as therapy to help improve vision. Copyright © 2014 Elsevier B.V. All rights reserved.

A THRESHOLD ANALYSIS OF THE TUNNEL INJECTION LASER.

DTIC Science & Technology

A new threshold analysis of the tunnel injection laser is given that differs from previous treatments in that an additional loss mechanism is...a slight increase in the threshold current density of the tunnel laser. For a device one millimeter long composed of GaAs at 77K, the threshold

Pacing in Olympic track races: competitive tactics versus best performance strategy.

PubMed

Thiel, Christian; Foster, Carl; Banzer, Winfried; De Koning, Jos

2012-01-01

The purpose of this study was to describe pacing strategies in the 800 to 10,000-m Olympic finals. We asked 1) if Olympic finals differed from World Records, 2) how variable the pace was, 3) whether runners faced catastrophic events, and 4) for the winning strategy. Publically available data from the Beijing 2008 Olympic Games gathered by four transponder antennae under the 400-m track were analysed to extract descriptors of pacing strategies. Individual pacing patterns of 133 finalists were visualised using speed by distance plots. Six of eight plots differed from the patterns reported for World Records. The coefficient of running speed variation was 3.6-11.4%. In the long distance finals, runners varied their pace every 100 m by a mean 1.6-2.7%. Runners who were 'dropped' from the field achieved a stable running speed and displayed an endspurt. Top contenders used variable pacing strategies to separate themselves from the field. All races were decided during the final lap. Olympic track finalists employ pacing strategies which are different from World Record patterns. The observed micro- and macro-variations of pace may have implications for training programmes. Dropping off the pace of the leading group is an active step, and the result of interactive psychophysiological decision making.

High power single mode 980 nm AlGaInAs/AlGaAs quantum well lasers with a very low threshold current

NASA Astrophysics Data System (ADS)

Zhen, Dong; Cuiluan, Wang; Hongqi, Jing; Suping, Liu; Xiaoyu, Ma

2013-11-01

To achieve low threshold current as well as high single mode output power, a graded index separate confinement heterostructure (GRIN-SCH) AlGaInAs/AlGaAs quantum well laser with an optimized ridge waveguide was fabricated. The threshold current was reduced to 8 mA. An output power of 76 mW was achieved at 100 mA current at room temperature, with a slope efficiency of 0.83 W/A and a horizon divergent angle of 6.3°. The maximum single mode output power of the device reached as high as 450 mW.

Constant-current regulator improves tunnel diode threshold-detector performance

NASA Technical Reports Server (NTRS)

Cancro, C. A.

1965-01-01

Grounded-base transistor is placed in a tunnel diode threshold detector circuit, and a bias voltage is applied to the tunnel diode. This provides the threshold detector with maximum voltage output and overload protection.

Booster vaccinations: can immunologic memory outpace disease pathogenesis?

PubMed

Pichichero, Michael E

2009-12-01

Almost all current vaccines work by the induction of antibodies in serum or on the mucosa to block adherence of pathogens to epithelial cells or interfere with microbial invasion of the bloodstream. However, antibody levels usually decline after vaccination to undetectable amounts if further vaccination does not occur. Persistence of vaccine-induced antibodies usually goes well beyond the time when they should have decayed to undetectable levels because of ongoing "natural" boosting or other immunologic mechanisms. The production of memory B and T cells is of clear importance, but the likelihood that a memory response will be fast enough in the absence of a protective circulating antibody level likely depends on the pace of pathogenesis of a specific organism. This concept is discussed with regard to Haemophilus influenzae type b, Streptococcus pneumoniae, and Neisseria meningitidis; hepatitis A and B; diphtheria, tetanus, and pertussis; polio, measles, mumps, rubella, and varicella; rotavirus; and human papilloma virus. With infectious diseases for which the pace of pathogenesis is less rapid, some individuals will contract infection before the memory response is fully activated and implemented. With infectious diseases for which the pace of pathogenesis is slow, immune memory should be sufficient to prevent disease.

Triple-site pacing for cardiac resynchronization in permanent atrial fibrillation - Acute phase results from a prospective observational study.

PubMed

Marques, Pedro; Nobre Menezes, Miguel; Lima da Silva, Gustavo; Bernardes, Ana; Magalhães, Andreia; Cortez-Dias, Nuno; Carpinteiro, Luís; de Sousa, João; Pinto, Fausto J

2016-06-01

Multi-site pacing is emerging as a new method for improving response to cardiac resynchronization therapy (CRT), but has been little studied, especially in patients with atrial fibrillation. We aimed to assess the effects of triple-site (Tri-V) vs. biventricular (Bi-V) pacing on hemodynamics and QRS duration. This was a prospective observational study of patients with permanent atrial fibrillation and ejection fraction <40% undergoing CRT implantation (n=40). One right ventricular (RV) lead was implanted in the apex and another in the right ventricular outflow tract (RVOT) septal wall. A left ventricular (LV) lead was implanted in a conventional venous epicardial position. Cardiac output (using the FloTrac™ Vigileo™ system), mean QRS and ejection fraction were calculated. Mean cardiac output was 4.81±0.97 l/min with Tri-V, 4.68±0.94 l/min with RVOT septal and LV pacing, and 4.68±0.94 l/min with RV apical and LV pacing (p<0.001 for Tri-V vs. both BiV). Mean pre-implantation QRS was 170±25 ms, 123±18 ms with Tri-V, 141±25 ms with RVOT septal pacing and LV pacing and 145±19 with RV apical and LV pacing (p<0.001 for Tri-V vs. both BiV and pre-implantation). Mean ejection fraction was significantly higher with Tri-V (30±11%) vs. Bi-V pacing (28±12% with RVOT septal and LV pacing and 28±11 with RV apical and LV pacing) and pre-implantation (25±8%). Tri-V pacing produced higher cardiac output and shorter QRS duration than Bi-V pacing. This may have a significant impact on the future of CRT. Copyright © 2016 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

Risk perception influences athletic pacing strategy.

PubMed

Micklewright, Dominic; Parry, David; Robinson, Tracy; Deacon, Greg; Renfree, Andrew; St Clair Gibson, Alan; Matthews, William J

2015-05-01

The objective of this study is to examine risk taking and risk perception associations with perceived exertion, pacing, and performance in athletes. Two experiments were conducted in which risk perception was assessed using the domain-specific risk taking (DOSPERT) scale in 20 novice cyclists (experiment 1) and 32 experienced ultramarathon runners (experiment 2). In experiment 1, participants predicted their pace and then performed a 5-km maximum effort cycling time trial on a calibrated Kingcycle mounted bicycle. Split times and perceived exertion were recorded every kilometer. In experiment 2, each participant predicted their split times before running a 100-km ultramarathon. Split times and perceived exertion were recorded at seven checkpoints. In both experiments, higher and lower risk perception groups were created using median split of DOSPERT scores. In experiment 1, pace during the first kilometer was faster among lower risk perceivers compared with higher risk perceivers (t(18) = 2.0, P = 0.03) and faster among higher risk takers compared with lower risk takers (t(18) = 2.2, P = 0.02). Actual pace was slower than predicted pace during the first kilometer in both the higher risk perceivers (t(9) = -4.2, P = 0.001) and lower risk perceivers (t(9) = -1.8, P = 0.049). In experiment 2, pace during the first 36 km was faster among lower risk perceivers compared with higher risk perceivers (t(16) = 2.0, P = 0.03). Irrespective of risk perception group, actual pace was slower than predicted pace during the first 18 km (t(16) = 8.9, P < 0.001) and from 18 to 36 km (t(16) = 4.0, P < 0.001). In both experiments, there was no difference in performance between higher and lower risk perception groups. Initial pace is associated with an individual's perception of risk, with low perceptions of risk being associated with a faster starting pace. Large differences between predicted and actual pace suggest that the performance template lacks accuracy, perhaps indicating greater reliance on momentary pacing decisions rather than preplanned strategy.

COMET Program Training Offerings to Support S-NPP and JPSS Utilization

NASA Astrophysics Data System (ADS)

Abshire, W. E.; Dills, P. N.; Weingroff, M.

2015-12-01

Are you up to speed on how to exploit new S-NPP capabilities and products? If not, don't worry, because UCAR's COMET program has self-paced online educational materials that highlight the capabilities and applications of current and next-generation operational polar-orbiting and geostationary satellites. The COMET® Program (www.comet.ucar.edu) has long received funding from NOAA NESDIS as well as EUMETSAT and the Meteorological Service of Canada to support education and training in satellite meteorology. By partnering with experts from NOAA-NESDIS and its Cooperative Institutes, Meteorological Service of Canada, EUMETSAT, the Naval Research Laboratory and others, COMET's self-paced training stimulates greater use of current and future satellite observations and products. Right now, over 70 satellite-focused, self-paced, online materials are freely available in English via the MetEd Web site at http://meted.ucar.edu/topics/satellite. Additionally, quite a few lessons are also available in Spanish and French making training more easily accessible to an international audience. This presentation will focus on COMET's latest satellite training and education offerings that are directly applicable to data and products from the S-NPP and JPSS satellite series. A recommended set of lessons for users who wish to learn more will be highlighted, including excerpts from the newest materials on the Suomi NPP VIIRS imager and its applications, as well as advances in nighttime visible observation with the VIIRS Day-Night Band. We'll show how the lessons introduce users to the advances these systems bring to forecasting, numerical weather prediction, and environmental monitoring. Finally, new relevant training initiatives will also be presented.

Application of decision-making theory to the regulation of muscular work rate during self-paced competitive endurance activity.

PubMed

Renfree, Andrew; Martin, Louise; Micklewright, Dominic; St Clair Gibson, Alan

2014-02-01

Successful participation in competitive endurance activities requires continual regulation of muscular work rate in order to maximise physiological performance capacities, meaning that individuals must make numerous decisions with regards to the muscular work rate selected at any point in time. Decisions relating to the setting of appropriate goals and the overall strategic approach to be utilised are made prior to the commencement of an event, whereas tactical decisions are made during the event itself. This review examines current theories of decision-making in an attempt to explain the manner in which regulation of muscular work is achieved during athletic activity. We describe rational and heuristic theories, and relate these to current models of regulatory processes during self-paced exercise in an attempt to explain observations made in both laboratory and competitive environments. Additionally, we use rational and heuristic theories in an attempt to explain the influence of the presence of direct competitors on the quality of the decisions made during these activities. We hypothesise that although both rational and heuristic models can plausibly explain many observed behaviours in competitive endurance activities, the complexity of the environment in which such activities occur would imply that effective rational decision-making is unlikely. However, at present, many proposed models of the regulatory process share similarities with rational models. We suggest enhanced understanding of the decision-making process during self-paced activities is crucial in order to improve the ability to understand regulation of performance and performance outcomes during athletic activity.

The effect of visitor number and spice provisioning in pacing expression by jaguars evaluated through a case study.

PubMed

Vidal, L S; Guilherme, F R; Silva, V F; Faccio, M C S R; Martins, M M; Briani, D C

2016-06-01

Captive animals exhibit stereotypic pacing in response to multiple causes, including the inability to escape from human contact. Environmental enrichment techniques can minimize pacing expression. By using an individual-based approach, we addressed whether the amount of time two males and a female jaguar (Panthera onca) devote to pacing varied with the number of visitors and tested the effectiveness of cinnamon and black pepper in reducing pacing. The amount of time that all jaguars engaged in pacing increased significantly with the number of visitors. Despite the difference between the males regarding age and housing conditions, both devoted significantly less time to pacing following the addition of both spices, which indicates their suitability as enrichment techniques. Mean time devoted to pacing among the treatments did not differ for the female. Our findings pointed out to the validity of individual-based approaches, as they can reveal how suitable olfactory stimuli are to minimizing stereotypies irrespective of particular traits.

Prevention of Adverse Electrical and Mechanical Remodeling with Bi-Ventricular Pacing in a Rabbit Model of Myocardial Infarction

PubMed Central

Saba, Samir; Mathier, Michael A.; Mehdi, Haider; Gursoy, Erdal; Liu, Tong; Choi, Bum-Rak; Salama, Guy; London, Barry

2008-01-01

Background: Biventricular (BIV) pacing can improve cardiac function in heart failure (HF). Objective: To investigate the mechanisms of benefit of BIV pacing using a rabbit model of myocardial infarction (MI). Methods: New Zealand White rabbits were divided into 4 groups: sham-operated (C), MI with no pacing (MI), MI with right ventricular pacing (MI+RV), and MI with BIV pacing (MI+BIV), and underwent serial electrocardiograms and echocardiograms. At 4 weeks, hearts were excised and tissue was extracted from various areas of the left ventricle (LV). Results: Four weeks after coronary ligation, BIV pacing prevented systolic and diastolic dilation of the LV as well as the reduction in its fractional shortening, restored the QRS width and the rate-dependent QT intervals to their baseline values, and prevented the decline of the ether-a-go-go (erg) protein levels. This prevention of remodeling was not documented in the MI+RV groups. Conclusions: In this rabbit model of BIV pacing and MI, we demonstrate prevention of adverse mechanical and electrical remodeling of the heart. These changes may underlie some of the benefits seen with BIV pacing in HF patients with more severe LV dysfunction. PMID:18180026

The efficacy of self-paced study in multitrial learning.

PubMed

de Jonge, Mario; Tabbers, Huib K; Pecher, Diane; Jang, Yoonhee; Zeelenberg, René

2015-05-01

In 2 experiments we investigated the efficacy of self-paced study in multitrial learning. In Experiment 1, native speakers of English studied lists of Dutch-English word pairs under 1 of 4 imposed fixed presentation rate conditions (24 × 1 s, 12 × 2 s, 6 × 4 s, or 3 × 8 s) and a self-paced study condition. Total study time per list was equated for all conditions. We found that self-paced study resulted in better recall performance than did most of the fixed presentation rates, with the exception of the 12 × 2 s condition, which did not differ from the self-paced condition. Additional correlational analyses suggested that the allocation of more study time to difficult pairs than to easy pairs might be a beneficial strategy for self-paced learning. Experiment 2 was designed to test this hypothesis. In 1 condition, participants studied word pairs in a self-paced fashion without any restrictions. In the other condition, participants studied word pairs in a self-paced fashion but total study time per item was equated. The results showed that allowing self-paced learners to freely allocate study time over items resulted in better recall performance. (c) 2015 APA, all rights reserved).

Income (In-) Adequacy? The Official Poverty Line, Possible Changes, and Some Historical Lessons.

ERIC Educational Resources Information Center

Fisher, Gordon

1999-01-01

Examines the current official poverty thresholds (including Orshansky's thresholds) and the possibility that a new poverty measure may be adopted soon, discussing the thresholds from a historical perspective. Lessons drawn from the history of poverty thresholds and of early unofficial poverty lines in the United States are included. Recent…

42 CFR 460.102 - Interdisciplinary team.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 4 2014-10-01 2014-10-01 false Interdisciplinary team. 460.102 Section 460.102... ELDERLY (PACE) PACE Services § 460.102 Interdisciplinary team. (a) Basic requirement. A PACE organization must meet the following requirements: (1) Establish an interdisciplinary team at each Pace center to...

42 CFR 460.102 - Interdisciplinary team.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 4 2011-10-01 2011-10-01 false Interdisciplinary team. 460.102 Section 460.102... ELDERLY (PACE) PACE Services § 460.102 Interdisciplinary team. (a) Basic requirement. A PACE organization must meet the following requirements: (1) Establish an interdisciplinary team at each Pace center to...

42 CFR 460.102 - Interdisciplinary team.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 4 2012-10-01 2012-10-01 false Interdisciplinary team. 460.102 Section 460.102... ELDERLY (PACE) PACE Services § 460.102 Interdisciplinary team. (a) Basic requirement. A PACE organization must meet the following requirements: (1) Establish an interdisciplinary team at each Pace center to...

42 CFR 460.102 - Interdisciplinary team.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 4 2013-10-01 2013-10-01 false Interdisciplinary team. 460.102 Section 460.102... ELDERLY (PACE) PACE Services § 460.102 Interdisciplinary team. (a) Basic requirement. A PACE organization must meet the following requirements: (1) Establish an interdisciplinary team at each Pace center to...

42 CFR 460.102 - Interdisciplinary team.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 4 2010-10-01 2010-10-01 false Interdisciplinary team. 460.102 Section 460.102... ELDERLY (PACE) PACE Services § 460.102 Interdisciplinary team. (a) Basic requirement. A PACE organization must meet the following requirements: (1) Establish an interdisciplinary team at each Pace center to...

Effect of transcranial direct current stimulation on vestibular-ocular and vestibulo-perceptual thresholds.

PubMed

Kyriakareli, Artemis; Cousins, Sian; Pettorossi, Vito E; Bronstein, Adolfo M

2013-10-02

Transcranial direct current stimulation (tDCS) was used in 17 normal individuals to modulate vestibulo-ocular reflex (VOR) and self-motion perception rotational thresholds. The electrodes were applied over the temporoparietal junction bilaterally. Both vestibular nystagmic and perceptual thresholds were increased during as well as after tDCS stimulation. Body rotation was labeled as ipsilateral or contralateral to the anode side, but no difference was observed depending on the direction of rotation or hemisphere polarity. Threshold increase during tDCS was greater for VOR than for motion perception. 'Sham' stimulation had no effect on thresholds. We conclude that tDCS produces an immediate and sustained depression of cortical regions controlling VOR and movement perception. Temporoparietal areas appear to be involved in vestibular threshold modulation but the differential effects observed between VOR and perception suggest a partial dissociation between cortical processing of reflexive and perceptual responses.

Comparison of DDD versus VVIR pacing modes in elderly patients with atrioventricular block.

PubMed

Kılıçaslan, Barış; Vatansever Ağca, Fahriye; Kılıçaslan, Esin Evren; Kınay, Ozan; Tigen, Kürşat; Cakır, Cayan; Nazlı, Cem; Ergene, Oktay

2012-06-01

Dual-chamber pacing is believed to have an advantage over single-chamber ventricular pacing. The aim of this study was to determine whether elderly patients who have implanted pacemakers for complete atrioventricular block gain significant benefits from dual-chamber (DDD) pacemakers compared with single chamber ventricular (VVIR) pacemakers. This study was designed as a randomized, two-period crossover study-each pacing mode was maintained for 1 month. Thirty patients (16 men, mean age 68.87 ± 6.89 years) with implanted DDD pacemakers were submitted to a standard protocol, which included an interview, pacemaker syndrome assessment, health related quality of life (HRQoL) questionnaires assessed by an SF-36 test, 6-minute walk test (6MWT), and transthoracic echocardiographic examinations. All of these parameters were obtained on both DDD and VVIR mode pacing. Paired data were compared. HRQoL scores were similar, and 6MWT results did not differ between the two groups. VVIR pacing elicited significant enlargement of the left atrium and impaired left ventricular diastolic functions as compared with DDD pacing. Two patients reported subclinical pacemaker syndrome, but this was not statistically significant. Our study revealed that in active elderly patients with complete heart block, DDD pacing and VVIR pacing yielded similar improvements in QoL and exercise performance. However, after a short follow-up period, we noted that VVIR pacing caused significant left atrial enlargement and impaired left ventricular diastolic functions.

Managing Current Developments in SEN and Inclusion: Developing Confidence in New Teachers

ERIC Educational Resources Information Center

Richards, Gill

2010-01-01

Developments in special and inclusive education have lead to increasing challenges for teachers. Initial Teacher Education has struggled to keep pace with these developments and equip all newly qualified teachers with the skills required to meet the needs of children with SEN. This paper reflects upon recent national initiatives designed to…

Computational challenges in modeling gene regulatory events.

PubMed

Pataskar, Abhijeet; Tiwari, Vijay K

2016-10-19

Cellular transcriptional programs driven by genetic and epigenetic mechanisms could be better understood by integrating "omics" data and subsequently modeling the gene-regulatory events. Toward this end, computational biology should keep pace with evolving experimental procedures and data availability. This article gives an exemplified account of the current computational challenges in molecular biology.

Predictors of Retention and Passing National Council Licensure Examination for Registered Nurses

ERIC Educational Resources Information Center

Elkins, Nancy

2013-01-01

The current nursing shortage has challenged colleges to educate nurses at a faster pace than in previous times. Successful completion of the nursing programs and passing the National Council Licensure Examination for Registered Nurses (NCLEX-RN) exam is important for the students, faculty, and nursing programs. The purpose of this retrospective…

Assessing the Applicability of 3D Holographic Technology as an Enhanced Technology for Distance Learning

ERIC Educational Resources Information Center

Kalansooriya, Pradeep; Marasinghe, Ashu; Bandara, K. M. D. N.

2015-01-01

Distance learning has provided an excellent platform for students in geographically remote locations while enabling them to learn at their own pace and convenience. A number of technologies are currently being utilized to conceptualize, design, enhance and foster distance learning. Teleconferences, electronic field trips, podcasts, webinars, video…

Implementing Educational Science Television in the Third Grade Classroom

ERIC Educational Resources Information Center

Shear, Ashley

2010-01-01

When educating children, teachers need to be aware of ways to make learning engaging. For young children, with their high exposure to current technology, listening to one person all day can be boring. Children today understand technology at a faster pace than did children of previous generations, so teachers need to implement more technology…

Independent Study in High School Chemistry: A Progress Report.

ERIC Educational Resources Information Center

DeRose, James V.

This is a progress report of an independent study program in chemistry at a senior high school. Currently in its fourth year of operation, the program is designed to provide students with individualized, self-paced instruction in college-preparatory chemistry. The author discusses the rationale for the program, the initial phases, the problems…

Using a Latino Lens to Reimagine Aid Design and Delivery

ERIC Educational Resources Information Center

Santiago, Deborah A.

2013-01-01

Federal financial aid is critical to student access and success in postsecondary education for many students, including most Latinos. However, three current realities are challenging the effectiveness of federal financial aid policy today: (1) the inability of federal aid to keep pace with the increase in college costs for students; (2) the…

An Analysis of States' Policies Regarding Social Media Use in Education

ERIC Educational Resources Information Center

Miller, Janette K.

2016-01-01

This policy analysis project focused on states' policies regarding social media use in education. Currently, policies, practices and laws are not keeping pace with the rapidly changing nature of technology. As a result of the quick advancement of social media practices, the need exists for organic policies and practices within the educational…

The Reality of Reference: Responsibilities and Competencies for Current Reference Librarians

ERIC Educational Resources Information Center

Saunders, Laura

2012-01-01

Academic reference services face great challenges as they cope with the pace of technological change, competition from other information service providers, and tight budgets. In fact, some critics suggest that reference services are no longer relevant or necessary as more information moves online. This study examines a nationwide survey that…

Education in China

ERIC Educational Resources Information Center

Fengzhen, Yang

2002-01-01

In the past 20 years, China's economy has been developing rapidly. Yet is China's education keeping up the same pace as its economic development? What is the current situation for China's education? With the advent of knowledge-based economy, how will education in China adjust itself in order to meet the growing demands of economy? This paper will…

"Because We Can": Pluralism and Structural Reform in Education

ERIC Educational Resources Information Center

Glatter, Ron

2017-01-01

This article revisits a major paper published a decade ago by the political scientist Christopher Pollitt about the highly activist approach to the reform of public services taken in England in recent years. In education, the pace has accelerated since that paper appeared. The weaknesses of the current structures and processes resulting from this…

Developing a Global Perspective in/for Science Teacher Education: The Case of Pollination

ERIC Educational Resources Information Center

Reis, Giuliano

2014-01-01

Science educators at all levels continuously struggle to keep pace with the rapidly developing understanding of the causes and potential solutions to current environmental issues while also trying to enthuse a new generation of passionate and knowledgeable scientists. However, how can future science teachers make science education more attractive…

Keeping Pace with Current Issues in Reporting Suicide and Mental Illness

ERIC Educational Resources Information Center

Skehan, Jaelea; Burns, Lynette Sheridan; Hazell, Trevor

2007-01-01

The Response Ability Project, funded under the Mindframe National Media Initiative in Australia, seeks to influence tertiary curricula so that graduates in journalism will be aware of and able to respond appropriately to issues relating to suicide and mental illness. Whilst the initial multi-media resources developed to support journalism…

Processing Efficiency in Preschoolers' Memory Span: Individual Differences Related to Age and Anxiety

ERIC Educational Resources Information Center

Visu-Petra, Laura; Miclea, Mircea; Cheie, Lavinia; Benga, Oana

2009-01-01

In self-paced auditory memory span tasks, the microanalysis of response timing measures represents a developmentally sensitive measure, providing insights into the development of distinct processing rates during recall performance. The current study first examined the effects of age and trait anxiety on span accuracy (effectiveness) and response…

Innovation Efforts in Education and School Administration: Views of Turkish School Administrators

ERIC Educational Resources Information Center

Akin, Ugur

2016-01-01

Problem Statement: In the current information era, nearly all organizations make efforts to make innovations in the fields of information, communication, technology, etc. Educational organizations are no exception to this trend. Moreover, it can be argued that educational institutions make a particular effort to rapidly keep pace with change. In…

An efficient estimator to monitor rapidly changing forest conditions

Treesearch

Raymond L. Czaplewski; Michael T. Thompson; Gretchen G. Moisen

2012-01-01

Extensive expanses of forest often change at a slow pace. In this common situation, FIA produces informative estimates of current status with the Moving Average (MA) method and post-stratification with a remotely sensed map of forest-nonforest cover. However, MA "smoothes out" estimates over time, which confounds analyses of temporal trends; and post-...

Enhancing Scientific Practice and Education through Collaborative Digital Libraries.

ERIC Educational Resources Information Center

Maini, Gaurav; Leggett, John J.; Ong, Teongjoo; Wilson, Hugh D.; Reed, Monique D.; Hatch, Stephan L.; Dawson, John E.

The need for accurate and current scientific information in the fast paced Internet-aware world has prompted the scientific community to develop tools that reduce the scientist's time and effort to make digital information available to all interested parties. The availability of such tools has made the Internet a vast digital repository of…

Preparing for the Real Web Generation

ERIC Educational Resources Information Center

Pence, Harry E.

2007-01-01

Some have called the current generation of college students the Web generation. They are wrong! The pace of technology change continues to quicken. The effects of globalization and social networking have not yet had their full impact. At best, the present students represent a transitional group. The tools we use define us, and the media revolution…

Integrating CALL into an Iranian EAP Course: Constraints and Affordances

ERIC Educational Resources Information Center

Mehran, Parisa; Alizadeh, Mehrasa

2015-01-01

Iranian universities have recently displayed a growing interest in integrating Computer-Assisted Language Learning (CALL) into teaching/learning English. The English for Academic Purposes (EAP) context, however, is not keeping pace with the current changes since EAP courses are strictly text-based and exam-oriented, and little research has thus…

Remote Access Laboratories in Australia and Europe

ERIC Educational Resources Information Center

Ku, H.; Ahfock, T.; Yusaf, T.

2011-01-01

Remote access laboratories (RALs) were first developed in 1994 in Australia and Switzerland. The main purposes of developing them are to enable students to do their experiments at their own pace, time and locations and to enable students and teaching staff to get access to facilities beyond their institutions. Currently, most of the experiments…

The Current Status of Women's Employment in Outdoor Leadership.

ERIC Educational Resources Information Center

Loeffler, T. A.

A common assumption in the outdoor field has been that women's development as outdoor leaders has not kept pace with their participation in outdoor adventure activities. A survey about women's employment was mailed to 103 outdoor education programs with an adventure component; 62 responded. The programs served 160,585 participants in 1994, of…

ENVIRONMENTAL JUSTICE ASSESSMENT OF INDUSTRIAL PORK PRODUCTION IN MISSISSIPPI AND NORTH CAROLINA

EPA Science Inventory

There are large numbers of industrial swine operations that may pose a risk to the health and quality of life of these communities if the industry continues to grow at its current pace. This study intends to evaluate this situation as one of the major and emerging environment...

Outpatient Art Therapy with Multiple Personality Disorder: A Survey of Current Practice.

ERIC Educational Resources Information Center

Mills, Anne

1995-01-01

Reports findings of a 1993 questionnaire completed by 46 North American art therapists that focuses on the outpatient treatment of multiple personality disorder. Includes information on role in diagnosing, fees and third-party payment, and therapeutic activities. Treatment issues include pacing and containment, and managing the client's chronic…

Single and Combined Effects of Curcumin and Trans-cinnamaldehyde to Inhibit the Growth of Salmonella Typhimurium

USDA-ARS?s Scientific Manuscript database

In the last 15 years Salmonella has stayed at a steady pace with no decrease than other foodborne pathogens. Currently, the antimicrobial resistance is one of the most serious health threats and there is a strong needs to search for alternative therapeutics including herbal plants extracts. Curcuma...

Beyond the Basics: Award-Winning Scholastic Newspapers Define Excellence.

ERIC Educational Resources Information Center

Konkle, Bruce E.

2001-01-01

Considers how a scholastic newspaper staff becomes "Award-Winning." Notes that it is important to consider developing effective and functional infographic formats; editing type and page designs with an eye for consistency; writing stories that are all targeted to their teen audience; or modernizing design to keep pace with current publication…

NEW GRADUATE PROGRAMS IN MODERN FOREIGN LANGUAGES, WHY THEY ARE NEEDED.

ERIC Educational Resources Information Center

TURNER, DAYMOND E., JR.

ADDITIONAL DOCTORAL PROGRAMS ARE NEEDED IN MODERN FOREIGN LANGUAGES. CURRENT PRODUCTION OF GRADUATE DEGREES APPEARS SCARCELY ADEQUATE FOR REPLACING FACULTY WHO ANNUALLY LEAVE TEACHING BECAUSE OF DEATH, ILLNESS, RETIREMENT, OR CHANGE OF VOCATION. THE SUPPLY WILL HARDLY KEEP PACE WITH THE DEMAND CREATED BY THE ESTABLISHMENT OF NEW INSTITUTIONS OF…

Speed Kills, Speed Thrills: Constraining and Enabling Accelerations in Academic Work-Life

ERIC Educational Resources Information Center

Vostal, Filip

2015-01-01

Intensification, speed of change and faster pace of life have recently emerged as significant issues in studies analysing the current academic climate. This article takes up the "social acceleration thesis" as a conceptual resource for capturing the relationship between the individual experience of time and the changing structure and…

Transverse tripolar stimulation of peripheral nerve: a modelling study of spatial selectivity.

PubMed

Deurloo, K E; Holsheimer, J; Boom, H B

1998-01-01

Various anode-cathode configurations in a nerve cuff are modelled to predict their spatial selectivity characteristics for functional nerve stimulation. A 3D volume conductor model of a monofascicular nerve is used for the computation of stimulation-induced field potentials, whereas a cable model of myelinated nerve fibre is used for the calculation of the excitation thresholds of fibres. As well as the usual configurations (monopole, bipole, longitudinal tripole, 'steering' anode), a transverse tripolar configuration (central cathode) is examined. It is found that the transverse tripole is the only configuration giving convex recruitment contours and therefore maximises activation selectivity for a small (cylindrical) bundle of fibres in the periphery of a monofascicular nerve trunk. As the electrode configuration is changed to achieve greater selectivity, the threshold current increases. Therefore threshold currents for fibre excitation with a transverse tripole are relatively high. Inverse recruitment is less extreme than for the other configurations. The influences of several geometrical parameters and model conductivities of the transverse tripole on selectivity and threshold current are analysed. In chronic implantation, when electrodes are encapsulated by a layer of fibrous tissue, threshold currents are low, whereas the shape of the recruitment contours in transverse tripolar stimulation does not change.

HgCdTe 256x256 NWIR FPA

NASA Technical Reports Server (NTRS)

Vural, Kadri; Blessinger, Michael; Chen, Jenkon; Kleinhans, William

1989-01-01

Researchers developed a HgCdTe 256x256 focal plane array (FPA) which operates in the 1 to 5 micron band. This is presently the largest demonstrated HgCdTe FPA. The detector material is HgCdTe on sapphire (PACE-1 technology) which has a low thermal expansion mismatch with silicon. The multiplexer is a CMOS FET-switch device processed through a commercial silicon foundry. The multiplexer input is direct injection and the charge capacity is about 2 times 10 to the 7th power electrons. The kTC limited read noise is 400 electrons. Researchers demonstrated high background imaging using the device. The broadband quantum efficiency is measured to be 59 percent. Dark currents less than 0.1 pA were measured at 77 K for detectors processed on PACE-1 material with 4.9 microns cutoff. The dark currents decrease as the temperature is lowered, and researchers are presently studying the T less than 77 K characteristics. The interconnect yield is greater than 95 percent. The devices are available for astronomical applications.

Symptoms of chronic fatigue syndrome/myalgic encephalopathy are not determined by activity pacing when measured by the chronic pain coping inventory.

PubMed

Thompson, D P; Antcliff, D; Woby, S R

2018-03-01

Chronic fatigue syndrome/myalgic encephalopathy (CFS/ME) is a chronic illness which can cause significant fatigue, pain and disability. Activity pacing is frequently advocated as a beneficial coping strategy, however, it is unclear whether pacing is significantly associated with symptoms in people with CFS/ME. The first aim of this study was therefore to explore the cross-sectional associations between pacing and levels of pain, disability and fatigue. The second aim was to explore whether changes in activity pacing following participation in a symptom management programme were related to changes in clinical outcomes. Cross-sectional study exploring the relationships between pacing, pain, disability and fatigue (n=114) and pre-post treatment longitudinal study of a cohort of patients participating in a symptom management programme (n=35). Out-patient physiotherapy CFS/ME service. One-hundred and fourteen adult patients with CFS/ME. Pacing was assessed using the chronic pain coping inventory. Pain was measured using a Numeric Pain Rating Scale, fatigue with the Chalder Fatigue Scale and disability with the Fibromyalgia Impact Questionnaire. No significant associations were observed between activity pacing and levels of pain, disability or fatigue. Likewise, changes in pacing were not significantly associated with changes in pain, disability or fatigue following treatment. Activity pacing does not appear to be a significant determinant of pain, fatigue or disability in people with CFS/ME when measured with the chronic pain coping index. Consequently, the utility and measurement of pacing require further investigation. Copyright © 2017 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

Influence of pacing site characteristics on response to cardiac resynchronization therapy.

PubMed

Wong, Jorge A; Yee, Raymond; Stirrat, John; Scholl, David; Krahn, Andrew D; Gula, Lorne J; Skanes, Allan C; Leong-Sit, Peter; Klein, George J; McCarty, David; Fine, Nowell; Goela, Aashish; Islam, Ali; Thompson, Terry; Drangova, Maria; White, James A

2013-07-01

Transmural scar occupying left ventricular (LV) pacing regions has been associated with reduced response to cardiac resynchronization therapy (CRT). However, spatial influences of lead tip delivery relative to scar at both pacing sites remain poorly explored. This study evaluated scar distribution relative to LV and right ventricular (RV) lead tip placement through coregistration of late gadolinium enhancement MRI and cardiac computed tomographic (CT) findings. Influences on CRT response were assessed by serial echocardiography. Sixty patients receiving CRT underwent preimplant late gadolinium enhancement MRI, postimplant cardiac CT, and serial echocardiography. Blinded segmental evaluations of mechanical delay, percentage scar burden, and lead tip location were performed. Response to CRT was defined as a reduction in LV end-systolic volume ≥15% at 6 months. The mean age and LV ejection fraction were 64±9 years and 25±7%, respectively. Mean scar volume was higher among CRT nonresponders for both the LV (23±23% versus 8±14% [P=0.01]) and RV pacing regions (40±32% versus 24±30% [P=0.04]). Significant pacing region scar was identified in 13% of LV pacing regions and 37% of RV pacing regions. Absence of scar in both regions was associated with an 81% response rate compared with 55%, 25%, and 0%, respectively, when the RV, LV, or both pacing regions contained scar. LV pacing region dyssynchrony was not predictive of response. Myocardial scar occupying the LV pacing region is associated with nonresponse to CRT. Scar occupying the RV pacing region is encountered at higher frequency and seems to provide a more intermediate influence on CRT response.

DDD versus VVIR pacing in patients, ages 70 and over, with complete heart block.

PubMed

Ouali, Sana; Neffeti, Elyes; Ghoul, Karima; Hammas, Sami; Kacem, Slim; Gribaa, Rim; Remedi, Fahmi; Boughzela, Essia

2010-05-01

Dual-chamber pacing is believed to have an advantage over single-chamber ventricular pacing. The aim of the study was to determine whether elderly patients with implanted pacemaker for complete atrioventricular block gain significant benefit from dual-chamber (DDD) compared with single-chamber ventricular demand (VVIR). The study was designed as a double-blind randomized two-period crossover study-each pacing mode was maintained for 3 months. Thirty patients (eight men, mean age 76.5 +/- 4.3 years) with implanted PM were submitted to a standard protocol, which included an interview, functional class assessment, quality of life (QoL) questionnaires, 6-minute walk test, and transthoracic echocardiographic examinations. QoL was measured by the SF-36. All these parameters were obtained on DDD mode pacing and VVIR mode pacing. Paired data were compared. QoL was significantly different between the two groups and showed the best values in DDD. Overall, no patient preferred VVIR mode, 18 preferred DDD mode, and 12 expressed no preference. No differences in mean walking distances were observed between patients with single-chamber and dual-chamber pacing. VVI pacing elicited marked decrease in left ventricle ejection fraction and significant enlargement of the left atrium. DDD pacing resulted in significant increase of the peak systolic velocities in lateral mitral annulus and septal mitral annulus. Early diastolic velocities on both sides of mitral annulus did not change. In active elderly patients with complete heart block, DDD pacing is associated with improved quality of life and systolic ventricular function compared with VVI pacing.

Low-threshold high-T/0/ constricted double heterojunction AlGaAs diode lasers

NASA Technical Reports Server (NTRS)

Botez, D.; Connolly, J. C.

1980-01-01

Constricted double heterojunction diode lasers of relatively low CW thresholds (28-40 mA) are obtained by growing structures that maximize the amount of current flow into the lasing spot. These values are obtained while still using standard 10 microns wide oxide-defined stripe contacts. Over the 20-70 C temperature interval, threshold current temperature coefficients as high as 320 C and a virtually constant external differential quantum efficiency, are found.

42 CFR 460.186 - PACE premiums.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 4 2011-10-01 2011-10-01 false PACE premiums. 460.186 Section 460.186 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE...

"U-Pace" Instruction: Improving Student Success by Integrating Content Mastery and Amplified Assistance

ERIC Educational Resources Information Center

Reddy, Diane M.; Pfeiffer, Heidi M.; Fleming, Raymond; Ports, Katie A.; Pedrick, Laura E.; Barnack-Tavlaris, Jessica L.; Jirovec, Danielle L.; Helion, Alicia M.; Swain, Rodney A.

2013-01-01

"U-Pace," an instructional intervention, has potential for widespread implementation because student behavior recorded in any learning management system is used by "U-Pace" instructors to tailor coaching of student learning based on students' strengths and motivations. "U-Pace" utilizes an online learning environment…

Unintended Outcomes of University-Community Partnerships: Building Organizational Capacity with PACE International Partners

ERIC Educational Resources Information Center

Lloyd, Kate; Clark, Lindie; Hammersley, Laura; Baker, Michaela; Rawlings-Sanaei, Felicity; D'ath, Emily

2015-01-01

Professional and Community Engagement (PACE) at Macquarie University provides experiential opportunities for students and staff to contribute to more just, inclusive and sustainable societies by engaging in activities with partner organizations. PACE International offers a range of opportunities with partners overseas. Underpinning PACE is a…

Rigorous Characterisation of a Novel, Statistically-Based Ocean Colour Algorithm for the PACE Mission

NASA Astrophysics Data System (ADS)

Craig, S. E.; Lee, Z.; Du, K.; Lin, J.

2016-02-01

An approach based on empirical orthogonal function (EOF) analysis of ocean colour spectra has been shown to accurately derive inherent optical properties (IOPs) and chlorophyll concentration in scenarios, such as optically complex waters, where standard algorithms often perform poorly. The algorithm has been successfully used in a number of regional applications, and has also shown promise in a global implementation based on the NASA NOMAD data set. Additionally, it has demonstrated the unique ability to derive ocean colour products from top of atmosphere (TOA) signals with either no or minimal atmospheric correction applied. Due to its high potential for use over coastal and inland waters, the EOF approach is currently being rigorously characterised as part of a suite of approaches that will be used to support the new NASA ocean colour mission, PACE (Pre-Aerosol, Clouds and ocean Ecosystem). A major component in this model characterisation is the generation of a synthetic TOA data set using a coupled ocean-atmosphere radiative transfer model, which has been run to mimic PACE spectral resolution, and under a wide range of geographical locations, water constituent concentrations, and sea surface and atmospheric conditions. The resulting multidimensional data set will be analysed, and results presented on the sensitivity of the model to various combinations of parameters, and preliminary conclusions made regarding the optimal implementation strategy of this promising approach (e.g. on a global, optical water type or regional basis). This will provide vital guidance for operational implementation of the model for both existing satellite ocean colour sensors and the upcoming PACE mission.

The Running Performance Profile of Elite Gaelic Football Match-Play.

PubMed

Malone, Shane; Solan, Barry; Collins, Kieran

2017-01-01

Malone, S, Solan, B, and Collins, K. The running performance profile of elite Gaelic football match-play. J Strength Cond Res 31(1): 30-36, 2017-The current study examined (a) the match running performance of Gaelic football and (b) the decrement in match running performance with respect to position. Global positioning satellite system technologies (4-Hz; VX Sport) were used with 3 elite intercounty teams across 3 full seasons with 250 full game data sets collected. Game movements were classified according to game actions and distance covered across speed zone thresholds (total distance [TD], high-speed running distance [HSRD; ≥17 km·h], sprint distance [SD; ≥22 km·h]; accelerations [n]; peak speed [km·h]). The influence of running performance in each quarter on the subsequent quarter was analyzed across all positional roles. The mean (±SD) TD and HSRD covered during the game were 8,889 ± 1,448 m and 1,596 ± 594 m, respectively. Results show a temporal profile for TD with reductions in the second (-4.1%), third (-5.9%) and fourth (-3.8%) quarters, respectively. There was a significant reduction in HSRD in the second (-8.8%), third (-15.9%), and fourth (-19.8%) quarters when compared to the first quarter (p < 0.001). Positional differences were observed for distance-based measures with the middle 3 positions (half-back, midfield, and half-forward) completing the highest running performances. These positions also showed increased decrements in TD and HSRD and SD across quarters. The current data indicate a reduction in exercise intensity over the duration of elite Gaelic football match-play. It is unclear if this reduction is because of fatigue, pacing, contextual factors, or nutritional strategies employed by players.

SONOS Nonvolatile Memory Cell Programming Characteristics

NASA Technical Reports Server (NTRS)

MacLeod, Todd C.; Phillips, Thomas A.; Ho, Fat D.

2010-01-01

Silicon-oxide-nitride-oxide-silicon (SONOS) nonvolatile memory is gaining favor over conventional EEPROM FLASH memory technology. This paper characterizes the SONOS write operation using a nonquasi-static MOSFET model. This includes floating gate charge and voltage characteristics as well as tunneling current, voltage threshold and drain current characterization. The characterization of the SONOS memory cell predicted by the model closely agrees with experimental data obtained from actual SONOS memory cells. The tunnel current, drain current, threshold voltage and read drain current all closely agreed with empirical data.

Observational and Modeling Studies of Mixed-Phase Arctic Stratus: Results From M-PACE and Future Investigations as a Part of SEARCH

NASA Astrophysics Data System (ADS)

de Boer, G.; Eloranta, E. W.; Tripoli, G. J.; Hashino, T.

2005-12-01

A combination of unique observational and modeling tools is being utilized at the University of Wisconsin-Madison to investigate mixed-phase Arctic stratus formation and evolution, and aerosol influence on these processes. The combination of detailed measurements and advanced simulation techniques provides increased insight into processes governing the existence of these cloud structures. Simulations are completed using the Univ. of Wisconsin Non-Hydrostatic Modeling System (UW-NMS). The NMS is fully scalable, and currently being updated to include the Spectral Habitat Ice Prediction System (SHIPS). This new form of microphysics is built on interacting predictive systems for ice and liquid hydrometeors, and aerosols. The hydrometeor size spectra evolve through a modified spectral approach. No a-priori assumptions are made about ice characteristics such as habit, size and density. Instead, they evolve freely. The Univ. of Wisconsin Arctic High-Spectral Resolution Lidar (UW-AHSRL) was designed for long-term unattended Arctic operation and features unique measurement capabilities. Utilizing a molecular reference channel, the AHSRL provides absolutely calibrated measurements of aerosol backscatter cross-section, polarization, and optical depth, in addition to traditional lidar backscatter profiles. Algorithms utilizing AHSRL data in conjunction with millimeter radar data determine microphysical properties such as particle equivalent radius, and potentially liquid and ice water content. The AHSRL was deployed to Barrow, AK as part of M-PACE and is currently located in Eureka, Canada for the SEARCH campaign. Both of these locations host a NOAA Millimeter Wave Cloud Radar, aiding in the implementation of the above-mentioned algorithms. The AHSRL, combined with additional cloud and aerosol measurement instrumentation at these Arctic locations, provides an expansive source of mixed-phase cloud data to be used individually and as validation for UW-NMS simulations. We will outline current work being completed at the Univ. of Wisconsin, as well as present results from M-PACE simulations and data analysis and preliminary SEARCH measurements.

Pacing for neurally mediated syncope: is placebo powerless?

PubMed

Brignole, M; Sutton, R

2007-01-01

After two recent controlled trials failed to prove superiority of cardiac pacing over placebo in patients affected by neurally mediated syncope, a widely accepted opinion is that cardiac pacing therapy is not very effective and that a strong placebo effect exists. To measure the effect of placebo pacing therapy. We compared the recurrence rate of syncope during placebo vs. no treatment in controlled trials of drug or pacing therapy. Syncope recurred in 38% of 252 patients randomized to placebo pooled from five trials vs. 34% of 881 patients randomized to no treatment pooled from eight trials. The corresponding recurrence rate with active cardiac pacing was 15% in 203 patients from six trials. Placebo is not an effective therapy for neurally mediated syncope. Different selection criteria in patients who are candidates for cardiac pacing-for example, presence, absence, or severity of the cardioinhibitory reflex may separate positive from negative trials.

Definition of temperature thresholds: the example of the French heat wave warning system.

PubMed

Pascal, Mathilde; Wagner, Vérène; Le Tertre, Alain; Laaidi, Karine; Honoré, Cyrille; Bénichou, Françoise; Beaudeau, Pascal

2013-01-01

Heat-related deaths should be somewhat preventable. In France, some prevention measures are activated when minimum and maximum temperatures averaged over three days reach city-specific thresholds. The current thresholds were computed based on a descriptive analysis of past heat waves and on local expert judgement. We tested whether a different method would confirm these thresholds. The study was set in the six cities of Paris, Lyon, Marseille, Nantes, Strasbourg and Limoges between 1973 and 2003. For each city, we estimated the excess in mortality associated with different temperature thresholds, using a generalised additive model, controlling for long-time trends, seasons and days of the week. These models were used to compute the mortality predicted by different percentiles of temperatures. The thresholds were chosen as the percentiles associated with a significant excess mortality. In all cities, there was a good correlation between current thresholds and the thresholds derived from the models, with 0°C to 3°C differences for averaged maximum temperatures. Both set of thresholds were able to anticipate the main periods of excess mortality during the summers of 1973 to 2003. A simple method relying on descriptive analysis and expert judgement is sufficient to define protective temperature thresholds and to prevent heat wave mortality. As temperatures are increasing along with the climate change and adaptation is ongoing, more research is required to understand if and when thresholds should be modified.

PACE (Revised). Resource Guide. Research & Development Series No. 240D.

ERIC Educational Resources Information Center

Ashmore, M. Catherine; Pritz, Sandra G.

This resource guide contains information on the Program for Acquiring Competence in Entrepreneurship (PACE) materials, a glossary, and listings of sources of information. Introductory materials include a description of PACE, information on use of PACE materials, and objectives of the 18 units for all three levels at which they are developed. An…

A Study of Instructional Methods Used in Fast-Paced Classes

ERIC Educational Resources Information Center

Lee, Seon-Young; Olszewski-Kubilius, Paula

2006-01-01

This study involved 15 secondary-level teachers who taught fast-paced classes at a university based summer program and similar regularly paced classes in their local schools in order to examine how teachers differentiate or modify instructional methods and content selections for fast-paced classes. Interviews were conducted with the teachers…

Predicting Successful Completion Using Student Delay Indicators in Undergraduate Self-Paced Online Courses

ERIC Educational Resources Information Center

Lim, Janine M.

2016-01-01

Self-paced online courses meet flexibility and learning needs of many students, but skepticism persists regarding the quality and the tendency for students to procrastinate in self-paced courses. Research is needed to understand procrastination and delay patterns of students in online self-paced courses to predict successful completion and…

Telomeres and replicative senescence: Is it only length that counts?

PubMed

von Zglinicki, T

2001-07-26

Telomeres are well established as a major 'replicometer', counting the population doublings in primary human cell cultures and ultimately triggering replicative senescence. However, neither is the pace of this biological clock inert, nor is there a fixed threshold telomere length acting as the universal trigger of replicative senescence. The available data suggest that opening of the telomeric loop and unscheduled exposure of the single-stranded G-rich telomeric overhang might act like a semaphore to signal senescent cell cycle arrest. Short telomere length, telomeric single-strand breaks, low levels of loop-stabilizing proteins, or other factors may trigger this opening of the loop. Thus, both telomere shortening and the ultimate signalling into senescence are able to integrate different environmental and genetic factors, especially oxidative stress-mediated damage, which might otherwise become a thread to genomic stability.

Subtle alternating electrocardiographic morphology as an indicator of decreased cardiac electrical stability

NASA Technical Reports Server (NTRS)

Smith, J. M.; Blue, B.; Clancy, E.; Valeri, C. R.; Cohen, R. J.

1985-01-01

Observations from finite-element computer models, together with analytic developments based on percolation theory have suggested that subtle fluctuations of ECG morphology might serve as an indicator diminished cardiac electrical stability. With fixed-rate atrial pacing in canines, we have previously observed a pattern of alternation in T wave energy which correlated with cardiac electrical stability. We report here on a series of 20 canine experiments in which cardiac electrical stability (measured via Ventricular Fibrillation Threshold determination) was compared to a non-degenerate, multidimensional measurement of the degree of alternating activity present in the ECG complex morphology. The decrease in cardiac electrical stability brought on by both coronary artery occlusion and systemic hypothermia was consistently accompanied by subtle alternation in ECG morphology, with the absolute degree of alternating activity being significantly (negatively) correlated with cardiac electrical stability.

Low energy transvenous cardioversion of short duration atrial tachyarrhythmias in humans using a single lead system.

PubMed

Heisel, A; Jung, J; Fries, R; Stopp, M; Sen, S; Schieffer, H; Ozbek, C

1997-01-01

The purpose of this study was to investigate the efficacy and safety of atrial cardioversion using an endocardial single lead system presently used for ventricular defibrillation. The study population consisted of 26 recipients of an ICD in combination with a conventional endocardial single lead system with the proximal spring electrode as anode in the SVC and the distal as cathode in the apex of the RV. Atrial tachyarrhythmias were induced by right atrial burst pacing. If the arrhythmia sustained > 1 minute, biphasic shocks synchronized with the R wave were delivered using the implanted device, beginning with an energy of 4 J. If 4 J failed to terminate the arrhythmia, energy was increased stepwise, if the first shock was successful, a step-down testing was performed after reinduction of atrial tachyarrhythmias. The mean atrial defibrillation threshold was 2.3 +/- 1.2 J (range, 0.5-5 J). A total of 154 shocks were delivered and no adverse effects were observed. The mean defibrillation threshold for atrial flutter was somewhat lower than that for AF (1.8 +/- 1 J vs 2.7 +/- 1.4 J, P = 0.08). There was no correlation between the atrial defibrillation threshold and a history of previously occurring atrial tachyarrhythmias, the kind of the underlying heart disease, a prescription of antiarrhythmic drugs, the dimension of the LA, the LVEF, or the ventricular DFT. Internal atrial cardioversion of short duration atrial tachyarrhythmias using a transvenous single lead system designed for ventricular defibrillation is feasible and safe at low energies, and may have important clinical applications.

Further evidence for the role of gap junctions in the delayed antiarrhythmic effect of cardiac pacing.

PubMed

Miskolczi, Gottfried; Gönczi, Márton; Kovács, Mária; Seprényi, György; Végh, Ágnes

2015-07-01

The objective of this study was to provide evidence that gap junctions are involved in the delayed antiarrhythmic effect of cardiac pacing. Twenty-four dogs were paced through the right ventricle (4 × 5 min, rate of 240 beats/min) 24 h prior to a 25 min occlusion of the left anterior descending coronary artery. Some of these paced dogs were infused with 50 (n = 7) or 100 μmol/L (n = 7) of the gap junction uncoupler carbenoxolone (CBX), prior to and during the occlusion. Ten sham-paced dogs, subjected only to occlusion, served as the controls. Cardiac pacing markedly reduced the number of ectopic beats and episodes of ventricular tachycardia (VT), as well the incidence of VT and ventricular fibrillation during occlusion. The changes in severity of ischaemia and tissue electrical resistance were also less marked compared with the unpaced controls. Pacing also preserved the permeability of gap junctions, the phosphorylation of connexin43, and the structural integrity of the intercalated discs. The closing of gap junctions with CBX prior to and during ischaemia markedly attenuated or even abolished these protective effects of pacing. Our results support the previous findings that gap junctions play a role in the delayed antiarrhythmic effect of cardiac pacing.

Differential effects of film on preschool children's behaviour dependent on editing pace.

PubMed

Kostyrka-Allchorne, Katarzyna; Cooper, Nicholas R; Gossmann, Anna Maria; Barber, Katy J; Simpson, Andrew

2017-05-01

Evidence on how the pace of television and film editing affects children's behaviour and attention is inconclusive. We examined whether a fast-paced film affected how preschool-aged children interacted with toys. The study comprised 70 children (36 girls) aged two to four-and-a-half years who attended preschools in Essex, United Kingdom. The children were paired up and tested with either a fast- or a slow-paced film of a narrator reading a children's story. The fast-paced version had 102 camera cuts and 16 still images, and the slow-paced version had 22 camera cuts and four still images. Each dyad took part in two video-recorded free-play sessions, before and after they watched one of the specially edited four-minute films. The number of toys the children played with before and after the film sessions was recorded. Before they watched the films, the children's behaviour did not differ between the groups. However, after watching the film, the children in the fast-paced group shifted their attention between toys more frequently than the children who watched the slow-paced film. Even a brief exposure to differently paced films had an immediate effect on how the children interacted with their toys. ©2017 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

Pacing and Self-regulation: Important Skills for Talent Development in Endurance Sports.

PubMed

Elferink-Gemser, Marije T; Hettinga, Florentina J

2017-07-01

Pacing has been characterized as a multifaceted goal-directed process of decision making in which athletes need to decide how and when to invest their energy during the race, a process essential for optimal performance. Both physiological and psychological characteristics associated with adequate pacing and performance are known to develop with age. Consequently, the multifaceted skill of pacing might be under construction throughout adolescence, as well. Therefore, the authors propose that the complex skill of pacing is a potential important performance characteristic for talented youth athletes that needs to be developed throughout adolescence. To explore whether pacing is a marker for talent and how talented athletes develop this skill in middle-distance and endurance sports, they aim to bring together literature on pacing and literature on talent development and self-regulation of learning. Subsequently, by applying the cyclical process of self-regulation to pacing, they propose a practical model for the development of performance in endurance sports in youth athletes. Not only is self-regulation essential throughout the process of reaching the long-term goal of athletic excellence, but it also seems crucial for the development of pacing skills within a race and the development of a refined performance template based on previous experiences. Coaches and trainers are advised to incorporate pacing as a performance characteristic in their talent-development programs by stimulating their athletes to reflect, plan, monitor, and evaluate their races on a regular basis to build performance templates and, as such, improve their performance.

Device for monitoring cell voltage

DOEpatents

Doepke, Matthias [Garbsen, DE; Eisermann, Henning [Edermissen, DE

2012-08-21

A device for monitoring a rechargeable battery having a number of electrically connected cells includes at least one current interruption switch for interrupting current flowing through at least one associated cell and a plurality of monitoring units for detecting cell voltage. Each monitoring unit is associated with a single cell and includes a reference voltage unit for producing a defined reference threshold voltage and a voltage comparison unit for comparing the reference threshold voltage with a partial cell voltage of the associated cell. The reference voltage unit is electrically supplied from the cell voltage of the associated cell. The voltage comparison unit is coupled to the at least one current interruption switch for interrupting the current of at least the current flowing through the associated cell, with a defined minimum difference between the reference threshold voltage and the partial cell voltage.

PACE4 is an important driver of ZR-75-1 estrogen receptor-positive breast cancer proliferation and tumor progression.

PubMed

Panet, François; Couture, Frédéric; Kwiatkowska, Anna; Desjardins, Roxane; Guérin, Brigitte; Day, Robert

2017-08-01

Breast cancer is the most frequent and deadly malignancy in women worldwide. Despite national screening programs combined with new treatments relapse rate remain high and new therapies are needed. From previous work, we identified PACE4, a member of the proprotein convertase (PCs) family of endoproteases, as a novel therapeutic target in prostate cancer. In the present study we asked the question if PACE4 could also be a potential target in breast cancer. In clinical samples of breast adenocarcinoma, we observed a specific overexpression of PACE4 in the estrogen-receptor (ER) positive subtype. We therefore looked for a breast cancer cell line model which would be representative and thus focused on the ZR-75-1 since it both expresses PACE4 and is estrogen-receptor positive. We compared stable knockdowns of furin, PACE4 and PC7 in the estrogen-receptor-positive cell line ZR-75-1 to evaluate their respective contribution to cell growth and tumor progression. PACE4 was the only PC displaying an impact on cell growth. A PACE4 peptide-based inhibitor (C23) was tested and shown to decrease proliferation of ZR-75-1 cells in cell based assays. C23 also had potent effects of tumor progression in vivo on xenografts of the ZR-75-1 cell line in athymic nude mice. Thus, PACE4-silencing and systemic administration of a PACE4 inhibitor resulted in hindered tumor progression with reduction in proliferative indices and increased cell quiescence assessed with biomarkers. Our results suggest that PACE4 is a promising target for estrogen-receptor-positive breast cancer. Copyright © 2017 Elsevier GmbH. All rights reserved.

Impact of high-grade Atrioventricular block and cumulative frequent pacing on atrial arrhythmias.

PubMed

Wali, Eisha; Deshmukh, Amrish; Bukari, Abdallah; Broman, Michael; Aziz, Zaid; Beaser, Andrew; Upadhyay, Gaurav; Nayak, Hemal M; Tung, Roderick; Ozcan, Cevher

2018-06-21

The relationship between high-grade AV block (HGAVB) with cumulative frequent pacing and risk of atrial arrhythmias (AAs) has not been well characterized. We hypothesized HGAVB and pacing may have significant impact on incidence and prevalence of AAs by modulating atrial substrate. To determine impact of HGAVB and pacing on AAs including atrial fibrillation (AF), atrial flutter (AFL), and atrial tachycardia (AT). All consecutive patients who underwent dual chamber pacemaker implantation for HGAVB from 2005 to 2011 at the University of Chicago were included. AAs and percent of pacing were detected through device interrogation. Patients' data were collected from electronic medical records and clinic visits. A total of 166 patients (mean age 71±15 years; 54% female, 56% African-American) were studied. AF was documented in 27% of patients before pacemaker implantation. During a mean 5.8±2.2 years of follow-up, 47% had device-detected AF, 10% AFL and 26% AT. New-onset AF was documented in 40 of the 122 patients without prior AF (33%). Continuous (≥99%) right ventricular pacing was associated with significantly decreased AF prevalence (34% versus 59%, p = 0.005), and correlated with lower incidence (26% versus 41%, p = 0.22). Pacing suppressed AF in 14% of patients with baseline AF; those patients had lower atrial pacing (3.2% versus 45%, p < 0.0001). Left atrial dilation was the only independent predictor of AF with frequent pacing (p = 0.009). HGAVB is associated with high incidence and prevalence of AAs with and without pacing. Cumulative frequent (≥99%) ventricular pacing reduces risk of AF in patients with HGAVB. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Prevalence of conduction delay of the right atrium in patients with SSS: implications for pacing site selection.

PubMed

Verlato, Roberto; Zanon, Francesco; Bertaglia, Emanuele; Turrini, Pietro; Baccillieri, Maria Stella; Baracca, Enrico; Bongiorni, Maria Grazia; Zampiero, Aldo; Zonzin, Pietro; Pascotto, Pietro; Venturini, Diego; Corbucci, Giorgio

2007-09-01

To evaluate the prevalence of severe right atrial conduction delay in patients with sinus node dysfunction (SND) and atrial fibrillation (AF) and the effects of pacing in the right atrial appendage (RAA) and in the inter-atrial septum (IAS). Forty-two patients (15 male, 72 +/- 7 years) underwent electrophysiologic study to measure the difference between the conduction time from RAA to coronary sinus ostium during stimulation at 600 ms and after extrastimulus (DeltaCTos). Patients were classified as group A if DeltaCTos > 60 ms and group B if < 60 ms. Each Group was randomized to RAA/IAS pacing and algorithms ON/OFF. Fifteen patients (36%, group A) had DeltaCTos = 76 +/- 11 ms and 27 patients (64%, group B) had DeltaCTos = 36 +/- 20 ms. Twenty-two patients were paced at the RAA and 20 at the IAS. During the study, no AF recurrences were reported in 11 of 42 (26%) patients, independently of RAA or IAS pacing. Patients from group A and RAA pacing had 0.79 +/- 0.81 episodes of AF/day during DDD, which increased to 1.52 +/- 1.41 episodes of AF/day during DDDR + Alg (P = 0.046). Those with IAS pacing had 0.5 +/- 0.24 episodes of AF/day during DDD, which decreased to 0.06 +/- 0.08 episodes of AF/day during DDDR + Alg (P = 0.06). In group B, no differences were reported between pacing sites and pacing modes. Severe right atrial conduction delay is present in one-third of patients with SND and AF: continuous pacing at the IAS is superior to RAA for AF recurrences. In patients without severe conduction delay, no differences between pacing site or mode were observed.

Temporary epicardial cardiac resynchronisation versus conventional right ventricular pacing after cardiac surgery: study protocol for a randomised control trial.

PubMed

Russell, Stuart J; Tan, Christine; O'Keefe, Peter; Ashraf, Saeed; Zaidi, Afzal; Fraser, Alan G; Yousef, Zaheer R

2012-02-20

Heart failure patients with stable angina, acute coronary syndromes and valvular heart disease may benefit from revascularisation and/or valve surgery. However, the mortality rate is increased- 5-30%. Biventricular pacing using temporary epicardial wires after surgery is a potential mechanism to improve cardiac function and clinical endpoints. A multi-centred, prospective, randomised, single-blinded, intervention-control trial of temporary biventricular pacing versus standard pacing. Patients with ischaemic cardiomyopathy, valvular heart disease or both, an ejection fraction ≤ 35% and a conventional indication for cardiac surgery will be recruited from 2 cardiac centres. Baseline investigations will include: an electrocardiogram to confirm sinus rhythm and measure QRS duration; echocardiogram to evaluate left ventricular function and markers of mechanical dyssynchrony; dobutamine echocardiogram for viability and blood tests for renal function and biomarkers of myocardial injury- troponin T and brain naturetic peptide. Blood tests will be repeated at 18, 48 and 72 hours. The principal exclusions will be subjects with permanent atrial arrhythmias, permanent pacemakers, infective endocarditis or end-stage renal disease.After surgery, temporary pacing wires will be attached to the postero-lateral wall of the left ventricle, the right atrium and right ventricle and connected to a triple chamber temporary pacemaker. Subjects will be randomised to receive either temporary biventricular pacing or standard pacing (atrial inhibited pacing or atrial-synchronous right ventricular pacing) for 48 hours.The primary endpoint will be the duration of level 3 care. In brief, this is the requirement for invasive ventilation, multi-organ support or more than one inotrope/vasoconstrictor. Haemodynamic studies will be performed at baseline, 6, 18 and 24 hours after surgery using a pulmonary arterial catheter. Measurements will be taken in the following pacing modes: atrial inhibited; right ventricular only; atrial synchronous-right ventricular; atrial synchronous-left ventricular and biventricular pacing. Optimisation of the atrioventricular and interventricular delay will be performed in the biventricular pacing group at 18 hours. The effect of biventricular pacing on myocardial injury, post operative arrhythmias and renal function will also be quantified. ClinicalTrials.gov: NCT01027299.

The nuclear pacemaker: Is renewed interest warranted

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parsonnet, V.; Berstein, A.D.; Perry, G.Y.

1990-10-01

From 1973 through 1987, 155 radioisotope-powered nuclear pacemakers were implanted in 132 patients at the Newark Beth Israel Medical Center. The longevity of the first 15 devices, all of which were fixed-rate (VOO) pacemakers, was significantly better than that of 15 lithium-chemistry demand (VVI) pacemakers used as control devices (p = 0.0002). Of the entire cohort of 155 nuclear pacemakers, 136 were VVI devices and 19 were VOO units. The patients with VOO pacemakers needed reoperations more often than did those with VVI pacemakers, chiefly for mode change (p less than 0.001). Power-source failure was observed in only 1 case,more » but 47 nuclear pacemakers were removed for other reasons, including component malfunction (15 units), mode change (12 units), high pacing thresholds (8 units) and lead or connector problems (5 units). The actuarial survival at 15 years was 99% for power sources and 82% for the entire pacing systems (pulse generators plus leads). The frequency of malignancy was similar to that of the population at large and primary tumor sites were randomly distributed. Deaths most commonly were due to cardiac causes (68%). Thus, nuclear pacemakers are safe and reliable and their greater initial cost appears to be offset by their longevity and the resulting decrease in the frequency of reoperations. It is reasonable to suggest that further use be made of long-lasting nuclear power sources for modern pacemakers and other implantable rhythm-management devices.« less

Value of information and pricing new healthcare interventions.

PubMed

Willan, Andrew R; Eckermann, Simon

2012-06-01

Previous application of value-of-information methods to optimal clinical trial design have predominantly taken a societal decision-making perspective, implicitly assuming that healthcare costs are covered through public expenditure and trial research is funded by government or donation-based philanthropic agencies. In this paper, we consider the interaction between interrelated perspectives of a societal decision maker (e.g. the National Institute for Health and Clinical Excellence [NICE] in the UK) charged with the responsibility for approving new health interventions for reimbursement and the company that holds the patent for a new intervention. We establish optimal decision making from societal and company perspectives, allowing for trade-offs between the value and cost of research and the price of the new intervention. Given the current level of evidence, there exists a maximum (threshold) price acceptable to the decision maker. Submission for approval with prices above this threshold will be refused. Given the current level of evidence and the decision maker's threshold price, there exists a minimum (threshold) price acceptable to the company. If the decision maker's threshold price exceeds the company's, then current evidence is sufficient since any price between the thresholds is acceptable to both. On the other hand, if the decision maker's threshold price is lower than the company's, then no price is acceptable to both and the company's optimal strategy is to commission additional research. The methods are illustrated using a recent example from the literature.

Analysis of Jingdong Mall Logistics Distribution Model

NASA Astrophysics Data System (ADS)

Shao, Kang; Cheng, Feng

In recent years, the development of electronic commerce in our country to speed up the pace. The role of logistics has been highlighted, more and more electronic commerce enterprise are beginning to realize the importance of logistics in the success or failure of the enterprise. In this paper, the author take Jingdong Mall for example, performing a SWOT analysis of their current situation of self-built logistics system, find out the problems existing in the current Jingdong Mall logistics distribution and give appropriate recommendations.

Determination of the anaerobic threshold by a noninvasive field test in runners.

PubMed

Conconi, F; Ferrari, M; Ziglio, P G; Droghetti, P; Codeca, L

1982-04-01

The relationship between running speed (RS) and heart rate (HR) was determined in 210 runners. On a 400-m track the athletes ran continuously from an initial velocity of 12-14 km/h to submaximal velocities varying according to the athlete's capability. The HRs were determined through ECG. In all athletes examined, a deflection from the expected linearity of the RS-HR relationship was observed at submaximal RS. The test-retest correlation for the velocities at which this deflection from linearity occurred (Vd) determined in 26 athletes was 0.99. The velocity at the anaerobic threshold (AT), established by means of blood lactate measurements, and Vd were coincident in 10 runners. The correlation between Vd and average running speed (mean RS) in competition was 0.93 in the 5,000 m (mean Vd = 19.13 +/- 1.08 km/h; mean RS = 20.25 +/- 1.15 km/h), 0.95 in the marathon (mean Vd = 18.85 +/- 1.15 km/h; mean RS = 17.40 +/- 1.14 km/h), and 0.99 in the 1-h race (mean Vd = 18.70 +/- 0.98 km/h; mean RS = 18.65 +/- 0.92 km/h), thus showing that AT is critical in determining the running pace in aerobic competitive events.

Comparisons between detection threshold and loudness perception for individual cochlear implant channels

PubMed Central

Bierer, Julie Arenberg; Nye, Amberly D

2014-01-01

Objective The objective of the present study, performed in cochlear implant listeners, was to examine how the level of current required to detect single-channel electrical pulse trains relates to loudness perception on the same channel. The working hypothesis was that channels with relatively high thresholds, when measured with a focused current pattern, interface poorly to the auditory nerve. For such channels a smaller dynamic range between perceptual threshold and the most comfortable loudness would result, in part, from a greater sensitivity to changes in electrical field spread compared to low-threshold channels. The narrower range of comfortable listening levels may have important implications for speech perception. Design Data were collected from eight, adult cochlear implant listeners implanted with the HiRes90k cochlear implant (Advanced Bionics Corp.). The partial tripolar (pTP) electrode configuration, consisting of one intracochlear active electrode, two flanking electrodes carrying a fraction (σ) of the return current, and an extracochlear ground, was used for stimulation. Single-channel detection thresholds and most comfortable listening levels were acquired using the most focused pTP configuration possible (σ ≥ 0.8) to identify three channels for further testing – those with the highest, median, and lowest thresholds – for each subject. Threshold, equal-loudness contours (at 50% of the monopolar dynamic range), and loudness growth functions were measured for each of these three test channels using various partial tripolar fractions. Results For all test channels, thresholds increased as the electrode configuration became more focused. The rate of increase with the focusing parameter σ was greatest for the high-threshold channel compared to the median- and low-threshold channels. The 50% equal-loudness contours exhibited similar rates of increase in level across test channels and subjects. Additionally, test channels with the highest thresholds had the narrowest dynamic ranges (for σ ≥ 0.5) and steepest growth of loudness functions for all electrode configurations. Conclusions Together with previous studies using focused stimulation, the results suggest that auditory responses to electrical stimuli at both threshold and suprathreshold current levels are not uniform across the electrode array of individual cochlear implant listeners. Specifically, the steeper growth of loudness and thus smaller dynamic ranges observed for high-threshold channels are consistent with a degraded electrode-neuron interface, which could stem from lower numbers of functioning auditory neurons or a relatively large distance between the neurons and electrodes. These findings may have potential implications for how stimulation levels are set during the clinical mapping procedure, particularly for speech-processing strategies that use focused electrical fields. PMID:25036146

Pacing, Pixels, and Paper: Flexibility in Learning Words from Flashcards

ERIC Educational Resources Information Center

Sage, Kara; Rausch, Joseph; Quirk, Abigail; Halladay, Lauren

2016-01-01

The present study focused on how self-control over pace might help learners successfully extract information from digital learning aids. Past research has indicated that too much control over pace can be overwhelming, but too little control over pace can be ineffective. Within the popular self-testing domain of flashcards, we sought to elucidate…

Effects of Modality and Pace on Achievement, Mental Effort, and Positive Affect in Multimedia Learning Environments

ERIC Educational Resources Information Center

Izmirli, Serkan; Kurt, Adile Askim

2016-01-01

The purpose of the study was to examine the effects of instruction given with different multimedia modalities (written text + animation or narration + animation) on the academic achievement, cognitive load, and positive affect in different paces (learner-paced or system-paced); 97 freshmen university students divided into four groups taught in…

Minimal invasive epicardial lead implantation: optimizing cardiac resynchronization with a new mapping device for epicardial lead placement.

PubMed

Maessen, J G; Phelps, B; Dekker, A L A J; Dijkman, B

2004-05-01

To optimize resynchronization in biventricular pacing with epicardial leads, mapping to determine the best pacing site, is a prerequisite. A port access surgical mapping technique was developed that allowed multiple pace site selection and reproducible lead evaluation and implantation. Pressure-volume loops analysis was used for real time guidance in targeting epicardial lead placement. Even the smallest changes in lead position revealed significantly different functional results. Optimizing the pacing site with this technique allowed functional improvement up to 40% versus random pace site selection.

The effects of husbandry training on stereotypic pacing in captive African wild dogs (Lycaon pictus).

PubMed

Shyne, Amanda; Block, Martin

2010-01-01

To examine the effects of operant conditioning on stereotypic pacing in 3 female African wild dogs located at the Franklin Park Zoo in Boston, this study made recordings of pacing behavior immediately following individual sessions of husbandry training and 2 no-training conditions. The study found significant differences in the percentage of observations spent in stereotypic pacing behaviors for all 3 dogs among the 3 different conditions. The authors discuss the data in terms of the contribution of motivated tasks to the effects and the role of food deprivation in the expression of stereotypic pacing. The study suggests that even short periods of training may improve the African wild dogs' welfare by reducing stereotypic pacing following the conditioning sessions.

Rate-dependent Loss of Capture during Ventricular Pacing.

PubMed

Wang, Jingfeng; Chen, Haiyan; Su, Yangang; Ge, Junbo

2015-01-01

A 63-year-old patient who had undergone atrial septal defect surgical repair received implantation of a single chamber VVI pacemaker for long RR intervals during atrial fibrillation. One week later, an intermittent loss of capture and sensing failure was detected at a pacing rate of 70 beats/min. However, a successful capture was observed during rapid pacing. Consequently, the pacing rate was temporarily adjusted to 90 beats/min. At the 3-month follow-up, the pacemaker was shown to be functioning properly independent of the pacing rate. An echocardiogram showed that the increased pacing rates were accompanied by a reduction in the right ventricular outflow tract dimension. The pacemaker was then permanently programmed at a lower rate of 60 beats/min.

High-wafer-yield, high-performance vertical cavity surface-emitting lasers

NASA Astrophysics Data System (ADS)

Li, Gabriel S.; Yuen, Wupen; Lim, Sui F.; Chang-Hasnain, Constance J.

1996-04-01

Vertical cavity surface emitting lasers (VCSELs) with very low threshold current and voltage of 340 (mu) A and 1.5 V is achieved. The molecular beam epitaxially grown wafers are grown with a highly accurate, low cost and versatile pre-growth calibration technique. One- hundred percent VCSEL wafer yield is obtained. Low threshold current is achieved with a native oxide confined structure with excellent current confinement. Single transverse mode with stable, predetermined polarization direction up to 18 times threshold is also achieved, due to stable index guiding provided by the structure. This is the highest value reported to data for VCSELs. We have established that p-contact annealing in these devices is crucial for low voltage operation, contrary to the general belief. Uniform doping in the mirrors also appears not to be inferior to complicated doping engineering. With these design rules, very low threshold voltage VCSELs are achieved with very simple growth and fabrication steps.

Unidirectional threshold switching in Ag/Si-based electrochemical metallization cells for high-density bipolar RRAM applications

NASA Astrophysics Data System (ADS)

Wang, Chao; Song, Bing; Li, Qingjiang; Zeng, Zhongming

2018-03-01

We herein present a novel unidirectional threshold selector for cross-point bipolar RRAM array. The proposed Ag/amorphous Si based threshold selector showed excellent threshold characteristics in positive field, such as high selectivity ( 105), steep slope (< 5 mV/decade) and low off-state current (< 300 pA). Meanwhile, the selector exhibited rectifying characteristics in the high resistance state as well and the rectification ratio was as high as 103 at ± 1.5 V. Nevertheless, due to the high reverse current about 9 mA at - 3 V, this unidirectional threshold selector can be used as a selection element for bipolar-type RRAM. By integrating a bipolar RRAM device with the selector, experiments showed that the undesired sneak was significantly suppressed, indicating its potentiality for high-density integrated nonvolatile memory applications.

Evidence for thermally assisted threshold switching behavior in nanoscale phase-change memory cells

NASA Astrophysics Data System (ADS)

Le Gallo, Manuel; Athmanathan, Aravinthan; Krebs, Daniel; Sebastian, Abu

2016-01-01

In spite of decades of research, the details of electrical transport in phase-change materials are still debated. In particular, the so-called threshold switching phenomenon that allows the current density to increase steeply when a sufficiently high voltage is applied is still not well understood, even though there is wide consensus that threshold switching is solely of electronic origin. However, the high thermal efficiency and fast thermal dynamics associated with nanoscale phase-change memory (PCM) devices motivate us to reassess a thermally assisted threshold switching mechanism, at least in these devices. The time/temperature dependence of the threshold switching voltage and current in doped Ge2Sb2Te5 nanoscale PCM cells was measured over 6 decades in time at temperatures ranging from 40 °C to 160 °C. We observe a nearly constant threshold switching power across this wide range of operating conditions. We also measured the transient dynamics associated with threshold switching as a function of the applied voltage. By using a field- and temperature-dependent description of the electrical transport combined with a thermal feedback, quantitative agreement with experimental data of the threshold switching dynamics was obtained using realistic physical parameters.

Method and system for controlling a rotational speed of a rotor of a turbogenerator

DOEpatents

Stahlhut, Ronnie Dean; Vuk, Carl Thomas

2008-12-30

A system and method controls a rotational speed of a rotor or shaft of a turbogenerator in accordance with a present voltage level on a direct current bus. A lower threshold and a higher threshold are established for a speed of a rotor or shaft of a turbogenerator. A speed sensor determines speed data or a speed signal for the rotor or shaft associated with a turbogenerator. A voltage regulator adjusts a voltage level associated with a direct current bus within a target voltage range if the speed data or speed signal indicates that the speed is above the higher threshold or below the lower threshold.

Computational challenges in modeling gene regulatory events

PubMed Central

Pataskar, Abhijeet; Tiwari, Vijay K.

2016-01-01

ABSTRACT Cellular transcriptional programs driven by genetic and epigenetic mechanisms could be better understood by integrating “omics” data and subsequently modeling the gene-regulatory events. Toward this end, computational biology should keep pace with evolving experimental procedures and data availability. This article gives an exemplified account of the current computational challenges in molecular biology. PMID:27390891

Assessing the Effectiveness of Web-Based Tutorials Using Pre-and Post-Test Measurements

ERIC Educational Resources Information Center

Guy, Retta Sweat; Lownes-Jackson, Millicent

2012-01-01

Computer technology in general and the Internet in particular have facilitated as well as motivated the development of Web-based tutorials (MacKinnon & Williams, 2006). The current research study describes a pedagogical approach that exploits the use of self-paced, Web-based tutorials for assisting students with reviewing grammar and mechanics…

Lessons Learned from MG George Crook’s Apache Campaigns with Applicability for the Current Global War on Terror

DTIC Science & Technology

2003-04-07

in Saudi Arabian internal politics. Islamism has other modern roots as well. In 1928 Hassan al- Banna formed the Islamic Brotherhood in Egypt.13...Soon afterward the Kandahar raid, the Northern Alliance / 5th SFG attacks increased the pace of peeling apart the opposition forces from each other

A Governance Examination of Idaho's Technological Literacy Policy and Standards for Teachers: Past, Present, and Future

ERIC Educational Resources Information Center

Moore, Terah R.

2010-01-01

Schools, colleges, and departments of education across America currently are investigating how preservice teachers are being prepared to use technology in the classroom. Technologies available in education have evolved but technological literacy for teachers has not always kept pace. Research suggested the need for continued development and study…

Why No Difference? A Controlled Flipped Classroom Study for an Introductory Differential Equations Course

ERIC Educational Resources Information Center

Yong, Darryl; Levy, Rachel; Lape, Nancy

2015-01-01

Flipped classrooms have the potential to improve student learning and metacognitive skills as a result of increased time for active learning and group work and student control over pacing, when compared with traditional lecture-based courses. We are currently running a 4-year controlled study to examine the impact of flipping an Introductory…

Integrating CALL in ESOL Classrooms: Understanding Teachers' Perspectives and Meeting Students' Needs

ERIC Educational Resources Information Center

Nia, Sara Farshad; Davey, Ronnie

2014-01-01

In line with the needs of the 21st century learners and dramatic improvements in schools' technological infrastructures, it is expected that the integration of digital tools into language learning courses would take a quicker pace and a smoother path. However, current research indicates that although this might be the case for foreign language…

Faculty Response to Retrenchment. AAHE-ERIC/Higher Education Research Currents, June 1981.

ERIC Educational Resources Information Center

Eddy, Margot Sanders

The innovative actions that faculty, and institutions on behalf of faculty, have taken to adjust to retrenchment and the changing academic profession are considered. It is suggested that faculty have three kinds of employment options to present conditions such as the scarcity of tenure-track positions and the failure of salaries to keep pace with…

Right atrial pacing impairs cardiac function during resynchronization therapy: acute effects of DDD pacing compared to VDD pacing.

PubMed

Bernheim, Alain; Ammann, Peter; Sticherling, Christian; Burger, Peter; Schaer, Beat; Brunner-La Rocca, Hans Peter; Eckstein, Jens; Kiencke, Stephanie; Kaiser, Christoph; Linka, Andre; Buser, Peter; Pfisterer, Matthias; Osswald, Stefan

2005-05-03

We aimed to compare the hemodynamic effects of right-atrial-paced (DDD) and right-atrial-sensed (VDD) biventricular paced rhythm on cardiac resynchronization therapy (CRT). Cardiac resynchronization therapy improves hemodynamics in patients with severe heart failure and left ventricular (LV) dyssynchrony. However, the impact of active right atrial pacing on resynchronization therapy is unknown. Seventeen CRT patients were studied 10 months (range: 1 to 46 months) after implantation. At baseline, the programmed atrioventricular delay was optimized by timing LV contraction properly at the end of atrial contraction. In both modes the acute hemodynamic effects were assessed by multiple Doppler echocardiographic parameters. Compared to DDD pacing, VDD pacing resulted in much better improvement of intraventricular dyssynchrony assessed by the septal-to-posterior wall motion delay (VDD 106 +/- 83 ms vs. DDD 145 +/- 95 ms; p = 0.001), whereas the interventricular mechanical delay (difference between onset of pulmonary and aortic outflow) did not differ (VDD 20 +/- 21 ms vs. DDD 18 +/- 17 ms; p = NS). Furthermore, VDD pacing significantly prolonged the rate-corrected LV filling period (VDD 458 +/- 123 ms vs. DDD 371 +/- 94 ms; p = 0.0001) and improved the myocardial performance index (VDD 0.60 +/- 0.18 vs. DDD 0.71 +/- 0.23; p < 0.01). Our findings suggest that avoidance of right atrial pacing results in a higher degree of LV resynchronization, in a substantial prolongation of the LV filling period, and in an improved myocardial performance. Thus, the VDD mode seems to be superior to the DDD mode in CRT patients.

Electric field characteristics of electroconvulsive therapy with individualized current amplitude: a preclinical study.

PubMed

Lee, Won Hee; Lisanby, Sarah H; Laine, Andrew F; Peterchev, Angel V

2013-01-01

This study examines the characteristics of the electric field induced in the brain by electroconvulsive therapy (ECT) with individualized current amplitude. The electric field induced by bilateral (BL), bifrontal (BF), right unilateral (RUL), and frontomedial (FM) ECT electrode configurations was computed in anatomically realistic finite element models of four nonhuman primates (NHPs). We generated maps of the electric field strength relative to an empirical neural activation threshold, and determined the stimulation strength and focality at fixed current amplitude and at individualized current amplitudes corresponding to seizure threshold (ST) measured in the anesthetized NHPs. The results show less variation in brain volume stimulated above threshold with individualized current amplitudes (16-36%) compared to fixed current amplitude (30-62%). Further, the stimulated brain volume at amplitude-titrated ST is substantially lower than that for ECT with conventional fixed current amplitudes. Thus individualizing the ECT stimulus current could compensate for individual anatomical variability and result in more focal and uniform electric field exposure across different subjects compared to the standard clinical practice of using high, fixed current for all patients.

A Closer Look at Split Visual Attention in System- and Self-Paced Instruction in Multimedia Learning

ERIC Educational Resources Information Center

Schmidt-Weigand, Florian; Kohnert, Alfred; Glowalla, Ulrich

2010-01-01

Two experiments examined visual attention distribution in learning from text and pictures. Participants watched a 16-step multimedia instruction on the formation of lightning. In Experiment 1 (N=90) the instruction was system-paced (fast, medium, slow pace), while it was self-paced in Experiment 2 (N=31). In both experiments the text modality was…

Helping Girls Get Back on Track: An Implementation Study of the PACE Center for Girls

ERIC Educational Resources Information Center

Treskon, Louisa; Millenky, Megan; Freedman, Lily

2017-01-01

PACE Center for Girls is a unique program that provides academic and social services to girls ages 11 to 18. Girls eligible for PACE exhibit multiple health, safety, and delinquency risk factors, such as poor academic performance, exposure to abuse or violence, truancy, risky sexual behavior, and substance abuse. PACE seeks to help them onto a…

What Pace Is Best? Assessing Adults' Learning from Slideshows and Video

ERIC Educational Resources Information Center

Sage, Kara

2014-01-01

When acquiring information from a 2D platform, self-control and/or optimal pacing may help reduce cognitive load and enhance learning outcomes. In the present research, adults viewed novel action sequences via one of four learning media: (1) self-paced slideshows, where viewers advanced through slides at their own pace by clicking a mouse, (2)…

77 FR 28900 - Amended Certification Regarding Eligibility to Apply for Worker Adjustment Assistance

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-16

... Enterprises, Inc., Fitzgerald, Georgia TA-W-81,004C Pace American Enterprises, Inc., Lebanon, Oregon TA-W-81... Enterprises, Inc., Lebanon, Oregon (TA-W- 81,004C); and Pace American Enterprises, Inc., Hurricane, Utah (TA-W...., Fitzgerald, Georgia (TA-W-81,004B), Pace American Enterprises, Inc., Lebanon, Oregon (TA-W-81,004C), Pace...

The Manipulation of Pace within Endurance Sport

PubMed Central

Skorski, Sabrina; Abbiss, Chris R.

2017-01-01

In any athletic event, the ability to appropriately distribute energy is essential to prevent premature fatigue prior to the completion of the event. In sport science literature this is termed “pacing.” Within the past decade, research aiming to better understand the underlying mechanisms influencing the selection of an athlete's pacing during exercise has dramatically increased. It is suggested that pacing is a combination of anticipation, knowledge of the end-point, prior experience and sensory feedback. In order to better understand the role each of these factors have in the regulation of pace, studies have often manipulated various conditions known to influence performance such as the feedback provided to participants, the starting strategy or environmental conditions. As with all research there are several factors that should be considered in the interpretation of results from these studies. Thus, this review aims at discussing the pacing literature examining the manipulation of: (i) energy expenditure and pacing strategies, (ii) kinematics or biomechanics, (iii) exercise environment, and (iv) fatigue development. PMID:28289392

Forms of work organization and associations with shoulder disorders: Results from a French working population.

PubMed

Bodin, Julie; Garlantézec, Ronan; Costet, Nathalie; Descatha, Alexis; Fouquet, Natacha; Caroly, Sandrine; Roquelaure, Yves

2017-03-01

The aim of this study was to identify forms of work organization in a French region and to study associations with the occurrence of symptomatic and clinically diagnosed shoulder disorders in workers. Workers were randomly included in this cross-sectional study from 2002 to 2005. Sixteen organizational variables were assessed by a self-administered questionnaire: i.e. shift work, job rotation, repetitiveness of tasks, paced work/automatic rate, work pace dependent on quantified targets, permanent controls or surveillance, colleagues' work and customer demand, and eight variables measuring decision latitude. Five forms of work organization were identified using hierarchical cluster analysis (HCA) of variables and HCA of workers: low decision latitude with pace constraints, medium decision latitude with pace constraints, low decision latitude with low pace constraints, high decision latitude with pace constraints and high decision latitude with low pace constraints. There were significant associations between forms of work organization and symptomatic and clinically-diagnosed shoulder disorders. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optimal pacing for right ventricular and biventricular devices: minimizing, maximizing, and right ventricular/left ventricular site considerations.

PubMed

Gillis, Anne M

2014-10-01

The results from numerous clinical studies provide guidance for optimizing outcomes related to RV or biventricular pacing in the pacemaker and ICD populations. (1) Programming algorithms to minimize RV pacing is imperative in patients with dual-chamber pacemakers who have intrinsic AV conduction or intermittent AV conduction block. (2) Dual-chamber ICDs should be avoided in candidates without an indication for bradycardia pacing. (3) Alternate RV septal pacing sites may be considered at the time of pacemaker implantation. (4) Biventricular pacing may be beneficial in some patients with mild LV dysfunction. (5) LV lead placement at the site of latest LV activation is desirable. (6) Programming CRT systems to achieve biventricular/LV pacing >98.5% is important. (7) Protocols for AV and VV optimization in patients with CRT are not recommended after device implantation but may be considered for CRT nonresponders. (8) Novel algorithms to maximize the benefit of CRT are in evolution further.

Understanding nonresponders of cardiac resynchronization therapy--current and future perspectives.

PubMed

Yu, Cheuk-Man; Wing-Hong Fung, Jeffrey; Zhang, Qing; Sanderson, John E

2005-10-01

Cardiac resynchronization therapy (CRT) is now an established nonpharmacologic therapy for advanced heart failure with electromechanical delay. Despite compelling evidence of the benefits of CRT, one troubling issue is the lack of a favorable response in about one-third of patients. Currently, there is no unifying definition of responders, and published data were based on acute hemodynamic changes, chronic left ventricular reverse remodeling, as well as the intermediate or long-term clinical response. The lack of improvement with CRT can be due to many factors including the placement of the left ventricular pacing lead in an inappropriate location, the absence of electrical conduction delay or mechanical dyssynchrony despite wide QRS complexes, and possibly failure to optimize the CRT settings after device implantation. In acute hemodynamic studies, placing the left ventricular leads at the free wall region has been suggested to generate the best pulse pressure and positive dp/dt. The degree of mechanical dyssynchrony has recently been assessed noninvasively in CRT patients by echocardiography and in particular by tissue Doppler imaging. These studies suggested that responders of left ventricular reverse remodeling or systolic function had more severe systolic dyssynchrony. However, further studies are needed to examine the clinical utility of these parameters when applied to the standardized anatomic or functional endpoints. Optimization of atrioventricular and interventricular pacing intervals may also reduce the number of nonresponders, though newer methods, especially interventricular pacing intervals, are still under clinical investigation. With the adjunctive use of imaging technology, physicians are able to characterize the response to CRT objectively, and cardiac imaging is an important clinical tool for determining more precisely the presence and degree of mechanical dyssynchrony.

42 CFR 460.162 - Voluntary disenrollment.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Participant Enrollment and Disenrollment § 460.162 Voluntary disenrollment. A PACE...

42 CFR 460.162 - Voluntary disenrollment.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Participant Enrollment and Disenrollment § 460.162 Voluntary disenrollment. A PACE...

Effects of linoleic acid on sweet, sour, salty, and bitter taste thresholds and intensity ratings of adults.

PubMed

Mattes, Richard D

2007-05-01

Evidence supporting a taste component for dietary fat has prompted study of plausible transduction mechanisms. One hypothesizes that long-chain, unsaturated fatty acids block selected delayed-rectifying potassium channels, resulting in a sensitization of taste receptor cells to stimulation by other taste compounds. This was tested in 17 male and 17 female adult (mean +/- SE age = 23.4 +/- 0.7 yr) propylthiouracil tasters with normal resting triglyceride concentrations (87.3 +/- 5.6 mg/day) and body mass index (23.3 +/- 0.4 kg/m(2)). Participants were tested during two approximately 30-min test sessions per week for 8 wk. Eight stimuli were assessed in duplicate via an ascending, three-alternative, forced-choice procedure. Qualities were randomized over weeks. Stimuli were presented as room-temperature, 5-ml portions. They included 1% solutions of linoleic acid with added sodium chloride (salty), sucrose (sweet), citric acid (sour), and caffeine (bitter) as well as solutions of these taste compounds alone. Participants also rated the intensity of the five strongest concentrations using the general labeled magnitude scale. The suprathreshold samples were presented in random order with a rinse between each. Subjects made the ratings self-paced while wearing nose clips. It was hypothesized that taste thresholds would be lower and absolute intensity ratings or slopes of intensity functions would be higher for the stimuli mixed with the linoleic acid. Thresholds were compared by paired t-tests and intensity ratings by repeated measures analysis of variance. Thresholds were significantly higher (i.e., lower sensitivity) for the sodium chloride, citric acid, and caffeine solutions with added fatty acid. Sweet, sour, and salty intensity ratings were lower or unchanged by the addition of a fatty acid. The two highest concentrations of caffeine were rated as weaker in the presence of linoleic acid. These data do not support a mechanism for detecting dietary fats whereby fatty acids sensitize taste receptor cells to stimulation by taste compounds.

Isthmus sites identified by Ripple Mapping are usually anatomically stable: A novel method to guide atrial substrate ablation?

PubMed

Luther, Vishal; Qureshi, Norman; Lim, Phang Boon; Koa-Wing, Michael; Jamil-Copley, Shahnaz; Ng, Fu Siong; Whinnett, Zachary; Davies, D Wyn; Peters, Nicholas S; Kanagaratnam, Prapa; Linton, Nick

2018-03-01

Postablation reentrant ATs depend upon conducting isthmuses bordered by scar. Bipolar voltage maps highlight scar as sites of low voltage, but the voltage amplitude of an electrogram depends upon the myocardial activation sequence. Furthermore, a voltage threshold that defines atrial scar is unknown. We used Ripple Mapping (RM) to test whether these isthmuses were anatomically fixed between different activation vectors and atrial rates. We studied post-AF ablation ATs where >1 rhythm was mapped. Multipolar catheters were used with CARTO Confidense for high-density mapping. RM visualized the pattern of activation, and the voltage threshold below which no activation was seen. Isthmuses were characterized at this threshold between maps for each patient. Ten patients were studied (Map 1 was AT1; Map 2: sinus 1/10, LA paced 2/10, AT2 with reverse CS activation 3/10; AT2 CL difference 50 ± 30 ms). Point density was similar between maps (Map 1: 2,589 ± 1,330; Map 2: 2,214 ± 1,384; P  =  0.31). RM activation threshold was 0.16 ± 0.08 mV. Thirty-one isthmuses were identified in Map 1 (median 3 per map; width 27 ± 15 mm; 7 anterior; 6 roof; 8 mitral; 9 septal; 1 posterior). Importantly, 7 of 31 (23%) isthmuses were unexpectedly identified within regions without prior ablation. AT1 was treated following ablation of 11/31 (35%) isthmuses. Of the remaining 20 isthmuses, 14 of 16 isthmuses (88%) were consistent between the two maps (four were inadequately mapped). Wavefront collision caused variation in low voltage distribution in 2 of 16 (12%). The distribution of isthmuses and nonconducting tissue within the ablated left atrium, as defined by RM, appear concordant between rhythms. This could guide a substrate ablative approach. © 2018 Wiley Periodicals, Inc.

Pixel structures to compensate nonuniform threshold voltage and mobility of polycrystalline silicon thin-film transistors using subthreshold current for large-size active matrix organic light-emitting diode displays

NASA Astrophysics Data System (ADS)

Na, Jun-Seok; Kwon, Oh-Kyong

2014-01-01

We propose pixel structures for large-size and high-resolution active matrix organic light-emitting diode (AMOLED) displays using a polycrystalline silicon (poly-Si) thin-film transistor (TFT) backplane. The proposed pixel structures compensate the variations of the threshold voltage and mobility of the driving TFT using the subthreshold current. The simulated results show that the emission current error of the proposed pixel structure B ranges from -2.25 to 2.02 least significant bit (LSB) when the variations of the threshold voltage and mobility of the driving TFT are ±0.5 V and ±10%, respectively.

On the threshold conditions for electron beam damage of asbestos amosite fibers in the transmission electron microscope (TEM).

PubMed

Martin, Joannie; Beauparlant, Martin; Sauvé, Sébastien; L'Espérance, Gilles

2016-12-01

Asbestos amosite fibers were investigated to evaluate the damage caused by a transmission electron microscope (TEM) electron beam. Since elemental x-ray intensity ratios obtained by energy dispersive x-ray spectroscopy (EDS) are commonly used for asbestos identification, the impact of beam damage on these ratios was evaluated. It was determined that the magnesium/silicon ratio best represented the damage caused to the fiber. Various tests showed that most fibers have a current density threshold above which the chemical composition of the fiber is modified. The value of this threshold current density varied depending on the fiber, regardless of fiber diameter, and in some cases could not be determined. The existence of a threshold electron dose was also demonstrated. This value was dependent on the current density used and can be increased by providing a recovery period between exposures to the electron beam. This study also established that the electron beam current is directly related to the damage rate above a current density of 165 A/cm 2 . The large number of different results obtained suggest, that in order to ensure that the amosite fibers are not damaged, analysis should be conducted below a current density of 100 A/cm 2 .

Transferring PACE Assessments Upon Home Sale

DOE Office of Scientific and Technical Information (OSTI.GOV)

National Renewable Energy Laboratory; Coughlin, Jason; Fuller, Merrian

A significant barrier to investing in renewable energy and comprehensive energy efficiency improvements to homes across the country is the initial capital cost. Property Assessed Clean Energy (PACE) financing is one of several new financial models broadening access to clean energy by addressing this upfront cost issue. Recently, the White House cited PACE programs as an important element of its 'Recovery through Retrofit' plan. The residential PACE model involves the creation of a special clean energy financing district that homeowners elect to opt into. Once opted in, the local government (usually at the city or county level) finances the upfrontmore » investment of the renewable energy installation and/or energy efficiency improvements. A special lien is attached to the property and the assessment is paid back as a line item on the property tax bill. As of April 2010, 17 states have passed legislation to allow their local governments to create PACE programs, two already have the authority to set up PACE programs, and over 10 additional states are actively developing enabling legislation. This policy brief analyzes one of the advantages of PACE, which is the transferability of the special assessment from one homeowner to the next when the home is sold. This analysis focuses on the potential for the outstanding lien to impact the sales negotiation process, rather than the legal nature of the lien transfer itself. The goal of this paper is to consider what implications a PACE lien may have on the home sales negotiation process so that it can be addressed upfront rather than risk a future backlash to PACE programs. If PACE programs do expand at a rapid rate, the chances are high that there will be other cases where prospective buyers uses PACE liens to negotiate lower home prices or require repayment of the lien as a condition of sale. As a result, PACE programs should highlight this issue as a potential risk factor for the sake of full disclosure. A good example of this is in Boulder County where the following statement is included in the ClimateSmart PACE program materials: 'Please Note: There is no legal requirement that the loan be paid off when you refinance or sell your home. However, this may be an item subject to negotiation with a future buyer and may also be a matter of negotiation with the mortgage lender.' Such candid disclosure for what might be a low risk event can be debated. However, a selling point of PACE programs is the transferability of the lien to the new homeowner. To the degree this benefit is questioned, PACE programs may end up looking more like home equity loan financing, with the associated debt repaid at closing, rather than property-based financing that remains with the improved home. While it is possible that upfront disclosure might negatively impact participation rates in PACE programs, it also will protect the integrity of a PACE program in later years if such situations come to pass. Ideally, this will become less of an issue over time as more homebuyers understand the positive economic and societal benefits of owning a home with clean energy features.« less

[Management of surgery patients with implanted cardiac pacemakers].

PubMed

Ugljen, R; Dadić, D; Ferek-Petrić, B; Jelić, I; Letica, D; Anić, D; Husar, J

1995-01-01

Patients having cardiac pacemaker implanted may be subjected to various general surgery procedures. Application of electrosurgery for the purpose of resection and coagulation, provides a high frequency electric field which produces electric voltage on the electrodes of the pacing system. This voltage may be detected within the pacing system, and various arrhythmias can be provoked in correlation with underlying rhythm and mode of pacing. Preoperative patient control and proper pacemaker programming can prevent the pacing malfunctions due to the electrosurgery application. Appropriate positioning of the neutral electrode in relation to the pacing system avoids the electric fields intersection and decreases their interference.

Enact legislation supporting residential property assessed clean energy financing (PACE)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saha, Devashree

Congress should enact legislation that supports residential property assessed clean energy (PACE) programs in the nation’s states and metropolitan areas. Such legislation should require the Federal Housing Finance Agency (FHFA) to allow Fannie Mae and Freddie Mac to purchase residential mortgages with PACE assessments while at the same time providing responsible underwriting standards and a set of benchmarks for residential PACE assessments in order to minimize financial risks to mortgage holders. Congressional support of residential PACE financing will improve energy efficiency, encourage job creation, and foster economic growth in the nation’s state and metropolitan areas.

42 CFR 460.12 - Application requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Organization Application and Waiver Process § 460.12 Application requirements. (a...

42 CFR 460.104 - Participant assessment.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Services § 460.104 Participant assessment. (a) Initial comprehensive assessment—(1...

42 CFR 460.12 - Application requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Organization Application and Waiver Process § 460.12 Application requirements. (a...

DiPALS: Diaphragm Pacing in patients with Amyotrophic Lateral Sclerosis - a randomised controlled trial.

PubMed

McDermott, Christopher J; Bradburn, Mike J; Maguire, Chin; Cooper, Cindy L; Baird, Wendy O; Baxter, Susan K; Cohen, Judith; Cantrill, Hannah; Dixon, Simon; Ackroyd, Roger; Baudouin, Simon; Bentley, Andrew; Berrisford, Richard; Bianchi, Stephen; Bourke, Stephen C; Darlison, Roy; Ealing, John; Elliott, Mark; Fitzgerald, Patrick; Galloway, Simon; Hamdalla, Hisham; Hanemann, C Oliver; Hughes, Philip; Imam, Ibrahim; Karat, Dayalan; Leek, Roger; Maynard, Nick; Orrell, Richard W; Sarela, Abeezar; Stradling, John; Talbot, Kevin; Taylor, Lyn; Turner, Martin; Simonds, Anita K; Williams, Tim; Wedzicha, Wisia; Young, Carolyn; Shaw, Pamela J

2016-06-01

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease resulting in death, usually from respiratory failure, within 2-3 years of symptom onset. Non-invasive ventilation (NIV) is a treatment that when given to patients in respiratory failure leads to improved survival and quality of life. Diaphragm pacing (DP), using the NeuRx/4(®) diaphragm pacing system (DPS)™ (Synapse Biomedical, Oberlin, OH, USA), is a new technique that may offer additional or alternative benefits to patients with ALS who are in respiratory failure. The Diaphragm Pacing in patients with Amyotrophic Lateral Sclerosis (DiPALS) trial evaluated the effect of DP on survival over the study duration in patients with ALS with respiratory failure. The DiPALS trial was a multicentre, parallel-group, open-label, randomised controlled trial incorporating health economic analyses and a qualitative longitudinal substudy. Eligible participants had a diagnosis of ALS (ALS laboratory-supported probable, clinically probable or clinically definite according to the World Federation of Neurology revised El Escorial criteria), had been stabilised on riluzole for 30 days, were aged ≥ 18 years and were in respiratory failure. We planned to recruit 108 patients from seven UK-based specialist ALS or respiratory centres. Allocation was performed using 1 : 1 non-deterministic minimisation. Participants were randomised to either standard care (NIV alone) or standard care (NIV) plus DP using the NeuRX/4 DPS. The primary outcome was overall survival, defined as the time from randomisation to death from any cause. Secondary outcomes were patient quality of life [assessed by European Quality of Life-5 Dimensions, three levels (EQ-5D-3L), Short Form questionnaire-36 items and Sleep Apnoea Quality of Life Index questionnaire]; carer quality of life (EQ-5D-3L and Caregiver Burden Inventory); cost-utility analysis and health-care resource use; tolerability and adverse events. Acceptability and attitudes to DP were assessed in a qualitative substudy. In total, 74 participants were randomised into the trial and analysed, 37 participants to NIV plus pacing and 37 to standard care, before the Data Monitoring and Ethics Committee advised initial suspension of recruitment (December 2013) and subsequent discontinuation of pacing (on safety grounds) in all patients (June 2014). Follow-up assessments continued until the planned end of the study in December 2014. The median survival (interquartile range) was 22.5 months (lower quartile 11.8 months; upper quartile not reached) in the NIV arm and 11.0 months (6.7 to 17.0 months) in the NIV plus pacing arm, with an adjusted hazard ratio of 2.27 (95% confidence interval 1.22 to 4.25; p = 0.01). Diaphragmatic pacing should not be used as a routine treatment for patients with ALS in respiratory failure. It may be that certain population subgroups benefit from DP. We are unable to explain the mechanism behind the excess mortality in the pacing arm, something the small trial size cannot help address. Future research should investigate the mechanism by which harm or benefit occurs further. Current Controlled Trials ISRCTN53817913. This project was funded by the National Institute for Health Research Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 20, No. 45. See the HTA programme website for further project information. Additional funding was provided by the Motor Neurone Disease Association of England, Wales and Northern Ireland.

The effect of aging on pacing strategies of cross-country skiers and the role of performance level.

PubMed

Nikolaidis, Pantelis Theodoros; Villiger, Elias; Rosemann, Thomas; Knechtle, Beat

2018-01-01

The participation of master cross-country (XC) skiers in training and competition has increased during the last decades; however, little is known yet about whether these athletes differ from their younger counterparts in aspects of performance such as pacing. Therefore, the aim of the present study was to examine the combined effect of age and performance (race time) on pacing in cross-country (XC) skiing. We analyzed all finishers ( n  = 79,722) in 'Vasaloppet' from 2012 to 2017, the largest cross-country skiing race in the world, classified according to their race time into 10 groups: 3-4 h, 4-5 h, ..., 12-13 h. A trivial main effect of sex on total pace range was observed ( p  < 0.001, η 2  = 0.002), where women (44.1 ± 10.2%) had larger total pace range than men (40.9 ± 11.8%). A large main effect of performance group on total pace range was shown ( p  < 0.001, η 2  = 0.160), where the smallest total pace range was 21.8 ± 1.9% (3-4 h group) and the largest 50.1 ± 9.9% (10-11 h group). A trivial sex×performance group interaction on total pace range was found ( p  < 0.001, η 2  = 0.001) with the largest sex difference in pacing shown in 9-10 h group. A trivial and small main effect of age was found in women ( p  < 0.001, η 2  = 0.005) and men ( p  < 0.001, η 2  = 0.011), respectively, where the masters had smaller total pace range than their younger counterparts. A trivial age group×performance group interaction on total pace range was observed in both women ( p  < 0.001, η 2  = 0.008) and men ( p  < 0.001, η 2  = 0.006) with smaller differences among age groups in the faster performance groups. In summary, master XC skiers adopted a relatively even pacing independently from their race time and the differences in pacing from the younger XC skiers were more pronounced in the slower masters. These findings suggest that exercise attenuates the decline of performance in master XC skiers as shown by the similar pacing strategies between fast master XC skiers and their younger counterparts.

Merging Theoretical Models and Therapy Approaches in the Context of Internet Gaming Disorder: A Personal Perspective.

PubMed

Young, Kimberly S; Brand, Matthias

2017-01-01

Although, it is not yet officially recognized as a clinical entity which is diagnosable, Internet Gaming Disorder (IGD) has been included in section III for further study in the DSM-5 by the American Psychiatric Association (APA, 2013). This is important because there is increasing evidence that people of all ages, in particular teens and young adults, are facing very real and sometimes very severe consequences in daily life resulting from an addictive use of online games. This article summarizes general aspects of IGD including diagnostic criteria and arguments for the classification as an addictive disorder including evidence from neurobiological studies. Based on previous theoretical considerations and empirical findings, this paper examines the use of one recently proposed model, the Interaction of Person-Affect-Cognition-Execution (I-PACE) model, for inspiring future research and for developing new treatment protocols for IGD. The I-PACE model is a theoretical framework that explains symptoms of Internet addiction by looking at interactions between predisposing factors, moderators, and mediators in combination with reduced executive functioning and diminished decision making. Finally, the paper discusses how current treatment protocols focusing on Cognitive-Behavioral Therapy for Internet addiction (CBT-IA) fit with the processes hypothesized in the I-PACE model.

Degradation of cognitive timing mechanisms in behavioural variant frontotemporal dementia

PubMed Central

Henley, Susie M.D.; Downey, Laura E.; Nicholas, Jennifer M.; Kinnunen, Kirsi M.; Golden, Hannah L.; Buckley, Aisling; Mahoney, Colin J.; Crutch, Sebastian J.

2014-01-01

The current study examined motor timing in frontotemporal dementia (FTD), which manifests as progressive deterioration in social, behavioural and cognitive functions. Twenty-patients fulfilling consensus clinical criteria for behavioural variant FTD (bvFTD), 11 patients fulfilling consensus clinical criteria for semantic-variant primary progressive aphasia (svPPA), four patients fulfilling criteria for nonfluent/agrammatic primary progressive aphasia (naPPA), eight patients fulfilling criteria for Alzheimer׳s disease (AD), and 31 controls were assessed on both an externally- and self-paced finger-tapping task requiring maintenance of a regular, 1500 ms beat over 50 taps. Grey and white matter correlates of deficits in motor timing were examined using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI). bvFTD patients exhibited significant deficits in aspects of both externally- and self-paced tapping. Increased mean inter-response interval (faster than target tap time) in the self-paced task was associated with reduced grey matter volume in the cerebellum bilaterally, right middle temporal gyrus, and with increased axial diffusivity in the right superior longitudinal fasciculus, regions and tracts which have been suggested to be involved in a subcortical–cortical network of structures underlying timing abilities. This suggests that such structures can be affected in bvFTD, and that impaired motor timing may underlie some characteristics of the bvFTD phenotype. PMID:25447066

PACE4 inhibitors and their peptidomimetic analogs block prostate cancer tumor progression through quiescence induction, increased apoptosis and impaired neovascularisation

PubMed Central

Levesque, Christine; Couture, Frédéric; Kwiatkowska, Anna; Desjardins, Roxane; Guérin, Brigitte; Neugebauer, Witold A.; Day, Robert

2015-01-01

Prostate cancer is the leading cancer in North American men. Current pharmacological treatments are limited to anti-androgen strategies and the development of new therapeutic approaches remains a challenge. As a fundamentally new approach, we propose the inhibition of PACE4, a member of the proprotein convertases family of enzymes, as a therapeutic target in prostate cancer. We developed an inhibitor named the Multi-Leu peptide, with potent in vitro anti-proliferative effects. However, the Multi-Leu peptide has not been tested under in vivo conditions and its potency under such conditions is most likely limited, due to the labile characteristics of peptides in general. Using a peptidomimetic approach, we modified the initial scaffold, generating the analog Ac-[DLeu]LLLRVK-Amba, which demonstrates increased inhibitory potency and stability. The systemic administration of this peptidomimetic significantly inhibits tumor progression in the LNCaP xenograft model of prostate cancer by inducing tumor cell quiescence, increased apoptosis and neovascularization impairment. Pharmacokinetic and biodistribution profiles of this inhibitor confirm adequate tumor delivery properties of the compound. We conclude that PACE4 peptidomimetic inhibitors could result in stable and potent drugs for a novel therapeutic strategy for prostate cancer. PMID:25682874

Next-generation pacemakers: from small devices to biological pacemakers.

PubMed

Cingolani, Eugenio; Goldhaber, Joshua I; Marbán, Eduardo

2018-03-01

Electrogenesis in the heart begins in the sinoatrial node and proceeds down the conduction system to originate the heartbeat. Conduction system disorders lead to slow heart rates that are insufficient to support the circulation, necessitating implantation of electronic pacemakers. The typical electronic pacemaker consists of a subcutaneous generator and battery module attached to one or more endocardial leads. New leadless pacemakers can be implanted directly into the right ventricular apex, providing single-chamber pacing without a subcutaneous generator. Modern pacemakers are generally reliable, and their programmability provides options for different pacing modes tailored to specific clinical needs. Advances in device technology will probably include alternative energy sources and dual-chamber leadless pacing in the not-too-distant future. Although effective, current electronic devices have limitations related to lead or generator malfunction, lack of autonomic responsiveness, undesirable interactions with strong magnetic fields, and device-related infections. Biological pacemakers, generated by somatic gene transfer, cell fusion, or cell transplantation, provide an alternative to electronic devices. Somatic reprogramming strategies, which involve transfer of genes encoding transcription factors to transform working myocardium into a surrogate sinoatrial node, are furthest along in the translational pipeline. Even as electronic pacemakers become smaller and less invasive, biological pacemakers might expand the therapeutic armamentarium for conduction system disorders.

Merging Theoretical Models and Therapy Approaches in the Context of Internet Gaming Disorder: A Personal Perspective

PubMed Central

Young, Kimberly S.; Brand, Matthias

2017-01-01

Although, it is not yet officially recognized as a clinical entity which is diagnosable, Internet Gaming Disorder (IGD) has been included in section III for further study in the DSM-5 by the American Psychiatric Association (APA, 2013). This is important because there is increasing evidence that people of all ages, in particular teens and young adults, are facing very real and sometimes very severe consequences in daily life resulting from an addictive use of online games. This article summarizes general aspects of IGD including diagnostic criteria and arguments for the classification as an addictive disorder including evidence from neurobiological studies. Based on previous theoretical considerations and empirical findings, this paper examines the use of one recently proposed model, the Interaction of Person-Affect-Cognition-Execution (I-PACE) model, for inspiring future research and for developing new treatment protocols for IGD. The I-PACE model is a theoretical framework that explains symptoms of Internet addiction by looking at interactions between predisposing factors, moderators, and mediators in combination with reduced executive functioning and diminished decision making. Finally, the paper discusses how current treatment protocols focusing on Cognitive-Behavioral Therapy for Internet addiction (CBT-IA) fit with the processes hypothesized in the I-PACE model. PMID:29104555

42 CFR 460.172 - Documentation of disenrollment.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Participant Enrollment and Disenrollment § 460.172 Documentation of disenrollment. A PACE...

Helping Girls Get Back on Track: An Implementation Study of the PACE Center for Girls. Executive Summary

ERIC Educational Resources Information Center

Treskon, Louisa; Millenky, Megan; Freedman, Lily

2017-01-01

PACE Center for Girls is a unique program that provides academic and social services to girls ages 11 to 18. Girls eligible for PACE exhibit multiple health, safety, and delinquency risk factors, such as poor academic performance, exposure to abuse or violence, truancy, risky sexual behavior, and substance abuse. PACE seeks to help them onto a…

Assessing the PACE of California residential solar deployment: Impacts of Property Assessed Clean Energy programs on residential solar photovoltaic deployment in California, 2010-2015

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deason, Jeff; Murphy, Sean

A new study by Berkeley Lab found that residential Property Assessed Clean Energy (R-PACE) programs increased deployment of residential solar photovoltaic (PV) systems in California, raising it by about 7-12% in cities that adopt these programs. R-PACE is a financing mechanism that uses a voluntary property tax assessment, paid off over time, to facilitate energy improvements and, in some jurisdictions, water and resilience measures. While previous studies demonstrated that early, regional R-PACE programs increased solar PV deployment, this new analysis is the first to demonstrate these impacts from the large, statewide R-PACE programs dominating the California market today, which usemore » private capital to fund the upfront costs of the improvements. Berkeley Lab estimated the impacts using econometric techniques on two samples: -Large cities only, allowing annual demographic and economic data as control variables -All California cities, without these annual data Analysis of both samples controls for several factors other than R-PACE that would be expected to drive solar PV deployment. We infer that on average, cities with R-PACE programs were associated with greater solar PV deployment in our study period (2010-2015). In the large cities sample, solar PV deployment in jurisdictions with R-PACE programs was higher by 1.1 watts per owner-occupied household per month, or 12%. Across all cities, solar PV deployment in jurisdictions with R-PACE programs was higher by 0.6 watts per owner-occupied household per month, or 7%. The large cities results are statistically significant at conventional levels; the all-cities results are not. The estimates imply that the majority of solar PV deployment financed by R-PACE programs would likely not have occurred in their absence. Results suggest that R-PACE programs have increased PV deployment in California even in relatively recent years, as R-PACE programs have grown in market share and as alternate approaches for financing solar PV have developed. The U.S. Department of Energy’s Building Technologies Office supported this research.« less

Increased base rate of atrial pacing for prevention of atrial fibrillation after implantation of a dual-chamber pacemaker: insights from the Atrial Overdrive Pacing Study.

PubMed

Kantharia, Bharat K; Freedman, Roger A; Hoekenga, David; Tomassoni, Gery; Worley, Seth; Sorrentino, Robert; Steinhaus, David; Wolkowicz, Joel M; Syed, Zaffer A

2007-11-01

Different pacing sites and various algorithms have been utilized to prevent atrial fibrillation (AF) in pacemaker recipients. However, the optimal pacing rate settings have not yet been established. In this randomized, prospective, multicentre, single-blinded, cross over study, rate-adaptive pacing at a high base rate (BR) in patients, age 60 years or above, or a history of paroxysmal AF, who underwent dual-chamber (DDD) pacemaker implantation for standard pacing indications, was evaluated for prevention of AF. In the study cohort of 145 patients implanted with DDD pacemakers with a programmable rest rate (RR) feature, the BR/RR settings were sequentially but randomly adjusted as follows: 60 bpm/Off for the baseline quarter (initial 3 months) and then to either 'A-B-C' or 'C-B-A' settings (A = 70/65 bpm, B = 70/Off, C = 80/65 bpm) for the subsequent quarters each of 3 months duration. Data on automatic mode switch episodes, device diagnostics, and a questionnaire evaluating pacemaker awareness and palpitations were collected. Ninety-nine patients, mean age 77 +/- 10 years, who completed the study protocol and followed for 12 months did not show significant differences in the number of mode switch episodes between any settings used. The percentage of atrial pacing was lower during baseline pacing compared to settings A, B, and C (P < 0.0001). Setting C produced a higher percentage of atrial pacing than A and B (P < 0.01). Although a higher percentage of atrial pacing correlated with a lower incidence of mode switch episodes, there was no statistically significant difference in the number of mode switch episodes between settings A, B, and C. There were no significant differences in the questionnaire scores relating to pacemaker awareness or palpitation. Overdrive single-site pacing in the right atrium achieved by programming analysed settings in the present study did not reduce AF as assessed by mode switch episodes. Additionally, no change in the symptoms of arrhythmia or awareness of pacing was seen.

Left ventricular epicardial activation increases transmural dispersion of repolarization in healthy, long QT, and dilated cardiomyopathy dogs.

PubMed

Bai, Rong; Lü, Jiagao; Pu, Jun; Liu, Nian; Zhou, Qiang; Ruan, Yanfei; Niu, Huiyan; Zhang, Cuntai; Wang, Lin; Kam, Ruth

2005-10-01

Benefits of cardiac resynchronization therapy (CRT) are well established. However, less is understood concerning its effects on myocardial repolarization and the potential proarrhythmic risk. Healthy dogs (n = 8) were compared to a long QT interval (LQT) model (n = 8, induced by cesium chloride, CsCl) and a dilated cardiomyopathy with congestive heart failure (DCM-CHF, induced by rapid ventricular pacing, n = 5). Monophasic action potential (MAP) recordings were obtained from the subendocardium, midmyocardium, subepicardium, and the transmural dispersion of repolarization (TDR) was calculated. The QT interval and the interval from the peak to the end of the T wave (T(p-e)) were measured. All these characteristics were compared during left ventricular epicardial (LV-Epi), right ventricular endocardial (RV-Endo), and biventricular (Bi-V) pacing. In healthy dogs, TDR prolonged to 37.54 ms for Bi-V pacing and to 47.16 ms for LV-Epi pacing as compared to 26.75 ms for RV-Endo pacing (P < 0.001), which was parallel to an augmentation in T(p-e) interval (Bi-V pacing, 64.29 ms; LV-Epi pacing, 57.89 ms; RV-Endo pacing, 50.29 ms; P < 0.01). During CsCl exposure, Bi-V and LV-Epi pacing prolonged MAPD, TDR, and T(p-e) interval as compared to RV-Endo pacing. The midmyocardial MAPD (276.30 ms vs 257.35 ms, P < 0.0001) and TDR (33.80 ms vs 27.58 ms, P=0.002) were significantly longer in DCM-CHF dogs than those in healthy dogs. LV-Epi and Bi-V pacing further prolonged the MAPD and TDR in this model. LV-Epi and Bi-V pacing result in prolongation of ventricular repolarization time, and increase of TDR accounted for a parallel augmentation of the T(p-e) interval, which provides evidence that T(p-e) interval accurately represents TDR. These effects are magnified in the LQT and DCM-CHF canine models in addition to their intrinsic transmural heterogeneity in the intact heart. This mechanism may contribute to the development of malignant ventricular arrhythmias, such as torsades de pointes (TdP) in congestive heart failure (CHF) patients treated with CRT.

Dynamic and dual-site atrial pacing in the prevention of atrial fibrillation: The STimolazione Atrial DInamica Multisito (STADIM) Study.

PubMed

De Simone, Antonio; Senatore, Gaetano; Donnici, Giovanni; Turco, Pietro; Romano, Enrico; Gazzola, Carlo; Stabile, G

2007-01-01

The impact of new algorithms to consistently pace the atrium on the prevention of atrial fibrillation (AF) remains unclear. Our randomized, crossover study compared the efficacy of single- and dual-site atrial pacing, with versus without dynamic atrial overdrive pacing in preventing AF. We studied 72 patients (mean age = 69.6 +/- 6.5 years, 34 men) with sick sinus syndrome (SSS) and paroxysmal or persistent AF, who received dual-chamber pacemakers (PM) equipped with an AF prevention algorithm and two atrial leads placed in the right atrial appendage (RAA), by passive fixation, and in the coronary sinus ostium (CS), by active fixation, respectively. At implant, the patients were randomly assigned to unipolar CS versus RAA pacing. The PM was programmed in DDDR mode 1 month after implant. Each patient underwent four study phases of equal duration: (1) unipolar, single site (CS or RAA) pacing with the AF algorithm ON (atrial lower rate = 0 ppm); (2) unipolar, single site pacing with the AF algorithm OFF (atrial lower rate = 70 bpm); (3) bipolar, dual-site pacing with AF algorithm ON; (4) bipolar, dual-site pacing with the AF algorithm OFF. Among 40 patients (56%), who completed the follow-up (15 +/- 4 months) no difference was observed in the mean number of automatic mode switch (AMS) corrected for the duration of follow-up, in unipolar (5.6 +/- 22.8 vs 2.6 +/- 5.5) or bipolar mode (3.3 +/- 12.7 vs 2.1 +/- 4.9) with, respectively, the algorithm OFF or ON. With the AF prevention algorithm ON, the percentage of atrial pacing increased significantly from 78.7 +/- 22.1% to 92.4 +/- 4.9% (P < 0.001), while the average ventricular heart rate was significantly lower with the algorithm ON (62.4 +/- 17.5 vs 79.9 +/- 3 bpm (P < 0.001). The AF prevention algorithm increased the percentage of atrial pacing significantly, regardless of the atrial pulse configuration and pacing site, while maintaining a slower ventricular heart rate. It had no impact on the number of AMS in the unipolar and bipolar modes in patients with SSS.

Effects of enhanced pacing modalities on health care resource utilization and costs in bradycardia patients: An analysis of the randomized MINERVA trial.

PubMed

Boriani, Giuseppe; Manolis, Antonis S; Tukkie, Raymond; Mont, Lluis; Pürerfellner, Helmut; Santini, Massimo; Inama, Giuseppe; Serra, Paolo; Gulizia, Michele; Samoilenko, Igor Vasilyevich; Wolff, Claudia; Holbrook, Reece; Gavazza, Federica; Padeletti, Luigi

2015-06-01

Many patients who suffer from bradycardia and need cardiac pacing also have atrial fibrillation (AF). New pacemaker algorithms, such as atrial preventive pacing and atrial antitachycardia pacing (DDDRP) and managed ventricular pacing (MVP), have been specifically designed to reduce AF occurrence and duration and to minimize the detrimental effects of right ventricular pacing. The randomized MINimizE Right Ventricular pacing to prevent Atrial fibrillation and heart failure trial established that DDDRP + MVP pacing modality reduced permanent AF in bradycardia patients as compared with standard dual-chamber pacing (DDDR). The aim of this study was to estimate the cost savings due to lower AF-related health care utilization events based on health care costs from the United States and the European Union. Dual-chamber pacemaker patients with a history of paroxysmal or persistent AF were randomly assigned to receive DDDR (n = 385) or the advanced features (DDDRP + MVP; n = 383). We used published health care costs from the United States and the European Union (Italy, Spain, and the United Kingdom) to estimate the costs associated with AF-related hospitalizations and emergency visits. The rate of AF-related hospitalizations was significantly lower in the DDDRP + MVP group than in the conventional pacemaker group (DDDR group; 42% reduction; incidence rate ratio 0.58). Similarly, a significant reduction of 68% was observed for AF-related emergency department visits (incidence rate ratio 0.32; P < .001). As a consequence, DDDRP + MVP could potentially reduce health care costs by 40%-44%. Over a ten-year period, the cost savings per 100 patients ranged from $35,702 in the United Kingdom to $121,831 in the United States. New pacing algorithms such as DDDRP + MVP used in the MINimizE Right Ventricular pacing to prevent Atrial fibrillation and heart failure trial successfully reduced AF-related health care utilization, resulting in significant cost savings to payers. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

The effect of atrial-based pacing on exercise capacity as measured by the 6-minute walk test: a substudy of the Canadian Trial of Physiological Pacing (CTOPP).

PubMed

Baranchuk, Adrian; Healey, Jeff S; Thorpe, Kevin E; Morillo, Carlos A; Nair, Girish; Crystal, Eugene; Kerr, Charles R; Connolly, Stuart J

2007-08-01

Although several randomized trials have detected no reduction in major cardiovascular events with the routine use of dual-chamber as opposed to ventricular pacemakers, many individuals continue to advocate their use as a means of improving exercise capacity. The Canadian Trial of Physiological Pacing (CTOPP) trial is the largest trial comparing ventricular pacing to atrial-based pacing (atrial or dual-chamber) in patients with bradycardia. All patients in this trial were asked to complete a 6-minute hall walk test (6MWT) at the time of their first study follow-up. The distance walked in 6 minutes and the patient's heart rate before and immediately after the walk were recorded. Of the 2568 patients in the CTOPP, 76% completed the 6MWT. The mean distance walked was 350 +/- 127 m in the ventricular pacing group and 356 +/- 127 m in the atrial-based group (P = NS). Similarly, there was no difference in the change in heart rate between the two groups (17 +/- 13 vs. 18 +/- 12 bpm: P = NS). However, among patients with an unpaced heart rate of

Sildenafil (Viagra) prolongs cardiac repolarization by blocking the rapid component of the delayed rectifier potassium current.

PubMed

Geelen, P; Drolet, B; Rail, J; Bérubé, J; Daleau, P; Rousseau, G; Cardinal, R; O'Hara, G E; Turgeon, J

2000-07-18

BACKGROUND-Several cases of unexpected death have been reported with sildenafil in patients predisposed to ischemic cardiac events. Although acute episodes of ischemia could account for some of these deaths, we hypothesized that sildenafil may have unsuspected electrophysiological effects predisposing some patients to proarrhythmia. METHODS AND RESULTS-Studies were undertaken in 10 isolated guinea pig hearts that demonstrated prolongation of cardiac repolarization in a reverse use-dependent manner by sildenafil 30 mcmol/L. Action potential duration increased 15% from baseline 117+/-3 to 134+/-2 ms with sildenafil during pacing at 250 ms cycle length, whereas a 6% increase from 99+/-2 to 105+/-2 ms was seen with pacing at 150 ms cycle length. Experiments in human ether-a-go-go-related gene (HERG)-transfected HEK293 cells (n=30) demonstrated concentration-dependent block of the rapid component (I(Kr)) of the delayed rectifier potassium current: activating current was 50% decreased at 100 mcmol/L. This effect was confirmed using HERG-transfected Chinese hamster ovary (CHO) cells, which exhibit no endogenous I(K)-like current. CONCLUSIONS-Sildenafil possesses direct cardiac electrophysiological effects similar to class III antiarrhythmic drugs. These effects are observed at concentrations that may be found in conditions of impaired drug elimination such as renal or hepatic insufficiency, during coadministration of another CYP3A substrate/inhibitor, or after drug overdose and offer a new potential explanation for sudden death during sildenafil treatment.

42 CFR 460.116 - Explanation of rights.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Participant Rights § 460.116 Explanation of rights. (a) Written policies. A PACE...

42 CFR 460.116 - Explanation of rights.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Participant Rights § 460.116 Explanation of rights. (a) Written policies. A PACE...

Left Ventricular Reverse Remodeling With Biventricular Versus Right Ventricular Pacing in Patients With Atrioventricular Block and Heart Failure in the BLOCK HF Trial.

PubMed

St John Sutton, Martin; Plappert, Ted; Adamson, Philip B; Li, Pei; Christman, Shelly A; Chung, Eugene S; Curtis, Anne B

2015-05-01

Biventricular pacing in heart failure (HF) improves survival, relieves symptoms, and attenuates left ventricular (LV) remodeling. However, little is known about biventricular pacing in HF patients with atrioventricular block because they are typically excluded from biventricular trials. The Biventricular versus Right Ventricular Pacing in Heart Failure Patients with Atrioventricular Block (BLOCK HF) trial randomized patients with atrioventricular block, New York Heart Association symptom classes I to III HF, and LV ejection fraction ≤50% to biventricular or right ventricular pacing. Doppler echocardiograms were obtained at randomization (after 30 to 60 days of right ventricular pacing postimplant) and every 6 months through 24 months. Data analysis comparing changes in 10 prespecified echo parameters over time was conducted using a Bayesian design. LV end systolic volume index was also evaluated as a predictor of mortality/morbidity. Of 691 randomized subjects, 624 had paired Doppler echocardiogram data for ≥1 analyses at 6, 12, 18, or 24 months. Biventricular pacing significantly reduced LV volume indices and intraventricular mechanical delay, and improved LV ejection fraction, consistent with LV reverse remodeling. These parameters showed little change with right ventricular pacing alone, indicating no systematic reverse remodeling with right ventricular pacing. LV end systolic volume index was predictive of mortality/morbidity; the estimated risk increased up to 1% for every 1 mL/m(2) increase in LV end systolic volume index. LV end systolic volume index is a significant predictor of mortality/morbidity in this population. Cardiac structure and function are improved with biventricular pacing for patients with atrioventricular block and LV systolic dysfunction. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00267098. © 2015 American Heart Association, Inc.

The Effect of Right Ventricular Apical and Nonapical Pacing on the Short- and Long-Term Changes in Left Ventricular Ejection Fraction: A Systematic Review and Meta-Analysis of Randomized-Controlled Trials.

PubMed

Hussain, Mohammad Akhtar; Furuya-Kanamori, Luis; Kaye, Gerald; Clark, Justin; Doi, Suhail A R

2015-09-01

The right ventricular apex (RVA) is the traditional lead site for chronic pacing but in some patients may cause impaired left ventricular (LV) systolic function over time. Comparisons with right ventricular nonapical (RVNA) pacing sites have generated inconsistent results and recent meta-analyses have demonstrated unclear benefit due to heterogeneity across studies. A systematic search for randomized controlled trials that compared LV ejection fraction (LVEF) outcomes between RVNA and RVA pacing was performed up to October 2014. Twenty-four studies (n = 1,628 patients) met the inclusion criteria. To avoid between study heterogeneity two homogenous groups were created; group 1 where studies reported a difference (in favor of RVNA pacing) and group 2 where studies reported no difference between pacing sites. For group 1, weighted mean difference between RVNA and RVA pacing in terms of LVEF at follow-up was 5.40% (95% confidence interval [CI]: 3.94-6.87), related in part to group one's RVA arm demonstrating a significant reduction (mean loss -3.31%; 95% CI: -6.19 to -0.43) in LVEF between study baseline and end of follow-up. Neither of these finding were seen in group 2. Weighted regression modeling demonstrated that inclusion of poor baseline LVEF (<40%) in combination with greater than 12 months follow-up was three times more common in group 1 compared to group 2 (weighted relative risk 2.82; 95% CI: 1.03-7.72; P = 0.043). In patients requiring chronic right ventricular pacing where there is inclusion of impaired baseline LVEF (<40%), RVA pacing is associated with deterioration in LV function relative to RVNA pacing. © 2015 Wiley Periodicals, Inc.

Validation of criteria for selective his bundle and para-hisian permanent pacing.

PubMed

Cantù, F; De Filippo, P; Cardano, P; De Luca, A; Gavazzi, A

2006-12-01

His Bundle (HB) pacing is a valid alternative to right ventricular pacing for patients with preserved His-ventricle conduction who are candidates for permanent stimulation. Permanent pacing in the HB area enables Selective HB pacing (SHBP) or para-Hisian pacing (PHP) to be achieved. The aim of our study was to draw up a set of easy criteria to differentiate and validate the two kinds of stimulations according to the pacing output and the ECG/EKG signals. From February to July 2005, 17 patients eligible for a pacemaker (PM) procedure underwent implantation with the Medtronic SelectSecure lead (Medtronic, Minneapolis, MN, USA) screwed into the HB area.SHBP was defined when the intrinsic QRS was equal, in both duration and morphology, to the paced QRS, the His-Ventricular (H-V) interval was equal to Pace-Ventricular interval (Vp-V) and, at low output, only the HB was captured, while increasing the output resulted in both the HB and right ventricular (RV) being captured (widening of QRS at high output). Conversely, PHP was defined when the intrinsic QRS differed from the paced one, either in morphology or in duration and, at high output, both the RV and HB were captured (non-SHBP), while decreasing the output resulted in losing HB capture (widening of QRS at low output). According to these criteria, SHBP was achieved in 11 patients, while in the remaining 6, PHP was obtained. No adverse events were reported. The above criteria enabled SHBP and PHP to be validated easily and clearly. A longer follow-up will be needed in order to ascertain whether the clinical outcome of these two approaches differs.

A proteomic approach reveals transient association of reticulocalbin-3, a novel member of the CREC family, with the precursor of subtilisin-like proprotein convertase, PACE4

PubMed Central

Tsuji, Akihiko; Kikuchi, Yayoi; Sato, Yukimi; Koide, Shizuyo; Yuasa, Keizo; Nagahama, Masami; Matsuda, Yoshiko

2006-01-01

SPCs (subtilisin-like proprotein convertases) are a family of seven structurally related serine endoproteases that are involved in the proteolytic activation of proproteins. In an effort to examine the substrate protein for PACE4 (paired basic amino-acid-cleaving enzyme-4), an SPC, a potent protein inhibitor of PACE4, an α1-antitrypsin RVRR (Arg-Val-Arg-Arg) variant, was expressed in GH4C1 cells. Ectopic expression of the RVRR variant caused accumulation of the 48 kDa protein in cells. Sequence analysis indicates that the 48 kDa protein is a putative Ca2+-binding protein, RCN-3 (reticulocalbin-3), which had previously been predicted by bioinformatic analysis of cDNA from the human hypothalamus. RCN-3 is a member of the CREC (Cab45/reticulocalbin/ERC45/calumenin) family of multiple EF-hand Ca2+-binding proteins localized to the secretory pathway. The most interesting feature of the RCN-3 sequence is the presence of five Arg-Xaa-Xaa-Arg motifs, which represents the target sequence of SPCs. Biosynthetic studies showed that RCN-3 is transiently associated with proPACE4, but not with mature PACE4. Inhibition of PACE4 maturation by a Ca2+ ionophore resulted in accumulation of the proPACE4–RCN-3 complex in cells. Furthermore, autoactivation and secretion of PACE4 was increased upon co-expression with RCN-3. Our findings suggest that selective and transient association of RCN-3 with the precursor of PACE4 plays an important role in the biosynthesis of PACE4. PMID:16433634

Pulmonary vein isolation using a pace-capture-guided versus an adenosine-guided approach: effect on dormant conduction and long-term freedom from recurrent atrial fibrillation--a prospective study.

PubMed

Andrade, Jason G; Pollak, Scott J; Monir, George; Khairy, Paul; Dubuc, Marc; Roy, Denis; Talajic, Mario; Deyell, Marc; Rivard, Léna; Thibault, Bernard; Guerra, Peter G; Nattel, Stanley; Macle, Laurent

2013-12-01

Atrial fibrillation recurrence after pulmonary vein (PV) isolation is associated with PV to left atrium reconduction. We prospectively studied the use of 2 procedural techniques designed to facilitate identification of residual gaps within the index ablation line. After wide circumferential PV isolation, 40 patients received additional ablation targeted at locations of left atrial capture during high-output pacing (pace-capture group), while 40 patients underwent adenosine testing with targeted ablation at sites of dormant conduction (adenosine group). Patients were followed up at 3, 6, and 12 months. After PV isolation, high-output pace-capture was documented in 39 PVs (25%; 50% of patients) in the pace-capture group. Dormant conduction was unmasked in 34 PVs (22%; 53% of patients) in the adenosine group. A subset of 25 patients in the pace-capture group underwent adenosine testing without targeted ablation of dormant conduction. In these patients, only 10 out of 86 PVs (11.6%; 24% of patients) demonstrated dormant conduction after the elimination of local pace-capture. At a follow-up of 329±124 days, the single procedure off antiarrhythmic drug freedom from recurrent atrial fibrillation was 67.5% in the adenosine group and 65.0% in the pace-capture group (P=0.814). Procedure duration and fluoroscopy time were significantly longer in the pace-capture group (P=0.002 and P<0.001), whereas radiofrequency ablation time was comparable (P=0.192). The use of high-output pacing post-PV isolation results in a significant reduction in the incidence of dormant conduction with a comparable long-term freedom from recurrent atrial fibrillation (versus adenosine-guided ablation). The use of these approaches requires evaluation in a long-term prospective randomized study. [corrected].

Swimmers' compliance with training prescription.

PubMed

Stewart, A M; Hopkins, W G

1997-10-01

The purpose of this study was to determine how closely competitive swimmers complied with their coaches' prescriptions when training in squads. A training session early in the buildup phase of the season was observed for each of 24 coaches who had been randomized to two groups: an experimental, high-intensity, low-distance program (E) and a control (usual) program (C). Swim distances, rest durations, and swim durations for at least one set of prescribed repetitions (reps) were recorded for each of 47 swimmers (87 sets, 429 reps) in E and for 49 swimmers (79 sets, 402 reps) in C. The pace of each rep, expressed as percent of the swimmer's current personal best pace for the distance of the rep, represented observed intensity. There was almost perfect agreement between the prescribed and observed swim distances for the set of reps (Spearman r = 0.99 in both groups). Prescribed and observed rest intervals were also closely matched in E and C (Spearman r = 0.87 and 0.77 respectively). Four coaches in E and 10 coaches in C prescribed intensity subjectively as easy, moderate, hard, or race-pace; mean +/- SD observed intensities (%) for their swimmers were 79 +/- 6, 81 +/- 3, 91 +/- 2, and 93 +/- 5, respectively. The relationship between these coaches' subjective training prescription and individual swimmers' interpretations of these intensities was poor (Cohen's kappa = 0.39). Nine coaches in E prescribed intensity as percent of personal best pace. Although the mean prescribed and observed intensities for their swimmers were similar (89 +/- 4 and 90 +/- 7, respectively), the relationship between individual values was poor (Pearson r = 0.30). We conclude that swimmers complied with prescribed distances and rest intervals but were less effective in judging the intensity of swim training. We recommend that coaches monitor training intensity more closely.

Safety of transvenous low energy cardioversion of atrial fibrillation in patients with a history of ventricular tachycardia: effects of rate and repolarization time on proarrhythmic risk.

PubMed

Simons, G R; Newby, K H; Kearney, M M; Brandon, M J; Natale, A

1998-02-01

The objective of this study was to assess the safety and efficacy of transvenous low energy cardioversion of atrial fibrillation in patients with ventricular tachycardia and atrial fibrillation and to study the mechanisms of proarrhythmia. Previous studies have demonstrated that cardioversion of atrial fibrillation using low energy, R wave synchronized, direct current shocks applied between catheters in the coronary sinus and right atrium is feasible. However, few data are available regarding the risk of ventricular proarrhythmia posed by internal atrial defibrillation shocks among patients with ventricular arrhythmias or structural heart disease. Atrial defibrillation was performed on 32 patients with monomorphic ventricular tachycardia and left ventricular dysfunction. Shocks were administered during atrial fibrillation (baseline shocks), isoproterenol infusion, ventricular pacing, ventricular tachycardia, and atrial pacing. Baseline shocks were also administered to 29 patients with a history of atrial fibrillation but no ventricular arrhythmias. A total of 932 baseline shocks were administered. No ventricular proarrhythmia was observed after well-synchronized baseline shocks, although rare inductions of ventricular fibrillation occurred after inappropriate T wave sensing. Shocks administered during wide-complex rhythms (ventricular pacing or ventricular tachycardia) frequently induced ventricular arrhythmias, but shocks administered during atrial pacing at identical ventricular rates did not cause proarrhythmia. The risk of ventricular proarrhythmia after well-synchronized atrial defibrillation shocks administered during narrow-complex rhythms is low, even in patients with a history of ventricular tachycardia. The mechanism of proarrhythmia during wide-complex rhythms appears not to be related to ventricular rate per se, but rather to the temporal relationship between shock delivery and the repolarization time of the previous QRS complex.

Modulation of cardiac tissue electrophysiological properties with light-sensitive proteins.

PubMed

Nussinovitch, Udi; Shinnawi, Rami; Gepstein, Lior

2014-04-01

Optogenetics approaches, utilizing light-sensitive proteins, have emerged as unique experimental paradigms to modulate neuronal excitability. We aimed to evaluate whether a similar strategy could be used to control cardiac-tissue excitability. A combined cell and gene therapy strategy was developed in which fibroblasts were transfected to express the light-activated depolarizing channel Channelrhodopsin-2 (ChR2). Patch-clamp studies confirmed the development of a robust inward current in the engineered fibroblasts following monochromatic blue-light exposure. The engineered cells were co-cultured with neonatal rat cardiomyocytes (or human embryonic stem cell-derived cardiomyocytes) and studied using a multielectrode array mapping technique. These studies revealed the ability of the ChR2-fibroblasts to electrically couple and pace the cardiomyocyte cultures at varying frequencies in response to blue-light flashes. Activation mapping pinpointed the source of this electrical activity to the engineered cells. Similarly, diffuse seeding of the ChR2-fibroblasts allowed multisite optogenetics pacing of the co-cultures, significantly shortening their electrical activation time and synchronizing contraction. Next, optogenetics pacing in an in vitro model of conduction block allowed the resynchronization of the tissue's electrical activity. Finally, the ChR2-fibroblasts were transfected to also express the light-sensitive hyperpolarizing proton pump Archaerhodopsin-T (Arch-T). Seeding of the ChR2/ArchT-fibroblasts allowed to either optogentically pace the cultures (in response to blue-light flashes) or completely suppress the cultures' electrical activity (following continuous illumination with 624 nm monochromatic light, activating ArchT). The results of this proof-of-concept study highlight the unique potential of optogenetics for future biological pacemaking and resynchronization therapy applications and for the development of novel anti-arrhythmic strategies.

Differentiation of ventricular and supraventricular tachycardias based on the analysis of the first postpacing interval after sequential anti-tachycardia pacing in implantable cardioverter-defibrillator patients.

PubMed

Arenal, Angel; Ortiz, Mercedes; Peinado, Rafael; Merino, Jose L; Quesada, Aurelio; Atienza, Felipe; Alberola, Arcadio García; Ormaetxe, Jose; Castellanos, Eduardo; Rodriguez, Juan C; Pérez, Nicasio; García, Javier; Boluda, Luis; del Prado, Mario; Artés, Antonio

2007-03-01

Current discrimination algorithms do not completely avoid inappropriate tachycardia detection. This study analyzes the discrimination capability of the changes of the first postpacing interval (FPPI) after successive bursts of anti-tachycardia pacing (ATP) trains in implantable cardioverter-defibrillator (ICD)-recorded tachycardias. We included 50 ICD patients in this prospective study. We hypothesized that the FPPI variability (FPPIV) when comparing bursts with different numbers of beats would be shorter in ventricular tachycardias (VTs) compared with supraventricular tachycardias (SVTs). The ATP (5-10 pulses, 91% of tachycardia cycle length) was programmed for tachycardias >240 ms. Anti-tachycardia pacing was delivered during 37 sinus tachycardias (STs) in an exercise test, 96 induced VTs in an electrophysiological study, and 198 spontaneous episodes (144 VTs and 54 SVTs). The FPPI remained stable after all ATP bursts in VT but changed continuously in SVT; when comparing bursts of 5 and 10 pulses, the FPPIV was shorter in VT (34 +/- 65 vs.138 +/- 69, P<.0001, in all T and 12 +/- 20 vs. 138 +/- 69, P<.0001, in T>or=320 ms) than in SVT. In T>or=320 ms an FPPIV

Defining indoor heat thresholds for health in the UK.

PubMed

Anderson, Mindy; Carmichael, Catriona; Murray, Virginia; Dengel, Andy; Swainson, Michael

2013-05-01

It has been recognised that as outdoor ambient temperatures increase past a particular threshold, so do mortality/morbidity rates. However, similar thresholds for indoor temperatures have not yet been identified. Due to a warming climate, the non-sustainability of air conditioning as a solution, and the desire for more energy-efficient airtight homes, thresholds for indoor temperature should be defined as a public health issue. The aim of this paper is to outline the need for indoor heat thresholds and to establish if they can be identified. Our objectives include: describing how indoor temperature is measured; highlighting threshold measurements and indices; describing adaptation to heat; summary of the risk of susceptible groups to heat; reviewing the current evidence on the link between sleep, heat and health; exploring current heat and health warning systems and thresholds; exploring the built environment and the risk of overheating; and identifying the gaps in current knowledge and research. A global literature search of key databases was conducted using a pre-defined set of keywords to retrieve peer-reviewed and grey literature. The paper will apply the findings to the context of the UK. A summary of 96 articles, reports, government documents and textbooks were analysed and a gap analysis was conducted. Evidence on the effects of indoor heat on health implies that buildings are modifiers of the effect of climate on health outcomes. Personal exposure and place-based heat studies showed the most significant correlations between indoor heat and health outcomes. However, the data are sparse and inconclusive in terms of identifying evidence-based definitions for thresholds. Further research needs to be conducted in order to provide an evidence base for threshold determination. Indoor and outdoor heat are related but are different in terms of language and measurement. Future collaboration between the health and building sectors is needed to develop a common language and an index for indoor heat and health thresholds in a changing climate.

The influence of current direction on phosphene thresholds evoked by transcranial magnetic stimulation.

PubMed

Kammer, T; Beck, S; Erb, M; Grodd, W

2001-11-01

To quantify phosphene thresholds evoked by transcranial magnetic stimulation (TMS) in the occipital cortex as a function of induced current direction. Phosphene thresholds were determined in 6 subjects. We compared two stimulator types (Medtronic-Dantec and Magstim) with monophasic pulses using the standard figure-of-eight coils and systematically varied hemisphere (left and right) and induced current direction (latero-medial and medio-lateral). Each measurement was made 3 times, with a new stimulation site chosen for each repetition. Only those stimulation sites were investigated where phosphenes were restricted to one visual hemifield. Coil positions were stereotactically registered. Functional magnetic resonance imaging (fMRI) of retinotopic areas was performed in 5 subjects to individually characterize the borders of visual areas; TMS stimulation sites were coregistered with respect to visual areas. Despite large interindividual variance we found a consistent pattern of phosphene thresholds. They were significantly lower if the direction of the induced current was oriented from lateral to medial in the occipital lobe rather than vice versa. No difference with respect to the hemisphere was found. Threshold values normalized to the square root of the stored energy in the stimulators were lower with the Medtronic-Dantec device than with the Magstim device. fMRI revealed that stimulation sites generating unilateral phosphenes were situated at V2 and V3. Variability of phosphene thresholds was low within a cortical patch of 2x2cm(2). Stimulation over V1 yields phosphenes in both visual fields. The excitability of visual cortical areas depends on the direction of the induced current with a preference for latero-medial currents. Although the coil positions used in this study were centered over visual areas V2 and V3, we cannot rule out the possibility that subcortical structures or V1 could actually be the main generator for phosphenes.

42 CFR 460.18 - CMS evaluation of applications.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Organization Application and Waiver Process § 460.18 CMS evaluation of applications...

42 CFR 460.22 - Service area designation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Organization Application and Waiver Process § 460.22 Service area designation. (a) An...

42 CFR 460.20 - Notice of CMS determination.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Organization Application and Waiver Process § 460.20 Notice of CMS determination. (a...

42 CFR 460.71 - Oversight of direct participant care.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Administrative Requirements § 460.71 Oversight of direct participant care...

42 CFR 460.94 - Required services for Medicare participants.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Services § 460.94 Required services for Medicare participants. (a) Except...

42 CFR 460.18 - CMS evaluation of applications.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Organization Application and Waiver Process § 460.18 CMS evaluation of applications...

42 CFR 460.22 - Service area designation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Organization Application and Waiver Process § 460.22 Service area designation. (a) An...

42 CFR 460.94 - Required services for Medicare participants.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Services § 460.94 Required services for Medicare participants. (a) Except...

42 CFR 460.20 - Notice of CMS determination.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Organization Application and Waiver Process § 460.20 Notice of CMS determination. (a...

Effects of generation mode in fMRI adaptations of semantic fluency: Paced production and overt speech

PubMed Central

Basho, Surina; Palmer, Erica D.; Rubio, Miguel A.; Wulfeck, Beverly; Müller, Ralph-Axel

2007-01-01

Verbal fluency is a widely used neuropsychological paradigm. In fMRI implementations, conventional unpaced (self-paced) versions are suboptimal due to uncontrolled timing of responses, and overt responses carry the risk of motion artifact. We investigated the behavioral and neurofunctional effects of response pacing and overt speech in semantic category-driven word generation. Twelve right-handed adults (8 female) ages 21–37 were scanned in four conditions each: Paced-Overt, Paced-Covert, Unpaced-Overt, and Unpaced-Covert. There was no significant difference in the number of exemplars generated between overt versions of the paced and unpaced conditions. Imaging results for category-driven word generation overall showed left-hemispheric activation in inferior frontal cortex, premotor cortex, cingulate gyrus, thalamus, and basal ganglia. Direct comparison of generation modes revealed significantly greater activation for the paced compared to unpaced conditions in right superior temporal, bilateral middle frontal, and bilateral anterior cingulate cortex, including regions associated with sustained attention, motor planning, and response inhibition. Covert (compared to overt) conditions showed significantly greater effects in right parietal and anterior cingulate, as well as left middle temporal and superior frontal regions. We conclude that paced overt paradigms are useful adaptations of conventional semantic fluency in fMRI, given their superiority with regard to control over and monitoring of behavioral responses. However, response pacing is associated with additional non-linguistic effects related to response inhibition, motor preparation, and sustained attention. PMID:17292926

Capture of activation during ventricular arrhythmia using distributed stimulation.

PubMed

Meunier, Jason M; Ramalingam, Sanjiv; Lin, Shien-Fong; Patwardhan, Abhijit R

2007-04-01

Results of previous studies suggest that pacing strength stimuli can capture activation during ventricular arrhythmia locally near pacing sites. The existence of spatio-temporal distribution of excitable gap during arrhythmia suggests that multiple and timed stimuli delivered over a region may permit capture over larger areas. Our objective in this study was to evaluate the efficacy of using spatially distributed pacing (DP) to capture activation during ventricular arrhythmia. Data were obtained from rabbit hearts which were placed against a lattice of parallel wires through which biphasic pacing stimuli were delivered. Electrical activity was recorded optically. Pacing stimuli were delivered in sequence through the parallel wires starting with the wire closest to the apex and ending with one closest to the base. Inter-stimulus delay was based on conduction velocity. Time-frequency analysis of optical signals was used to determine variability in activation. A decrease in standard deviation of dominant frequencies of activation from a grid of locations that spanned the captured area and a concurrence with paced frequency were used as an index of capture. Results from five animals showed that the average standard deviation decreased from 0.81 Hz during arrhythmia to 0.66 Hz during DP at pacing cycle length of 125 ms (p = 0.03) reflecting decreased spatio-temporal variability in activation during DP. Results of time-frequency analysis during these pacing trials showed agreement between activation and paced frequencies. These results show that spatially distributed and timed stimulation can be used to modify and capture activation during ventricular arrhythmia.

A Low-Cost Simulation Model for R-Wave Synchronized Atrial Pacing in Pediatric Patients with Postoperative Junctional Ectopic Tachycardia

PubMed Central

Michel, Miriam; Egender, Friedemann; Heßling, Vera; Dähnert, Ingo; Gebauer, Roman

2016-01-01

Background Postoperative junctional ectopic tachycardia (JET) occurs frequently after pediatric cardiac surgery. R-wave synchronized atrial (AVT) pacing is used to re-establish atrioventricular synchrony. AVT pacing is complex, with technical pitfalls. We sought to establish and to test a low-cost simulation model suitable for training and analysis in AVT pacing. Methods A simulation model was developed based on a JET simulator, a simulation doll, a cardiac monitor, and a pacemaker. A computer program simulated electrocardiograms. Ten experienced pediatric cardiologists tested the model. Their performance was analyzed using a testing protocol with 10 working steps. Results Four testers found the simulation model realistic; 6 found it very realistic. Nine claimed that the trial had improved their skills. All testers considered the model useful in teaching AVT pacing. The simulation test identified 5 working steps in which major mistakes in performance test may impede safe and effective AVT pacing and thus permitted specific training. The components of the model (exclusive monitor and pacemaker) cost less than $50. Assembly and training-session expenses were trivial. Conclusions A realistic, low-cost simulation model of AVT pacing is described. The model is suitable for teaching and analyzing AVT pacing technique. PMID:26943363

Right Ventricular Pacing for Assessment of Cavo-Tricuspid Isthmus Block.

PubMed

Venkataraman, Ganesh; Wish, Marc; Friehling, Ted; Strickberger, S Adam

2016-01-01

Background: Cavo-tricuspid isthmus (CTI) dependent atrial flutter is typically treated with cardiac ablation. Standard techniques to assess CTI block after ablation can be technically challenging. Right ventricular (RV) pacing may allow for another technique to assess CTI block after ablation. Objective: The purpose of this study was to evaluate RV pacing as a method to assess CTI block after ablation of CTI dependent atrial flutter, and define endpoints of ablation using this technique. Methods: 28 patients undergoing ablation of CTI dependent atrial flutter with intact ventriculoatrial (VA) conduction were prospectively enrolled in this study and underwent the RV pacing protocol, as well as standard coronary sinus (CS) pacing techniques to assess CTI block. Results: The mean trans-isthmus conduction interval during CS pacing (TICI CS ) at 600 and 400ms after CTI ablation was 168 +/- 9ms and 175 +/- 18ms, respectively. The mean trans-isthmus conduction interval during RV pacing (TICI RV ) at 600ms and 400ms after CTI ablation was 109 +/- 5ms and 111 +/- 5ms, respectively. A TICI RV >100ms was associated with a successful outcome after CTI ablation. Conclusions: RV pacing may add incremental value in the assessment of CTI block in patients undergoing ablation of CTI dependent atrial flutter.

Kinematic hand parameters in front crawl at different paces of swimming.

PubMed

Samson, Mathias; Monnet, Tony; Bernard, Anthony; Lacouture, Patrick; David, Laurent

2015-11-05

The aim of this study was to investigate the evolution of kinematic hand parameters (sweepback angle, angle of attack, velocity, acceleration and orientation of the hand relative to the absolute coordinate system) throughout an aquatic stroke and to study the possible modifications caused by a variation of the swimming pace. Seventeen competitive swimmers swam at long distance, middle distance and sprint paces. Parameters were calculated from the trajectory of seven markers on the hand measured with an optoelectronic system. Results showed that kinematic hand parameters evolve differently depending on the pace. Angle of attack, sweepback angle, acceleration and orientation of the hand do not vary significantly. The velocity of the hand increases when the pace increases, but only during the less propulsive phases (entry and stretch and downsweep to catch). The more the pace increases and the more the absolute durations of the entry and stretch and downsweep to catch phases decrease. Absolute durations of the insweep and upsweep phases remain constant. During these phases, the propulsive hand forces calculated do not vary significantly when the pace increases. The increase of swimming pace is then explained by the swimmer's capacity to maintain propulsive phases rather than increasing the force generation within each cycle. Copyright © 2015 Elsevier Ltd. All rights reserved.

Implantable cardioverter defibrillator does not cure the heart.

PubMed

Sławuta, Agnieszka; Boczar, Krzysztof; Ząbek, Andrzej; Gajek, Jacek; Lelakowski, Jacek; Vijayaraman, Pugazhendhi; Małecka, Barbara

2018-01-23

A man with non-ischemic cardiomyopathy, EF 22%, permanent AF and ICD was admitted for elective device replacement. The need for the optimization of the ventricular rate and avoidance of right ventricular pacing made it necessary to up-grade the existing pacing system using direct His bundle pacing and dual chamber ICD. This enabled the regularization of ventricular rate, avoiding the RV pacing and optimize the beta-blocker dose. The one month follow-up already showed reduction in left ventricle diameter, improvement in ejection fraction, NYHA class decrease to II. The His bundle pacing enabled the optimal treatment of the patient resulting in excellent clinical improvement.

The PACE trial: It's time to broaden perceptions and move on.

PubMed

Petrie, Keith J; Weinman, John

2017-08-01

The continued critiques of the PACE trial highlight how differing beliefs about the causes of chronic fatigue syndrome still influence how scientific studies in this area are accepted and evaluated. Causal beliefs about chronic fatigue syndrome and a modern version of Cartesian dualism are important in understanding the reaction to the PACE trial. The continued debate on the PACE trial seems to miss the fact that science is incremental. An unfortunate outcome of the PACE controversy and intimidation of researchers may be less research in the area. It is time to move on from criticism and collect more data on effective treatments.

42 CFR 460.150 - Eligibility to enroll in a PACE program.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Participant Enrollment and Disenrollment § 460.150 Eligibility to enroll in a...

42 CFR 460.28 - Notice of CMS determination on waiver requests.

Code of Federal Regulations, 2011 CFR

2011-10-01

... HUMAN SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Organization Application and Waiver Process § 460.28 Notice of...

42 CFR 460.28 - Notice of CMS determination on waiver requests.

Code of Federal Regulations, 2010 CFR

2010-10-01

... HUMAN SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Organization Application and Waiver Process § 460.28 Notice of...

42 CFR 460.150 - Eligibility to enroll in a PACE program.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Participant Enrollment and Disenrollment § 460.150 Eligibility to enroll in a...

College Perspective '74: Changes, Challenges, Choices. Proceedings, Annual International Institute on the Community College (5th, Lambton College, Sarnia, Ontario, June 10-13, 1974).

ERIC Educational Resources Information Center

Delgrosso, G. M., Ed.; Colford, G. D., Ed.

These conference papers deal with many topics of current interest to community college educators in Canada and the United States. Subjects discussed include: performance-based, individualized, self-paced, and personalized systems of instruction; institutional goals; systems approaches to instruction; the integration of community colleges, public…

Getting the Most out of Pay-Per-View: A Feasibility Study and Discussion of Mediated and Unmediated Options

ERIC Educational Resources Information Center

Hosburgh, Nathan

2012-01-01

The increasing costs of science, technology, and medical journals, combined with decreasing or stagnant budgets, have forced libraries to take a hard look at current journal subscriptions. Even when budgets remain stable or increase, they may not keep pace with the escalating costs of subscriptions from various publishers. In the face of potential…

College and University Endowments--Or, Singing the Inflation Blues. AAHE-ERIC/Higher Education Research Currents, February 1980.

ERIC Educational Resources Information Center

Shulman, Carol Herrnstadt

The role of endowments in academic finances of higher education is examined. Two effects of the decline of endowment funding, their failure to keep pace with inflation and loss of income for innovative programs, are cited. The historical role of endowments in institutional finances is reviewed. Present concepts of endowment management are…

Caught By Our Dangling Paradigms: How Our Metaphysical Assumptions Influence Gifted Education

ERIC Educational Resources Information Center

Johnson, Andrew

2005-01-01

Notions of intelligence and giftedness should keep pace with current knowledge of quantum physics and what is known abut the nature of reality. There are three perspectives as to the nature of reality. Materialistic monism views the universe as being made up of only matter and energy. Dualism views the universe as being made up of matter and…

Qualitative Analysis of Organizational Change in One U.S. Dental School

ERIC Educational Resources Information Center

Crain, Geralyn Dell

2010-01-01

Currently, there is need for change in the way that dental schools in the United States educate their students to keep pace with the rapidly changing nature of the profession and to better address societal needs. Despite a well-documented change agenda put forth by individual authors and agencies both within and outside of dental education,…

77 FR 68167 - Self-Regulatory Organizations; Chicago Stock Exchange, Inc.; Notice of Filing and Immediate...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-15

... Section E.1 On January 9, 2012, the Exchange adopted the current Fee Schedule that incorporated, inter... the fees and rebates of proposed Section E.1, the Exchange proposes to mostly adopt the fee and rebate... flexibility will allow the Exchange to adapt to fast-paced changes in today's orders marketplace and will, in...

Global Education: Controversy Remains, But Support Growing: Field Strives To Better Link Global Studies, Civics.

ERIC Educational Resources Information Center

O'Neil, John

1989-01-01

The pace of global change and the increasing interdependence of people worldwide are the driving forces behind the need for a contemporary global education movement that reinterprets current knowledge to educate students to meet their responsibilities as citizens of an increasingly complex global society. Evaluations of U.S. 18-24-year-olds reveal…

A Comprehensive Analysis of High School Genetics Standards: Are States Keeping Pace with Modern Genetics?

ERIC Educational Resources Information Center

Dougherty, M. J.; Pleasants, C.; Solow, L.; Wong, A.; Zhang, H.

2011-01-01

Science education in the United States will increasingly be driven by testing and accountability requirements, such as those mandated by the No Child Left Behind Act, which rely heavily on learning outcomes, or "standards," that are currently developed on a state-by-state basis. Those standards, in turn, drive curriculum and instruction.…

Non-native plant invasion along elevation and canopy closure gradients in a Middle Rocky Mountain ecosystem

Treesearch

Joshua P. Averett; Bruce McCune; Catherine G. Parks; Bridgett J. Naylor; Tim DelCurto; Ricardo Mata-Gonz??lez; RunGuo Zang

2016-01-01

Mountain environments are currently among the ecosystems least invaded by non-native species; however, mountains are increasingly under threat of non-native plant invasion. The slow pace of exotic plant invasions in mountain ecosystems is likely due to a combination of low anthropogenic disturbances, low propagule supply, and extreme/steep environmental gradients. The...

Pre-School Educational Institutions and Family Interaction in the System of Pre-School Education in Ukraine and Poland

ERIC Educational Resources Information Center

Perepelyuk, Inna

2017-01-01

The problem of the relationship between a child's institution and a family that acquires a new social significance has been considered. It has been defined that for the current level and pace of civilization development, cooperation with the pupils' families goes beyond the educators' implementation of the traditional social order for supervision,…

The Placer Media Management System or Using the Computer in the Small Film Library.

ERIC Educational Resources Information Center

Luckey, Jacqueline

In describing this media management system, which currently serves 84 public schools (K-12) in four rural counties east of Sacramento, this report suggests that the computer is a practical solution for film libraries trying to keep pace with increased use while not reducing their expenditures for purchasing and repairing film stock. The major…

Characterizing, Classifying, and Understanding Information Security Laws and Regulations: Considerations for Policymakers and Organizations Protecting Sensitive Information Assets

ERIC Educational Resources Information Center

Thaw, David Bernard

2011-01-01

Current scholarly understanding of information security regulation in the United States is limited. Several competing mechanisms exist, many of which are untested in the courts and before state regulators, and new mechanisms are being proposed on a regular basis. Perhaps of even greater concern, the pace at which technology and threats change far…

Aligning What We Do and What We Measure in Business Schools: Incorporating Active Learning and Effective Media Use in the Assessment of Instruction

ERIC Educational Resources Information Center

Serva, Mark A.; Fuller, Mark A.

2004-01-01

Current methods of evaluating learning and instruction have not kept pace with changes in learning theory, or with the transformed technological infrastructure of the modern business school classroom. Without reliable and valid instructional measurement systems, it is virtually impossible to benchmark new pedagogical techniques, assess the value…

Colony pace: a life-history trait affecting social insect epidemiology.

PubMed

Buechel, Séverine Denise; Schmid-Hempel, Paul

2016-01-13

Among colonies of social insects, the worker turnover rate (colony 'pace') typically shows considerable variation. This has epidemiological consequences for parasites, because in 'fast-paced' colonies, with short-lived workers, the time of parasite residence in a given host will be reduced, and further transmission may thus get less likely. Here, we test this idea and ask whether pace is a life-history strategy against infectious parasites. We infected bumblebees (Bombus terrestris) with the infectious gut parasite Crithidia bombi, and experimentally manipulated birth and death rates to mimic slow and fast pace. We found that fewer workers and, importantly, fewer last-generation workers that are responsible for rearing sexuals were infected in colonies with faster pace. This translates into increased fitness in fast-paced colonies, as daughter queens exposed to fewer infected workers in the nest are less likely to become infected themselves, and have a higher chance of founding their own colonies in the next year. High worker turnover rate can thus act as a strategy of defence against a spreading infection in social insect colonies. © 2016 The Author(s).

PACE4 regulates proliferation, migration and invasion in human breast cancer MDA-MB-231 cells.

PubMed

Wang, Feifei; Wang, Lin; Pan, Jihong

2015-01-01

PACE4 is one of the proprotein convertases (PC) that participate in the post-translational activation of inactive proteins, leading to mature, biologically active proteins. The processing reactions occur in pairs of basic amino acids. PACE4 is an extracellular PC that binds to growth factors and several components of the extracellular matrix contributing to tumor progression. In the present study, the PACE4 gene was silenced by small interfering RNA (siRNA), and the knockdown human breast cancer MDA-MB-231 cells showed significantly reduced proliferation, migration and invasion rates. Flow cytometry analysis indicated that downregulation of PACE4 increases the percentage of cells arrested at the G0/G1 phase. Moreover, the expression of genes involved in cell growth, invasion and adhesion, i.e., IGF-2, MMP9 and MPZL2 was significantly decreased following siRNA-mediated silencing of PACE4. Taken together, these results indicate that PACE4 plays an important role in human breast cancer, and that it might represent a novel target for breast cancer therapy.

Evidence for thermally assisted threshold switching behavior in nanoscale phase-change memory cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Le Gallo, Manuel; Athmanathan, Aravinthan; Krebs, Daniel

2016-01-14

In spite of decades of research, the details of electrical transport in phase-change materials are still debated. In particular, the so-called threshold switching phenomenon that allows the current density to increase steeply when a sufficiently high voltage is applied is still not well understood, even though there is wide consensus that threshold switching is solely of electronic origin. However, the high thermal efficiency and fast thermal dynamics associated with nanoscale phase-change memory (PCM) devices motivate us to reassess a thermally assisted threshold switching mechanism, at least in these devices. The time/temperature dependence of the threshold switching voltage and current inmore » doped Ge{sub 2}Sb{sub 2}Te{sub 5} nanoscale PCM cells was measured over 6 decades in time at temperatures ranging from 40 °C to 160 °C. We observe a nearly constant threshold switching power across this wide range of operating conditions. We also measured the transient dynamics associated with threshold switching as a function of the applied voltage. By using a field- and temperature-dependent description of the electrical transport combined with a thermal feedback, quantitative agreement with experimental data of the threshold switching dynamics was obtained using realistic physical parameters.« less

State of the (net)work address Developing criteria for applying social networking to the work environment.

PubMed

Valdez, André Calero; Schaar, Anne Kathrin; Ziefle, Martina

2012-01-01

In an increasingly faster paced innovative world, maintaining the ability to innovate in spite of an aging work force will become every company's strongest leverage for success. Tapping the latent knowledge resources and creativity of overlooked employees and persisting crucial information for business conduct are promising results for social networking sites (SNS) in a working context. Usability and usefulness are exponential factors in creating a successful SNS. In order to make a SNS usable for a heterogeneous user group, analyses of user diversity in regard to social media need to be done. Furthermore differences in communication medium and frequency in regard to age, content, hierarchy position, departmental thresholds and company size need to be analyzed. For analysis purposes both qualitative and quantitative research methods were applied. Strong effects of age and communication content were found in survey with 194 participants.

Low-Energy Defibrillation Failure Correction is Possible Through Nonlinear Analysis of Spatiotemporal Arrhythmia Data

NASA Astrophysics Data System (ADS)

Simonotto, Jennifer; Furman, Michael; Beaver, Thomas; Spano, Mark; Kavanagh, Katherine; Iden, Jason; Hu, Gang; Ditto, William

2004-03-01

Explanted Porcine hearts were Langendorff-perfused, administered a voltage-sensitive fluorescent dye (Di-4-ANEPPS) and illuminated with a ND:Yag laser (532 nm); the change in fluorescence resulting from electrical activity on the heart surface was recorded with an 80 x 80 pixel CCD camera at 1000 frames per second. The heart was put into fibrillation with rapid ventricular pacing and shocks were administered close to the defibrillation threshold. Defibrillation failure data was analyzed using synchronization, space-time volume plots and recurrence quantification. Preliminary spatiotemporal synchronization results reveal a short window of time ( 1 second) after defibrillation failure in which the disordered electrical activity becomes ordered; this ordered period occurs 4-5 seconds after the defibrillation shock. Recurrence analysis of a single time series confirmed these results, thus opening the avenue for dynamic defibrillators that can detect an optimal window for cardioversion.

The Relationship of Walking Intensity to Total and Cause-Specific Mortality. Results from the National Walkers’ Health Study

PubMed Central

Williams, Paul T.; Thompson, Paul D.

2013-01-01

Purpose Test whether: 1) walking intensity predicts mortality when adjusted for walking energy expenditure, and 2) slow walking pace (≥24-minute mile) identifies subjects at substantially elevated risk for mortality. Methods Hazard ratios from Cox proportional survival analyses of all-cause and cause-specific mortality vs. usual walking pace (min/mile) in 7,374 male and 31,607 female recreational walkers. Survival times were left censored for age at entry into the study. Other causes of death were treated as a competing risk for the analyses of cause-specific mortality. All analyses were adjusted for sex, education, baseline smoking, prior heart attack, aspirin use, diet, BMI, and walking energy expenditure. Deaths within one year of baseline were excluded. Results The National Death Index identified 1968 deaths during the average 9.4-year mortality surveillance. Each additional minute per mile in walking pace was associated with an increased risk of mortality due to all causes (1.8% increase, P=10-5), cardiovascular diseases (2.4% increase, P=0.001, 637 deaths), ischemic heart disease (2.8% increase, P=0.003, 336 deaths), heart failure (6.5% increase, P=0.001, 36 deaths), hypertensive heart disease (6.2% increase, P=0.01, 31 deaths), diabetes (6.3% increase, P=0.004, 32 deaths), and dementia (6.6% increase, P=0.0004, 44 deaths). Those reporting a pace slower than a 24-minute mile were at increased risk for mortality due to all-causes (44.3% increased risk, P=0.0001), cardiovascular diseases (43.9% increased risk, P=0.03), and dementia (5.0-fold increased risk, P=0.0002) even though they satisfied the current exercise recommendations by walking ≥7.5 metabolic equivalent (MET)-hours per week. Conclusions The risk for mortality: 1) decreases in association with walking intensity, and 2) increases substantially in association for walking pace ≥24 minute mile (equivalent to <400m during a six-minute walk test) even among subjects who exercise regularly. PMID:24260542

Excitable Neurons, Firing Threshold Manifolds and Canards

PubMed Central

2013-01-01

We investigate firing threshold manifolds in a mathematical model of an excitable neuron. The model analyzed investigates the phenomenon of post-inhibitory rebound spiking due to propofol anesthesia and is adapted from McCarthy et al. (SIAM J. Appl. Dyn. Syst. 11(4):1674–1697, [2012]). Propofol modulates the decay time-scale of an inhibitory GABAa synaptic current. Interestingly, this system gives rise to rebound spiking within a specific range of propofol doses. Using techniques from geometric singular perturbation theory, we identify geometric structures, known as canards of folded saddle-type, which form the firing threshold manifolds. We find that the position and orientation of the canard separatrix is propofol dependent. Thus, the speeds of relevant slow synaptic processes are encoded within this geometric structure. We show that this behavior cannot be understood using a static, inhibitory current step protocol, which can provide a single threshold for rebound spiking but cannot explain the observed cessation of spiking for higher propofol doses. We then compare the analyses of dynamic and static synaptic inhibition, showing how the firing threshold manifolds of each relate, and why a current step approach is unable to fully capture the behavior of this model. PMID:23945278

Redefining the Speed Limit of Phase Change Memory Revealed by Time-resolved Steep Threshold-Switching Dynamics of AgInSbTe Devices

NASA Astrophysics Data System (ADS)

Shukla, Krishna Dayal; Saxena, Nishant; Durai, Suresh; Manivannan, Anbarasu

2016-11-01

Although phase-change memory (PCM) offers promising features for a ‘universal memory’ owing to high-speed and non-volatility, achieving fast electrical switching remains a key challenge. In this work, a correlation between the rate of applied voltage and the dynamics of threshold-switching is investigated at picosecond-timescale. A distinct characteristic feature of enabling a rapid threshold-switching at a critical voltage known as the threshold voltage as validated by an instantaneous response of steep current rise from an amorphous off to on state is achieved within 250 picoseconds and this is followed by a slower current rise leading to crystallization. Also, we demonstrate that the extraordinary nature of threshold-switching dynamics in AgInSbTe cells is independent to the rate of applied voltage unlike other chalcogenide-based phase change materials exhibiting the voltage dependent transient switching characteristics. Furthermore, numerical solutions of time-dependent conduction process validate the experimental results, which reveal the electronic nature of threshold-switching. These findings of steep threshold-switching of ‘sub-50 ps delay time’, opens up a new way for achieving high-speed non-volatile memory for mainstream computing.

Is the diagnostic threshold for bulimia nervosa clinically meaningful?

PubMed

Chapa, Danielle A N; Bohrer, Brittany K; Forbush, Kelsie T

2018-01-01

The DSM-5 differentiates full- and sub-threshold bulimia nervosa (BN) according to average weekly frequencies of binge eating and inappropriate compensatory behaviors. This study was the first to evaluate the modified frequency criterion for BN published in the DSM-5. The purpose of this study was to test whether community-recruited adults (N=125; 83.2% women) with current full-threshold (n=77) or sub-threshold BN (n=48) differed in comorbid psychopathology and eating disorder (ED) illness duration, symptom severity, and clinical impairment. Participants completed the Clinical Impairment Assessment and participated in semi-structured clinical interviews of ED- and non-ED psychopathology. Differences between the sub- and full-threshold BN groups were assessed using MANOVA and Chi-square analyses. ED illness duration, age-of-onset, body mass index (BMI), alcohol and drug misuse, and the presence of current and lifetime mood or anxiety disorders did not differ between participants with sub- and full-threshold BN. Participants with full-threshold BN had higher levels of clinical impairment and weight concern than those with sub-threshold BN. However, minimal clinically important difference analyses suggested that statistically significant differences between participants with sub- and full-threshold BN on clinical impairment and weight concern were not clinically significant. In conclusion, sub-threshold BN did not differ from full-threshold BN in clinically meaningful ways. Future studies are needed to identify an improved frequency criterion for BN that better distinguishes individuals in ways that will more validly inform prognosis and effective treatment planning for BN. Copyright © 2017 Elsevier Ltd. All rights reserved.

Recommendations for pacemaker implantation for the treatment of atrial tachyarrhythmias and resynchronisation therapy for heart failure: A report from the task force on pacemaker indications of the Dutch Working Group on Cardiac Pacing.

PubMed

van Hemel, N M; Dijkman, B; de Voogt, W G; Beukema, W P; Bosker, H A; de Cock, C C; Jordaens, L J L M; van Gelder, I C; van Gelder, L M; van Mechelen, R; Ruiter, J H; Sedney, M I; Slegers, L C

2004-01-01

Today, new pacing algorithms and stimulation methods for the prevention and interruption of atrial tachyarrhythmias can be applied on patients who need bradycardia pacing for conventional reasons. In addition, biventricular pacing as additive treatment for patients with severe congestive heart failure due to ventricular systolic dysfunction and prolonged intraventricular conduction has shown to improve symptoms and reduce hospital admissions. These new pacing technologies and the optimising of the pacing programmes are complex, expensive and time-consuming. Based on many clinical studies the indications for these devices are beginning to emerge. To support the cardiologist's decision-making and to prevent waste of effort and resources, the 'ad hoc committee' has provided preliminary recommendations for implantable devices to treat atrial tachyarrhythmias and to extend the treatment of congestive heart failure respectively.

Breaking the current density threshold in spin-orbit-torque magnetic random access memory

NASA Astrophysics Data System (ADS)

Zhang, Yin; Yuan, H. Y.; Wang, X. S.; Wang, X. R.

2018-04-01

Spin-orbit-torque magnetic random access memory (SOT-MRAM) is a promising technology for the next generation of data storage devices. The main bottleneck of this technology is the high reversal current density threshold. This outstanding problem is now solved by a new strategy in which the magnitude of the driven current density is fixed while the current direction varies with time. The theoretical limit of minimal reversal current density is only a fraction (the Gilbert damping coefficient) of the threshold current density of the conventional strategy. The Euler-Lagrange equation for the fastest magnetization reversal path and the optimal current pulse is derived for an arbitrary magnetic cell and arbitrary spin-orbit torque. The theoretical limit of minimal reversal current density and current density for a GHz switching rate of the new reversal strategy for CoFeB/Ta SOT-MRAMs are, respectively, of the order of 105 A/cm 2 and 106 A/cm 2 far below 107 A/cm 2 and 108 A/cm 2 in the conventional strategy. Furthermore, no external magnetic field is needed for a deterministic reversal in the new strategy.