bluuebunny/crossref_metadata_2025_split huggingface dataset:
Benchmarking masonry labor productivity
Authors: Enshassi Adnan , Mohamed Sherif , Mayer Peter , Abed Karem 
Published: April 2007

PurposeLabor productivity is one of the most important factors that affect the physical progress of any construction project. In order to improve labor productivity, site production should be measured on a regular basis, and then compared to acceptable standard benchmarks. The objective of this paper is to measure masonry labor productivity in Gaza Strip, Palestine, using a consistent benchmarking approach.Design/methodology/approachProduction data were collected from nine different construction projects located in Gaza. For each project, values for baseline productivity, disruption index, performance index and project management index were calculated.FindingsBased on the nine targeted projects, the baseline productivity of masonry works in Gaza seems to range from 0.29 to 0.80 work‐hours per square meter. Calculated values were utilized to develop a correlation between two project benchmarks (i.e. disruption and project management indices). AS only four out of the targeted nine projects performed reasonably well, the paper strongly recommends developing a benchmarking standard for each local construction firm in Palestine which may lead to an improvement in the national construction productivity.Originality/valueThe outcome of this research will improve the national construction productivity in Palestine and highlights the benefit of improving benchmarking standard.
Quantifying stochastic and deterministic threats to island seabirds: last endemic prions face extinction from falcon peregrinations
Authors: Jiguet F. , Robert A. , Micol T. , Barbraud C. 
Published: April 2007

AbstractUnderstanding how anthropically induced interacting factors may compromise the viability of a particular species or population necessitates expressing them in terms of quantitative effects on population dynamics. The use of mechanistic models to assess these effects is especially helpful to management plans when the causes of species decline are multi‐factorial and potentially interacting. Here, we took the opportunity of observed predation by a vagrant falcon on a rare and endemic seabird to develop a population dynamics model encompassing multiple deterministic and stochastic threats. The Macgillivray's prion Pachyptila macgillivrayi, with a world breeding population of c. 540 individuals confined to one rat‐free islet off Saint‐Paul Island (Southern Indian Ocean), faces high extinction risk from vagrant falcon predation. Extinction is predicted to occur within 200 years if one falcon preys on prions every 5 years, with predation occurring either on breeders only or also on non‐breeders. The minimum initial prion population size ensuring a low extinction risk increased linearly with the annual probability of predator occurrence. Therefore, increasing the initial population size is a useful management option to help the prion face stochastic predation. Recent rat eradication on Saint‐Paul Island helps the prion to face this threat as it released the carrying capacity of the colony, but the earlier population size might never be recovered if falcons carry on preying on prions frequently. This rare burrowing petrel provides a remarkable case study of an endemic insular species threatened with predation by alien mammals, which reduced historical population size dramatically, and by genuine vagrants as catastrophic events that reduce population growth and increase its temporal variance, and might cause the extinction.
Global population size of a critically endangered lemur, Perrier's sifaka
Authors: Banks M. A. , Ellis E. R. , Antonio  , Wright P. C. 
Published: April 2007

AbstractThe Perrier's sifaka Propithecus perrieri, considered critically endangered by the IUCN (World Conservation Union; 2004), is one of the least studied and most endangered primates in the world, yet baseline information on its distribution and population levels has not been updated for over 10 years. Density estimates from former studies suggest that only between 100 and 2000 individuals remain in the wild. In 2003–2004, using the line‐transect method, information on the distribution and population levels of this and sympatric primate species were obtained. Multi‐spectral, Landsat 7 satellite images of areas comprising the known Perrier's sifaka distribution, acquired in 1994 and 2002, were compared using spatial analysis techniques to quantify regional patterns of deforestation. Results from this study indicate that the global population of the Perrier's sifaka consists of about 915 individuals and the effective population size is unlikely to exceed 230 individuals. Furthermore, an annual deforestation rate of 1.2% was detected in the only protected area where this species occurs. Deforestation, the decline of taboos against hunting and human immigration patterns influence primate population status in northern Madagascar and threaten to drive the Perrier's sifaka to extinction in the near future.
Is attempting to change marine mammal behaviour a generic solution to the bycatch problem? A dugong case study
Authors: Hodgson A. J. , Marsh H. , Delean S. , Marcus L. 
Published: April 2007

AbstractIncidental bycatch in fishing nets is a global cause of incidental mortality of marine mammals. Two classes of approaches attempt to mitigate this impact: (1) approaches that change the behaviour of the fisher (e.g. closures and gear modifications), (2) approaches that attempt to change the behaviour of the bycatch species (e.g. acoustic alarms or pingers). Even though the effectiveness of pingers has been established for very few bycatch species, pingers are now mandatory in many fisheries throughout the world. Pingers are being trialled in commercial gill net fisheries in tropical Australia to reduce the bycatch of the dugong and three species of coastal dolphins, despite an absence of robust assessments of: (1) their effectiveness in reducing bycatch, (2) the likelihood of alienating bycatch species from critical habitats. We conducted replicate experiments to test the behavioural responses of dugongs to 4 and 10 kHz pingers in an array simulating a net. Each experiment comprised three sequential 10‐min treatments in which two pingers were: (1) inactive, (2) active, (3) inactive. The rate of decline of the number of dugongs within the focal arena did not change significantly while pingers were activated. Dugongs passed between the pingers (where a net would be located) irrespective of whether the alarms were active or inactive, fed throughout the experiments and did not change their orientation to investigate pinger noise, or their likelihood of vocalizing. We conclude that: (1) pingers are unlikely to alienate dugongs from critical habitats or reduce dugong mortalities in fishing nets, (2) bycatch mitigation strategies such as pingers that rely on changing animal behaviour should only be used after rigorous testing on all likely bycatch species.
Mechanisms Underlying Different Surface ECG Morphologies of Recurrent Monomorphic Ventricular Tachycardia and Their Modification by Procainamide
Authors: OSSWALD STEFAN , WILBER DAVID J. , LIN JIUNN‐LEE , DU DUKE , HOLDEN HARTLEY B. , RUSKIN JEREMY N. , GARAN HASAN 
Published: April 2007

ECG Pleomorphism of Ventricular Tachycardia. Introduction: Distinct surface ECG morphologies (ECGMs), from one episode to the next, of recurrent monomorphic ventricular tachycardia (VT) in the same patient complicate endocardial catheter mapping and the success of ablative therapy. This study investigates the incidence and mechanisms of multiple ECGMs during recurrent monomorphic VTs in a canine model of experimental myocardial infarction (MI). Methods and Results: Computerized ECG analysis and simultaneous endocardial and epicardial activation mapping with a 64 bipolar electrode array were used to analyze the relation between site of VT origin, local activation sequence, and surface ECGM in 72 VT episodes induced in 9 of 17 dogs with experimental MI. Pairwise comparisons of all VTs induced in the same animal were done in drug‐free state (47 VTs) and after intravenous procainamide (25 VTs). In drug‐free state, VT pairs with similar surface ECGMs manifested endocardial hreak‐through sites (BSs) within a distance < 10 mm in 46 (100%) of 46 VT pairs compared to 43 (45%) of 95 VT pairs with different surface ECGMs (P < 0.0001). Of all 89 VT pairs with endocardial BSs within < 10 mm, similar endocardial activation patterns were found in 34 (74%) of 46 pairs with similar ECGMs in contrast to 6 (14%) of 43 pairs with different ECGMs (P < 0.001). Similar comparisons of VT pairs induced after intravenous procainamide administration showed that the endocardial BSs were located within < 10 mm in 9 (75%) of 12 VT pairs with similar and in 17 (49%) of 95 with different surface ECGMs, respectively (P = NS). Conclusions: In the same heart, similar surface ECGMs of recurrent VT are highly predictive of closely spaced endocardial BSs in drug‐free state, hut not after procainamide administration. Nearly half of the VTs with different surface ECGMs still originate from closely spaced endocardial BSs but commonly manifest a change in the endocardial activation spread from this site. Thus, assumptions about different mechanisms and sites of VT origin based on dilTerent surface ECGMs should be made with caution.
Atrial Fibrillation/Flutter Induced by Implantable Ventricular Defibrillator Shocks:
Authors: KATZ AMOS , EVANS JOSEPH J. , FOGEL RICHARD I. , SCHIER JOHN J. , MATHENY ROBERT G. , BARANOWSKI GENA M. , PRYSTOWSKY ERIC N. 
Published: April 2007

Atrial Fibrillation/Flutter Induced by Defibrillator Shocks. Introduction: We evaluated the incidence and energy dependence of atrial fibrillation/flutter (AF) induced by implantable ventricular defibrillator shocks in 63 patients tested in the operating room or electrophysiology laboratory. Methods and Results: Defibrillator shocks were epicardial monophasic in 32 patients, and through an Endotak® lead endocardial monophasic in 19 and biphasic in 12 patients. The epicardial and endocardial patient groups had similar clinical characteristics. A total of 517 defibrillator shocks were given. The epicardial group received 336 total defibrillator shocks and 10 ± 6 shocks (mean ± SD) per patient compared with the endocardial group, which received 181 total shocks and 6 ± 4 defibrillator shocks per patient (P = 0.004). In the epicardial group, AF occurred in 13 (41 %) patients and in 17 (5%) of the 336 shocks. No AF was induced with endocardial defibrillator shocks. The epicardial mean energy was 16 ± 9 J, lower than the endocardial mean energy of 20 ± 9 J (P < 0.004). In the epicardial monophasic group, energy correlated with AF induction. Each patient received 7 ± 6 defibrillator shocks < 15 J and 4 ± 2 shocks ≥ 15 J, yet AF occurred in only 2.3% versus 9.6% (P < 0.05) of defibrillator shocks < 15 J and ≥ 15 J, respectively. Of note, AF was not induced with energy < 4 J or > 31 J. Conclusions: In the epicardial configuration, AF induction is energy dependent, with an apparent lower and upper limit of vulnerability. AF induction by defibrillator shocks delivered through an Endotak lead is very rare, possibly related to an apparent upper limit of vulnerability of less energy, avoidance of thoracotomy, or different energy field distribution.
Efficacy of Midodrine Hydrochloride in Neurocardiogenic Syncope Refractory to Standard Therapy
Authors: SRA JASBIR , MAGLIO CHERYL , BIEHL MICHAEL , DHALA ANWER , BLANCK ZALMEN , DESHPANDE SANJAY , JAZAYERI MOHAMMAD R. , AKHTAR MASOOD 
Published: April 2007

Midodrine for Refractory Neurocardiogenic Syncope. introduction: Some patients with neurocardiogenic syncope continue to have recurrent syncope or presyncope despite the use of currently available drug therapy. The purpose of this study was to determine whether midodrine hydrochloride, a selective adrenergic agonist, could he effective in patients resistant to, or intolerant of, currently used medications in the treatment of neurocardiogenic syncope. Methods and Results: Eleven patients with a history of recurrent syncope or presyncope in whom hypotension with syncope or presyncope could be provoked during head‐up tilt testing were included. There were 4 men and 7 women with a mean age (± SD) age of 34 ± 13 years. In all patients, standard therapy with beta‐adrenergic receptor blocking agents, ephedrine, theophylline, disopyramide, fludrocortisone, and sertraline hydrochloride, was either ineffective, poorly tolerated, or contraindicated. Midodrine was initially administered orally at a dose of 2.5 mg three times daily. After adjustment of dosage over 2 to 4 weeks, patients were followed‐up clinically. Midodrine was discontinued in one patient because of side effects. Frequency of syncope or presyncope during the 3 months prior to starting treatment was compared during a mean follow‐up of 17 ± 4 weeks after starting treatment with midodrine. There was significant (P < 0.01) reduction in syncopal and presyncopal episodes on midodrine. Five patients had complete resolution of symptoms, while four patients had significant improvement. Symptoms did not improve in one patient. Conclusions: Midodrine hydrochloride can he effective in preventing recurrent symptoms in selected patients with neurocardiogenic syncope unresponsive to, or intolerant of, standard drug therapy.
Electrophysiology of the Right Anterior Approach to the Atrioventricular Node:
Authors: ANTZ MATTHIAS , SCHERLAG BENJAMIN J. , PATTERSON EUGENE , OTOMO KENICHIRO , TONDO CLAUDIO , PITHA JAN , GONZALEZ MARIO D. , JACKMAN WARREN M. , LAZZARA RALPH 
Published: April 2007

Electrophysiology of Anterior AVN Input. Introduction: Previous reports have described electrophysiologic properties and rate‐dependent responses in the transitional cell zone of the posterior AV nodal input (slow pathway). The purpose of this study was to investigate the electrophysiology of the anterior transitional cell zone (fast pathway) in vivo and in a Langendorff preparation perfused with a nonblood solution containing butanedionemonoxime to inhibit contraction. Methods and Results: In five anesthetized dogs, the His‐bundle electrogram recorded from the aortic root included atrial activity in close proximity to the anterior limbus of the fossa ovalis. During decremental atrial pacing, the atrial potential exhibited amplitude alternans at a pacing cycle length (CL) of 135 ± 14 msec. In ten isolated pertused canine hearts, a bipctlar electrode catheter was positioned with its tip against the right anterior interatrial septum just superior to the tendon of Todaro. The AV Wenckebach CL (WCL) averaged 262 ± 21 msec. During further decreases in pacing CL, the bipolar atrial potential developed a 2:1 amplitude alternans (9/10 dogs) at CL = 168 ± 15 msec and then split into two components with subsequent 2:1 block between these components (10/10 dogs) at CL = 152 ± 19 msec. Radiofrequency ablation at this site in six dogs prolonged the stimulus to HB interval from 113 ± 19 to 151 ± 30 msec (P < 0.01) without changing the WCL, consistent with ablation of the fast AV nodal pathway. In six other isolated perfused canine hearts, an octapolar catheter (2‐mm spacing) was positioned along the anterior limbus of the fossa ovalLs with the tip electrode located over the anterior portion (apex) of the triangle of Koch. The aforementioned 2:1 amplitude alternans occurred at a longer CL in the distal electrodes located at the tendon of Todaro than in the proximal electrodes at farther distances from the tendon of Todaro (185 ± 25 vs 171 ± 20 msec, P < 0.05), as did the 2:1 block between the two components (161 ± 18 vs 150 ± 18 msec, P < 0.05). Microelectrode recordings obtained adjacent to the catheter demonstrated 2:1 alternans and block patterns in the action potentials of transitional cells but not in atrial cells, which exhibited 1:1 conduction at all CL. Conclusions: The transitional cell zone in the anterior interatrial septum exhibits a specific rate‐dependent, spatial gradient of conduction block, which can be recorded in bipolar electro‐grams as well as microelectrode recordings. Electrophysiologic changes induced by radiofrequency ablation of this anterior atrial/transitional cell zone (corroborated by histology) provide strong presumptive evidence that this area constitutes all or a major part of the fast AV nodal pathway.
Demonstration of Retrograde Conduction over an Atriofascicular Accessory Pathway
Authors: KREINER GERHARD , HETNZ GOTTFRIED , FREY BERNHARD , GÖSSINGER HEINZ DAVID 
Published: April 2007

Atriofascicular Pathway with Retrograde Conduction. Introduction: Absence of retrograde conduction over a right atriofascicular accessory pathway causing reciprocating tachycardia has been considered a hallmark of this clinical entity. Methods and Results: This report describes successful catheter ablation in a patient presenting with the distinctive pattern of preexcited left bundle branch block tachycardia utilizing a right atriofascicular accessory pathway. This pathway, however, exhibited the unique capability of ventriculoatrial conduction. Both anterograde and retrograde conduction were characterized by “node‐like” properties. Conclusion: Demonstration of retrograde accessory pathway conduction in this particular setting does not exclude the diagnosis of a single, atriofascicular accessory pathway.
Adenosine‐Sensitive Bundle Branch Reentry
Authors: RUBENSTEIN DONALD S. , BURKE MARTIN C. , KALL JOHN G. , KINDER CHARLES A. , KOPP DOUGLAS E. , WILBER DAVID J. 
Published: April 2007

Adenosine‐Sensitive Bundle Branch Reentry. Introduction: Bundle branch reentry is an uncommon mechanism for ventricular tachycardia. More infrequently, both fascicles of the left bundle may provide the substrate for such macroreentrant bundle branch circuits, so‐called interfascicular reentry. The effect of adenosine on bundle branch reentrant mechanisms of tachycardia is unknown. Methods and Results: A 59‐year‐old man with no apparent structural heart disease and history of frequent symptomatic wide complex tachycardias was referred to our center for further electrophysiologic evaluation. During electrophysiologic study, a similar tachycardia was reproducibly initiated only during isoproterenol infusion, which had the characteristics of bundle branch reentry, possibly using a left interfascicular mechanism. Intravenous adenosine reproducibly terminated the tachycardia. Application of radiofrequency energy to the breakout site from the left posterior fascicle prevented subsequent tachycardia induction and rendered the patient free of spontaneous tachycardia during long‐term follow‐up. Conclusions: Patients with ventricular tachycardia involving a bundle branch reentrant circuit may be sensitive to adenosine. These results suggest that adenosine may not only inhibit catecholamine‐mediated triggered activity but also some catecholamine‐mediated reentrant ventricular arrhythmias.
T Wave Alternans During Exercise and Atrial Pacing in Humans
Authors: HOHNLOSER STEFAN H. , KLINGENHEBEN THOMAS , ZABEL MARKUS , LI YI‐GANG , ALBRECHT PAUL , COHEN RICHARD J. 
Published: April 2007

T Wave Alternans in Humans. Introduction: Evidence is accumulating that microvolt T wave alternans (TWA) is a marker of increased risk for ventricular tachyarrhythmias. Initially, atrial pacing was used to elevate heart rate and elicit TWA. More recently, a noninvasive approach has been developed that elevates heart rate using exercise. Methods and Results: In 30 consecutive patients with a history of ventricular tachyarrhythmias, the spectral method was used to detect TWA during both atrial pacing and submaximal exercise testing. The concordance rate for the presence or absence of TWA using the two measurement methods was 84%. There was a patient‐specific heart rate threshold for the detection of TWA that averaged 100 ± 14 beats/min during exercise compared with 97 ± 9 beats/min during right atrial pacing (P = NS). Beyond this threshold, there was a significant and comparable increase in level of TWA with decreasing pacing cycle length and increasing exercise heart rates. Conclusions: The present study is the first to demonstrate that microvolt TWA can be assessed reliably and noninvasively during exercise stress. There is a patient‐specific heart rate threshold beyond which TWA continues to increase with increasing heart rates. Heart rate thresbolds for the onset of TWA measured during atrial pacing and exercise stress were comparable, indicating that heart rate alone appears to be the main factor of determining the onset of TWA during submaximal exercise stress.
Shock‐Induced Dispersion of Ventricular Repolarization:
Authors: BEHRENS STEFFEN , LI CUILAN , FABRITZ C. LARISSA , KIRCHHOF PAULUS F. , FRANZ MICHAEL R. 
Published: April 2007

Shock‐induced Dispersion and VF Induction. Introduction: Shock‐induced dispersion of ventricular repolarization (SIDR) caused by an electrical field stimulus has been suggested as a mechanism of ventricular fibrillation (VF) induction: however, this hypothesis has not been studied systematically in the intact heart. Likewise, the mechanism underlying the upper (ULV) and lower (LLV) limit of vulnerability remains unclear. Methods and Results: In eight Langendorff‐perfused rabbit hearts, monophasic action potentials were recorded simultaneously from ten different sites of both ventricles. Truncated biphasic T wave shocks were randomly delivered at various coupling intervals and strengths, exceeding the vulnerable window, ULV, and LLV. SIDR, defined as the difference between the longest and shortest postshock repolarization times, was 64 ± 15 msec for sbocks inducing VF. SIDR was 41 ± 17 msec for shocks delivered above the ULV, and 33 ± 14 and 27 ± 8 msec for shocks delivered 10 msec before and after the vulnerable window, respectively (all P < 0.01 vs VF‐inducing shocks). Although SIDR was larger for shocks delivered below the LLV(93 ± 24 msec, P < 0.01 vs VF‐inducing shocks), the repolarization extension was significantly smaller for shocks below the LLV (10.3%± 3.9% vs 16.3%± 4.9%, P < 0.01). Conclusion: SIDR is influenced by the shock timing and intensity. Large SIDR within the vulnerable window and an SIDR decrease toward its borders suggest that SIDR is essential for VF induction. The decrease in SIDR toward greater shock strengths may explain the ULV. Small repolarization extension for shocks below the LLV may explain why these shocks, despite producing large SIDR, fail to induce VF.