bluuebunny/crossref_metadata_2025 huggingface dataset:
Aerodynamic dislodgement of multiple‐size sand grains over time
Authors: LI LONG , MARTZ LAWRENCE W.
Published: June 2006

An experimental study was undertaken in a large‐scale wind tunnel to investigate sand particle dislodgement by wind over time in the absence of grain‐bed collisions. Aerodynamic dislodgement was measured for six groups of sand particles under two known wind velocity profiles. The results show that the dislodgement rate for both fine and coarse particles decreases rapidly during the transition of the particle surface from a non‐wind‐worked condition to a wind‐worked condition, and that the dislodgement rate continues to decay under a wind‐worked condition even though the mean grain size of surface particles remains nearly the same. A previously developed theoretical method for calculating the number of particles left on the bed by wind was developed further. The derived method was used to calculate the time‐decay of the dislodgement rate and the length of time required for the dislodgement rate to reach an equilibrium. The length of time for dislodgement rate to reach an equilibrium in this study is of the order of 10–15 min. This not only provides further observation of the second, long stage of aeolian sediment transport system development reported previously but also indicates a potentially large variation in the time‐decay of transport rate under different conditions. The results indicate that the time‐decay of the particle dislodgement rate is related to sorting processes. Because of the artificial method of preparation of the grain surface and the wind velocity profiles, the results of this study should be applied with caution to natural conditions.
Sedimentation in a disequilibrium river‐dominated estuary: the Raša River Estuary (Adriatic Sea, Croatia)
Authors: SONDI IVAN , JURAČIĆ MLADEN , PRAVDIĆ VELIMIR
Published: June 2006

This paper examines sediment transport, sedimentation and properties of suspended matter and sediments in the Raša River estuary, a small, rock‐bounded, microtidal, low‐wave‐energy karstic estuary in the north‐eastern Adriatic. The Raša River is characterized by large variation in water flow and variable load of mineral particles. More than 90% of this load is brought into the estuary as fine‐grained suspended matter, consisting of only 24–36% of carbonates, the rest being clays. Sedimentation occurs at the salt wedge, resulting in a prograding estuarine delta. Salt‐induced flocculation is the predominant process of sediment deposition.

The Raša estuary is infilling with sediment, and classifies as a disequilibrium estuary. We propose a modification of Cooper's (1993) classification scheme to include river‐dominated, disequilibrium estuaries, with the Raša River as an example.
Ground‐penetrating radar and coring used to study the large‐scale structure of point‐bar deposits in three dimensions
Authors: BRIDGE JOHN S. , ALEXANDER JAN , COLLIER RICHARD E. LL. , GAWTHORPE ROB. L. , JARVIS JACK
Published: June 2006

Detailed three‐dimensional (3‐D) observations of sandy point‐bar deposits from the River South Esk in Scotland were made using very closely spaced (metres) vibracores and ground‐penetrating radar (GPR) profiles. In order to explain the origin of the observed patterns of deposition, use was made of previous studies of channel geometry, flow and sediment transport. In addition, the mode and nature of channel migration and point‐bar accretion were determined using published maps, aerial photographs and detailed topographic surveys. Point‐bar deposits accumulated in response to channel‐bend expansion and downstream migration, resulting in preservation of sequences that fine upwards and downstream. Lower‐bar deposits are mainly very‐coarse to coarse sands with medium‐scale trough cross‐strata overlying basal gravels: associated radar facies are generally low‐amplitude, relatively discontinuous inclined reflectors. Upper‐bar deposits are mainly fine to medium sands with medium‐ and small‐scale cross‐strata and vegetation‐rich layers: associated radar facies are generally moderate‐ to high‐amplitude, laterally continuous, inclined reflectors. Large‐scale inclined stratasets seen in GPR profiles resulted from episodic point‐bar accretion. Abrupt lateral changes in inclination of these stratasets, and preservation of distinct unit bars (bar heads, scroll bars), lower‐bar platforms and inner‐bank swale fills, record discrete episodes of erosion and deposition associated with floods with recurrence intervals of decades to centuries. Such detailed 3‐D description and interpretation of these large‐scale features of point‐bar deposits was only possible through the use of GPR profiles tied closely to cores, and through the availability of much previously collected information on channel geometry, water flow, sediment transport, erosion and deposition.
Ooidal ironstones and ferruginous microbialites: origin and relation to sequence stratigraphy (Aalenian and Bajocian, Swiss Jura mountains)
Authors: BURKHALTER RETO M.
Published: June 2006

Aalenian and lower Bajocian rocks in the central and northern Swiss Jura mountains comprise a series of parasequences that mainly reflect a shallowing‐upward trend in a shallow, mixed carbonate/siliciclastic depositional environment. Within a parasequence, ooidal ironstones may occur at three specific types of horizons. These are: regressional discontinuities and transgressional discontinuities formed by sediment bypassing, and omissional discontinuities formed by starvation.

Ooidal ironstones, which principally are autochthonous, accumulated during both sea‐level rises and falls in a relatively broad bathymetric and hydrodynamic spectrum. The key physical factor for ferruginous ooid genesis is non‐deposition.

Ferruginous ooids and microbialites consist of goethite, chamosite and mixtures thereof, with subordinate amounts of apatite and silica. Ferruginous ooids grew stepwise on the sediment surface in an oxygenated marine environment. Ferruginous microbialites, being the product of benthic microbial communities, grew − partly in cavities − in aerated moderate‐ to high‐energy environments. Thus, chamosite evolved from a precursor substance stable under oxidizing conditions.

The close mineralogical and micromorphological resemblance of ferruginous microbialites and ooids suggests a common biogenic origin. Structural rearrangement of a biologically accreted gel‐like precursor substance consisting of various amorphous hydroxides is considered a probable mode of mineral genesis in both ferruginous ooids and microbialites.
Dynamics of sediment‐laden underflows passing over a subaqueous sill: glacier‐fed Peyto Lake, Alberta, Canada
Authors: CHIKITA KAZUHISA A. , SMITH NORMAN D. , YONEMITSU NOBORU , PEREZ‐ARLUCEA MARTA
Published: June 2006

The dynamic behaviour of sediment‐laden underflows was examined in Peyto Lake, Alberta, Canada, which contains a midlake sill 7 m high. Sediment‐laden underflows are driven by the downslope component of negative buoyant gravity multiplied by the current's thickness. Our measurements of wind, lake currents and water properties indicate that underflows pass over the sill due to the active storage of turbid suspension near the bottom in the deepest proximal region. Sill overflows occurred only when a hydrological threshold of the inflowing river was exceeded, causing quasicontinuous underflow and associated sedimentation in the distal region of the lake basin.
Ordovician low‐ to intermediate‐Mg calcite marine cements from Sweden: marine alteration and implications for oxygen isotopes in Ordovician seawater
Authors: TOBIN KENNETH J. , WALKER KENNETH R.
Published: June 2006

Petrography demonstrates the presence of three types of fibrous calcite cement in buildup deposits of the Kullsberg Limestone (middle Caradoc), central Sweden. Translucent fibrous calcite has intrinsic blue luminescence (CL) indicative of pure calcite. This cement has 2–5 mol% MgCO3, low Mn and Fe (≤ 100 p.p.m.), and is considered to be slightly altered to unaltered, primary low‐ to intermediate‐Mg calcite. Grey turbid fibrous calcite has variable but generally low MgCO3 content (most analyses <2 mol%) and variable CL response, with Mn and Fe concentrations up to 1200 and 500 p.p.m., respectively. The heterogeneous characteristics of this variety of fibrous calcite are caused by diagenetic alteration of a translucent fibrous calcite precursor. Light‐brown turbid fibrous calcite has low MgCO3 (near 1 mol%) and variable Mn (up to 800 p.p.m.) and Fe (up to 500 p.p.m.) concentrations, with an abundance of bright luminescent patches, which formed during alteration caused by reducing diagenetic fluids. The δ13C and δ18O values of all fibrous calcite form a tight field (δ13C=1·7 to 3·1‰ PDB, δ18O= − 2·6 to − 4·1‰ PDB) compared with fibrous calcite isotope values from other units. Fibrous calcite δ18O values are larger than adjacent meteoric or burial cements, which have δ18O δ − 8‰ PDB. Consequently, most diagenetic alteration of Kullsberg fibrous calcite is interpreted to have occurred in the marine diagenetic realm. First‐generation equant and bladed calcite cements, which pre‐date fibrous calcite, are interpreted as unaltered, low‐Mg calcite marine cements based on δ13C and δ18O data (δ13C = 2·3 to 2·7‰ PDB, δ18O= − 2·8 to − 3·5‰ PDB). Unlike fibrous cement, which reflects global sea water chemistry, first‐generation equant and bladed calcite are indicators of localized modification of seawater chemistry in restricted settings. Kullsberg abiotic marine cements have larger δ18O values than most Caradoc marine precipitates from equatorial Laurentia. Positive Kullsberg δ18O values are attributed to lower seawater temperatures and/or slightly elevated salinity on the Baltic platform relative to seawater from which other marine precipitates formed.
Ulster White Limestone Formation (Upper Cretaceous) of Northern Ireland: effects of basalt loading on chalk diagenesis
Authors: MALIVA R. G. , DICKSON J. A. D.
Published: June 2006

The Ulster White Limestone Formation is an unusual chalk because it underwent a period of post‐depositional emergence and erosion, followed by burial under 1·5–2·0 km of Tertiary basalts. A high degree of pressure solution and cementation produced a well‐lithified limestone with low porosities (2·3–10·4%). The Ulster White Limestone shows no evidence of thermally induced textural alteration, except for thin (<0·5 m) pseudospar contact recrystallization zones adjoining basalt dykes. Whole‐rock δ18O values of samples not associated with basalt dykes range from ‐ 3·26%o to ‐ 6·50%o (PDB). The δ18O values of macropore cements range from ‐ 4·96%o to ‐ 11·52%o (mean=‐8·27%o). Modelling of the diagenesis of the Ulster White Limestone using trace element concentrations and carbon, oxygen and strontium isotopic ratios of whole rock and cement samples suggests a low water‐rock ratio and either marine or mixed marine‐meteoric pore water environment during the main episode of recrystallization. The maximum possible burial temperature was modelled to be ≃ 105°C.

The diagenetic history of the Ulster White Limestone is similar to that of North Sea chalks that are at comparable burial depths as the Ulster White Limestone after basalt deposition. The geochemical data show no indication of hydrothermal alteration associated with the overlying basalts. The degree of alteration of fine‐grained limestones composed predominantly of low‐magnesium calcite, such as the Cretaceous/Tertiary chalks, appears to be controlled largely by the burial (effective stress) history of the limestone.
Preservation of planar laminae due to migration of low‐relief bed waves over aggrading upper‐stage plane beds: comparison of experimental data with theory
Authors: BRIDGE JOHN , BEST JIM
Published: June 2006

Experimental studies of the formation of planar laminae by migration of low‐relief bed waves over aggrading upper‐stage plane beds show that the average thickness of laminae at a point increases with both aggradation rate and the variance of the heights of bed waves passing that point. In general, the preserved laminae represent only a small proportion (generally less than 50%) of the height of the largest bed waves in the population. The theory developed by Paola & Borgman (1991), relating the probability density function of stratal thickness to that of bed wave height for the case of no net aggradation, was adapted for aggrading conditions and shown to agree well with data. These results suggest that the theory can be used to estimate, from the distribution of thickness of planar laminae, either the distribution of bed wave heights, mean aggradation rate, mean bed wave length or mean bed wave celerity, provided the other parameters can be estimated.
Gravel antidunes in the tropical Burdekin River, Queensland, Australia
Authors: ALEXANDER JAN , FIELDING CHRIS
Published: June 2006

The geological record is punctuated by the deposits of extreme event phenomena, the identification and interpretation of which are hindered by a lack of data on contemporary examples. It is impossible to directly observe sedimentary bedforms and grain fabrics forming under natural particle‐transporting, high‐velocity currents, and therefore, their characteristics are poorly documented. The deposits of such flows are exposed however, in the dry bed of the Burdekin River, Queensland, Australia following tropical cyclone‐induced floods.

Long wave‐length (up to 19 m) gravel antidunes develop during short (days) high‐discharge flows in the upper Burdekin River (maximum recorded discharge near the study reach over 25 600 m3 s−1 in February 1927). Flood water levels fall quickly (metres in a day) and flow is diverted away from raised areas of the river bed into subchannels, exposing many of the high‐stage bedforms with little reworking by falling‐stage currents. Gravel bedforms were observed on the dry river bed after the moderate flows of February 1994 (max. 7700 m3 s−1) and January 1996 (max. 3200 m3 s−1). The bedforms had wave‐lengths in the range 8–19 m, amplitudes of up to 1 m with steeper stoss than lee faces and crest lines generally transverse to local peak‐discharge flow direction. The gravel fabric and size sorting change systematically up the stoss and down the lee faces. The antidune deposits form erosive based lenses of sandy gravel with low‐angle downstream dipping lamination and generally steep upstream dipping a‐b planes. The internal form and fabric of the antidune gravel lenses are distinctly different from those of dune lee gravel lenses. The erosive based lenses of low‐angle cross‐bedded gravel with steep upstream dipping a‐b planes are relatively easy to recognize and may be diagnostic of downstream migrating antidunes. The antidune gravel lenses are associated with thick (to 1 m) high‐angle cross bed sets. Ancient antidune gravel lenses may be diagnostic of episodic high‐discharge conditions and particularly when they are associated with high‐angle cross‐bedded gravelly sand they may be useful for palaeoenvironmental interpretation.
ENZYMATIC STUDIES ON THE METABOLISM OF VESICULAR‐ARBUSCULAR MYCORRHIZA. III. ULTRASTRUCTURAL LOCALIZATION OF ACID AND ALKALINE PHOSPHATASE IN ONION ROOTS INFECTED BY GLOMUS MOSSEAE (NICOL. & GERD.)
Authors: GIANINAZZI S. , GIANINAZZI‐PEARSON V. , DEXHEIMER J.
Published: June 2006

Summary

The ultrastructural distribution of acid and alkaline phosphatase in 6‐week‐old onion roots infected by Glomus mosseae has been investigated cytochemically. Significant acid phosphatase activity was only observed in the little vacuolated, immature terminal arbuscule branches of the mycorrhizal fungus whilst strong alkaline α‐naphthyl phosphatase and β‐glycerophosphatase activities were localized within the vacuoles of the mature arbuscular and intercellular hyphae. In the host cells neither acid nor alkaline phosphatase distribution was modified with vesicular‐arbuscular mycorrhiza formation. These results are discussed in relation to previously reported mycorrhiza‐specific alkaline phosphatase (Gianinazzi‐Pearson and Gianinazzi, 1976, 1978) and the metabolism of phosphorus in vesicular‐arbuscular mycorrhizal systems.
AUTORADIOGRAPHY OF THE DEPLETION ZONE OF PHOSPHATE AROUND ONION ROOTS IN THE PRESENCE OF VESICULAR‐ARBUSCULAR MYCORRHIZA
Authors: OWUSU‐BENNOAH E. , WILD A.
Published: June 2006

Summary

Using autoradiography a comparison was made of the depletion zones of 33P‐labelled phosphate around mycorrhizal (Glomus mosseae) and non‐mycorrhizal onion roots grown in a silty clay loam for 42 days.

Mycorrhizal inoculation increased the growth and 33P content of the onion plants in both irradiated and non‐irradiated soil. Successive autoradiographs showed that for the mycorrhizal and non‐mycorrhizal roots most P uptake was within 0·2 and 0·1 cm respectively of the root surface. The effect of the mycorrhiza was similar to that of a cylinder of root hairs 0·1 cm long.
INTERACTION BETWEEN A VESICULAR‐ARBUSCULAR MYCORRHIZA AND RHIZOBIUM AND THEIR EFFECTS ON SOYBEAN IN THE FIELD
Authors: BAGYARAJ D. J. , Manjunath A. , Patil R. B.
Published: June 2006

Summary

Interaction between Glomus fasciculatus and Rhizobium japonicum and their effects on soybean in the field was studied in a phosphorus deficient sandy loam soil with pH 5·6. The number, dry weight and nitrogen content of the root nodules in plants inoculated with Glomus plus Rhizobium were significantly more compared to plants inoculated with only Rhizobium. Rhizobium inoculation did not have any significant effect on sporulation of G. fasciculatus in the rhizosphere. Although soybean plants inoculated with G. fasciculatus recorded increased phosphorus content, dry weight and grain yield than uninoculated plants the differences were not statistically significant.

In Rhizobium only inoculation markedly increased the nitrogen content of the plant and grain yield. Dual inoculation with both the symbionts increased significantly the dry weight of the shoot and its nitrogen content over single inoculation with either Glomus or Rhizobium. These results suggest that vesicular–arbuscular (VA) mycorrhiza can greatly assist nodulation and nitrogen fixation in field growth soybean inoculated with rhizobia.
PHOTOSYNTHETIC CONTRIBUTION OF FLOWERS AND SEEDS TO REPRODUCTIVE EFFORT OF AN ANNUAL COLONIZER
Authors: BAZZAZ F. A. , CARLSON R. W.
Published: June 2006

Summary

The energetic cost for a plant to produce reproductive structures is termed reproductive effort and is most frequently expressed as the ratio of reproductive biomass to total plant biomass. This expression may lead to an incorrect analysis of reproductive effort unless an account is taken of (a) the cost of producing male flowers or male flower parts, and (b) the photosynthetic contribution (reproductive assimilation) of reproductive structures to propagule production.

An analysis was made of the carbon budget for reproduction in Ambrosia trifida L., based on measurements of CO2 flux, and the elaboration of seed by excised immature pollinated inflorescences in the absence of carbohydrate from the main stem. Reproductive assimilation accounted for 41 and 57 % respectively of the carbohydrate required to produce male and female inflorescences on intact plants. Individual flowers retain their ability to elaborate seed even after being removed from the parent plant at the time of pollination.
LONGEVITY AND PRODUCTIVITY OF LEAVES OF A CULTIVATED ANNUAL, GLYCINE MAX MERRILL. I. LONGEVITY OF LEAVES IN RELATION TO DENSITY AND SOWING TIME
Authors: MIYAJI KEN‐ICHI , TAGAWA HIDEO
Published: June 2006

Summary

A life‐table approach has been applied to the leaf population of the soybean plant (Glycine max Merrill) in order to determine leaf longevity, a basic factor in production of dry matter. Longevity of leaves was determined at various heights on the stems of plants grown at three densities at three different sowing times.

In general, longevity increases with the height of the leaf on the stem, but the uppermost leaves have short lives due to frost‐damage. In the plants sown earlier than the standard sowing time the lowest leaves fell very rapidly as a result of physiological ageing.

It was concluded that, at the densities examined, density does not show a generalized relationship with leaf longevity.

At the lower nodes, most leaves fell due to physiological ageing, but those at the higher nodes suffered from noxious insects. Two typhoons had little influence on leaf longevity.
A Prospective, Randomized Evaluation of a Nonthoracotomy Implantable Cardioverter Defibrillator Lead System
Authors: BAKER JAMES H. , EPSTEIN ANDREW E. , VOSHAGE‐STAHL LYNNETT ,   with the assistance of THE ENDOTAK/PRX INVESTIGATOR GROUP
Published: June 2006

Nonthoracotomy lead systems for ICDs have been developed that obviate the need for a thoracotomy and reduce the morbidity and mortality associated with implantation. However, an adequate DFT cannot be achieved in some patients using transvenous electrodes alone. Thus, a new subcutaneous “array” electrode was designed and tested in a prospective, randomized trial that compared the DFT obtained using monophasic shock waveforms with a single transvenous lead alone that has two defibrillating electrodes, the transvenous lead linked to a subcutaneous/submuscular patch electrode, and the transvenous lead linked to the investigational array electrode. There were 267 patients randomized to one of the three nonthoracotomy ICD lead systems. All had DFTs that met the implantation criterion of ≤ 25 J. The resultant study population was 82% male and 18% female, mean age of 63 ± 11 years. The indication for ICD implantation was monomorphic VT in 70%, VF in 19%, monomorphic VT/VF in 6%, and polymorphic VT in 4% of the patients, respectively. The mean LVEF was 0.33 ± 0.13. The mean DFT obtained with the transvenous lead alone was 17.5 ± 4.9 J as compared to 16.9 ± 5.5 J with the lead linked to a patch electrode (P = NS), and 14.9 ± 5.6 with the lead linked to the array electrode (array versus lead alone, P = 0.0001; array versus lead/patch, P = 0.007). The results of this investigation suggest that the subcutaneous array may be superior to the standard patch as a subcutaneous electrode to lower the DFT and increase the margin of safety for successful nonthoracotomy defibrillation.
Standardized Assessment of Psychological Well‐Being and Quality‐of‐Life in Patients with Implanted Defibrillators
Authors: HERRMANN CHRISTOPH , von zur MÜHEN FRIEDERIKE , SCHAUMANN ANSELM , BUSS ULLRICH , KEMPER SYLKE , WANTZEN CHRISTIAN , GONSKA BERND‐DIETER
Published: June 2006

The ICD has become a standard treatment for patients with malignant arrhythmias. Despite its benefits it may cause additional discomfort to the patients. Thus, quality‐of‐life needs to be assessed in these patients. Previous studies have used only small samples or unstandardized measures of quality‐of‐life that do not allow comparisons with other patient groups. The present study used standardized questionnaires for a cross‐sectional assessment of psychological well‐being and quality‐of‐life in ICD patients and to compare them to a similar group of coronary artery disease (CAD) patients without ICD. Overall, quality‐of life did not differ between both groups, ICD patients being less anxious than the CAD group. With increasing numbers of ICD shocks, however, the percentage of psychologically distressed ICD patients rose from 10% to > 50%. Psychologically distressed patients had significantly worse scores on most of the quality‐of‐life subscales, showed less treatment satisfaction, and more negative attitudes. It is concluded that ICD patients have an acceptable mean quality‐of‐life and low mean anxiety. However, a relevant subgroup of about 15%, especially patients with frequent shocks, experience psychological distress and reduced quality‐of‐life and should receive special care.
Radiofrequency Catheter Ablation of Atrial Flutter That Elicits Inappropriate Implantable Cardioverter Defibrillator Discharge
Authors: SCHUMACHER BURGHARD , TEBBENJOHANNS JÜRGEN , JUNG WERNER , KORTE THOMAS , PFEIFFER DIETRICH , LÜDERITZ BERNDT
Published: June 2006

The case of a patient with recurrent VT and an ICD is reported. After appropriate device discharges, the patient experienced 40 episodes of inappropriate shock therapy due to atrial arrhythmias confirmed as type I atrial flutter. Since programmed stimulation could reliably initiate atrial flutter, catheter ablation was performed. During delivery of RF current, atrial flutter terminated and was no longer inducible. The patient had no further inappropriate device discharges during 12 months of follow‐up. In patients with ICDs suffering from recurrences of atrial flutter leading to inappropriate shock therapy, RF catheter ablation is an effective and curative approach.
Does An SVC Electrode Further Reduce DFT In A Hot‐Can ICD System?
Authors: MOUCHAWAR GABRIEL A. , WOLSLEGER WENDY K. , DOAN PHONG D. , CAUSEY JAMES D. , KROLL MARK W.
Published: June 2006

Pectorally implanted ICDs that defibrillate with the RV electrode and the ICD housing have gained clinical acceptance. However, it is still debatable whether adding an SVC electrode connected to the housing will further reduce the threshold of defibrillation (DFT). This study utilized eight pigs. DFTs were measured with a 50 V step‐down protocol starting at 650 V (20 J). Shock strength for 50% success (E50) was estimated with the average of three reversals. In addition to a dummy device, Lead I (Pacesetter Models 1558 and 1538) or Lead II (Endotak 72) were used. Leads I are active fixation, true bipolar sensing with 5‐cm shocking coils. Lead II has an integrated bipolar sensing with a 4.7‐cm RV and 6.9‐cm SVC shocking coils. A 95 μF defibrillation system was used to deliver a 44% tilt tuned biphasic 1.6/2.5 ms waveform, and to measure lead impedance. The RV electrode was the anode during phase I. With Lead I RV → CAN the DFT was 531 ± 75 V (13.6 ± 3.8 J) and the E50 was 496 ± 89 (12 ± 4.3 J). These were not significantly (NS) different than the DFT for RV → CAN and SVC which was 518 ± 84 V (13 ± 4.2 J) or the E50 which was 476 ± 84 V (11 ± 3.9 J). Similar results were obtained with Lead II. Despite a decrease in lead impedance there was no apparent benefit from the addition of the SVC electrode. Lead I provided equivalent DFT performance to Lead II.
The Value of DDD Pacing in Patients with an Implantable Cardioverter Defibrillator
Authors: GEELEN PETER , F ADALBERTO LORGA , CHAUVIN MICHEL , WELLENS FRANCIS , BRUGADA PEDRO
Published: June 2006

Although the beneficial effects of DDD pacing are well known, currently available ICDs provide only fixed rate ventricular antibradycardia pacing. In a consecutive series of 139 patients with ICDs, we have analyzed the need for antibradycardia pacing and the indications for DDD pacing. We also report our initial experience with the Defender 9001 (ELA Medical, France) DDD‐ICD. Out of 139 patients, 25 (18%) were in need of antibradycardia pacing. Ten patients already had a pacemaker at the time of ICD implantation and ten other patients had a conventional pacemaker indication at that time. Five patients became pacemaker dependent during a follow‐up of 20 ± 8 months. The disorders necessitating pacemaker therapy were high degree AV conduction disturbances in 72%, sick sinus syndrome in 12%, and AF with a slow ventricular response in 16% of patients. Based upon current indications, DDD pacing was indicated in 20 (80%) of 25 patients. The Defender 9001 DDD‐ICD (ELA Medical) was used in two patients with ischemic cardiomyopathy and pacemaker syndrome with VVI pacing. Cardiac output during DDD pacing increased by 36% in one patient with an increase in VO2 max during exercise of 29%. The other patient showed an increase in cardiac output of 50% with DDD pacing, and, while unable to exercise with VVI pacing, had a VO2max of 24 mL/kg per minute during DDD pacing. Up to 18% of our ICD patients are in need of antibradycardia pacing. Of these pacemaker dependent patients, 80% have an indication for DDD pacing. Our first clinical experience with a DDD‐ICD confirms the hemodynamic benefit of AV synchronous pacing in ICD patients with pacemaker syndrome.
Implantable Cardioverter Defibrillators in Patients with Chagas' Disease: Are They Different from Patients with Coronary Disease?
Authors: MURATORE CLAUDIO , RABINOVICH RAFAEL , IGLESIAS RICARDO , GONZÁLEZ MIGUEL , DARÚ VICTOR , LIPRANDI ALVARO SOSA
Published: June 2006

Chagas' disease is a parasitic affliction, endemic to certain regions of South America, which may lead to a chronic dilated nonischemic cardiomyopathy. Ten Chagasic patients were compared to 18 coronary patients undergoing transvenous ICD implantation for ventricular tachycardia (VT), ventricular fibrillation (VF), or aborted cardiac arrest. Indications for ICD implantation were either drug intolerance or refractoriness, or no inducible tachyarrhythmia at EPS. There were no statistically significant differences between the Chagas and coronary artery disease groups with respect to age (60.2 vs 62.6 yrs], NYHA Class II (50% vs 62%), ejection fraction (31.1% vs 29.7%), and incidence of cardiac arrest (20% vs 33%), respectively. The following ICD implant and long‐term follow‐up variables were compared between the two groups: pacing threshold (0.94 V vs 0.95V), defibrillation threshold (19.5 J vs 19.6 J), number of VT episodes (414 vs 435), number of spontaneous VT terminations (86 vs 187), percent efficacy of antitachycardia pacing (93.9% vs 92.1 %), and total number of shocks (112 vs 145). These differences were not statistically significant. We conclude that patients with Chagas’ disease, compared with coronary artery disease patients, have similar clinical characteristics leading to ICD implantation. Furthermore, no differences were found with respect to ICD and long‐term follow‐up characteristics between the two groups.
A Cardiac Evoked Response Algorithm Providing Threshold Tracking: A North American Multicenter Study
Authors: LAU CHING , CAMERON DOUGLAS A. , NISHIMURA SANDRA C. , AHERN THOMAS , FREEDMAN ROGER A. , ELLENBOGEN KENNETH , GREENBERG STEVEN , BAKER JAMES , MEACHAM DONALD ,   CLINICAL INVESTIGATORS OF THE MICRONY‐REGENCY CLINICAL EVALUATION STUDY
Published: June 2006

The purpose of this study was to evaluate, a pacing system using the recognition of cardiac evoked response for the automatic adjustment of pacing output. Patients were prospectively followed after primary implantation of VVIR pacemakers using AutoCapture (St. Jude Medical CRMD). Sensing and pacing thresholds, polarization signal, evoked response, and AutoCapture performance were evaluated with serial visits and 24‐hour Holier monitoring. Three hundred ninety‐eight patients (mean age 71 ± 15 years) were followed for an average duration of 1 year (3 days‐1.75 years) with the algorithm functional in > 90% of patients. Backup pacing in the event of exit block was confirmed in all patients. Pacing thresholds remained stable at 0.89 ± 0.34 V with a pulse width of 0.31 ms (with chronic output au‐toset at 0.3 V above the actual threshold). Evoked response exhibited a small but statistically significant increase with time (8.92 in V at implant, 9.60 mV at 12 months), however, this finding did not result in any change in AutoCapture function during our follow‐up period. The polarization signal remained stable with minimal variation (1.12 mV at implant, 1.18 at 12 months). No clinical adverse events were observed using the AutoCapture algorithm. In this initial experience with the AutoCapture algorithm the evoked response and polarization measurements remained adequate, allowing the system to function in the majority of patients with safe, low output pacing. High energy backup pacing provided on added safety feature over fixed output devices in cases of unexpected threshold rises. Longer follow‐up is required for continued long‐term validation of the algorithm.
Temporal and Geographical Trends in Indications for Implantation of Cardiac Defibrillators in Europe 1993–1998
Authors: COPIE XAVIER , PIOT OLIVIER , SAID MINA AIT , LAVERGNE THOMAS , OLLITRAULT JACKY , GUIZE LOUIS , LE HEUZEY JEAN‐YVES ,   MEDTRONIC ICD SYSTEM INVESTIGATORS
Published: June 2006

Despite the demonstrated efficacy of implantable cardioverter defibrillators (ICDs) in reducing sudden and total mortality in selected populations, their implantation rates vary greatly between countries. The aim of our study was to analyze temporal and geographical trends in ICD implantations in countries with similar health related expenditure in Western Europe. A total of 2,257 patients from ten European evaluation studies of Medtronic defibrillators and defibrillation electrodes, conducted between 1993 and 1998, representing 12 countries, was included in this analysis. Rates of implantation and clinical characteristics were compared between countries and years of implantation. Rates of implantation differed greatly between Western European countries and did not correlate with indices of health related expenditure (i.e., number of patients per physician and number of patients per hospital bed). However, there was a strong and statistically significant negative correlation between the use of amiodarone and the rates of implantation (r =−0.66, P = 0.02). Temporal trends showed a significant increase in the age of the patients receiving an ICD between 1993 and 1998(57 ± 14 vs 61 ± 12years, mean ± SD, P < 0.001). There was also a temporal trend towards an increased incidence of coronary artery disease and a significant decrease in the incidence of cardiomyopathy. There was a temporal increase in implantations in patients with a history of ventricular tachycardia. Despite a general scientific agreement that ICDs are a first line treatment for patients at high risk of sudden cardiac death, their acceptance remains low in several developed countries. This low acceptance may not be entirely related to budget constraint but may also be related to their perceived efficacy by physicians and health authorities.
Permanent Pacemaker Therapy Before and After the Reunification of Germany: 16 Years of Experience at an East German Regional Pacing Center
Authors: KARNATZ P. , ELSNER C. , MÜLLER G. , WOLTER C. , NELLESSEN U.
Published: June 2006

The reunification of Germany had a significant influence on the management of patients with bradyarrhythmias. The current study was performed in a regional pacing center heated in the former German Democratic Republic. It compares the situation of patients with critical bradyarrhythmias before and after the reunification of Germany in 1990 focusing on (1) indication for pacemaker implantation. (2) pacemaker modalities and function, (3) type of leads, (4) frequency of reintervention, and (5) early and late complications. The study covers 9 years before and 7 years after the reunification. A total of 1,125 patients were included, and the database was formed by the patients' files and the protocols of implantation. The situation before reunification was characterized by a nonavailability of modern physiological pacing devices and insufficient diagnostic equipment. Between 1981 and 1990, 384 patients underwent pacemaker implantation solely receiving single chamber devices with no or only minimal feasibility of programming. Between 1990 and 1996, 741 patients were treated, and they all received modern pacemakers having the capability of multiprogramming and telemetry. Regarding complications of pacemaker therapy, lead related problems significantly decreased after the reunification (dislocation, 5.3% vs 1.7%, P < 0.05; exit block, 6.7% vs 1.4%. P < 0.05) opposite to pacemaker infections, which significantly increasing after dual chamber pacemakers were implanted (2.2% vs 6.0%, P < 0.05). The reunification of Germany dramatically improved the situation of patients with critical bradyarrhythmias leading to free access to high‐tech pacing equipment within a few months. However, the abrupt change from antiquated to modern pacemaker therapy created some new problems, especially regarding application and handling of modern physiological pacing devices.
The 1998 NASPE Prospective Catheter Ablation Registry
Authors: SCHEINMAN MELVIN M. , HUANG SUE
Published: June 2006

The results of the NASPE Prospective Voluntary Registry are reported. A total of 3,357 patients were entered. For those undergoing atrioventricular (AV) junctional ablation (646 patients), the success rate was 97.4% and significant complications occurred in 5 patients. A total of 1,197 patients underwent AV nodal modification for AV nodal reentrant tachycardia, which was successful in 96.1% and the only significant complication was development of AV block (1 %). Accessory pathway ablation was performed in 654 patients and was successful in 94%. Major complications included cardiac tamponade (7 patients), acute myocardial infarction (1 patient), femoral artery pseudoaneurysm (1 patient), AV block (1 patient), pneumothorax (1 patient), and pericarditis (2 patients). A total of 447 patients underwent atrial flutter ablation and acute success was achieved in 86% of patients. Significant complications included inadvertent AV block (3 patients), significant tricuspid regurgitation (1 patient), cardiac tamponade (1 patient), and pneumothorax (1 patient). Atrial tachycardia was attempted for 216 patients and the success rate was higher for those with right atrial (80%) or left atrial (72%) compared to those with septal foci (52%). A total of 201 patients underwent ablation for ventricular tachycardia. The success rate was higher for those with idiopathic ventricular tachycardia compared to those with ventricular tachycardia due to ischemic heart disease or car‐diomyopathy. While the number of AV junction ablation were higher for those > 60 years of age, there was no significant difference in the success rate or incidence of complication comparing patients ≥ 60 to those < 60 years of age. In addition, we found no differences in incidence of success or complications comparing large volume centers (> 100 ablation/year) with lower volume centers or between teaching and non‐teaching hospitals.
Advantages and Disadvantages of Trial Designs: A Review of Analysis Methods for ICD Studies
Authors: HALLSTROM ALFRED P. , ANDERSON JEFFREY L. , COBB LEONARD A. , FRIEDMAN PETER L. , HERRE JOHN M. , KLEIN RICHARD C. , MCANULTY JOHN , STEINBERG JONATHAN S. ,   AVID INVESTIGATORS
Published: June 2006

General modalities of analyses that have, been used for ICD studies are reviewed. Published “typical” examples are briefly described. The historical cohort method is exemplified with previously unpublished data from the Seattle Cardiac Arrest Survivor database. The AVID Study database is used to compare the results obtained from nonrandomized methodologies with randomized methodologies. Particular issues related to the use of the ICD for example, mode of death, inability to blind, selection practice, and treatment decision times make this a natural pedagogic platform.
Differences in plans for living at home between temporary residents of a health‐care facility for the elderly and their family caregivers in Japan
Authors: HOSHINO Junko , HAMAHATA Akiko , MAGILVY Joan K.
Published: June 2006

Aim:  Older residents in Japan requiring rehabilitation often reside in health‐care facilities for the elderly (HCFE) prior to being discharged to home. The return home can be very stressful for both the elder and family caregiver. The purpose of this study was to clarify the differences in plans for home life between the residents of a HCFE who were scheduled for discharge home and their family caregivers.

Method:  Semistructured interviews were conducted with eight pairs of elders and caregivers.

Results:  Differences were seen in several areas, including dietary preferences, recognition of the elder’s independence, preconceptions or not knowing about the elder’s pleasurable activities, and the way of care.

Conclusions:  Differences with regard to enjoyable activities for the elderly arose from a lack of understanding of the lives of the elderly on the part of their families.
Mid‐term report on St Luke’s College of Nursing’s 21st century Center of Excellence Program: Core elements and specific goals of people‐centered care
Authors: KOMATSU Hiroko
Published: June 2006

Aim:  This paper, at the halfway point of the 5 year Center of Excellence (COE) Program, aims to extract common core elements of each COE project working on the development of people‐centered care and to clarify future issues related to the COE Program through the evaluation of those elements.

Methods:  All data obtained in such research activities, including records, interviews, meeting minutes, and results, are shared for each project in COE section meetings or general assemblies and the findings that are established there are accumulated. We also have set up a working group to develop the people‐centered care concept by continuously reviewing the core elements of people‐centered care based on the collected data. In order to track the projects in an orderly manner, we classified and organized the activities of the 11 COE projects based on the Process Evaluation Model and reviewed common important elements.

Results:  The characteristic components, related to participation, relationships, capacity‐building, empowerment, and product (specific achievements), were extracted as common core elements of each COE project.

Conclusion:  In order to maintain the sustainability of people‐centered care incorporated in communities, concrete strategies for improving economic efficiency, social significance and utility, and evaluation methods need to be developed.
Comparison of metal distributions in snow, peat, lakes and humus around a Cu smelter in western Québec, Canada
Authors: Bonham-Carter G.F. , Henderson P.J. , Kliza D.A. , Kettles I.M.
Published: June 2006

Concentrations of metals around the Cu smelter at Rouyn-Noranda, Québec, in snow, peat, the humus horizon of soil, lake water and sediments, show generally similar spatial distribution patterns. The contours of smelter-related metal concentrations in all these media are approximately circular in shape, centred on the smelter, and elongated somewhat towards the east due to the prevailing wind direction. Close to the smelter, the concentrations are up to 1000 times greater than regional background levels. The distances at which concentrations of smelter-related metals decrease to background levels is in the range 65 ± 5 km.

The ratio of (Cu+As)/(Al+Fe) is a useful indicator of source apportionment for comparing the results between sampling media because it is independent of measurement units and maximizes the contrast between smelter and non-smelter materials. The value of the ratio, which changes as a function of distance from the smelter, reflects the mixing and dilution of emissions with non-smelter dust and aerosols.

Deposition rates of metal calculated for snow and peat integrated over the area of the smelter-centred anomaly allow estimates to be made of the amounts of metal deposited from the smelter, after correcting for deposition of background metal. The proportions of reported metal emissions accounted for by deposition within 150 km of the smelter are: Cu, 25–50%; Pb, 10–20%; Zn, 25%; As, 5%; and Cd 20–25%. Metals in excess of these proportions are probably transported outside the immediate smelter footprint, but deposition of smelter-emitted metals becomes so small at these distances, and so mixed with airborne metals from other sources, that it is difficult to discriminate between smelter and non-smelter sources in samples taken on the ground.
Effects of sample drying on element forms in lake sediments
Authors: Hall Gwendy E.M. , Vaive Judy E. , Pelchat Pierre , Bonham-Carter Graeme F. , Kliza-Petelle Deborah A. , Telmer Kevin
Published: June 2006

The application of a sequential extraction scheme provides information on the phase association of elements in a sample, such phases being described, for example, as ‘exchangeable/adsorbed’, ‘amorphous Fe/Al oxides’ and ‘soluble organics’. It is therefore critical to maintain the chemistry of a sample from the time of collection to its analysis and during its preparation for analysis. This paper focuses on the redistribution of elements, amongst five operationally defined phases, that occurs on air-drying of the sample; the effect of subsequent storage of the sample is not addressed. Two lake sediment cores (‘Green Lake’, 31 cm, and ‘Gravel Pit Lake’, 19 cm) were sampled at 1-cm intervals and divided into two sets immediately prior to sequential leach analysis of the ‘wet’ sample. The other set was air-dried prior to sequential leach analysis. Most of the 39 elements determined in the Green Lake sediment showed, on drying, a redistribution to more labile forms. For example, increases in Fe concentration in the oxide phases were observed with a concomitant decrease in the crystalline forms of Fe reporting to the final aqua regia digestion. These changes are generally small in magnitude (<10% of the total element extracted) but they can change the shape of the element profile down the core for an affected leach which in turn could lead to misinterpretation of the sequential leach data. Surprisingly, S did not show any changes on drying, suggesting that the kinetics of oxidation are reasonably slow and that storage of the sample rather than drying is more important. The fact that some elements in the Gravel Pit Lake core behaved differently to Green Lake indicates that redistribution of elements on sample drying is both element and matrix dependent.
Lead concentrations and isotope ratios in the exchangeable fraction: tracing soil contamination near a copper smelter
Authors: Hou X. , Parent M. , Savard M. M. , Tassé N. , Bégin C. , Marion J.
Published: June 2006

A total of 75 soil samples were collected from podzolic soils at eight sites in northwestern Quebec in order to compare results in contaminated locations near the Horne Copper smelter in Rouyn-Noranda with those near Hudson Bay, 800 km further north, and
a priori
devoid of pollution. Lead concentrations and Pb isotopic compositions were determined on soil samples leached by 0.25 M HCl.

Lead is enriched in the surface organic horizons at all sites in Rouyn-Noranda. Its concentration decreases abruptly from the surface organic horizons to the underlying mineral horizons. The
206
Pb/
207
Pb ratios are low in surface organic horizons, and they increase sharply in the mineral horizons. Along a NE–SW transect, the highest average Pb concentration (869 ppm) in organic horizons is found at the test site, 9 km from the smelter. The lowest average of 39 ppm Pb in surface organic layers is accompanied by the highest average
206
Pb/
207
Pb ratio (1.15) at site 5, 116 km NE of the Horne smelter. At the test site, the highest Pb concentration of 1414 ppm is also accompanied by the lowest
206
Pb/
207
Pb ratio (0.98), which is close to the isotopic composition of Noranda galena (
206
Pb/
207
Pb=0.92). Both Pb concentration and isotopic composition indicate that the Horne smelter is the main source of Pb contamination of soils in the Rouyn-Noranda region. The two soil profiles from near Hudson Bay display much lower Pb concentration and different trends of isotope ratios with depth.