bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic marking with the ΔLNGFR‐gene for tracing goat cells in bone tissue engineering
Authors: Kruyt M. C. , Stijns M. M. C. , Fedorovich N. E. , de Bruijn J. D. , van Blitterswijk C. A. , Verbout A. J. , Rozemuller H. , Hagenbeek A. , Dhert W. J. A. , Martens A. C. M.
Published: December 2003

The use of bone marrow derived stromal cells (BMSC's) for bone tissue engineering has gained much attention as an alternative for autologous bone grafting. Little is known however, about the survival and differentiation of the cells, especially in the clinical application. The aim of this study was to develop a method to trace goat BMSC's in vivo. We investigated retroviral genetic marking, which allows stable expression of the label with cell division.

Goat BMSC's were subjected to an amphotropic envelope containing a MoMuLV‐based vector expressing the human low affinity nerve growth factor receptor (ΔLNGFR). Labeling efficiency and effect on the cells were analyzed. Furthermore, transduced cells were seeded onto porous ceramic scaffolds, implanted subcutaneously in nude mice and examined after successive implantation periods.

Flow cytometry indicated a transduction efficiency of 40–60%. Immunohistochemistry showed survival and subsequent bone formation of the gene‐marked cells in vivo. Besides, marked cells were also found in cartilage and fibrous tissue. These findings indicate the maintenance of the precursor phenotype following gene transfer as well as the ability of the gene to be expressed following differentiation. We conclude that retroviral gene marking with ΔLNGFR is applicable to trace goat BMSC's in bone tissue engineering research. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Continuing dangers of disinformation in corporate accounting reports
Authors: Kane Edward J.
Published: December 2003

Insiders can artificially deflect the market prices of financial instruments from their full information or “inside” value by issuing deceptive accounting reports. Incentive support for disinformational activity comes through forms of compensation that allow corporate insiders to profit extravagantly from temporary boosts in a firm's accounting condition or performance. In principle, outside auditing firms and other watchdog institutions help outside investors to identify and ignore disinformation. In practice, accountants can and do earn substantial profits from credentialling loophole‐ridden measurement principles that conceal adverse developments from outside stakeholders. Although the Sarbanes–Oxley Act now requires top corporate officials to affirm the essential economic accuracy of any data their firms publish, officials of outside auditing firms are not obliged to express every reservation they may have about the fundamental accuracy of the reports they audit. This asymmetry in obligations permits auditing firms to continue to be compensated for knowingly and willfully employing valuation and itemization rules that generate misleading reports without fully exposing themselves to penalties their clients face for hiding adverse information. It is ironic that what are called accounting “ethics” fail to embrace the profession's common‐law duty of assuring the economic meaningfulness of the statements that clients pay it to endorse.
Quinacrine sterilization (QS): the ethical issues
Authors: Bhattacharyya S.
Published: December 2003

QS has generated debates that are ultimately grounded in various principles, norms, and values. Through a careful analysis of opposing arguments, this paper focuses on two ethical principles claimed by both sides, namely: respect for life and beneficence. Though issues surrounding QS are complex, from the common ground of these two principles, this paper proposes a course of action that addresses many of the concerns from both points of view.
A comparison of quinacrine sterilization (QS) and surgical sterilization (TL) in 600 women in Guizhou Province, China
Authors: Lu W. , Zhu J. , Zhong C. , Zhao Y.
Published: December 2003

Objectives: Compare the safety and efficacy of quinacrine sterilization (QS) and surgical sterilization, also known as tubal ligation (TL). Methods: 300 women accepted QS in Guiyang, China during the period from July 1995 to September 1997. Each patient was scheduled for follow‐up at 3, 6, 12 and 24 months. In March 1998, a comparison group of 300 women electing TL during the same time period was systematically chosen. Researchers visited the village of every woman and conducted a structured interview. Each candidate was given a general health and pelvic exam at a clinic in her village. All interviews and exams were completed in August 1998. Results: Of the 289 QS patients interviewed (a follow‐up rate of 96.3%), 265 had had 2 insertions. There were 3 pregnancy failures for a cumulative life table failure rate of 1.2 per 100 women at 24 months. The 299 TL patients (a follow‐up rate of 99.7%) had a similar rate of 0.7. There were no life‐threatening side effects or deaths in either group. QS was less disruptive, more easily tolerated, required fewer resources and was viewed more favorably than TL by women and their spouses. Conclusions: Both methods were found safe and very effective. However, QS was considered to be more acceptable than TL.
Quinacrine sterilization (QS) among high‐risk women: a study of 134 cases
Authors: Sarin A.R. , Sarin R.K.
Published: December 2003

Objective: To determine if quinacrine sterilization (QS) is safe and effective in women at high risk for surgery. Methods: A trial was initiated at the Government Medical College in Patiala, India, in December 1993. Patient intake was terminated in July 1999 and the cut‐off date for this analysis was March 31, 2003. Using a modified IUD inserter, seven 252 mg quinacrine pellets with 50 mg of diclofenac were transcervically inserted into the uterus. DMPA 150 mg was administered IM at the time of the first insertion as a back‐up contraceptive. This same combination was inserted a month later. A total of 134 women underwent QS. Of these, 92 were considered to be at high risk for surgery, 27 were afraid of surgery or voluntarily opted for QS, and 15 had failed surgical sterilization or surgery was found not to be technically feasible. Follow‐up was scheduled for 1, 3, 6 and 12 months, and then annually after the second insertion or whenever side effects or complications were experienced. Results: Mean follow‐up was 7.2 years. No pregnancies or serious complications were experienced. Conclusions: QS is a safe and effective option for women at high risk of surgical complications.
Hysteroscopic and hysterosalpingographic study after intrauterine insertion of quinacrine pellets for non‐surgical sterilization: results in 180 women
Authors: El Sahwi S. , Kamel M. , El Faham M. , El Makhzangy I.
Published: December 2003

Objectives: Document the effects on the tube and uterus of one, two and three doses of 252 mg of quinacrine. Method: The study included 180 fertile women seeking permanent contraception at the Shatby Family Planning Clinic in Alexandria, Egypt, in 1988. All cases received three applications of seven 36 mg quinacrine hydrochloride pellets during the proliferative phase of three consecutive menstrual cycles. The patients were randomly divided into groups A, B and C. Hysterosalpingography (HSG) was performed on the 6th day of menstruation and hysteroscopy on the 10th day of the same cycle after the first application in group A, the second, in group B and the third, in group C. The study was concluded in 1999. Results: HSG showed 52 cases of bilateral obstruction, four of bilateral patency, and four of unilateral patency in group A. All in groups B and C elicited bilateral tubal obstruction. Cornual obstruction was seen in 33%, 65% and 85% in group A, B and C, respectively. Intramural obstruction was found in 50%, 33% and 10% in the three groups. Isthmic tubal obstruction was detected in 8%, 2.5% and 5% in groups A, B and C, respectively. Four types of ostial appearances could be recognized hysteroscopically. Type 0 (patent tubes), Type I (distal tubal blockage), Type II (intramural obstruction) and Type III (cornual obstruction). In group A, Type 0 was evident in 10%, Type I in 8%, Type II in 50% and Type III in 33% of cases. The respective figures in group B were 0%, 2.5%, 33% and 65%, while in group C, they were 0%, 5%, 10% and 85%. Hysteroscopy showed no abnormal endometrial findings in group A, but 35% and 85% of cases in group B and C showed some changes. Conclusions: Two applications of quinacrine were 100% effective. The side effects of quinacrine pellet applications were minimal and well tolerated by all the users. The possibility of reversal of the procedure is outlined.
Female sterilization with quinacrine using hysterosalpingography (HSG) as an endpoint after a single‐insertion protocol in Caracas, Venezuela
Authors: Giugni Chalbaud A. , Plaza Mora G.
Published: December 2003

Objective: To evaluate the intrauterine insertion of quinacrine as an alternative nonsurgical female sterilization method by confirming bilateral occlusion of the fallopian tubes using HSG in a group of women who desire permanent sterilization. Methods: After doing hysterosalpingography to confirm patency of both fallopian tubes, 324 mg of quinacrine were introduced with a modified IUD inserter in 30 patients who came to Conceptión Palacios Maternity Hospital seeking permanent sterilization, between June 2000 and September 2001. Follow‐up with HSG was done 3 months later to verify occlusion of the fallopian tubes. Results: 26 of 30 patients (86%) had bilateral tubal occlusion as determined by HSG. There were minor side effects such as: pain (66.7%), yellow discharge (100%) and menstrual abnormalities (13.3%). One woman became pregnant after HSG showed bilateral occlusion. HSG may interfere with the action of the quinacrine. Conclusion: QS is a simple and safe alternative to surgical sterilization with few side effects.
Quinacrine sterilization in Libya: 200 cases
Authors: El Mahaishi M.S. , Azzidani A.M.
Published: December 2003

Objective: Document the safety, effectiveness and acceptability of quinacrine sterilization (QS) as an alternative to surgical sterilization in Libyan women. Methods: This study was initiated 1 October 1998 at the Misurata Central Hospital and Lamis Clinic. Patient intake was completed 30 September 2002. The cut‐off date for this analysis was 31 December 2002. A total of 200 women were given 2 doses, each consisting of 252 mg of quinacrine hydrochloride in the form of 7 pellets inserted one month apart. They were placed at the uterine fundus during the proliferative phase of the menstrual cycle using a modified IUD inserter. Women were asked to report any unusual observations or side effects and instructed to use a barrier method or safe period for one month from the time of the first insertion. Follow‐up was scheduled at 3, 6 and 12 months after the date of the second insertion and every 6 months thereafter. Results: Sixty‐six women have been monitored for up to 3 years and follow‐up of all patients continues. There has been no loss to follow‐up. No side effects of any consequence have been reported. Thus far, no pregnancies have been reported for this protocol. Conclusions: Findings in this study are consistent with those seen in other countries. QS has been shown to be safe, effective and acceptable among Libyan women.
Quinacrine sterilization (QS) in Costa Rica: 694 cases
Authors: Alpizar F.
Published: December 2003

Objectives: To evaluate the safety, efficacy and acceptability of quinacrine sterilization (QS) in Costa Rica. Methods: From 1989 though August 1993, 694 women volunteered for QS in my private practice. All were referred by a family planning clinic or a local hospital obstetric service. The protocol used involved the transcervical insertion of 216 mg of quinacrine hydrochloride in the form of 6 pellets. A second dose was given 4 weeks later. All insertions were done in the first 14 days of the menstrual cycle. The procedure was similar to the CuT IUD placement. Temporary contraception was recommended for 3 months after the last insertion. The cut‐off date for this analysis was April 1994. Results: With 7 months to 5 years of follow‐up, the gross pregnancy rate was 2.5%. Side effects were relatively minor, none requiring hospitalization. Conclusion: QS was found to be safe, effective and acceptable.
Cryptosporidium parvum: infectivity and pathogenicity of the ‘porcine’ genotype
Authors: ENEMARK H. L. , AHRENS P. , BILLE-HANSEN V. , HEEGAARD P. M. H. , VIGRE H. , THAMSBORG S. M. , LIND P.
Published: December 2003

Genetic studies have demonstrated profound differences between the ‘porcine’ genotype of Cryptosporidium parvum, versus ‘human’ and ‘bovine’ genotypes. The study analysed infectivity and pathogenicity of the ‘porcine’ genotype (CPP-13 isolate) of C. parvum, and compared the results with published data on the ‘bovine’ genotype (CPB-0 isolate). This was investigated in calves and piglets from commercial herds. Piglets were mildly affected by the CPP-13 isolate, contrary to piglets infected with the CPB-0 isolate, which caused diarrhoea of a mean duration of 3·5 days. CPP-13 produced no or very mild clinical signs in piglets despite the excretion of high numbers of oocysts. Concomitant infection with rotavirus, however, caused a dramatic aggravation of the clinical signs, and 5 of 6 experimentally infected piglets died. CPP-13 appeared to be adapted to porcine hosts as illustrated by the lack of infectivity to 1 experimentally inoculated calf, and the absence of clinical signs, the long pre-patent period (15 days), and the excretion of very low numbers of oocysts following experimental infection of another calf. Thus, in accordance with other molecular studies, our results support the genetic evidence for the existence of a new species of Cryptosporidium adapted to pigs.
Expressed sequence tag survey of gene expression in the scab mite Psoroptes ovis – allergens, proteases and free-radical scavengers
Authors: KENYON F. , WELSH M. , PARKINSON J. , WHITTON C. , BLAXTER M. L. , KNOX D. P.
Published: December 2003

Psoroptes ovis, the causative agent of sheep scab, is an important ectoparasitic mite infecting sheep, goats and cattle. Infection is characterized by an extensive dermatitis, scab formation and intense itching. Initial focal lesions spread outwards, coalesce and may extend over the whole body. The host response to infestation has all the characteristics of an immediate-type hypersensitivity reaction but the mite antigens and allergens which initiate this response are almost completely undefined. Here, 507 randomly selected cDNAs derived from a mixed population of P. ovis were sequenced and the resultant nucleotide sequences subjected to Cluster analysis and Blast searches. This analysis yielded 280 clusters of which 49 had >1 sequence with 24 showing significant Blast X homology to another protein in the databases. There were 231 sequences which appeared on one occasion and 109 of these showed significant Blast X homology to other sequences in the databases. This analysis identified homologues of 9 different types of allergens which have been characterized in other allergic conditions such as responses to house dust mites. It also identified a number of cysteine proteases which may contribute to lesion development as well as several free-radical scavenging enzymes which may protect the mite from host immune effector responses.
Patterns of the tapeworm Raillietina trapezoides infection in the fat sand rat Psammomys obesus in Tunisia: season, climatic conditions, host age and crowding effects
Authors: FICHET-CALVET E. , WANG JUEFEI , JOMÂA I. , BEN ISMAIL R. , ASHFORD R. W.
Published: December 2003

The tapeworm Raillietina trapezoides was studied in a Tunisian population of the fat sand rat Psammomys obesus. Seasonal changes in the abundance of parasite and host were monitored in a longitudinal field survey lasting 20 months. In total 582 intestinal samples were collected during 10 trapping sessions between May 1995 and January 1997 and examined. The impact of abiotic and biotic factors on the prevalence and parasite burden were explored, using generalized linear models. R. trapezoides showed a seasonal pattern with most transmission occurring in summer and autumn. In August–September when the rodents were at low density and most adult (90–100%) were infected. In winter, infections with R. trapezoides were highly prevalent in the cohort of adults only. The worm burden by number was also high in late summer and autumn. Prevalence and parasite burden by number or by biomass were highly age dependent. Season and age act in synergy so that the rodents were highly infected in late summer and autumn. Unusually dry conditions in winter seemed to increase prevalence and to reduce the number of worms. There was no difference between males and females in prevalence or parasite burden (by number or by biomass). Prevalence was not correlated with the relative density of the hosts whereas parasite burden depended upon their densities. The more numerous the worms were, the smaller they were individually, reflecting a crowding effect. The possibility of an immune response regulating P. obesus is discussed, in regard to the very high natural prevalence and the variation in worm burden, and compared with other parasite–host systems.
Genetic variation within and among infrapopulations of the marine digenetic trematode Lecithochirium fusiforme
Authors: VILAS R. , PANIAGUA E. , SANMARTÍN M. L.
Published: December 2003

Allozyme markers were used to study genetic variation in Lecithochirium fusiforme within a natural population of Conger conger. Six of 16 enzyme-coding loci studied were found to be polymorphic. These loci were surveyed in 12 infrapopulations of adult flukes. High levels of genetic variation were detected (P=0·375); Ho=0·048; He=0·085). However, the population did not conform to Hardy-Weinberg expectations, as it showed a significant deficit of heterozygotes. L. fusiforme also exhibited low differentiation between infrapopulations (FST=0·064). Despite significant linkage disequilibrium at Pgm-1 and Pgm-2 (P<0·05), mating system does not appear to be the principal reason for the deficit of heterozygotes detected, because some polymorphic loci were in Hardy-Weinberg equilibrium. Association between FIS and FST statistics suggests the existence of the Wahlund effect. However, all infrapopulations showed a strong deficit of heterozygotes for most polymorphic loci (FIS=0·409). Detection of significant genetic differentiation among temporal samples and the existence of paratenic hosts in the life-cycle suggests the Wahlund effect, caused by the mixture of genetically distinct temporal samples in the infrapopulations. Occasional temporal gene flow also might explain the high estimated genetic polymorphism.
Description of a tandem repeated DNA sequence of Echinostoma caproni and methods for its detection in snail and plankton samples
Authors: HERTEL J. , HABERL B. , HAMBURGER J. , HAAS W.
Published: December 2003

Echinostome larval stages in the snail have a great potential as effective competitors for the control of schistosomes and adult worms can cause painful intestinal diseases in humans. Ecology and transmission of the larval stages of trematodes are poorly understood, especially because their identification in field-collected samples by microscopy is difficult. We cloned, sequenced and analysed a 192 bp tandem repreated DNA sequence of Echinostoma caproni (EcSau3A), an often discussed antagonist of Schistosoma mansoni in Biomphalaria snails. PCR primers against this sequence can detect less than 10 fg of E. caproni DNA, 2 miracidia in snails 1 day p.i., 1 metacercaria in 50 mg snail tissue and 1 cercaria in 50 mg plankton with high specificity. Methods described in this study can support the discovery of fundamental ecological principles on distribution, host specificity and epidemiology of E. caproni larvae under field conditions.
An experimental study of the reproductive success of Echinostoma friedi (Trematoda: Echinostomatidae) in the golden hamster
Authors: TOLEDO R. , ESPERT A. , CARPENA I. , MUÑOZ-ANTOLI C. , ESTEBAN J. G.
Published: December 2003

Viable eggs produced weekly per infective stage was used as a measure of the reproductive success of Echinostoma friedi during the first 12 weeks of infection in hamsters. The weekly reproductive success was not constant during the experiment in relation to the egg output and the proportion of viable eggs produced. The egg release started during week 2 post-inoculation, attaining a maximum during week 3. A decline in egg output was observed from week 9. Viable eggs were only produced from week 3 post-inoculation and a maximum was attained at week 4 of the experiment. A decline in egg viability was observed from week 9. Considering together the egg output and the egg viability, the maximum weekly reproductive success was obtained during week 4 post-inoculation. The changes in the weekly reproductive success were not reflected in variations in worm numbers and body sizes during the course of the infection. The humoral immune response of golden hamsters during the infection with E. friedi was determined. Increases of IgG levels against somatic and excretory/secretory products of E. friedi were detected coinciding with the reduction in the reproductive success.
Verkehrsmedizinische Aspekte im Alter
Authors: Becker Susanne , Albrecht Martina
Published: December 2003

Zusammenfassung: Bei jeder Form der Verkehrsteilnahme besteht ein gewisses Unfallrisiko, das in verschiedenen Lebensphasen durch unterschiedliche Faktoren bestimmt wird. Im Alter sind dies besonders biologisch und medizinisch determinierte Faktoren. Das Alter ist jedoch auch eine Lebensphase, die durch große interindividuelle Unterschiede charakterisiert ist. Daher stellt ein hohes Lebensalter alleine keinen berechtigten Grund für Zweifel an der Fahreignung dar. Fahreignung und Fahrtüchtigkeit sind dennoch wichtige Aspekte bei der Verkehrsteilnahme dieser Altersgruppe. Ihre sachgerechte Einschätzung durch den Kraftfahrer selbst und auch durch den behandelnden Arzt ist eine Voraussetzung für Verkehrssicherheit im Alter. Ein wesentliches Ziel verkehrsmedizinischer Aufklärungsarbeit im Alter besteht darin, das Verantwortungsbewusstsein der Senioren im Hinblick auf eine kritische Selbstkontrolle zu stärken. Hierzu müssen die Kompetenz der betreuenden Hausärzte im Hinblick auf Verkehrssicherheitsfragen ausgebaut und Kenntnisse über gesetzliche Regelungen vermittelt werden. Relevante verkehrsmedizinische Aspekte des Alters werden dargestellt, wobei auf die Rolle des Arztes im Rahmen einer sachgerechten Beratung eingegangen wird. Wichtige Bestimmungen im Fahrerlaubnisrecht werden erläutert und die einschlägige Rechtsprechung im Hinblick auf die Pflicht zur kritischen Selbstprüfung der Fahrtüchtigkeit wird dargelegt.
Zur Bedeutung von Aktivität und Mobilität für die Entwicklung im Alter
Authors: Engeln Arnd
Published: December 2003

Zusammenfassung: In dem Artikel werden die komplexen Zusammenhänge zwischen funktionalem Alter, individuellen Anpassungskompetenzen, der Mobilität, den Aktivitäten außer Haus und der Lebenszufriedenheit bzw. -qualität betrachtet. Mit Hilfe empirischer Daten des Forschungsprojektes ANBINDUNG kann gezeigt werden, dass die genannten Aspekte mit unterschiedlichen Entwicklungen im Alter in Zusammenhang gebracht werden können. Die multidimensionale Verknüpfung der Einflussfaktoren belegt, dass Interventionen auf unterschiedlichen Ebenen den Alternsprozess erfolgreich stützen können.
Differentialpsychologisch-gerontologische Anmerkungen zur Verkehrssicherheitsarbeit mit Älteren
Authors: Kaiser H.J.
Published: December 2003

Zusammenfassung: Verkehrssicherheitsmaßnahmen wenden sich üblicherweise an bestimmte Zielgruppen, von denen man weiß, dass sie in spezifischer Weise zum Gesamtrisiko des Straßenverkehrs beitragen. Eine Veränderung dieser Spezifika stellt das Ziel von zielgruppenorientierten Verkehrssicherheitsmaßnahmen dar. Der Erfolg der Maßnahmen hängt allerdings davon ab, ob die jeweiligen Zielgruppen auch erreicht werden, was nicht nur ein Problem der eingesetzten Methoden oder Zugangsweisen ist. Die Maßnahmen müssen inhaltlich auch auf einem zutreffenden Bild der Zielgruppenmitglieder beruhen, sie dürfen nicht an deren Charakteristika “vorbeikonstruiert” werden. Was ältere Menschen als Zielgruppe angeht, weiß man, dass sie diesbezüglich eine sehr inhomogene Gruppe bilden. Man sollte deshalb eine Binnendifferenzierung vornehmen, z.B. nach Leistungsstand, Gesundheitsstatus, bestimmten Persönlichkeitsmerkmalen und Handlungsorientierungen. Zur Differenzierung brauchbar sind außerdem die Erkenntnisse der verschiedenen Disziplinen der Gerontologie. Gerontosoziologische, gerontopsychologische oder geragogische Erkenntnisse beispielsweise geben wertvolle Hinweise darauf, auf welchem Weg welche Teilgruppe angesprochen werden kann.
Juristische Aspekte der Verkehrsteilnahme älterer Menschen
Authors: Greißinger Georg
Published: December 2003

Zusammenfassung: Der Beitrag definiert vorab die Begriffe “ältere Menschen”, “Verkehrsteilnahme” und “juristische Aspekte”. Er befasst sich dann mit der bestehenden Gesetzeslage - Straßenverkehrsordnung, Strafrecht, Fahrerlaubnisrecht, Haftungsrecht -, dies ausgehend davon, dass das geltende Recht nur wenige konkrete Vorschriften kennt, in denen “ältere Menschen” im Wortsinn erwähnt oder durch entsprechende Begriffe, z.B. Senioren oder durch Benennung eines bestimmten Lebensalters, bezeichnet werden. Die demographischen Aspekte belegen, dass ältere Verkehrsteilnehmer gegenwärtig und verstärkt zukünftig bedeutsam sind. Es gibt zwar typische Unfallursachen älterer Autofahrer (Reaktionsverzögerung, schlechtes Sehvermögen, Unaufmerksamkeit, zu langsames Fahren), doch sind sie gegenüber Jüngeren weder als Opfer noch als Täter eine herausragende Gruppe. Im Ergebnis wird letztlich festgestellt, das kein Anlass besteht, Sonderregelungen für ältere Verkehrsteilnehmer zu treffen. Das vorhandene Instrumentarium ist ausreichend.
Simulation of carbon pathways in the planktonic ecosystem off Peru during the 1997–1998 El Niño and La Niña
Authors: Carr Mary‐Elena
Published: December 2003

A numerical model is used to quantify the pathways of carbon flow through the planktonic ecosystem from 1996 through 1998 at 9.5°S off the coast of Peru. The objective was to evaluate the response of the planktonic ecosystem to the forcing associated with normal conditions in 1996, the 1997–1998 El Niño, and the La Niña which began in June of 1998. During El Niño, the depth of the upper layer increased, temperature increased, and the nitrate concentration in the source water for upwelling was reduced. La Niña forcing was the opposite. The simulated phytoplankton biomass, carbon uptake, vertical export, and food available for higher trophic levels were reduced during the El Niño period compared to normal conditions. Phytoplankton biomass and uptake were slightly less during La Niña than in 1996, though carbon export and advective loss were significantly enhanced. A series of numerical experiments were run to determine whether the upwelling rate, source water characteristics, depth of the upper layer, or phytoplankton size composition of the source water was the primary forcing factor for the planktonic community. Although all factors contributed to the magnitude of the simulated response, the primary determinant for El Niño conditions was the concentration of new nitrogen in the upwelling source water, followed by depth of the upper layer and upwelling rate. The depth of the upper layer was the dominant forcing term for La Niña, followed by upwelling rate and temperature of the source water.
Microbial community abundance and biomass along a 180° transect in the equatorial Pacific during an El Niño‐Southern Oscillation cold phase
Authors: Brown Susan L. , Landry Michael R. , Neveux Jacques , Dupouy Cécile
Published: December 2003

As part of the French Joint Global Ocean Flux Study Etude du Broutage en Zone Equatoriale program, we investigated the distributions of microorganisms (bacteria and protists <200 μm) in the upper 120 m of the equatorial Pacific from 8°S to 8°N, along 180°. Population distributions, determined by a combination of flow cytometry, microscopy and spectrofluorometry, were closely related to physical features across the study site. Phytoplankton biomass, ranging from 1.2 to 34.2 μg C L−1 and averaging 15.5 μg C L−1, was most enhanced in the divergence zone. Carbon to chlorophyll ratios were also enhanced in the divergence zone and showed distinct latitudinal variations. Heterotrophic biomass, excluding ciliates, was patchy across the area, ranging from 5 to 36 μg C L−1 and averaging 13 μg C L−1. Prokaryotic species (Prochlorococcus spp., Synechococcus spp., and heterotrophic bacteria) showed similar patterns of abundance, with the main feature being their distributional asymmetry to the south of the equator. Both autotrophic and heterotrophic biomass were enriched in the convergent zone at 4°–5°N between the South Equatorial Current and the North Equatorial Counter Current. Heterotrophic biomass exceeded phytoplankton biomass in the more nutrient‐impoverished waters to the north and in the branch of a tropical instability wave eddy. Microplankton represented only a small portion of the total autotrophic carbon and was comprised mostly of dinoflagellates. Large species dominated the relatively modest diatom biomass. Food web interactions and biogeochemical fluxes in the central equatorial Pacific may be significantly influenced by temporal and spatial variability of the microbial community associated with physical features of the region.
Primary production, new production, and growth rate in the equatorial Pacific: Changes from mesotrophic to oligotrophic regime
Authors: Le Bouteiller Aubert , Leynaert Aude , Landry Michael R. , Le Borgne Robert , Neveux Jacques , Rodier Martine , Blanchot Jean , Brown Susan L.
Published: December 2003

Under an apparent monotony characterized by low phytoplankton biomass and production, the Pacific equatorial system may hide great latitudinal differences in plankton dynamics. On the basis of 13 experiments conducted along the 180° meridian (8°S–8°N) from upwelled to oligotrophic waters, primary production was strongly correlated to chlorophyll a (chl a), and the productivity index PI (chl a‐normalized production rate) varied independently of macronutrient concentrations. Rates of total (14C uptake) and new (15N‐NO3 uptake) primary production were measured in situ at 3°S in nutrient‐rich advected waters and at 0° where the upwelling velocity was expected to be maximal. Primary production was slightly higher at the equator, but productivity index profiles were identical. Despite similar NO3 concentrations, new production rates were 2.6 times higher at 0° than at 3°S, in agreement with much higher concentrations of biogenic particulate silica and silicic acid uptake rates (32Si method) at the equator. Furthermore, phytoplankton carbon concentrations from flow cytometric and microscopical analyses were used with pigment and production values to assess C:chl a ratios and instantaneous growth rates (μ). Growth rates in the water column were significantly higher, and C:chl a ratios lower at 0° than at 3°S, which is consistent with the more proximate position of the equatorial station to the source of new iron upwelling into the euphotic zone. For the transect as a whole, compensatory (inverse) changes of C:chl a and μ in response to varying growth conditions appear to maintain a high and relatively invariant PI throughout the equatorial region, from high‐nutrient to oligotrophic waters.
Present‐day lithospheric strength of the Eastern Alps and its relationship to neotectonics
Authors: Willingshofer Ernst , Cloetingh Sierd
Published: December 2003

We calculate the present‐day lithospheric strength of the Eastern Alps along the new reflection seismic profile TRANSALP to examine vertical and lateral strength variations and their implications on neotectonic activity of the Eastern Alps. The large‐scale geometry of the Eastern Alps and the spatial distribution of upper, and lower crustal layers, and the lithospheric mantle is constrained by the deep seismic line. Two rheological models, coupled to a kinematic thermal model that accounts for the thermal evolution of the Eastern Alps for the last 30 Myr, are investigated for the present‐day lithospheric configuration in the Eastern Alps. Models with strong (Model A) and weak (Model B) crustal rheologies predict the European and the Adriatic plates to be stronger than the central zone of the orogen comprising the region between the Inntal Fault and the Periadriatic Fault. Model A is characterized by a brittle‐ductile boundary between 14 and 9 km depth and strong coupling of the mechanically strong lower crust to the upper mantle, whereas Model B suggests the presence of a thick decoupling zone between the upper crust and the upper mantle and a shallower brittle‐ductile boundary (7–10 km). Of these end‐member scenarios, Model A is in better agreement with neotectonic data including seismicity down to the upper‐lower crust boundary within the Adriatic plate, uplift of the central zone of the Eastern Alps and the Southern Alps, and eastward escape of fault‐bound blocks. Such deformation pattern is best explained by lateral extrusion upon north‐south compression supporting a strong‐weak‐strong configuration of tectonic units along the TRANSALP line.
A multiresolution index of valley bottom flatness for mapping depositional areas
Authors: Gallant John C. , Dowling Trevor I.
Published: December 2003

Valley bottoms function as hydrological buffers that significantly affect runoff behavior. Distinguishing valley bottoms from hillslopes is an important first step in identifying and characterizing sediment deposits for hydrologic and geomorphic purposes. Valley bottoms occur at a range of scales from a few meters to hundreds of kilometers in extent. This paper describes an algorithm for using digital elevation models to identify valley bottoms based on their topographic signature as flat low‐lying areas. The algorithm operates at a range of scales and combines the results at different scales into a single multiresolution index. This index classifies degrees of valley bottom flatness, which may be related to depth of deposit. The index can also be used to identify groundwater constrictions and to delineate hydrologic and geomorphic units.
Do volcanic eruptions enhance or diminish net primary production? Evidence from tree rings
Authors: Krakauer Nir Y. , Randerson James T.
Published: December 2003

Low growth rates of atmospheric CO2 were observed following the 1991 Pinatubo (Luzon) volcanic eruption. One hypothesis for this CO2 anomaly is that since diffuse light is more efficiently used by forests than direct light, the increase in the diffuse fraction of sunlight due to scattering by volcanic sulfur aerosol in the years following the eruption substantially increased forest net primary production (NPP). However, other observations suggest a decrease in northern forest NPP because of the cooler conditions following the eruption. Here we used a global database of dated tree ring widths (which correlate with forest NPP) to test this hypothesis. Ice core records of sulfur deposition allowed us to identify the timing and magnitude of 23 Pinatubo‐scale eruptions since 1000 CE. We found a significant decrease in ring width for trees in middle to high northern latitudes (north of 45°N) following eruption sulfur peaks. Decreases in tree ring widths were in the range of 2–8% and persisted for ∼8 years following sulfur peaks, with minima at around 4–6 years. Ring width changes at lower latitudes in the Northern Hemisphere (30°N to 45°N) and in the Southern Hemisphere (30°S to 56°S) were not significant. In the tropics (30°N to 30°S) the paucity of tree ring records did not permit the evaluation of NPP changes. Given that elevated aerosol levels and summer cooling last only ∼2–3 years after an eruption, the persistence of declines in northern tree growth for up to 8 years after eruptions implies some additional mechanism that links these shorter‐lived global eruption effects to sustained changes in tree physiology, biogeochemistry, or microclimate. At least for this sample of trees, the beneficial effect of aerosol light scattering appears to be entirely offset by the deleterious effect of eruption‐induced climate change.
Observations on the evolution of tidal vorticity at a stratified deep water headland
Authors: Pawlak G. , MacCready P. , Edwards K. A. , McCabe R.
Published: December 2003

The lifespan of a barotropic tidal eddy generated by flow around a coastal headland in deep (∼200 m) stratified water is examined. Field observations recorded the evolution of the flood tide eddy from its generation, through the eddy release at the turn of the tide, until its dissipation during subsequent tidal cycles. Ship‐based acoustic profiling reveals vortical structure that extends throughout the flow depth. Tracks from subsurface drifters from successive days indicated that flow structure was repeatable. Vorticity decay times, estimated from combined set of drifter tracks, are less than a tidal period. These are significantly shorter than simple estimates using boundary friction would imply, and it is suggested that baroclinic mechanisms associated with tilted vorticity in the deep stratified flow over the sloping headland may play a significant role in the dissipation of vorticity.
Modelling the depth of penetration of the wind's momentum at super‐inertial frequencies due to non‐linear effects in frontal regions
Authors: Xing Jiuxing , Davies Alan M.
Published: December 2003

A numerical model with a coast and density front is used to examine the influence of the front upon the depth of penetration of the wind's momentum. We find that non‐linear processes associated with spatial variations in vorticity play an important role in driving wind‐induced currents at depth. Internal wave generation and propagation also occur in the frontal region. For a bottom front, the downward propagation of internal waves in the frontal region is inhibited by the presence of sloping isotherms and a region of enhanced current magnitude develops at depth at the front's edge on the stratified side. For a surface front the presence of enhanced surface vorticity on the well mixed side of the front, means that the wind's energy is trapped in the surface layer. These calculations help to explaining the large spatial variability of wind forced energy found in observations.
Landslide basal friction as measured by seismic waves
Authors: Brodsky Emily E. , Gordeev Evgenii , Kanamori Hiroo
Published: December 2003

Dynamical predictions of landslide runout require measurements of the basal friction. Here we present the first seismically determined bounds on the frictional coefficients for three large volcanic landslides. The three landslides (Bezymianny, Russia 1956, Sheveluch, Russia 1964 and Mount St. Helens, USA 1980) have masses that vary by a factor of 5 and were all followed immediately by eruptions. We use teleseismic and regional seismic data to show that all three landslides are consistent with an apparent coefficient of friction of 0.2 which corresponds to an actual areally‐averaged frictional coefficient of 0.2–0.6. The apparent friction is independent of the quantity of hot gas subsequently released.
Ion cyclotron waves in the high altitude cusp: CLUSTER observations at varying spacecraft separations
Authors: Nykyri K. , Cargill P. J. , Lucek E. A. , Horbury T. S. , Balogh A. , Lavraud B. , Dandouras I. , Rème H.
Published: December 2003

We have analysed high‐resolution Cluster magnetic field data during three high‐altitude cusp crossings in 2001 and 2002. The Cluster separations for these crossings varied between 100 and 600 km and therefore provided an unique opportunity to study wave properties at different length scales. In the cusp Cluster sees frequent intervals of magnetic field fluctuations with clear peaks in power close to the local ion cyclotron frequency, and both left‐ and right‐handed polarisations. At large separations the power seen at different spacecraft can differ by orders of magnitude. For smaller separations, the power seen at the four spacecraft agrees better but still shows some differences. For all separations there was no significant correlation between the signals seen at different spacecraft, indicative of very local structure. The origin of the waves appears to lie in highly filamented sheared plasma flows present in the cusp.
The seismic cycle and the difference between foreshocks and aftershocks in a mechanical fault model
Authors: Ziv A. , Schmittbuhl J.
Published: December 2003

We examine the evolution of and the exchange between two forms of elastic energies stored in the quasi‐static fault model of Ziv and Rubin [2003]. The first, Etect, is due to the integrated slip deficit accumulated between the plate boundaries and the fault surface, and the second, Efault, is the result of differential slip along the fault surface. The results of our analysis reveal cyclic exchange between the two energies. On a Efault versus Etect plot, the seismic cycle has a triangular shape with the large earthquakes occurring at the top corner of the triangle (where Efault is maximum), and the foreshocks and the aftershocks occupying the right side and left side, respectively. While both foreshocks and aftershocks dissipate tectonic energies, the cumulative effect of the foreshocks is to increase the potential elastic energy along the fault plane and the cumulative effect of the aftershocks is to reduce it.
Opal‐A/opal‐CT phase boundary inferred from bottom‐simulating reflectors in the southern South Korea Plateau, East Sea (Sea of Japan)
Authors: Lee Gwang Hoon , Kim Han‐Joon , Jou Hyeong‐Tae , Cho Hyun‐Moo
Published: December 2003

Multi‐channel seismic reflection profiles from the trough areas of the southern South Korea Plateau, East Sea (Sea of Japan), reveal high‐amplitude, positive‐polarity bottom‐simulating reflectors (BSRs) at about 500 ms two‐way travel time (ca. 450 m) below the seafloor. The positive polarity and no noticeable drop of frequency (low‐frequency shadow) below the BSR strongly suggest that the BSR is due to an opal‐A/opal‐CT phase boundary. The BSR often marks a sharp interface between low‐amplitude reflections above and high‐amplitude reflections below. The weak, but distinct reverse‐polarity event, seen 70–150 ms two‐way travel time below the BSR, may represent the base of the silica diagenetic zone. The geothermal gradients (78–111°C/km) estimated from the sub‐bottom depth of the BSR are comparable to that (98°C/km) measured at the nearby Kita‐Yamato Trough, where the opal‐A/opal‐CT boundary has been penetrated by the Ocean Drilling Program (ODP) drilling.
Observational evidence of new current sheets trailing coronal mass ejections
Authors: Webb D. F. , Burkepile J. , Forbes T. G. , Riley P.
Published: December 2003

Field line reconnection in the wake of coronal mass ejections (CMEs) is a fundamental aspect of some magnetically driven eruptive flare/CME models, e.g., the standard reconnection model [cf. Svestka and Cliver, 1992]. This model features a growing hot loop arcade beneath a rising X‐type neutral point that is connected to the retreating CME. In models invoking reconnection the rising CME and neutral point are connected by a stretched current sheet. Two recent models, Lin and Forbes [2000] and Linker et al. [2003], predict that an extended, long‐lived current sheet must be formed for any physically plausible reconnection rate. Lin and Forbes derive estimates for heights or lengths of current sheets and the energy input as functions of time. In a previous observational study of SMM CMEs observed from 1984–1989 having candidate magnetic disconnection features, primarily transient concave‐outward bright regions following the CME leading edge, we found that about half were followed by coaxial, bright rays suggestive of newly formed current sheets. The rays appeared relatively suddenly several hours after the main CME had left the field of view. In this paper we present the results of analysis of these structures, including their heights and lengths, widths, alignments, and motions, all as functions of time, and show that they are consistent with the existence of current sheets lasting for several hours and extending more than five solar radii into the outer corona.
Three‐dimensional coronal density structure: 1. Model
Authors: Gibson S. E. , Foster D. J. , Guhathakurta M. , Holzer T. , St. Cyr O. C.
Published: December 2003

The three‐dimensional (3‐D) density structure of the solar corona is a fundamental boundary condition on the solar wind. Most easily applied models of the global coronal density have been restricted to date to axisymmetric 2‐D cases. We present here a 3‐D model made up of a superposition of multiple streamers, having distinct gaussian widths in longitude and latitude and both longitudinal and latitudinal dependence of the neutral lines implicit beneath the streamer cores. Nonradiality of streamers and solar B‐angle tilt are also explicitly treated. We show how this simple model can capture many of the general properties of coronal white light observations and demonstrate how such a model can assist in the interpretation of the multiple views on coronal structures such as will be provided by the upcoming STEREO mission.
Analysis of flow variability in the Yucatan Channel
Authors: Abascal A. J. , Sheinbaum J. , Candela J. , Ochoa J. , Badan A.
Published: December 2003

The structure and variability of the velocity and temperature fields in Yucatan Channel are analyzed using data from an eight‐mooring array deployed from August 1999 to June 2000. The area‐averaged kinetic energy and transport fluctuations spectra show that the extrema of these quantities do not coincide, and that flow variability is dominated by highly energetic processes with weak transport contributions. Transport fluctuations peak in the 20–40 and 5–10 day period bands, but show no clear correlation with the local wind‐stress forcing. Empirical orthogonal function (EOF) analysis of the along‐channel velocity component shows that approximately 55% of the total velocity variance is retained in the first two EOFs, which depict tripolar (the center of the channel is out of phase with the sides) and dipolar structures. A multivariate complex EOF analysis of low‐passed temperature and velocity components suggests the tripole‐dipole structures are the components of irregular oscillations of the flow, related to the northwestward propagation of anticyclones and cyclones through the channel. The weak transport signal in these modes is consistent with the eddies being advected by the mean flow. In contrast to other western boundary current regions, the passage of eddies provides the predominant explanation for the variability in the Yucatan Channel. However, the processes controlling transport variability remain unclear.
A year‐long record of size‐segregated aerosol composition at Halley, Antarctica
Authors: Rankin Andrew M. , Wolff Eric W.
Published: December 2003

Size‐segregated aerosol samples were collected with a cascade impactor at 2 week intervals for a year at the research station Halley, situated near the coast in the Weddell Sea region of Antarctica. Sea salt is a major component of aerosol throughout the year, and we estimate that at least 60% of the total sea salt arriving at Halley is from brine and frost flowers on the sea ice surface rather than open water. Chloride in sea‐salt particles is depleted relative to sodium in summer, consistent with loss of HCl as sea‐salt particles react with gaseous acidic species, but is enhanced in large particles in winter because of fractionation occurring during the production of new sea ice. Non‐sea‐salt sulphate peaks in the summer, with the majority being in small particles indicative of a gas phase origin. The distribution of methane sulphonic acid closely follows that of non‐sea‐salt sulphate. In the winter, non‐sea‐salt sulphate is frequently negative, especially on stages collecting large particle sizes, consistent with the source of sea salt during the winter being predominantly the sea ice surface rather than open water. Nitrate peaks in the spring and summer and shows some association with sea‐salt particles.