bluuebunny/crossref_metadata_2025 huggingface dataset:
Two‐fluid model of superconducting condensates and spin gaps in d‐wave high Tc cuprates from repulsive electronic correlations
Authors: Dunne Lawrence J. , Brändas Erkki J.
Published: June 2004

In this review, a model is presented that accounts in a simple way for the existence of the condensate and spin gap in high Tc superconducting cuprates. The finding of many types of high Tc superconducting cuprates occurred more than a decade ago, but the cause of the superconductivity and electronic structure of such materials remains controversial, and there is no broad agreement as to the origin of pairing or of the spin gap. Our view is that these are correlation effects in a weakly doped electronic system with the appropriate alternant C4v symmetry, as found in the layers of high Tc superconducting cuprates. This two‐fluid model can adequately describe much of the essential behavior of these strange materials. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Chelate effect: The importance of reorganization energy
Authors: Davydova E. I. , Sevastianova T. N. , Timoshkin A. Y. , Suvorov A. V. , Frenking G.
Published: June 2004

The chelate effect has been theoretically studied at the Becke's three‐parameter exchange functional and the gradient‐corrected functional of Lee, Yang, and Paar/double‐ζ polarization level of theory. The influence of ligand, metal, and halogen nature on the chelate effect was analyzed for complexes of group 14 element tetrahalides with monodentate and bidentate nitrogen‐containing donors. It is shown that the large reorganization energy of the 2,2′‐bipyridine ligand (≈32 kJ mol‐1) shadows the chelate effect. The same conclusion holds for other ligands, which undergo significant reorganization upon complex formation. 1,10‐Phenanthroline does not have such a large reorganization energy, and its complexes are therefore more stable in the gas phase than are complexes with bipyridine. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Physics: Frightful, but fun. Pupils' and teachers' views of physics and physics teaching
Authors: Angell Carl , Guttersrud Øystein , Henriksen Ellen K. , Isnes Anders
Published: June 2004

There is widespread concern for the situation of school physics regarding recruitment, contents, teaching methods, etc. In this study based on questionnaire and focus group data, we explore how upper secondary pupils and teachers perceive physics as a subject, how they experience physics instruction, and how physics compares to other subjects.

Our study shows that pupils find physics interesting, but difficult and work‐intensive; formalistic in nature, but still describing the world and everyday phenomena. Pupils express that “exoti” topics like astrophysics are closer to their life‐world than mechanics etc. Whereas teachers complain about pupils' poor mathematics skills, pupils do not see this as a major problem. Physics instruction is still dominated by traditional content knowledge and seems to attract and reward pupils with this orientation. Pupils have a relatively weak understanding of the central role of experiments in science. Generally, pupils appear conservative in their views on teaching and learning; however, they would like stronger emphasis on qualitative and pupil‐centred approaches.

Based on our findings, we suggest that an upper secondary physics education preparing pupils for tomorrow's society should be characterized by variety, both within and among courses, integration of mathematics in the physics courses, more pupil‐centred instruction, and a stronger emphasis on knowledge in context. © 2004 Wiley Periodicals, Inc.Sci Ed88:683–706, 2004
Problem‐based learning: Using students' questions to drive knowledge construction
Authors: Chin Christine , Chia Li‐Gek
Published: June 2004

This study employed problem‐based learning for project work in a year 9 biology class. The purpose of the study was to investigate (a) students' inspirations for their self‐generated problems and questions, (b) the kinds of questions that students asked individually and collaboratively, and (c) how students' questions guided them in knowledge construction. Data sources included observation and field notes, students' written documents, audiotapes and videotapes of students working in groups, and student interviews. Sources of inspiration for students' problems and questions included cultural beliefs and folklore; wonderment about information propagated by advertisements and the media; curiosity arising from personal encounters, family members' concerns, or observations of others; and issues arising from previous lessons in the school curriculum. Questions asked individually pertained to validation of common beliefs and misconceptions, basic information, explanations, and imagined scenarios. The findings regarding questions asked collaboratively are presented as two assertions. Assertion 1 maintained that students' course of learning were driven by their questions. Assertion 2 was that the ability to ask the “right'' questions and the extent to which these could be answered, were important in sustaining students' interest in the project. Implications of the findings for instructional practice are discussed. © 2004 Wiley Periodicals, Inc. Sci Ed 88:707–727, 2004
Complete deterministic stream X-machine testing
Authors: Ipate Florentin
Published: June 2004

One of the strengths of using
stream X-machines
to specify a system is that, under certain well defined conditions, it is possible to produce a test set that is guaranteed to determine the correctness of an implementation. However, the existing method assumes that the implementation of each processing function is proved to be correct before the actual testing can take place, so it only test the system
integration
. This paper presents a new method for generating test sets from a deterministic stream X-machine specification that generalises the existing integration testing method. This method no longer requires the implementations of the processing functions to be proved correct prior to the actual testing. Instead, the testing of the processing functions is performed along with the integration testing.
Biliary Atresia Revisited
Authors: Kahn Ellen
Published: June 2004

Extrahepatic biliary atresia (EHBA) is an inflammatory fibrosing process affecting the extrahepatic and intrahepatic biliary tree resulting in fibrous obliteration of the extrahepatic biliary tract, ductopenia of intrahepatic bile ducts, and biliary cirrhosis. EHBA is divided into a correctable and a noncorrectable type with focal patency of the otherwise atretic biliary tree in the former and no patency of the biliary tree in the noncorrectable type. EHBA is divided in a fetal, prenatal or embryonic, and a more common, perinatal, acquired form. The symptoms of the former start shortly after birth and there is frequently an association with a variety of congenital anomalies. Children with the perinatal form become jaundiced several weeks after birth; no associated congenital anomalies are present. Morphologically, an inflammatory and fibrosing process of the extrahepatic biliary tree leads to complete lumenal obliteration. The liver is characterized by a nonspecific giant cell transformation, and portal expansion by fibrous connective tissue with marked ductular proliferation. With time, ductopenia and biliary cirrhosis develop. The diffential diagnosis with other conditions with similar microscopic patterns such as alpha-1 antitrypsin deficiency, total parental nutrition, obstruction by a choledochal cyst, arteriohepatic dysplasia, familial progressive intra-hepatic cholestasis, and alteration of the bile acid metabolism is discussed. In the fetal group, abnormalities in different genes seem to play a role; ductal plate malformation is another possibility. Different etiologies have been postulated in the perinatal form of EHBA: genetic susceptilibility, vascular factors, toxins, and infections mainly by rotavirus and reovirus. The pathogenesis is complex. EHBA is a heterogenous disease, resulting from a combination of genetic factors, insults, and activation of different genetic and immunologic pathways. The treatment of EHBA is surgical, with anastomosis between the biliary tree and the intestine in the correctable type and a hepatic portoenterostomy (HPE) for the noncorrectable group. HPE is a temporizing treatment allowing the infant to develop and grow, followed in the majority of the patients by liver transplantation.
Myogenesis in Wilms' Tumors is Associated with Mutations of the WT1 Gene and Activation of Bcl-2 and the Wnt Signaling Pathway
Authors: Fukuzawa Ryuji , Heathcott Rosemary W. , Sano Makoto , Morison Ian M. , Yun Kankatsu , Reeve Anthony E.
Published: June 2004

Wilms tumors with WT1 mutations [ WT1(—)] have a stromal-predominant histology with varying extents of rhabdomyogenesis. These tumors also frequently have mutations in the beta-catenin gene (CTNNB1). We have investigated the molecular events that may explain the origins of rhabdomyogenesis in WT1(-) tumors. Of 35 Wilms tumors, we identified 12 with WT1 mutations, of which 9 carried CTNNB1 mutations. We compared WT1 wild-type tumors [ WT1(+)] with WT1(-) tumors for histological features, localization of beta-catenin, Bcl-2 expression, and apoptosis using an in-situ end-labeling technique. WT1(+) tumors showed triphasic and blast-emal- and epithelial predominant-histology. Expression of WT1, beta-catenin, and Bcl-2 recapitulated those of normal kidney epithelial development. Localization of beta-catenin was observed in the cytoplasm and cytoplasmic membrane of early glomerular epithelial structures. Bcl-2 is also expressed in condensing blastema and early glomerular epithelial structures which had little apoptosis. WT1(-) tumors, regardless of whether CTNNB1 mutations were detected or not, showed a stromal-rich phenotype with abundant expression of beta-catenin in the nucleus of the rhabdomyoblasts. Bcl-2 was expressed in rhabdomyoblasts, but not in blastemal cells undergoing apoptosis, suggesting that WT1 regulates Bcl-2 positively in the epithelial pathway, but negatively in the myogenic pathway. These data indicate that mutations in WT1 might alter the Wnt signaling pathway and Bcl-2 related-apoptosis. In WT1(-) tumors, the nuclear accumulation of beta-catenin and Bcl-2 expression are associated with rhabdomyogenesis, and dysregulation of Bcl-2 may be a mechanism by which the histogenesis (loss of blastemal component, muscle differentiation) may be explained.
Prognostic Limitations of the Daumas-Duport Grading Scheme in Infratentorial Neuroglial Tumors in Children
Authors: Gilles Floyd H. , Tavaré C. Jane , Leviton Alan , Hedley-Whyte E. Tessa , Sotrel Anna , Adelman Lester , Davis Richard L. , Rorke Lucy B. ,   For The Childhood Brain Tumor Consortium
Published: June 2004

The Daumas-Duport grading scheme (DDGS) utilizes four histologic features in an additive method (grade 1 if none present, grade 2 if only one is present, etc.). Its efficacy in achieving prognostically homogeneous groups of childhood infratentorial neuroglial tumors and its concordance with World Health Organization (WHO) diagnoses has not been evaluated. We investigated these questions using the Childhood Brain Tumor Consortium (CBTC) database of 1241 neuroglial tumors limited to the infratentorial compartment. We calculated survival function estimates for various DDGS grades as well as the histologic features within each grade. The feature of endothelial prominence improved survival expectation, whereas the remaining three features of nuclear atypia, mitoses, and necrosis were associated with worsened survival. Survival estimates for tumors with DDGS grades 2 and 3 did not differ. Some grades contained feature subsets with significantly different survival distributions. The survival distributions of DDGS grade 1, DDGS grade 2 with only endothelial prominence, and DDGS grade 3 with nuclear atypia and endothelial prominence were not significantly different. DDGS grade within WHO diagnoses had no significant effect on survival expectation. We conclude that grading by summation of only four histologic features, as in the DDGS, is inappropriate for assessment of childhood neuroglial tumors. A classification scheme considering the complete histologic content is more likely to provide clinically useful diagnoses. Such a scheme, based on the CBTC database is available. This scheme uses 26 histologic features identified as reliable in read–reread studies.
Increased expression of tumor necrosis factor‐α converting enzyme and tumor necrosis factor‐α in peripheral blood mononuclear cells in patients with advanced congestive heart failure
Authors: Satoh Mamoru , Iwasaka Junji , Nakamura Motoyuki , Akatsu Tomonari , Shimoda Yudai , Hiramori Katsuhiko
Published: May 2004

Background:

Tumor necrosis factor‐α converting enzyme (TACE) has recently been identified as a metalloproteinase‐disintegrin, which converts pro‐tumor necrosis factor‐α (TNF‐α) to the mature form, and is an important mediator in the pathogenesis of CHF.

Aims:

In order to establish the importance of TACE in the regulation of TNF‐α synthesis in peripheral blood mononuclear cells (PBMC), we analyzed mRNAs and protein‐positive cells of both TACE and TNF‐α in PBMC obtained from patients with congestive heart failure (CHF).

Methods and results:

PBMC were obtained from 46 patients with CHF and 22 controls. PBMC were activated by phorbol 12‐myristate 13‐acetate and ionomycin and assessed for TACE and TNF‐α mRNAs by real‐time RT‐PCR, intracellular TACE and TNF‐α levels by flow cytometry, and TNF‐α secretion by supernatant ELISA. Levels of TACE and TNF‐α mRNAs, intracellular TACE and TNF‐α, and supernatant TNF‐α were higher in CHF than in controls (P<0.001). There was a positive correlation between TACE and TNF‐α levels in CHF patients (mRNA: r=0.60, P<0.001, intracellular protein levels: r=0.76, P<0.001). When the CHF group was divided into two subgroups by NYHA functional class (I and II vs. III and IV), levels of TACE and TNF‐α were significantly higher in severe CHF patients (NYHA III or IV) than in mild CHF patients (NYHA I or II) (mRNA: P<0.001; intracellular protein levels: P<0.001).

Conclusion:

These results demonstrate that in patients with CHF, and especially those with severe CHF, TACE expression in PBMC increases with TNF‐α expression. These observations suggest that TACE in PBMC is an important regulator of TNF‐α maturation, meaning that TACE may be a potential target for the inhibition of cellular TNF‐α production in CHF.
Examination of type I/type II alcoholism typology in a Greek hospital treatment population
Authors: Lykouras Lefteris , Moussas George , Botsis Alexander
Published: May 2004

Objective

The study aims at testing the validity of two types of classification of male alcoholism in a Greek hospital treatment sample.

Method

The study population was drawn from male patients with alcohol dependence admitted to the Alcohol Treatment Unit of the Psychiatric Hospital of Attica. Seventy-three patients comprised the study sample after exclusion of subjects with alcohol dependence suffering from a comorbid serious medical condition, schizophrenic disorder, bipolar disorder, drug dependence or abuse, organic mental disorder or inability to read. The alcoholics were grouped in type I and II adopting the criterion of age-of-onset used by von Knorring et al. (1985). Impulsivity, suicide risk and violence risk were measured by means of the impulse control scale (ICS), the suicide risk scale (SRS) and the past feelings and acts of violence scale (PFAVS).

Results

Fifty patients with alcohol dependence were defined as late-onset and 23 as early-onset. Compared to late-onset patients, early-onset individuals with alcohol dependence had more familial alcoholism (P = 0.032); they were in a higher rate unmarried (P = 0.001), had no stable job before entry in the Unit (P = 0.007) and scored higher on ICS (P = 0.046) and SRS (P = 0.024).

Conclusion

The present study confirms type I/type II dichotomy of male alcoholism and also shows that the age-of-onset is a valid classification criterion.
Effect of cortical thickness and cancellous bone density on the holding strength of internal fixator screws
Authors: Seebeck J. , Goldhahn J. , Städele H. , Messmer P. , Morlock M. M. , Schneider E.
Published: May 2004

Internal fixators are a new class of implants designed to preserve the periosteal blood supply of the bone. In contrast to conventional plate fixation in which the screws have spherical heads and are loaded mainly by axial pullout forces, screws in internal fixators are “locked” within the plate and therefore subjected to axial as well as bending loads. In this study the ultimate loads of screws of a commercially available internal fixator system were tested in a pullout (n = 72) and cantilever bending mode (n = 72) in metaphyseal and diaphyseal regions of four pairs of human tibiae with different bone qualities. Cortical thickness and cancellous bone density were determined at the screw insertion sites. Stepwise multiple linear regression revealed that cortical thickness and cancellous density can explain 93% and 98% of the variance of the ultimate load of the screws in an axial pullout and cantilever bending mode. Screws in internal fixators are better suited to transmit shear forces and thereby make better use of the strength potential of bone than screws used in conventional plate fixation: this is especially advantageous when bone strength is reduced, e.g. due to osteoporosis. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Tinnitus
Authors: Müller Stephanie , Pasiziel Maria
Published: June 2004

Zusammenfassung. In den letzten zehn Jahren konnten 17 Beiträge zum Thema Musiktherapie und Tinnitus gefunden werden. Bisher liegen individuell entwickelte Behandlungsmethoden vor, d.h. es existiert keine einheitliche musiktherapeutische Behandlungsform bei chronischem Tinnitus. Eine wissenschaftliche Absicherung der bisherigen Konzepte ist nicht vorhanden.
Systemische Therapie
Authors: Servic Selin , Abdelsayed John
Published: June 2004

Zusammenfassung. In den letzten 20 Jahren wurden 14 Beiträge zum Thema Musiktherapie und systemischer Therapie veröffentlicht. Bisher gibt es vereinzelt Kliniken, in denen eine musiktherapeutische Arbeit mit systemischen Ansätzen etabliert ist. Die Rechercheergebnisse zeigen, dass keine empirischen Studien vorhanden sind.
Anorexia Nervosa
Authors: Junge Lisbeth , Schoch David
Published: June 2004

Zusammenfassung. In den letzten 20 Jahren wurden 19 Beiträge zum Thema Musiktherapie und Anorexia Nervosa veröffentlicht. Magersüchtige Patientinnen und Patienten werden häufig im aktiven Setting behandelt. Die Musiktherapie wird dabei immer innerhalb eines interdisziplinären Behandlungskontexts angeboten. Wirksamkeitsnachweise der Musiktherapie bei Anorexia Nervosa stehen noch aus.
Aufmerksamkeits-Defizit-Syndrom mit Hyperaktivität
Authors: Schneider Regina , Wilmers Christiane
Published: June 2004

Zusammenfassung. In den letzten acht Jahren wurden neun Beiträge zum Thema Musiktherapie und Aufmerksamkeits-Defizit-Syndrom mit Hyperaktivität veröffentlicht. Die musiktherapeutischen Behandlungsansätze basieren in der Regel auf subjektiven Therapiekonzepten und Überlegungen. Obwohl erfahrungsgemäß viele ADHS-Patienten eine Musiktherapie besuchen, gibt es bisher wenige Wirksamkeitsnachweise.
Autismus
Authors: Schreiber Andreas , Kühn Sebastian
Published: June 2004

Zusammenfassung. In den letzten 15 Jahren wurden 20 Beiträge zum Thema Musiktherapie und Autismus veröffentlicht. Obwohl theoretische Grundlagen sowie Behandlungsansätze die Indikation der Musiktherapie bei Autismus bekräftigen, steht deren wissenschaftliche Absicherung noch aus.
Behinderte/entwicklungsverzögerte Kinder
Authors: Reif Veronika , Ehrhardt Franziska
Published: June 2004

Zusammenfassung. In den letzten 20 Jahren wurden 17 Beiträge zum Thema Musiktherapie und behinderte/entwicklungsverzögerte Kinder veröffentlicht. Die entwicklungsfördernde Musiktherapie orientiert sich grundsätzlich an der Heil- und Sonderpädagogik. Durch Forschungsstudien konnte nachgewiesen werden, dass die Musiktherapie einen bedeutenden Einfluss auf die Entwicklung der Kinder hat.
Bulimie
Authors: Niebler Margarethe , Heine Susanne
Published: June 2004

Zusammenfassung. In den letzten 15 Jahren wurden zehn Beiträge zum Thema Musiktherapie und Bulimie veröffentlicht. Der Schwerpunkt der Beiträge liegt in der Entwicklung von musiktherapeutischen Behandlungsansätzen und Fallbeschreibungen. Eine wissenschaftliche Erforschung steht noch aus.
Dialyse
Authors: Wormit Alexander F. , Schneider Peter , Müller Alexander , Bolay Hans Volker
Published: June 2004

Zusammenfassung. In den letzten 20 Jahren wurden sieben Beiträge zum Thema Musiktherapie und Dialyse veröffentlicht. Bisher gibt es vereinzelt musiktherapeutische Angebote für Dialysepatienten. Der aktuell zunehmende Bedarf an psychosozialer Betreuung von Patienten im Rahmen der Dialysebehandlung könnte ein neues Arbeitsfeld für Musiktherapeuten erschließen.
Hörgeschädigte Kinder
Authors: Tränkle Sonja M. , Goßmann Grit R.
Published: June 2004

Zusammenfassung. In den letzten 20 Jahren wurden neun Beiträge zum Thema Musiktherapie und hörgeschädigte Kinder veröffentlicht. Die bisher wenigen Beiträge befassen sich hauptsächlich mit der Entwicklung einer Behandlungsmethodik. Wirksamkeitsnachweise sind bisher nicht vorhanden.
Koma (Apallisches Syndrom)
Authors: Kobe Anne , Sutter Rahel
Published: June 2004

Zusammenfassung. In den letzten 20 Jahren wurden 20 Beiträge zum Thema Musiktherapie und Koma/Apallisches Syndrom veröffentlicht. Die angewandte Behandlungsmethodik umfasst rezeptive musiktherapeutische Methoden in Verbindung mit basaler Stimulation. Bisher sind wenige Wirksamkeitsnachweise auf Grund des schwer operationalisierbaren Kontexts vorhanden.
Krebs
Authors: Lee Eun-Jeong , Laudenbach Harald
Published: June 2004

Zusammenfassung. In den letzten 25 Jahren wurden 52 Beiträge zum Thema Musiktherapie und Krebs veröffentlicht. Musiktherapie kann sowohl rezeptiv als auch aktiv angewandt werden. In den vorhandenen internationalen Forschungsstudien steht die rezeptive Anwendung (z.B. während Chemotherapie) im Vordergrund. Es besteht noch ein Bedarf an Studien zur aktiven Musiktherapie in der Behandlung von erwachsenen Krebspatienten.
Rett-Syndrom
Authors: von Dalwigk Anna , Schwibs Stefan
Published: June 2004

Zusammenfassung. In den letzten 20 Jahren wurden zehn Beiträge zum Thema Musiktherapie und Rett-Syndrom verfasst. Die Recherchen ergaben, dass der Musiktherapie insgesamt einen hohen Stellenwert in der Behandlung von Mädchen mit Rett-Syndrom zugeschrieben wird, wobei die benötigten Wirksamkeitsnachweise noch zu belegen sind.
Schmerz
Authors: Hillecke Thomas K. , Wormit Alexander F. , Bardenheuer Hubert J. , Bolay Hans Volker
Published: June 2004

Zusammenfassung. In den letzten 15 Jahren wurden 25 Beiträge zum Thema Musiktherapie und Schmerz veröffentlicht. Die Forschungsergebnisse zeigen, dass sowohl der Einsatz von aktiver als auch rezeptiver Musiktherapie eine signifikante Reduktion der chronischen sowie akuten Schmerzen hervorruft. Im Bereich der musiktherapeutischen Schmerzbehandlung sind die notwendigen Wirksamkeitsnachweise vorhanden, die auf eine zukünftige Etablierung in der Schmerzbehandlung hoffen lassen.
Sexueller Missbrauch
Authors: Mager Andreas , Sukale Thorsten
Published: June 2004

Zusammenfassung. In den letzten zehn Jahren konnten zehn Beiträge zum Thema Musiktherapie und sexueller Missbrauch gefunden werden. Eine zusätzlich von den Autoren durchgeführte Umfrage zeigte, dass Musiktherapeuten häufig mit sexuell missbrauchten Patienten arbeiten. Empirische Belege sind momentan nicht vorhanden.
Sterbebegleitung
Authors: Németh Helag K. , Keil Niklas
Published: June 2004

Zusammenfassung. Für den Zeitraum der letzten 25 Jahren konnten 35 Beiträge zum Thema Musiktherapie und Sterbebegleitung gefunden werden. Es zeigt sich, dass die Musiktherapie in diesem Arbeitsbereich einen sehr wertvollen Beitrag leistet. Eine wissenschaftliche Erforschung der Musiktherapie in der Sterbebegleitung ist aus ethischen Gründen als sehr schwierig einzustufen.
El Niño/La Niña shelf edge flow and Australian western rock lobsters
Authors: Clarke A. J. , Li J.
Published: June 2004

Due to the leak in the gappy western equatorial Pacific, sea level (SL) is highly correlated with El Niño all along the western Australian coast. According to standard theory, this coastal interannual (IA) signal should propagate westward as Rossby waves with large zonal scale. High‐resolution satellite SL estimates show that along the shelf edge south of 23°S the IA SL signal does not have the expected large spatial scale as it decreases rapidly seaward from the shelf edge. The drop in IA SL amplitude coincides with the mean position of the Leeuwin Current (LC). Theory shows how a nearly meridional mean flow, as in the case of the LC, can induce this fall in IA signal amplitude. The associated IA shelf‐edge flow tends to strengthen the LC during La Niña, weaken it during El Niño and may profoundly affect the recruitment of the western rock lobster.
In‐situ observations of mid‐latitude forest fire plumes deep in the stratosphere
Authors: Jost Hans‐Jürg , Drdla Katja , Stohl Andreas , Pfister Leonhard , Loewenstein Max , Lopez Jimena P. , Hudson Paula K. , Murphy Daniel M. , Cziczo Daniel J. , Fromm Michael , Bui T. Paul , Dean‐Day J. , Gerbig Christoph , Mahoney M. J. , Richard Erik C. , Spichtinger Nicole , Pittman Jasna Vellovic , Weinstock Elliot M. , Wilson James C. , Xueref Irène
Published: June 2004

We observed a plume of air highly enriched in carbon monoxide and particles in the stratosphere at altitudes up to 15.8 km. It can be unambiguously attributed to North American forest fires. This plume demonstrates an extra‐tropical direct transport path from the planetary boundary layer several kilometers deep into the stratosphere, which is not fully captured by large‐scale atmospheric transport models. This process indicates that the stratospheric ozone layer could be sensitive to changes in forest burning associated with climatic warming.
Magnetospheric toroidal Alfvén wave harmonics and the field line distribution of mass density
Authors: Denton Richard E. , Takahashi Kazue , Anderson Roger R. , Wuest Martin P.
Published: June 2004

Measurements of electric and magnetic field taken by instruments on the Combined Release and Radiation Effects Satellite (CRRES) spacecraft on 29 July 1991 reveal seven or eight toroidal Alfvén wave frequency bands. By using observations of the waves near the magnetic equator and the symmetry of the theoretical modes as a function of magnetic latitude, we can identify which theoretical Alfvén wave harmonic corresponds to a particular frequency band. This, along with the L shell frequency dependence, gives convincing evidence that we are in fact observing the toroidal Alfvén mode. Because the harmonics of the toroidal Alfvén wave have a different response to mass density at different points along a magnetic field line, the frequencies of these harmonics can be used to infer the distribution of mass density along the field line. While there is a significant uncertainty in the results due to the uncertainty in the observed frequencies, it is nevertheless true that both the solution based on the peak (mean) frequencies and the majority of solutions using a Monte Carlo simulation of the effects of uncertainty in frequency show the same result, that there is a local maximum in ρ within about 30° of the magnetic equator. A similar result is found for the wave event observed on 28 August 1990, a local maximum in ρ within about 15° of the magnetic equator. These results imply that heavy ions are preferentially concentrated at the magnetic equator.
Thickness distribution, texture and stratigraphy, and a simple probabilistic model for dynamical thickening of sea ice in the southern Sea of Okhotsk
Authors: Toyota Takenobu , Kawamura Toshiyuki , Ohshima Kay I. , Shimoda Haruhito , Wakatsuchi Masaaki
Published: June 2004

Sea ice thickness data and sea ice samples were analyzed to examine the characteristics of the ice thickness distribution and ice texture, and to understand ice growth processes in the southern Sea of Okhotsk. Ice thickness data and samples were obtained aboard the icebreaker Soya in early February, the ice growth season. Ice thickness data, which were obtained with a video monitoring system installed on the side deck of the ship each winter from 1991 to 2000 except 1995, show that the average thickness ranges from 19 ± 7 to 55 ± 23 cm and that it matches the characteristics of a Poisson distribution. Ice structure analysis reveals that granular texture occupies about three quarters of the total ice thickness and that the ice exhibits a layered structure with unit thickness averaging 5 to 10 cm. Stratigraphy and stable isotopic composition of the ice indicate that snow ice accounts for 10% and frazil ice accounts for 64% of the total ice thickness. This suggests that dynamic ice thickening processes such as frazil ice growth and piling up are more significant than congelation growth. On the basis of these characteristics, which resemble more those of Antarctic than Arctic sea ice, we propose a conceptual model for the ice thickening process in this region. It is shown that this model can explain the shape of the ice thickness distribution well, and is analogous with the concept of the “pancake cycle” and multiple rafting of Antarctic sea ice growth and thickening.
Ocean dynamics associated with rapid J2 fluctuations: Importance of circumpolar modes and identification of a coherent Arctic mode
Authors: Hughes C. W. , Stepanov V. N.
Published: June 2004

Fluctuations of the Earth's dynamic oblateness J2 are a measure of global redistributions of mass between equatorial and polar regions, sensitive to the component which is symmetric about the equator. Cox and Chao recently published a time series of monthly values of J2 based on satellite orbit determination, which showed rapid fluctuations from month to month, as well as a large change in J2 in 1997/1998. We here investigate the ocean dynamics associated with these rapid fluctuations using a barotropic ocean model forced by atmospheric wind stress and pressure. We find that the model has significant skill in reproducing the observations, though not the change in 1997/1998. Much of the model variability is related to coherent circumpolar fluctuations in Arctic and Antarctic bottom pressure which, despite their apparent symmetry, are forced by quite different mechanisms. The Antarctic mode is forced by circumpolar winds, whereas the Arctic mode is forced by northward winds over the entrances to the polar sea. Comparison with in situ observations shows that the model has skill in reproducing the polar modes. Arctic tide gauge records confirm the presence of a coherent mode at short periods, and at long periods over at least the Eurasian Arctic shelf. If barotropic, and representative of the whole Arctic, this would be large enough to make a major contribution to measured J2 fluctuations, but does not account for the 1997/1998 event.
A case study of excessive subtropical transport in the stratosphere of a data assimilation system
Authors: Tan Wei Wu , Geller Marvin A. , Pawson Steven , da Silva Arlindo
Published: June 2004

Assessments of transport show that results derived from assimilated (or analyzed) winds exhibit significantly larger mixing and entrainment rates compared to those derived from general circulation model (GCM) winds, where the GCM transport is somewhat closer (statistically) to values inferred from observations. This discrepancy presents a challenge to our ability to understand and model the global distributions of long‐lived trace gases. We use the Goddard Earth Observation System's Finite Volume Data Assimilation System to explore this issue by examining how the data assimilation process alters the dynamics of the underlying GCM and how this leads to greater lower stratospheric mixing and transport in the subtropics. We show that the excessive subtropical transport is related to the proliferation of eddy features in the subtropics, and we examine various possibilities that may cause this. These include the generation of upward propagating features, equatorward propagating features, and meridionally confined features in the process of data assimilation. In particular, it is argued that unstable regions forced directly by the analysis increments play an important role in generating the excess subtropical transport.
Surface temperature retrieval from Along Track Scanning Radiometer 2 data: Algorithms and validation
Authors: Sobrino J. A. , Sòria G. , Prata A. J.
Published: June 2004

A study has been carried out using MODTRAN 3.5 simulations of the Along Track Scanning Radiometer 2 (ATSR‐2) data at 3.7, 11, and 12 μm wavelengths to give a range of algorithms for estimating surface. Making use of the dual‐angle feature of the ATSR‐2, algorithms based on dual‐angle, split‐window, and mixed structure have been considered. The coefficients of the algorithms are derived by regression analysis using the MATLAB code. The evaluation of the sensitivity of each algorithm shows that in general, dual‐angle algorithms provide smaller errors in the estimation of surface temperature than the split‐window algorithms and that the algorithms with water vapor dependence give an improvement in the accuracy of the results. Finally, a validation for a homogenous test site in Australia under conditions of low atmospheric water vapor content is included; the results show a root‐mean‐square deviation lower than 1.8 K for split‐window algorithms and 1.4 K for dual‐angle algorithms.
Atmospheric mercury speciation and deposition in the Bay St. François wetlands
Authors: Poissant Laurier , Pilote Martin , Xu Xiaohong , Zhang Hong , Beauvais Conrad
Published: June 2004

Atmospheric mercury speciation and deposition are critical to understanding the fate of mercury in the environment. The importance of atmospheric mercury speciation and deposition was investigated during an intensive field campaign in the Bay St. François wetlands in late summer 2002. Measured gaseous elemental mercury (GEM), reactive gaseous mercury (RGM), and particulate mercury (PM: 0.1–2.5 μm) concentrations were 0.85–2.16 ng/m3 (average 1.38 ng/m3), 0–22 pg/m3 (average 3.63 pg/m3), and 0.5–18 pg/m3 (average 6.44 pg/m3), respectively. PM and RGM represented <1% of the total mercury. We reported the first synchronized automated high‐time‐resolution mercury species fluxes. The average GEM flux was 32.1 ng/m2/h (positive sign means volatilization, and negative sign indicates deposition) with a maximum deposition value of 110 ng/m2/h and a maximum volatilization value of 278 ng/m2/h. The average RGM flux was −2.6 ng/m2/h with a maximum deposition value of 25.6 ng/m2/h and a maximum evasion value of 0.6 ng/m2/h. The average PM flux was −0.4 ng/m2/h with a maximum deposition value of 8.7 ng/m2/h and a maximum resuspension value of 32.7 ng/m2/h. RGM contributed over 90% to the total dry deposition of mercury (GEM, RGM, and PM). GEM evasion exceeded deposition of GEM, RGM, and PM, thus suggesting other sources of mercury to the mercury budget such as wet deposition through precipitation or soil. The median dry deposition velocities calculated from flux and concentration measurements were 0.19 cm/s (GEM) < 2.1 cm/s (PM) < 7.6 cm/s (RGM). The dry deposition velocity of PM is large and should be viewed as upper limits only. Although RGM should be rapidly depositing species, as predicted by its solubility, little RGM flux was observed at night. Time series of canopy wetness and RGM fluxes suggested that RGM fluxes are not driven by RGM solubility (in water) since the canopy was dry when larger RGM deposition periods were observed during daytime. It is suggested that the vegetation might directly uptake RGM and release elemental gaseous mercury during daytime. Our experimental data showed that photochemically reactive air masses could produce RGM, which is rapidly removed by dry deposition to the surfaces. Lifetime of RGM over vegetation canopy is on the order of a few hours.
Trans‐Eurasian transport of ozone and its precursors
Authors: Wild Oliver , Pochanart Pakpong , Akimoto Hajime
Published: June 2004

Long‐range transport of air across the European and Asian continents brings substantial quantities of ozone and other oxidants to northeast Asia from upwind sources over Europe and North America. This transport differs significantly from that over the Pacific and Atlantic Oceans because of weaker and less frequent frontal systems over the continent and because of weaker convective lifting over European sources. Slower O3 formation, faster destruction at low altitudes, and greater deposition over continental regions lead to Europe having a smaller impact on O3 than other source regions. We present chemical transport model studies of the formation and transport of O3 from European precursor sources and investigate the extent of their impacts over Eurasia. We focus on measurement sites at 100°E, representing the inflow to east Asia on which regional pollutant sources build, and on northeast Asia, which may be directly affected by transport across Eurasia. The seasonality in O3 production over Europe is simulated well, and transport principally in the boundary layer propagates these changes in O3 over Eurasia, leading to monthly mean impacts at Mondy, Siberia, of 0.5–3.5 ppbv. Impacts over Japan are smaller, 0.2–2.5 ppbv, and are very similar to those from North American sources, which dominate at higher altitudes. By following the effect of daily emissions independently, we clearly demonstrate that this greater North American impact is associated with lifting over the Atlantic. European and North American sources contribute to background O3 over Japan in the anticyclonic conditions that favor regional O3 buildup and are thus expected to have a small but significant effect on regional air quality. Finally, we demonstrate that location and transport lead to European sources having a different impact on OH, and hence on tropospheric oxidizing capacity and climate, from other major Northern Hemisphere source regions.
Seismic waves from elephant vocalizations: A possible communication mode?
Authors: Günther Roland H. , O'Connell‐Rodwell Caitlin E. , Klemperer Simon L.
Published: June 2004

We conducted experiments with trained African elephants that show that low‐frequency elephant vocalizations produce Rayleigh waves. We model a potential range for these seismic waves, under ideal conditions, of c. 2 km. In appropriate conditions, surface waves from an elephant's infrasonic vocalizations might propagate further than airborne sound and provide advantages over acoustic communication. However, if we use the detection capabilities of the human ear as a benchmark for the signal‐detection thresholds of elephants, our estimates of attenuation and ambient seismic noise suggest that the seismic detection range is unlikely to exceed the acoustic detection range under normal atmospheric conditions. We conclude that elephants may benefit from seismic detection in circumstances where the range of acoustic communication is limited, or in cases where multimodal communication is advantageous. Given our current understanding, elephants are unlikely to rely on seismic waves as their primary mode for long‐range communication.
Geophysical evidence of a mantle derived intrusion in SW Iberia
Authors: Carbonell R. , Simancas F. , Juhlin C. , Pous J. , Pérez‐Estaún A. , Gonzalez‐Lodeiro F. , Muñoz G. , Heise W. , Ayarza P.
Published: June 2004

Deep seismic reflection data acquired as part of the SW‐Iberia EUROPROBE project across the transpressional Variscan orogen sample three tectonic terranes: the South Portuguese Zone, the Ossa‐Morena Zone, and the Central Iberian Zone. The seismic data reveal the existence of a mid‐crustal reflective body 140 km long and of variable thickness (up to 5 km), the Iberian Reflective body. The conductivity image provided by coincident MT soundings, the amplitude characteristics of the seismics, mineralization studies related to magmatic ore deposits, and the surface geology suggest that the IRB is a mantle‐derived mafic intrusion. The geophysical, geological and petrological data suggest that the IRB is most probably an Early Carboniferous (approximately at 350–340 Ma) mantle‐derived intrusion possibly linked to plume activity that took place in Europe in the Carboniferous and Permian.
Time series of coccolithophore activity in the Barents Sea, from twenty years of satellite imagery
Authors: Smyth T. J. , Tyrrell T. , Tarrant B.
Published: June 2004

Blooms of the coccolithophorid Emiliana huxleyi may be sensitive to climate change. A comparison of global Coastal Zone Color Scanner (CZCS, 1978–1986) and Sea‐viewing Wide Field‐of‐view Sensor (SeaWiFS, 1997–present) imagery appears to show them advancing into some sub‐Arctic seas. To determine when coccolithophore blooms appeared in the Barents Sea this paper makes use of Advanced Very High Resolution Radiometer (AVHRR) visible channel data which bridges the gap between the CZCS and SeaWiFS missions (1981–present). Analysis of over 3700 AVHRR images has shown coccolithophore blooms to be unambiguously present between 1989–1992 but probably absent in other pre‐SeaWiFS years. This paper shows a correlation between positive temperature ‐ negative salinity anomalies in the Barents Sea and bloom occurrence. If global warming continues to trigger increased warmth and freshwater runoff in the region then there may be an increased frequency of coccolithophore blooms within the Barents Sea.
On the generation of totem pole emissions
Authors: Brinca A. L. , Romeiras F. J. , Gomberoff L. , Marçal M. H.
Published: June 2004

Understanding of the generation of electron cyclotron harmonic waves by almost monoenergetic perpendicular ion beams contributes to the interpretation of the totem pole (TP) emissions observed at the Earth's magnetopause by Geotail and not fully explained by the standard model invoked for the stimulation of magnetospheric electron Bernstein modes. This study uses parameters for the background medium arising from particle and field measurements concurrent with the TP observations and adopts free energy sources that have been recently observed by Interball‐1. Through application of exact criteria, the stability analysis discriminates between convective and absolute (nonconvective) instabilities and shows that the latter can occur in spectral bands both below and, in contrast to the situation encountered in the standard paradigm, above the upper hybrid frequency, covering the spectrum of harmonic bands detected in the TP emissions.
Test of edge wave forcing during formation of rhythmic beach morphology
Authors: Masselink Gerhard , Russell Paul , Coco Giovanni , Huntley David
Published: June 2004

This paper reports on concurrent measurements of evolving rhythmic beach morphology and the associated water motion on a macrotidal, coarse sandy beach. Beach cusps with a spacing of 19 m developed over a 3‐day period of low‐energy swell after which they were destroyed by energetic wind waves. The beach cusps were clearly accretionary features and developed mainly during the rising tide. Detailed hydrodynamic measurements were conducted at three locations in the swash and inner surf zone in the vicinity of a developing cusp horn and revealed that energetic standing, mode‐zero, subharmonic edge waves were not present during the initiation of the beach cusps. Specifically, analysis of the hydrodynamic data indicated that: (1) the amount of subharmonic energy was limited (<10% of the total energy); (2) none of the computed energy spectra exhibited a significant peak at the subharmonic frequency; (3) the cross‐shore velocity amplitude at the subharmonic frequency was 2–3 times larger than the longshore velocity amplitude; (4) the longshore current motion at the subharmonic frequency was barely coherent between adjacent locations in the surf zone; and (5) the time series of pressure and cross‐shore current were in phase at either side of the developing cusp horn. It is concluded that, at least during this event of beach cusp formation, energetic standing edge waves are not a prerequisite to initiate the development of rhythmic beach morphology.
Pressure measurement using thermal properties of materials
Authors: Cruz Pessoa José Dalton , Calbo Adonai Gimenes
Published: June 2004

This work presents a design and two methods, one isothermal and one isovolumetric, for pressure measurements based on the compressibility coefficient (κ) and thermal expansibility (α) of the fluid under test. The setup and relevant construction details are described. To demonstrate the applicability of the isovolumetric measurement method, the setup was calibrated with respect to a Bourdon-type manometer; the other isothermic method was analyzed to determine construction details that could realize resolution requirements. The authors determined the effect of ambient temperature on device operation and the time response of the isovolumetric method. The device can be used to estimate the compressibility of a fluid and, in addition, could become an alternative for direct plant cell turgor measurement.
Native oxide decomposition and local oxidation of 6H-SiC (0001) surface by atomic force microscopy
Authors: Xie X. N. , Chung H. J. , Sow C. H. , Wee A. T. S.
Published: June 2004

We have observed the native oxide decomposition and local oxide growth on 6H-silicon carbide (0001) surface induced by atomic force microscopy (AFM). When the biased AFM probe was scanned over surface areas, native oxide was decomposed and assembled into protruded lines. The decomposition is accompanied by simultaneous graphitization of the scanned areas, leading to metal–semiconductor contact as evidenced in I–V characteristics. When the probe was immobilized and longer bias duration applied, direct oxidation of silicon carbide (SiC) surface was achieved. The dielectrical properties of AFM oxide on SiC were also investigated in terms of interface barrier height.
Simple broad-band frequency-independent analog I/Q generator
Authors: Orellana C. , Labbé R.
Published: June 2004

A wide frequency range, analog in-phase/quadrature generator was developed for use in synchronous detectors. With the parameters chosen for the realization reported in this Note, it can, in principle, operate from 60 Hz up to 400 kHz. Using good quality sine input, deviations from the 90° phase lag of the quadrature output are not larger than 0.2° in the frequency range between 60 Hz and 100 kHz.
Trapping and tracking a local probe with a photonic force microscope
Authors: Rohrbach Alexander , Tischer Christian , Neumayer Dirk , Florin Ernst-Ludwig , Stelzer Ernst H. K.
Published: June 2004

An improved type of scanning probe microscope system able to measure soft interactions between an optically trapped probe and local environment is presented. Such a system that traps and tracks thermally fluctuating probes to measure local interactions is called a photonic force microscope (PFM). The instrument can be used to study two-dimensional and three-dimensional surface forces, molecular binding forces, entropic and viscoelastic forces of single molecules, and small variations in particle flow, local diffusion, and viscosities. We introduce and characterize a PFM, and demonstrate its outstanding stability and very low noise. The probe’s position can be measured within a precision of 0.2–0.5 nm in three dimensions at a 1 MHz sampling rate. The trapping system facilitates stable trapping of latex spheres with diameter D=λ0/2 at laser powers as low as 0.6 mW in the focal plane. The ratio between the trapping stiffness and laser power was able to be optimized for various trapping conditions. The measured trap stiffnesses coincide well with the calculated stiffnesses obtained from electromagnetic theory. The design and the features of the novel PFM setup are discussed. The optical and thermodynamical principles as well as signal analysis are explained. Applications for three-dimensional, hard-clipping interaction potentials are shown. The technique discussed in this article and the results presented should be of great interest also to people working in the fields of classical optical tweezing, particle tracking, interferometry, surface inspection, nanotechnology, and scanning probe microscopy.