bluuebunny/crossref_metadata_2025 huggingface dataset:
Variable permeability effect on vortex instability of a horizontal natural convection flow in a saturated porous medium with variable wall temperature
Authors: Hassanien I.A. , Salama A.A. , Elaiw A.M.
Published: December 2003

A linear stability theory is used to analyze the vortex instability of free convection boundary layer flow in a saturated porous medium adjacent to a horizontal surface where the wall temperature is a power function of the distance from the origin. The variation of permeability in the vicinity of the solid boundary is approximated by an exponential function. The variation rate itself depends slowly on the streamwise coordinate, such as to allow the problem to possess a set of solutions, invariant under a group of transformations. Velocity and temperature profiles as well as local Nusselt number for the base flow are presented for the uniform permeability UP and variable permeability VP cases. The critical Rayleigh numbers and the associated wave numbers are obtained for both UP and VP cases. It is found that the variable permeability effect tends to increase the heat transfer rate and destabilize the flow to the vortex mode of disturbance.
Cutaneous Lymphoblastic Lymphoma in Children: Report of Six Cases with Precursor B-cell Lineage
Authors: Kahwash Samir B. , Qualman Stephen J.
Published: December 2003

Precursor B lymphoblastic lymphomas (B-LBL) are generally rare, but appear to have a higher incidence in children than in adults. In this report, we describe in detail six cases of B-LBL presenting with cutaneous lesions. Three occurred in the scalp, one in the skin of the thigh, one in the skin of the face and breast, and one in the subcutaneous tissue of the orbit. All six patients are females ranging in age at presentation from 5 to 15 years (mean = 9.6). None of the cases had bone marrow involvement, while two had bone involvement (maxilla, distal tibia, and distal humerus in one case, and distal tibia and orbital bone in another case); only one case had lymphadenopathy (retroperitoneal). Immunohistochemical staining showed positivity for CD79a and CD43 in all six cases. LCA and L26 positivity were also each seen in one case. Staining for MIC-2 (CD99) showed strong positivity in three cases. Vimentin was positive in four cases and TdT was positive in all five patients tested. Staining for keratin, UCHL-1, or CD30 was not encountered. Cases in which cell marker studies by flow cytometry were performed showed positivity for CD10, CD19 with negative CD20, pan-T-cell, and myeloid markers. The five patients who received multiagent chemotherapy are alive with follow-up intervals of 2 to 18 years. Two patients had local recurrences and were given radiation therapy (one with repeating multiagent chemotherapy). One patient (diagnosed in 1962) died of disseminated disease; she had been treated with radiation therapy and 6MP only. Cutaneous B-LBL must be included in the differential diagnosis of small blue cell tumors, especially in children. In contrast to its T-cell counterpart, B-LBL occurs more frequently in females, tends to present as skin or bone lesions, and is associated with a potential cure, even in cases that relapse.
Pediatric Intestinal Transplantation: The Resected Allograft
Authors: Noguchi Shin-ichi , Reyes Jorge , Mazariegos George V. , Parizhskaya Maria , Jaffe Ronald
Published: December 2003

We reviewed the clinical and pathologic finding of 22 resected allografts from 19 of the 83 children who underwent a variety of small intestinal transplant procedures in the years 1990–2000 at the Children's Hospital of Pittsburgh. Resections were compared with prior mucosal biopsies because resections allow for evaluation of the entire bowel thickness, including the feeding vessels, and obviate the problems of limited sampling. Partial resections that were done soon after the transplant, or soon after additional surgery, were for surgical problems such as leaks, adhesions, and volvulus. None had biopsy features suggestive of rejection or infection. Partial resections done late (6 months or more) after transplantation were more likely to be related to allograft immune biology; two had a sclerosing peritonitis that was confined to the allograft, and one had an obstructing carcinoma arising in the allograft mucosa. One patient had a localized stricture, demonstrated to be due to graft vascular disease at partial resection, and this patient went on to have the allograft removed a year later for chronic rejection. Early complete allograft enterectomies were for refractory acute cellular rejection, 1–2 months following transplant. One was removed for pancreatitis and liver failure from operative complications. Late allograft enterectomies were generally for chronic rejection, some with residual acute rejection, but there were also a number of patients who had multiple superimposed conditions such as cytomegalovirus, Epstein-Barr virus, and post-transplant lymphoproliferative disorder in various combinations. One had idiopathic scarring and developed an adynamic bowel that remains unexplained. Examination of the resected specimens allows for dissection of the multiple contributions to graft failure, especially the vascular disease that can rarely be seen on mucosal biopsy. An unexpected finding was the impressive hypertrophy of neural elements, nerves, and ganglion cells in many of the patients, the significance of which requires further investigation.
Histopathology of Congenital Hyperinsulinism: Retrospective Study with Genotype Correlations
Authors: Suchi Mariko , MacMullen Courtney , Thornton Paul S. , Ganguly Arupa , Stanley Charles A. , Ruchelli Eduardo D.
Published: December 2003

The majority of the most severe cases of congenital hyperinsulinism (HI) are caused by defects in the β-cell adenosine triphosphate (ATP)-sensitive potassium channel and usually require pancreatectomy to control blood sugar levels. In contrast to the recent advances in understanding the pathophysiology and genetic bases of HI, the histologic classification of this condition remains controversial. A recent proposal to classify the HI pancreata into diffuse and focal forms has drawn much interest because of its relative simplicity and its good correlation with the genetic abnormalities. We undertook a retrospective study to determine whether this classification scheme could be applied to 38 pancreata resected for HI at our institution. We also obtained leukocyte genomic DNA from 29 cases and screened the exons of ABCC8 and KCNJ11 genes for the presence of mutations. Nineteen cases (50.0%) were histologically classified as diffuse HI and 14 cases (36.8%) were categorized as focal form. The mutational analysis revealed that 14 of the 16 diffuse cases analyzed had either homozygous or compound heterozygous mutations of ABCC8 or KCNJ11 and 7 of 10 focal cases had only the paternally inherited mutations, consistent with the previous observations. Two patients (5.3%) had normal pancreatic histology but had persistent hypoglycemia postoperatively, leaving the possibility of residual focal lesion. Three of 38 cases (7.9%) did not fit well into either diffuse or focal category. Two cases differed from the described pattern for the diffuse form in that the nuclear enlargement was confined to a single area of the pancreas. The other case had a focal lesion but β-cell nuclear enlargement was present in nonadjacent areas. Mutations for typical diffuse or focal HI were not identified in two of these three equivocal cases. We conclude from this study that nearly 90% of HI cases can be classified into either a diffuse or a focal form. However, a small percentage of cases represented a diagnostic challenge.
Facio-Auriculo-Vertebral Sequence in Association with DiGeorge Sequence, Rokitansky Sequence, and Dandy-Walker Malformation: Case Report
Authors: Pillay Komala , Matthews Louise S. , Wainwright Helen C.
Published: December 2003

Extreme variability of expression is characteristic of the facio-auriculo-vertebral sequence. Sporadic and familial cases have been reported with obvious etiologic heterogeneity. Most reports in the literature are of clinical cases. The purpose of this paper is to present a fetal autopsy case report of the facio-auriculo-vertebral sequence in association with DiGeorge sequence, Rokitansky sequence, and Dandy-Walker malformation. A standard neonatal autopsy was performed on a macerated female fetus, gestational age 29 wk. External examination of the fetus revealed hypoplastic right face, low-set microtic right ear, and macrostomia. Internal examination showed hypoplastic thymus and lungs, a type I truncus arteriosus, and ventricular septal defect. Both kidneys showed evidence of pelvi-ureteric junction obstruction. The ovaries and fallopian tubes were present with an absent uterus and vagina (Rokitansky sequence). In addition, Dandy-Walker malformation was identified. Microscopically, a single hypoplastic parathyroid gland was noted and there was cystic renal dysplasia. We report the sixth case of the facio-auriculo-vertebral sequence in association with Rokitansky sequence and the first case of this sequence in association with Dandy-Walker malformation. In addition, features of DiGeorge sequence were present.
Undifferentiated Mesenchymal Neoplasm of the Esophagus in a Child: Case Report and Comparison with Gastrointestinal Stromal Tumor
Authors: Jollimore Jason V. , Zamakhshary Mohammed , Giacomantonio Michael , Yu Weiming
Published: December 2003

Mesenchymal neoplasms of the esophagus are relatively uncommon in adults and exceedingly rare in children. Childhood tumors consist almost exclusively of smooth muscle tumors (leiomyomas). We report a case of an undifferentiated mesenchymal neoplasm occurring in the distal esophagus of a 15-year-old boy which is not a gastrointestinal stromal tumor. To our knowledge, this is the first reported case of such a neoplasm occurring in the esophagus of either an adult or child.
Motivation and self‐perception profiles and links with physical activity in adolescent girls
Authors: Biddle Stuart J.H , Wang C.K.John
Published: December 2003

Research shows a decline in participation in physical activity across the teenage years. It is important, therefore, to examine factors that might influence adolescent girl's likelihood of being physically active. This study used contemporary theoretical perspectives from psychology to assess a comprehensive profile of motivational and self‐perception variables in 11–16 year old English girls (n=516). A cross‐sectional design was employed. Cluster analysis was conducted to (a) map cluster profiles and (b) test whether clusters differed in physical self‐worth, global self‐esteem, and physical activity. Results revealed a five‐cluster solution depicting 40% of the sample as moderately motivated, 30% lowly motivated in two clusters, and 30% highly motivated, also in two clusters. However, differences between clusters on physical activity were quite small. Results show potential areas for intervention to enhance the motivation of adolescent girls for physical activity.
Trajectories of delinquent behaviour in adolescence and their covariates: relations with initial and time‐averaged factors
Authors: Wiesner Margit , Silbereisen Rainer K
Published: December 2003

This longitudinal study examined individual, family, and peer covariates of distinctive trajectories of juvenile delinquency, using data from a community sample of 318 German adolescents (mean age at the first wave was 11.45 years). Latent growth mixture modelling analysis revealed four trajectory groups: high‐level offenders, medium‐level offenders, low‐level offenders, and rare offenders. The trajectory groups were discriminated better by time‐averaged covariates than by initial status covariates. High peer tolerance of deviance and low parental empathy were consistently linked to varying offending trajectories, whereas gender, low academic achievement, and low parental monitoring appeared to be trajectory‐specific covariates.
Associations among sexual attraction status, school belonging, and alcohol and marijuana use in rural high school students
Authors: Rostosky Sharon Scales , Owens Gina P , Zimmerman Rick S , Riggle Ellen D.B
Published: December 2003

Analysis of data collected from 1725 9th graders from 25 rural high schools revealed that students reporting same‐sex attraction or uncertainty about their attraction status also reported significantly lower GPAs, lower school belonging, and higher marijuana and alcohol use. Regression analyses confirmed that beyond the effects of GPA and biological sex, sexual minority attraction status was negatively associated with school belonging. Further, while higher school belonging significantly decreased the odds of alcohol and marijuana use, sexual attraction status did not significantly contribute to the model. Post‐hoc analyses indicated that sexual minority students systematically reported that they perceived less privacy in completing the survey, lending support to the notion that these adolescents may feel less trusting of their school environments. These findings are discussed in light of the need for interventions to address the developmental challenges of sexual minority students.
Morphological development of microglia in the postnatal rat brain
Authors: Orłowski Dariusz , Sołtys Zbigniew , Janeczko Krzysztof
Published: December 2003

Morphological transformation of lectin‐positive microglia/macrophages in the developing rat cerebral hemisphere was analysed using quantitative methods. During the first postnatal month, the cells showed increases in their size and fractal dimension accompanied by a simultaneous decrease in their solidity. Regional variations in dynamics of the process indicated the existence of spatio‐temporal developmental gradients within the cerebral hemisphere wall which might correspond with regional patterns of neuronal differentiation. Results of the present study prove that the quantitative methods can be the source of reliable data replacing subjective cell typologies.
Introduction of histidine residues into avidin subunit interfaces allows pH‐dependent regulation of quaternary structure and biotin binding
Authors: Nordlund Henri R , Hytönen Vesa P , Laitinen Olli H , Uotila Sanna T.H , Niskanen Einari A , Savolainen Janne , Porkka Eevaleena , Kulomaa Markku S
Published: December 2003

In order to turn the subunit association and biotin binding of avidin into pH‐sensitive phenomena, we have replaced individually three amino acid residues in avidin (Met96, Val115 and Ile117) with histidines in the 1–3 interface, and in combination with a histidine conversion in the 1–2 interface (Trp110). The single replacements Met96His and Val115His in the 1–3 interface were found to have a clear effect on the quaternary structure of avidin, since subunit associations of these mutants became pH‐dependent. The histidine replacement in the 1–2 interface affected the biotin‐binding properties of the mutants, in particular reversibility of binding and protein–ligand complex formation were pH‐sensitive, as measured by IAsys biosensor and fluorescence correlation spectroscopy, respectively. The possibility of regulating the quaternary structure and function of avidin in a controlled and predictable manner, due to introduced interface histidines, will expand even further the range and versatility of the avidin–biotin technology.
Expression of hepatitis C virus non‐structural 5A protein in the liver of transgenic mice
Authors: Majumder Mainak , Steele Robert , Ghosh Asish K , Zhou Xiao Yan , Thornburg Larry , Ray Ranjit , Phillips Nancy J , Ray Ratna B
Published: December 2003

Hepatitis C virus (HCV) is a major etiologic agent for chronic hepatitis worldwide often leading to the development of cirrhosis and hepatocellular carcinoma. However, the mechanism for development of chronic hepatitis or hepatocarcinogenesis by HCV remains unclear. HCV NS5A protein possesses many intriguing properties, including sequestration of p53 in the cytoplasm, downregulation of p21 protein, activation of STAT3, and inhibition of tumor necrosis factor‐α‐mediated apoptosis. Thus, we investigated whether this viral protein has oncogenic property in vivo. In the absence of an efficient cell culture system for virus growth and a suitable small animal model for HCV infection, transgenic FVB mice were generated by targeting the HCV NS5A genomic region cloned under the control of a liver‐specific apoE promoter or mouse major urinary promoter (MUP). The apoE promoter is constitutively expressed in liver, on the other hand, the MUP is developmentally regulated and expressed in the liver after birth. Reverse transcription polymerase chain reaction and Western blot analysis indicated establishment of HCV NS5A transgene expression in several lines from both groups of mice. Immunohistochemical studies suggested the presence of NS5A in the cytoplasm of hepatocytes. The transgenic animals were phenotypically similar to their normal littermates and did not exhibit a major histological change within the liver up to 24 months of age. Our results suggested HCV NS5A protein is not directly cytopathic or oncogenic in this FVB transgenic mouse model, although this viral protein promotes cell growth in vitro. These animals will be a valuable model of HCV immunopathology as well as for evaluation of siRNA, interferon and other cytokine therapies.
tBid forms a pore in the liposome membrane
Authors: Yan Ling , Miao Qi , Sun Yang , Yang Fuyu
Published: December 2003

We investigated the ability of tBid (truncated form of Bid) to bind and permeabilize the liposomes (large unilamellar vesicles, LUVs) and release fluorescent marker molecules (fluorescein‐isothiocyanate‐conjugated dextrans, FITC‐dextrans) of various molecular diameters (FD‐20, FD‐70, FD‐250S) from LUVs. Obtained data showed that tBid was more efficient in promoting leakage of FITC‐dextrans from LUVs composed of cardiolipin and dioleoylphosphatidylcholine (DOPC) than LUVs made of dioleoylphosphatidic acid or dioleoylphosphatidylglycerol and DOPC. The leakage efficiency was reduced with increasing amount of dioleoylphosphatidylethanolamine or dielaidoylphosphatidylethanolamine. Phospholipid monolayer assay and fluorescence quenching measurements revealed that tBid inserted deeply into the hydrophobic acyl chain of acidic phospholipids. Taking into account the tBid three‐dimensional structure, we propose that tBid could penetrate into the hydrophobic core of membrane, resulting in the leakage of entrapped content from LUVs via a pore‐forming mechanism.
The intestinal zonula occludens toxin (ZOT) receptor recognises non‐native ZOT conformers and localises to the intercellular contacts
Authors: Lee Alvin , White Natalie , van der Walle Christopher F
Published: December 2003

A preliminary structural analysis ofVibrio choleraezonula occludens toxin (ZOT) was made by equilibrium denaturation and circular dichroism. ZOT is a structurally unstable protein in aqueous solution (ΔG(H2O)3.82 kcal/mol), the putative intra‐ and extracellular domains unfold co‐operatively, with complete denaturation via observed conformational intermediates. Refolding of denatured ZOT is not dependent on disulphide bridge formation. Partial refolding of a maltose binding protein–ZOT fusion did not prevent its specific binding to the ZOT receptor on Caco‐2 cells. Immuno‐gold labelling showed that the ZOT receptor localises to the intercellular contacts between cells in a confluent monolayer.
Tetrahydrofolate and 5‐methyltetrahydrofolate are folates with high antioxidant activity. Identification of the antioxidant pharmacophore
Authors: Rezk Bashir M , Haenen Guido R.M.M , van der Vijgh Wim J.F , Bast Aalt
Published: December 2003

The presumed protective effect of folic acid on the pathogenesis of cardiovascular, hematological and neurological diseases and cancer has been associated with the antioxidant activity of folic acid. Peroxynitrite (PON) scavenging activity and inhibition of lipid peroxidation (LPO) of the physiological forms of folate and of structurally related compounds were tested. It was found that the fully reduced forms of folate, i.e. tetrahydrofolate (THF) and 5‐methyltetrahydrofolate (5‐MTHF), had the most prominent antioxidant activity. It appeared that their protection against LPO is less pronounced than their PON scavenging activity. The antioxidant activity of these forms of folic acid resides in the pterin core, the antioxidant pharmacophore is 4‐hydroxy‐2,5,6‐triaminopyrimidine. It is suggested that an electron donating effect of the 5‐amino group is of major importance for the antioxidant activity of 4‐hydroxy‐2,5,6‐triaminopyrimidine. A similar electron donating effect is probably important for the antioxidant activity of THF and 5‐MTHF.
Redox characteristics of the tungsten DMSO reductase of Rhodobacter capsulatus
Authors: Hagedoorn Peter-Leon , Hagen Wilfred R. , Stewart Lisa J. , Docrat Arefa , Bailey Susan , Garner C.David
Published: December 2003

The dimethylsulfoxide reductase (DMSOR) from Rhodobacter capsulatus is known to retain its three‐dimensional structure and enzymatic activity upon substitution of molybdenum, the metal that occurs naturally at the active site, by tungsten. The redox properties of tungsten‐substituted DMSOR (W‐DMSOR) have been investigated by a dye‐mediated reductive titration with the concentration of the WV state monitored by EPR spectroscopy. At pH 7.0, E
m(WVI/WV) is −194 mV and E
m(WV/WIV) is −134 mV. Each E
m value of W‐DMSOR is significantly lower (220 and 334 mV, respectively) than that of the corresponding couple of Mo‐DMSOR. These redox potentials are consistent with the ability of Mo‐DMSOR to catalyze both the reduction of DMSO to DMS and the back reaction, whereas W‐DMSOR is very effective in catalyzing the forward reaction, but shows no ability to catalyze the oxidation of DMS to DMSO.
A FRAMEWORK FOR ENHANCING AND GUARDING THE RELEVANCE AND QUALITY OF SCIENCE: THE CASE OF THE CGIAR
Authors: KASSAM A. H. , GREGERSEN H. M. , FERERES E. , JAVIER E. Q. , HARWOOD R. R. , de JANVRY A.
Published: December 2003

As part of the reform process of the Consultative Group on International Agricultural Research (CGIAR), its Technical Advisory Committee is being transformed into a Science Council. An interim Science Council has been operating since January 2002. The primary role of the Council will be to enhance and guard the relevance and quality of science in the CGIAR System. Relevance is viewed as researching the ‘right things’ to address the System's goals, and deals with the relevance of identified research priorities and strategies and the nature of the planning and consultation process. Ex-ante analyses of need and potential impact to formulate the priorities and strategies are important elements in defining relevance. Quality is viewed as researching the ‘right things well’ and deals with the efficient use of state-of-the-art knowledge, research methods and protocols. The paper outlines the interim Council's suggestions for an operational framework of the Science Council. It serves as a starting point for the development of specific criteria, procedures and guidelines for carrying out the envisioned responsibilities. The Science Council must act in a strategic advisory role, basing its advice on: (i) planning and strategy development in the context of CGIAR goals; (ii) internal self-assessments by CGIAR Centres and Programmes and independent external monitoring and evaluation; and (iii) impact assessments. The paper discusses these three complementary functions. Each depends on the other in a dynamic feedback process that is essential if the CGIAR is to remain at the frontiers of science and development, maintain its science relevance and quality, and contribute in the most effective and efficient manner to the mission and goal of the Group.
The change that never happened: the story of oblique subjects
Authors: BARĐDAL JÓHANNA , EYTHÓRSSON THÓRHALLUR
Published: December 2003

This paper contributes to an ongoing debate on the syntactic status of oblique subject-like NPs in the ‘impersonal’ construction (of the type me-thinks) in Old Germanic. The debate is caused by the lack of canonical subject case marking in such NPs. It has been argued that these NPs are syntactic objects, but we provide evidence for their subject status, as in Modern Icelandic and Faroese. Thus, we argue that the syntactic status of the oblique subject-like NPs has not changed at all from object status to subject status, contra standard claims in the literature. Our evidence stems from Old Icelandic, but the analysis has implications for the other old Germanic languages as well. However, a change from non-canonical to canonical subject case marking (‘Nominative Sickness’) has affected all the Germanic languages to a varying degree.
Commentary: moral truisms, empirical evidence, and foreign policy
Authors: Chomsky Noam
Published: December 2003

Many studies of world politics fail to take evidence seriously or consider basic moral truisms (for example, that the standards we apply to others we must apply to ourselves). This commentary illustrates these assessments in relation to two subjects which have attracted much interest in the West recently – terrorism and just war to combat terrorism. The evidence shows that the United States has engaged extensively in terrorism and that application of just war principles would entitle the victims of that terrorism to use force against the United States to defend themselves if the United States is accorded that right.
Constructing identity and relating to difference: understanding the EU's mode of differentiation
Authors: Rumelili Bahar
Published: December 2003

The case of the EU points to the need to re-conceptualise the relationship between self and other in the IR literature. I argue that the literature forces us into an artificial choice between the liberal constructivist approach of disregarding the constitutive role of difference in identity formation and the critical constructivist approach of assuming a behavioural relationship between self and other, and therefore cannot account for the diversity in the EU's interactions with various states on its periphery. I identify three constitutive dimensions along which self/other relationships vary to produce or not produce relationships of Othering: nature of difference, social distance, and response of other. I analyse how the EU's interactions with Morocco, Turkey, and Central and Eastern European states are situated differently on these dimensions, and evaluate the question of whether the EU is a postmodern collectivity based on these analyses.
Adelieledone, a new genus of octopodid from the Southern Ocean
Authors: ALLCOCK A.L. , HOCHBERG F.G. , RODHOUSE P.G.K. , THORPE J.P.
Published: December 2003

The syntypes of the endemic Southern Ocean octopodid Pareledone polymorpha (Robson, 1930) were re-examined and measurements, counts and indices are presented. The two forms described by Robson, namely oblonga and affinis, are determined to have no taxonomic validity. The species polymorpha shows morphological similarities with Pareledone adelieana (Berry, 1917) but differs in relative arm lengths, sucker counts, external colouration and size at maturity. Both species are transferred to the new genus Adelieledone, which is separated from the genus Pareledone s.s. by the transverse ridges in the ligula groove of the hectocotylus, the sharp tip of the lower beak, the enlarged posterior salivary glands, the absence of stylets and by skin sculpture, especially by the presence of two longitudinal integumentary ridges on the dorsal mantle. A new species, Adelieledone piatkowski, is described from the Antarctic Peninsula. Beak morphology can discriminate the genera in predator studies.
The classification of Antarctic appendicularians: the Oikopleura gaussica group
Authors: CAPITANIO F.L. , DAPONTE M.C. , ESNAL G.B.
Published: December 2003

The validity of the Antarctic species of the “Oikopleura gaussica group” (O. gaussica, O. valdiviae, O. drygalskii, and O. weddelli) is discussed. The characteristics of new material from South Georgia and the Bellingshausen Sea are compared with the original descriptions. We examined 495 specimens at different stages of maturity and concluded that the characters used to differentiate these species of Oikopleura have not enough weight to justify their separation. The morphological variations found were ascribed either to intraspecific variability and/or to the different degree of maturity of the specimens examined of a single species, Oikopleura gaussica. The main taxonomic characters for the identification of this species are: the particular way in which the flat triangular gonads surround the intestinal ball like a sheath, the equal size of the two lobes of the stomach, the oesophagus entering the postero-dorsal edge of the rounded left lobe of the stomach, the presence of oval and some times lobate oral glands, and the variable number of subchordal cells (4 to 14) arranged in a single row on the right (ventral) side of the chorda.
First record of an Early Cretaceous shark (Chondrichthyes, Neoselachii) from Antarctica
Authors: KRIWET JÜRGEN
Published: December 2003

A shark tooth from the Spartan Glacier Formation of the Fossil Bluff Group of Alexander Island, Antarctic Peninsula is described and assigned to Palaeospinacidae, an extinct group of neoselachian sharks. This tooth was previously supposed to have been recovered from Middle Jurassic strata and to belong to Hybodus. However, sedimentation of the Spartan Glacier Formation was from the Valangian to Aptian. Consequently, an Early Cretaceous age is assigned to the specimen although its exact stratigraphical horizon is unknown. A generic assignment, however, is not possible although it may belong to Paraorthacodus. This specimen represents the first record of a neoselachian from the Early Cretaceous of Antarctica.
Palaeoenvironmental implications of Tertiary sediments from Kainan Maru Seamount and northern Gunnerus Ridge
Authors: HILLENBRAND CLAUS-DIETER , EHRMANN WERNER
Published: December 2003

Sedimentary sequences spanning early Oligocene and Neogene time intervals were recovered with piston and gravity cores along erosional structures at northern Gunnerus Ridge and Kainan Maru Seamount in the southernmost Indian Ocean. Results of sedimentological investigations help to reconstruct the Cenozoic palaeoenvironment. Main emphasis was placed on grain size and clay mineral data. The clay mineral assemblages are dominated by illite and smectite. Chlorite and kaolinite occur in trace amounts. Whereas illite has a distinct source on the East Antarctic craton, smectite is of somewhat speculative origin, but probably is derived from erosion of Cenozoic or older shelf sediments. The presence of terrigenous sand indicates that ice-rafting was active throughout the time represented by the investigated cores, although with varying intensity. During the early Oligocene interval (30.1–29.0 Ma), siliceous phytoplankton production dominated sedimentation. Environmental conditions were quite different from those on Maud Rise and Kerguelen Plateau. The middle Miocene sedimentary sequence (14.1–12.8 Ma) documents an intensification of East Antarctic glaciation. The sediments deposited during the late Miocene interval (8.7–6.5 Ma) and the Pliocene interval (5.1–2.7 Ma) indicate continued cooling of Antarctica, but a more dynamic Antarctic ice sheet resulting in episodic sedimentation patterns.
Water masses and bottom boundary layer dynamics above a sediment drift of the Antarctic Peninsula Pacific Margin
Authors: GIORGETTI ALESSANDRA , CRISE ALESSANDRO , LATERZA ROBERTO , PERINI LUCIANO , REBESCO MICHELE , CAMERLENGHI ANGELO
Published: December 2003

Data from eight CTD casts and two one-year long current time series collected at 8 and 60 m above the seafloor of a sediment drift, off the Pacific Margin of the Antarctic Peninsula are presented, with special emphasis on bottom boundary layer dynamics and processes relevant to sediment settling and re-suspension. The water masses over the drift are characterized, including also a comparison with other measurements available from that region. The south-westward flow along the continental rise exhibits a strong topographic (bathymetric) control in the near-bottom current regime. A consistent mean flow deflection between an upper and lower current regime suggests that only the lower regime falls within a bottom (turbulent) Ekman layer. The bottom current regime is not energetic enough to maintain the coarse sediment fraction in suspension. The absence of evidence for a nepheloid layer justifies the assumption that most sediment was supplied to the margin during glacial periods. Two events, with peak velocities of up to 20 cm s−1, are associated with barotropic eddies shown as negative (cyclonic) mean sea level anomalies detected by ERS/TOPEX satellite altimeters. These energetic bottom current pulses may give way to episodic sediment re-suspensions of the sortable (non-cohesive) part of the sediment, thus exerting a minor role in redistributing fine sediments through the mean flow regime.
A numerical simulation of the geomagnetic sudden commencement: 1. Generation of the field‐aligned current associated with the preliminary impulse
Authors: Fujita S. , Tanaka T. , Kikuchi T. , Fujimoto K. , Hosokawa K. , Itonaga M.
Published: December 2003

The magnetospheric response to a solar wind impulse, a geomagnetic sudden commencement, is studied using an MHD model of the coupled solar wind‐magnetosphere‐ionosphere system. This paper discusses propagation of the first signal launched by the impulse and generation of the field‐aligned current that causes the ground magnetic signal detected as the preliminary impulse (PI). It is revealed that the PI current is first excited as an enhanced Chapman‐Ferraro current in the magnetopause and next turns to the magnetosphere along the wavefront of the compressional signal launched by the impulse. It is finally converted to a field‐aligned current via mode coupling due to plasma nonuniformity. The current in the wavefront region is an inertia current. We present a quantitative model of the PI model presented by Araki [1994] by using a numerical simulation.
Longwave radiative forcing of Saharan dust aerosols estimated from MODIS, MISR, and CERES observations on Terra
Authors: Zhang Jianglong , Christopher Sundar A.
Published: December 2003

Using observations from the Multi‐angle Imaging Spectroradiometer (MISR), the Moderate Resolution Imaging Spectroradiometer (MODIS), and the Clouds and the Earth's Radiant Energy System (CERES) instruments onboard the Terra satellite; we present a new technique for studying longwave (LW) radiative forcing of dust aerosols over the Saharan desert for cloud‐free conditions. The monthly‐mean LW forcing for September 2000 is 7 Wm−2 and the LW forcing efficiency (LWeff) is 15 Wm−2 per unit aerosol optical depth. Using radiative transfer calculations, we show that simultaneous measurements of the vertical distribution of aerosols, surface temperature and water vapor are critical to the understanding of dust LW aerosol forcing, and must come from other sources. Using well calibrated, spatially and temporally collocated data sets, we have combined the strengths of three sensors from the same satellite to quantify the LW forcing, and show that dust aerosols have a “warming” effect over the Saharan desert that will counteract the shortwave “cooling effect” of other aerosols.
Palaeomagnetism of flood basalts in the Pilbara Craton, Western Australia: Late Archaean continental drift and the oldest known reversal of the geomagnetic field
Authors: Strik Geert , Blake Tim S. , Zegers Tanja E. , White Stan H. , Langereis Cor G.
Published: December 2003

A late Archaean (circa 2775–2715 Ma) succession of terrestrial continental flood basalts, mafic tuffs, felsic volcanic rocks, and clastic sedimentary rocks in the Nullagine Synclinorium (and Meentheena Centrocline) of the East Pilbara Basin, Western Australia, has been sampled for a palaeomagnetic study. Over 500 oriented, mostly basalt, drill cores were collected from the supracrustal succession and associated dykes. Thermal and alternating field demagnetization revealed two distinct components. Positive fold, conglomerate, and reversal tests confirm that the primary natural remanent magnetization (NRM) is still preserved. The secondary component is interpreted as the record of remagnetization during a major thermal event, possibly in the Early Proterozoic. Analysis of the primary NRM directions results in a magnetostratigraphy and an apparent polar wander path (APWP) for the 60 Myr interval covered by the sampled succession. Assuming a geocentric axial dipole during this time interval, the APWP shows that the Pilbara Craton was drifting during the late Archaean and that drift rates probably varied significantly. In particular, a mean 27.2° shift in palaeolatitude is recorded across an unconformity that represents a relatively short time period and that marks a significant change in basalt geochemistry. This study suggests that continents moved horizontally during the late Archaean and that the rates of movement were significantly faster than in the Phanerozoic. In addition, a reversed polarity interval, with a positive reversal test, is recorded. We argue that it documents the oldest known geomagnetic reversals of the geomagnetic field.
A Lagrangian method to study stratospheric nitric acid variations in the polar regions as measured by the Improved Limb Atmospheric Spectrometer
Authors: Rivière Emmanuel D. , Terao Yukio , Nakajima Hideaki
Published: December 2003

Denitrification is well known to affect the severity of springtime ozone depletion in Polar Regions. In winter 1996/1997 in the Northern Hemisphere and winter 1997 in the Southern Hemisphere, the Improved Limb Atmospheric Spectrometer (ILAS) on board the Advanced Earth Observing Satellite (ADEOS) detected denitrification in both hemispheres. Here the Match technique and a Lagrangian model are used to analyze the nitric acid variation between a pair of measurements belonging to the same air parcel. Eleven cases are studied in Antarctica and seventeen in the Arctic, permitting testing of the laboratory‐measured homogeneous freezing rate of liquid ternary aerosol into nitric acid hydrates, thought to be the determining step of the denitrification process. Over the Antarctica, eight cases out of eleven lead to results in agreement with the measurements, taking into account uncertainties of the measurement and possible acceptable bias in the temperature field used for the modeling study. Over the Arctic, more cases remain unexplained even after taking into account the possible scavenging of nitric acid by large nitric acid trihydrate (NAT) particles falling from the layers above. These disagreements are mainly due to relatively high temperatures along the trajectories that do not lead to significant NAT or nitric acid dihydrate (NAD) freezing. Thus it appears that some additional mechanisms are required to explain the denitrification in the Arctic winter. Moreover, the occurrence of denitrification due to the few NAT particles with very large radius (few μm), the so‐called “NAT rocks,” over the Antarctic winter in 1997 is suggested.
Can a solid inner core of Mars be detected from observations of polar motion and nutation of Mars?
Authors: Dehant V. , Van Hoolst T. , de Viron O. , Greff‐Lefftz M. , Legros H. , Defraigne P.
Published: December 2003

The core of a terrestrial planet such as Mars is generally considered to evolve, as a result of cooling of the planet, from an initially entirely liquid state, through the growth of a solid inner core, to an entirely solid state. Both theoretical evolution studies and geodesy observations indicate that at least part of the Martian core is still liquid. However, at present, there is no conclusive evidence for the existence or the absence of a solid inner core. A liquid outer core and a solid inner core can strongly affect the rotational dynamics of the planet, in particular, polar motion and nutation, through resonances with three rotational normal modes of the core. For a sequence of Martian models with a growing inner core, the normal modes and their effects on polar motion and nutation are calculated from an analytical model. In particular, the frequencies of the modes and the associated resonance strengths for polar motion and nutation are studied, and the parameters of the interior structure most important for the changes of these quantities are identified. We show that the amplification of nutation and polar motion can be extremely important for particular radii of the inner core that yield resonance frequencies close to the forcing frequencies. Future observations of polar motion and nutation of Mars therefore offer a unique way to observe the deep interior of the planet.
Analysis of small‐scale gravel bed topography during armoring
Authors: Marion Andrea , Tait Simon J. , McEwan Ian K.
Published: December 2003

In evaluating the resistance of sediment particles to entrainment by the action of the flow in a river, the grain geometry is usually characterized using representative sizes. This approach has been dictated, initially by lack of physical insight, but more recently by the lack of analytical tools able to describe the 3‐D nature of surface grain organization on water‐worked sediment beds. Laboratory experiments are presented where mixed grain size beds were mobilized under a range of hydraulic and sediment input conditions. Detailed bed topography was measured at various stages. Statistical tools have been adopted which describe the degree of surface organization on water‐worked sediment bed surfaces. The degree of particle organization and the bed stability can be evaluated in relative terms using the properties of the probability density distribution of the bed surface elevations and in absolute terms using a properly defined 2‐D structure function. The methods described can be applied directly to natural water‐worked surfaces given the availability of appropriate bed surface elevation data sets.
The bone resorbing activity released by gingival fibroblasts isolated from patients with periodontitis is independent of interleukin‐1
Authors: Sjöström Staffan , Hänström Lennart , Lerner Ulf H.
Published: December 2003

Supernatants from gingival fibroblast cultures obtained from 14 patients with periodontal disease contained factor(s) capable of stimulating bone resorption in vitro, as assessed by the release of 45Ca from neonatal mouse calvariae. The possibility that the factor(s) was interleukin‐1α(IL‐1α), IL‐1β or prostaglandin E2(PGE2) was next investigated. The human fibroblast conditioned media (HFCM) stimulated PGE2 biosynthesis in bone. The stimulatory effect by HFCM on 45Ca release, however, was not affected by blocking prostaglandin biosynthesis with indomethacin. In contrast, 45Ca release induced by IL‐1α, IL‐1β, thrombin and bradykinin was significantly reduced by indomethacin, whereas the effects of PTH and PTHrP were unaffected by indomethacin. The concentration of PGE2 in HFCM was too low to be solely responsible for the 45Ca release response. In addition, the amount of bone resorbing activity produced by the gingival fibroblasts was unaffected by cyclo‐oxygenase inhibitors. Similar to IL‐1α and IL‐ 1β, the stimulatory effect of HFCM was inhibited by γ‐interferon. HFCM did not stimulate cyclic AMP formation in the mouse calvarial bones. Antisera which specifically blocked human IL‐1α or IL‐1β induced 45Ca release, and the specific IL‐ 1 receptor antagonistic protein, did not inhibit the stimulatory effect of HFCM. These data show that gingival fibroblasts secrete bone resorbing factor(s) which is not due to IL‐ 1 and which stimulates bone resorption by a prostaglandin‐ and cyclic AMP‐independent mechanism.
An immunohistochemical study of matrix molecules associated with barrier membrane‐mediated periodontal wound healing
Authors: Ivanovski S. , Li H. , Daley T. , Bartold P. M.
Published: December 2003

Guided tissue regeneration (GTR) is a clinical procedure developed to facilitate periodontal regeneration by using barrier membranes to selectively promote the repopulation of a periodontal defect by periodontal ligament and bone cells at the expense of epithelial and gingival connective tissue cells. The aim of this study was to gain insight into the biological events occurring during membrane mediated periodontal wound healing by examining the immunohistochemical expression of a number of extracellular matrix components in tissues treated via the GTR technique. Experimental periodontal defects were created around the second premolar tooth in 4 dogs and wound closure was achieved by application of expanded polytetrafluoroethylene membranes around each tooth and flap positioning coronal to the cemento–enamel junction. The dogs were sacrificed after a 4‐wk healing period, block dissections of the part of the mandible containing the experimental tooth were obtained and paraffin sections were prepared. Using standard immunohistochemical techniques, the sections were stained with a monoclonal antibody against bone morphogenetic proteins 2 and 4 (BMP‐2 and ‐4) and polyclonal antibodies against collagen I, collagen III, decorin, biglycan, bone sialoprotein, osteopontin and osteocalcin. Collagen I was predominantly localized within the regenerating bone, whereas collagen III staining was more abundant in the soft connective tissues of the defect. Decorin and biglycan staining was faint within the extracellular matrix of the regenerating defect, although both proteoglycans exhibited intense intracellular localization within some of the cells inhabiting the defect. The staining for BMP‐2 and ‐4 was weak within the bone but strong within the extracellular matrix of the regenerating soft tissue. Osteopontin and bone sialoprotein were strongly localized in the regenerating bone and cementum found within the defect. Osteocalcin staining was present in both the regenerating and mature cementum and associated cementoblasts, and it was relatively weaker in the regenerating bone compared to the mature bone. The observed pattern of immunolocalization of the extracellular matrix macromolecules suggests that the heterogeneous cell population filling the GTR wound had created an environment that was conducive to periodontal regeneration.
Expression and activity of thrombomodulin in human gingival epithelium: in vivo and in vitro studies
Authors: Matsuyama T. , Izumi Y. , Shibatate K. , Yotsumoto Y. , Obama H. , Uemura M. , Maruyama I. , Sueda T.
Published: December 2003

Epidermal keratinocytes thrombomodulin (TM) has been shown to regulate thrombin at sites of cutaneous injury in addition to a role for epidermal differentiation. TM, a major anticoagulant proteoglycan of the endothelial cell membrane, is a thrombin receptor that acts as a co‐factor for protein C activation. Thrombin has pro‐inflammatory effects for periodontitis. However, little is known about TM in gingival tissue with periodontitis. We used immunohistochemistry to examine expression of TM in gingival epithelium from patients with periodontitis. In vitro, we observed TM expression at varying Ca2+ concentrations by confocal laser scanning microscopy, examined the expression of TM mRNA and tested TM co‐factor activity. Furthermore, we measured TM concentration in gingival crevicular fluid (GCF) from 11 severe adult cases of periodontitis using enzyme‐linked immunosorbent assay. Immunoreactive TM was present in gingival epithelium and junctional epithelium, and was reduced in inflamed gingival epithelium compared to healthy gingival epithelium. Ultrastructurally, TM, including microvilli, was observed on the cell membrane. TM localization in cells cultured in 0.09 mm Ca2+ differed from that in cells exposed to 1.2 mm Ca2+. Northern analysis demonstrated TM mRNA in gingival keratinocytes more than in human umbilical vein endothelial cells (HUVEC). Gingival keratinocytes also facilitated protein C activation by thrombin, although less strongly than HUVEC. TM in GCF at sites with bleeding on probing in patients was significantly elevated (p<0.001, Student's t‐test). TM in gingival epithelium may regulate thrombin activity at sites of coagulation and inflammation with periodontal disease, although inflammation may impair this regulation of thrombin.