bluuebunny/crossref_metadata_2025 huggingface dataset:
Leukemia inhibitory factor signaling is implicated in embrionic development of the HPA axis
Authors: Ware Carol B. , Kariagina Anastasia , Zonis Svetlana , Alon Dana , Chesnokova Vera
Published: July 2005

Leukemia inhibitory factor (LIF) is expressed in the hypothalamic‐pituitary adrenal (HPA) axis and stimulates pituitary POMC transcription. The role of LIF receptor signaling in HPA axis development was examined. Lifr −/− and Lifr +/+ fetuses were obtained by Cesarean section on E18.5. Despite a 3‐fold induction of hypothalamic CRH mRNA, pituitary POMC mRNA and RU486‐induced ACTH levels were decreased in Lifr −/− mice. High CRH may be caused by increased central TNFα and IL‐6 expression. Lifr −/− mice demonstrate elevated pituitary glucocorticoid (GR) and mineralocorticoid (MR) receptor mRNA and protein levels, indicating the importance of LIF signaling for HPA axis development.
Expression of neuritin during liver maturation and regeneration
Authors: Kojima Nobuhiko , Shiojiri Nobuyoshi , Sakai Yasuyuki , Miyajima Atsushi
Published: July 2005

Cell surface molecules are not only important for cell–cell interactions but also useful for a marker to define cell types and differentiation stages. Unlike hematopoietic system in which numerous such antigens have been identified, only a few cell surface molecules have been used to define differentiation stage of hepatocytes. In order to identify such cell surface molecules, we performed DNA microarray analysis using mRNA from fetal hepatocytes in E12.5 and E17.5 mice and cDNAs encoding a membrane protein were selected. Northern blot analysis was employed to confirm the genes upregulated during maturation of fetal hepatocytes and neuritin, a GPI‐anchored protein, was found as a membrane protein expressed in hepatocytes, but not in nonparenchymal cells. Its expression increased along with liver development and the maximum expression was achieved from the neonatal to adult stage. The neuritin protein was localized in sinusoidal lumen of hepatocytes in adult liver. Partial hepatectomy transiently downregulated the expression of neuritin. The expression of neuritin mRNA in C/EBPα deficient liver was reduced to about 50% of that of wild type mice. Thus, neuritin expression is well correlated to the maturation of hepatocytes and can be a useful tool to define the differentiation stage of hepatocytes.
Crystal structure of a mutant elongation factor G trapped with a GTP analogue
Authors: Hansson Sebastian , Singh Ranvir , Gudkov Anatoly T. , Liljas Anders , Logan Derek T.
Published: July 2005

Elongation factor G (EF‐G) is a G protein factor that catalyzes the translocation step in protein synthesis on the ribosome. Its GTP conformation in the absence of the ribosome is currently unknown. We present the structure of a mutant EF‐G (T84A) in complex with the non‐hydrolysable GTP analogue GDPNP. The crystal structure provides a first insight into conformational changes induced in EF‐G by GTP. Comparison of this structure with that of EF‐G in complex with GDP suggests that the GTP and GDP conformations in solution are very similar and that the major contribution to the active GTPase conformation, which is quite different, therefore comes from its interaction with the ribosome.
STAT4 is a target of the hematopoietic zinc‐finger transcription factor Ikaros in T cells
Authors: Yap Wai-Ho , Yeoh Elizabeth , Tay Alice , Brenner Sydney , Venkatesh Byrappa
Published: July 2005

STAT4 is a transcription factor activated in response to IL‐12, and is involved in Th1 cell development. The molecular mechanisms controlling the transcription of the STAT4 gene are however, unclear. Sequence comparison of the 5′ flanking regions of human, mouse and pufferfish (Fugu rubripes) Stat4 genes revealed a high frequency of Ikaros (Ik) binding elements in all three species. We then investigated the role of Ik binding elements in the human STAT4 promoter using Jurkat T cells. Transactivation, electrophoretic mobility shift assay and RNA interference‐mediated gene knockdown experiments revealed that Ik is involved in the regulation of STAT4 in human T cells.
Oxidative stress and metal ions effects on the cores of phycobilisomes in Synechocystis sp. PCC 6803
Authors: Liu Xing-Guo , Zhao Jing-Jing , Wu Qing-Yu
Published: July 2005

Inactivation of the chlN gene in Synechocystis sp. PCC 6803 resulted in no chlorophyll and photosystems when the mutant was grown in darkness, providing an in vivo system to study the structure and function of phycobilisomes (PBSs). The effects of hydrogen peroxide (H2O2) and metal ions on the mutant PBSs in vivo were investigated by low temperature fluorescence emission measurement. H2O2 induced an obvious disassembly of the cores of PBSs and interruption of energy transfer from allophycocyanin to the terminal emitter. Among many metal ions only silver induced disassembly of the cores of PBSs. Our results demonstrated for the first time that the cores of PBSs act as targets in vivo for oxidative stress or silver induced damage.
Tobamovirus‐resistant tobacco generated by RNA interference directed against host genes
Authors: Asano Momoko , Satoh Rena , Mochizuki Atsuko , Tsuda Shinya , Yamanaka Takuya , Nishiguchi Masamichi , Hirai Katsuyuki , Meshi Tetsuo , Naito Satoshi , Ishikawa Masayuki
Published: July 2005

Two homologous Nicotiana tabacum genes NtTOM1 and NtTOM3 have been identified. These genes encode polypeptides with amino acid sequence similarity to Arabidopsis thaliana TOM1 and TOM3, which function in parallel to support tobamovirus multiplication. Simultaneous RNA interference against NtTOM1 and NtTOM3 in N. tabacum resulted in nearly complete inhibition of the multiplication of Tomato mosaic virus and other tobamoviruses, but did not affect plant growth or the ability of Cucumber mosaic virus to multiply. As TOM1 and TOM3 homologues are present in a variety of plant species, their inhibition via RNA interference should constitute a useful method for generating tobamovirus‐resistant plants.
Oxidized phospholipids induce phase separation in lipid vesicles
Authors: Megli Francesco M. , Russo Luciana , Sabatini Karen
Published: July 2005

The thermal behaviour of phospholipid multilamellar vesicles (MLV) made of various molar percentages of DPPC and LPPC, containing also oxidized LPPC (LPPCox), was studied by use of EPR spectroscopy and n‐DSPC spin label in order to determine variations in the membrane fluidity brought about by lipid oxidation. Experimental variables were temperature, ranging from 4 to 44 °C, and molar percentage composition of DPPC/LPPC/LPPCox ternary mixture. We found that the presence of LPPCox in a percentage higher than both normal phospholipids’ heavily hindered membrane formation, while lower percentage of the oxidized lipid with higher DPPC percentages yielded two‐components EPR spectra, showing the presence of two different fluidity domains, indicative of membrane phase separation. When LPPC was the dominant lipid in the ternary mixture, simple EPR spectra were observed, indicating homogeneity of MLV membranes. Phase separation observed in the presence of LPPCox was better visible at lower temperature (12 °C or less), and almost disappeared with increasing temperature (36 °C or more). Furthermore, the correlation time of 16‐DSPC in ternary mixture MLVs with higher LPPC percentage (homogeneous membranes) was not affected by the presence of LPPCox, while it normally increased upon DPPC percentage increase, as readily calculated from the EPR spectra featuring simple bands at 24 °C. It is concluded that oxidized lipid induces phase separation in more rigid DPPC‐rich membranes, while leaving fluidity unaffected in more fluid LPPC‐rich membranes, and at higher temperature.
Treatment of rectosigmoid endometriosis by laparoscopically assisted vaginal rectosigmoidectomy
Authors: Abrao M.S. , Sagae U.E. , Gonzales M. , Podgaec S. , Dias J.A.
Published: July 2005

Objective: To describe the use of mechanical anastomoses in cases of laparoscopically assisted vaginal rectosigmoidectomy for the treatment of rectosigmoid endometriosis. Methods: Pilot study evaluating eight patients with rectosigmoid endometriosis referred for surgical treatment. All patients were submitted to laparoscopically assisted vaginal segmental resection of the rectosigmoid with anastomoses performed using linear and circular staplers. Results: The average length of the surgical procedure was 177.5 min and average duration of hospitalization was 4.13 days. There were no intra‐operative complications and integrity of the anastomoses was confirmed in all patients. One patient reported partial improvement of symptoms and 7 patients presented complete clinical remission 12 months following surgery. Conclusion: Laparoscopically assisted vaginal segmental resection of the sigmoid infiltrated by endometriosis is a feasible surgical procedure. The technique combines transvaginal access with mechanical intestinal anastomoses performed using linear and circular staplers, and achieves good results with low morbidity.
Stock returns and inflation in Greece: A Markov switching approach
Authors: Hondroyiannis George , Papapetrou Evangelia
Published: July 2005

The paper studies the dynamic relationship between real stock returns and expected and unexpected inflation utilizing a Markov Switching vector autoregressive model (MS‐VAR). The MS‐VAR model has the advantage that it is able to capture the dependence structure of the series both in terms of mean and variance. Univariate and multivariate innovation decompositions are employed to separate inflation into two components, the expected and unexpected. The empirical evidence suggests that real stock returns are not related to expected and unexpected inflation and this result is independent of the method used to separate inflation into the two components. Rather, the results suggest that stock market movements are regime dependent, implying that stock market performance is not predictable.
Phylogeography of Aedes (Stegomyia) aegypti (L.) and Aedes (Stegomyia) albopictus (Skuse) (Diptera: Culicidae) based on mitochondrial DNA variations
Authors: MOUSSON LAURENCE , DAUGA CATHERINE , GARRIGUES THOMAS , SCHAFFNER FRANCIS , VAZEILLE MARIE , FAILLOUX ANNA-BELLA
Published: July 2005

Aedes (Stegomyia) aegypti (L.) and Aedes (Stegomyia) albopictus (Skuse) are the most important vectors of the dengue and yellow-fever viruses. Both took advantage of trade developments to spread throughout the tropics from their native area: A. aegypti originated from Africa and A. albopictus from South-East Asia. We investigated the relationships between A. aegypti and A. albopictus mosquitoes based on three mitochondrial-DNA genes (cytochrome b, cytochrome oxidase I and NADH dehydrogenase subunit 5). Little genetic variation was observed for A. albopictus, probably owing to the recent spreading of the species via human activities. For A. aegypti, most populations from South America were found to be genetically similar to populations from South-East Asia (Thailand and Vietnam), except for one sample from Boa Vista (northern Amazonia), which was more closely related to samples from Africa (Guinea and Ivory Coast). This suggests that African populations of A. aegypti introduced during the slave trade have persisted in Boa Vista, resisting eradication campaigns.
The carpenter's revolt: youth, violence and the reinvention of culture in Nigeria
Authors: Adebanwi Wale
Published: July 2005

This paper examines the cultural repertoires of the youthful, ‘militant’ faction of the Oodua People's Congress (OPC) in Nigeria, pointing to ways in which violence and ritual can be interpreted both as an instrumentally rational strategy of power struggle and as a form of symbolic action with cultural meanings. The OPC case strongly challenges the bifurcation of tradition and modernity, given the way the group appropriate culture in negotiating Yoruba identity, while also retaining democratic rhetoric. It argues that the activities of the OPC constitute not stable, bounded manifestations of culture, but rather fluid, ambivalent and paradoxical ethnic-power relations and formations.
South Africa's economic relations with Africa: hegemony and its discontents
Authors: Alden Chris , Soko Mills
Published: July 2005

South Africa's growing economic presence across the African continent has sparked a debate in public and scholarly circles as to its intentions. While some have been quick to see South African business and parastatals as part of a larger hegemonic project pursued by Pretoria, the authors’ more structured analysis of economic ties with Africa reveals a more complex picture. Institutionalised forms of regional cooperation, such as SACU and SADC, must be contrasted with the activities of South African multinationals and parastatals on the wider African stage to understand the possibilities and limitations of hegemonic practice open to South Africa. Beyond its own region, a key determinant will be its relations with the other leading African power, Nigeria, as well as its ability to compete with other external actors. Finally, the role of ideology is a crucial measure of South African hegemony, and while certainly its ‘soft power’ is evident at the societal level, some African elites actively resist the pull of South Africa-based ideas.
Reforming the Algerian electoral system
Authors: Bouandel Youcef
Published: July 2005

In October 1988, Algeria began a process of transition from authoritarianism. Political reforms were introduced, on the surface, to facilitate the process of transition, but in reality to ensure the survival of the incumbent regime. The reform of the electoral system played a significant part in this survival strategy. Between 1989 and 1997, Algeria witnessed the adoption of three distinct electoral systems as the authorities sought ways to give a façade of democratisation while manipulating the rules to suit their purposes. This paper looks at the Algerian transition, asks why the Algerian authorities switched from one system to another, and assesses the impact of the three different electoral systems that the country has experienced.
Continuidade na renovação? Ten years of multiparty politics in Mozambique: roots, evolution and stabilisation of the Frelimo–Renamo party system
Authors: Carbone Giovanni M.
Published: July 2005

Post-conflict elections in Mozambique, held in 1994, 1999 and 2004, established a formally competitive and pluralistic system. This paper examines the country's emerging two-party system as an essential feature affecting prospects for democratic deepening and consolidation. The condition for political parties to actually help the establishment of democratic politics is their development as durable, socially rooted, country-wide effective and legitimate organisations. The paper contends that the current party system has indeed been a major instrument for political expression and for the channelling and peaceful management of conflicts. It shows how both Frelimo and Renamo – and the competition between them – have deep-seated historical origins and well-established regional roots. Yet, a number of aspects concerning the Mozambican party system negatively affect the deepening of democratic politics: the legitimacy of the party system is weakened by post-conflict polarisation and uncertain mutual recognition; the ethno-regional entrenchment of the two main parties bestows a communal connotation on electoral competition; and most importantly, the party system remains unbalanced and unevenly institutionalised, with Frelimo's disciplined and fundamentally institutionalised organisation opposed by a strongly personalistic and weakly organised Renamo, which struggles to operate within state institutions and to accommodate internal differences.
Getting the state right: think tanks and the dissemination of New Public Management ideas in Ghana
Authors: Ohemeng Frank Louis Kwaku
Published: July 2005

Private research institutions, commonly referred to as think tanks, are a recent phenomenon in the Ghanaian policy environment. They are part of a growing number of NGOs that have emerged with Ghana's political liberalisation and are attempting to influence policymaking. These institutions exert a greater influence on policies affecting the functioning of the ‘administrative state’ than other NGOs. Through their efforts, ideas pertaining to administrative reform appear to have taken root strongly in Ghana. This paper examines the processes and methods that have been adopted by these institutions in developing policies that are being pursued to change the ‘administrative state’ in Ghana. It argues that the ability of these institutions to influence policies geared towards changing the administrative state can be attributed to the calibre of personnel as well as the processes and methods they have adopted.
Caught in the headlights of history: Eritrea, the EPLF and the post-war nation-state
Authors: Reid Richard
Published: July 2005

A little over a decade after the achievement of independence, Eritrea is confronted by a range of social and political problems, problems which are rooted both in the nation's past and in the ruling movement's interpretation of that past. This paper is concerned with the widening gulf between the nation-state, as envisaged by the Eritrean People's Liberation Front (EPLF) during the liberation struggle and as currently ‘imagined’ by the government, and the socio-political reality. Eritrean society is now marked by widening divisions between the ‘struggle generation’ and the membership of the former EPLF on the one hand, and large sections of the remainder of the population, notably youth. The 1998–2000 war with Ethiopia, the root causes of which are as yet unresolved, has proved more destructive than was apparent even at the time, and has been used by the state as a vindication of the EPLF's particular interpretation of the past. Political and social repression, rooted in a militaristic tradition and a profound fear of disunity, has intensified since the war. In this paper the current situation is examined in terms of the deep frustration felt by younger Eritreans, the urban–rural divide, the state-level determination to cling to the values and the aims of the liberation struggle, and the position of Eritrea in international politics.
Toxoplasma gondiidense granule protein 3 (GRA3) is a type I transmembrane protein that possesses a cytoplasmic dilysine (KKXX) endoplasmic reticulum (ER) retrieval motif
Authors: HENRIQUEZ F. L. , NICKDEL M. B. , MCLEOD R. , LYONS R. E. , LYONS K. , DUBREMETZ J.-F. , GRIGG M. E. , SAMUEL B. U. , ROBERTS C. W.
Published: July 2005

Studies using antibodies to immunolocalize theToxoplasma gondiidense granule protein GRA3, have shown that this protein associates strongly with the parasitophorous vacuole membrane (PVM). However, as there was no predicted membrane-spanning domain this highlighted an unanswered paradox. We demonstrate that the previously published sequence for GRA3 is actually an artificial chimera of 2 proteins. One protein, of molecular weight 65 kDa, shares the C-terminus with published GRA3 and possesses no significant sequence similarity with any protein thus far deposited in Genbank. The second, with a predicted molecular weight of 24 kDa shares the N-terminal region, is recognized by the monoclonal antibody 2H11 known to react with the dense granules ofT. gondiiand is therefore the authentic GRA3. The corrected GRA3 has an N-terminal secretory signal sequence and a transmembrane domain consistent with its insertion into the PVM. Antibodies to recombinant GRA3 recognize a protein of 24 kDa inT. gondiiexcretory–secretory antigen preparations. The signal peptide is necessary and sufficient to target GFP to the dense granules and parasitophorous vacuole. A homologue was identified inNeospora caninum. Finally, GRA3 possesses a dilysine ‘KKXX’ endoplasmic reticulum (ER) retrieval motif that rationalizes its association with PVM and possibly the host cell ER.
Analysis of the ITS region and partial ssu and lsu rRNA genes ofBlastocystisandProteromonas lacertae
Authors: HOEVERS J. D. , SNOWDEN K. F.
Published: July 2005

Blastocystisis a common single-celled enteric parasite found in a large variety of hosts. Recent molecular analysis supports the concept that this eukaryotic organism is a stramenopile most closely related toProteromonas lacertae, a parasite of reptiles. In this study, the internal transcribed spacer region, partial small subunit rRNA and large subunit rRNA genes from 7Blastocystisisolates (5 human, 1 pig and 1 sheep), and aProteromonas lacertaeisolate were amplified by PCR, cloned and sequenced.Blastocystiswas found to be a typical eukaryote with both ITS1 and ITS2 regions present. Phylogenetic analysis based on the entire PCR amplicon revealed that theBlastocystisisolates did not segregate according to host or geographic origin. The highest sequence identities with the conservedBlastocystis5·8S rDNA sequence were with the stramenopilesFibrocapsa japonica,Chattonella marina,Cylindrotheca closteriumandHyphochytrium catenoides. The most parsimonious tree based on the 5·8S rDNA sequence fromP. lacertae, 11 other stramenopiles, 2 fungi, 3 algae and 3 alveolates showedBlastocystispositioned within the stramenopiles, withP. lacertaeas its closest relative. This work therefore supports the hypothesis thatBlastocystisis most closely related toP. lacertae, and that it should be regarded as an unusual stramenopile.
Significant familial differences in the frequency of abortion and Toxoplasma gondii infection within a flock of Charollais sheep
Authors: MORLEY E. K. , WILLIAMS R. H. , HUGHES J. M. , TERRY R. S. , DUNCANSON P. , SMITH J. E. , HIDE G.
Published: July 2005

A study was carried out to investigate the frequencies of abortion and congenital Toxoplasma gondii infection within 27 families (765 individuals) of a pedigree Charollais sheep flock maintained on a working farm in Worcestershire, UK, since 1992. Pedigree lambing records were analysed to establish the frequency of abortion for each family. The frequency of congenital infection was determined for each family by PCR analysis of tissue samples taken from newborn lambs. A total of 155 lambs were tested for congenital T. gondii infection, which were all born during the study period 2000–2003. Significant differences in the frequency of abortion between sheep families within this flock were observed with frequencies ranging between 0% and 48% (P<0·01). Significantly different infection frequencies with T. gondii were also observed for different families and ranged between 0% and 100% (P<0·01). Although the actual cause of each abortion was not verified, a highly significant positive correlation was found to exist between the frequency of abortion and the frequency of T. gondii infection in the same families (P<0·01). The data presented here raise further questions regarding the significance of congenital transmission of T. gondii within sheep populations, the possible successive vertical transmission of T. gondii within families of sheep, and the potential role of inherited genetic susceptibility to abortion with respect to T. gondii infection. This work invites further study into the epidemiology of ovine toxoplasmosis and may have implications for sheep husbandry methods in the future.
Interaction between the blood fluke,Sanguinicola inermisand humoral components of the immune response of carp,Cyprinus carpio
Authors: ROBERTS M. L. , LEWIS J. W. , WIEGERTJES G. F. , HOOLE D.
Published: July 2005

The effect ofSanguinicola inermison serum antibody and complement activity inCyprinus carpiowas assessed using an ELISA and haemolytic assays. Possible immune evasion strategies were assessed using immunodetection of host proteins on the surface of the parasite. Carp acclimatized to 20 or 25 °C were infected by exposure to 500 cercariae or injected intraperitoneally with 150 cercariae, and serum monitored over a 63-day period. In cercariae-injected carp, irrespective of time and temperature, a significant increase occurred in complement activity being greatest at 25 °C. In addition, fish exposed to the cercariae ofS. inermisand maintained at 20 °C the level of complement activity was significantly higher after 5 weeks compared to controls. At 20 °C intraperitoneal injections of parasites increased serum antibody levels which peaked after 7 days. In contrast, at 25 °C, antibody levels were maintained over 63 days. Exposure of fish to infection did not appear to stimulate antibody production. Immunofluorescence studies revealed ‘host-like’ molecules on the surface of the cercarial body exposed to carp serum and adult flukes obtained directly from the fish or cultured for 24 h in L15 medium. The possible role of ‘host-like’ molecules in immune evasion is discussed and the response at different temperatures is related to infection dynamics.
Altered tubulin dynamics, localization and post-translational modifications in sodium arsenite resistantLeishmania donovaniin response to paclitaxel, trifluralin and a combination of both and induction of apoptosis-like cell death
Authors: JAYANARAYAN K. G. , DEY C. S.
Published: July 2005

In this study the anti-leishmanial activity and anti-microtubule effects of paclitaxel, trifluralin and a combination of paclitaxel and trifluralin have been tested in a wild type and sodium arsenite-resistant strain ofLeishmania donovani. Both paclitaxel and trifluralin have been shown to be effective in limiting parasite growth. Specific alterations in morphology, tubulin polymerization dynamics, post-translational modifications and cellular distribution of the tubulins have been confirmed to be a part of the intracellular anti-microtubule-events that occur in arsenite-resistantL. donovaniin response to these agents, ultimately leading to death of the parasite. DNA analyses of the drug-treated wild type and arsenite-resistant strains revealed an apoptosis-like death in response to paclitaxel and the combination but not to trifluralin. Data provide valuable information for further development of chemotherapeutic strategies based on anti-microtubule agents against drug resistantLeishmaniaparasites.
A direct interview family study of obsessive–compulsive disorder. I
Authors: FYER ABBY J. , LIPSITZ JOSHUA D. , MANNUZZA SALVATORE , ARONOWITZ BONNIE , CHAPMAN TIMOTHY F.
Published: July 2005

Background. This and the companion paper present two sequential family studies of obsessive–compulsive disorder (OCD) conducted by the same research group, but with different sampling and best-estimate procedures. In addition to providing further data on familial transmission of OCD, we used comparison of disparate findings (moderate, specific familial aggregation in this first study versus a stronger effect for other anxiety disorders than for OCD alone in the second) to examine possible effects of proband characteristics and informant data on outcome.

Method. In this initial study we interviewed 179 first-degree relatives of 72 OCD probands and 112 relatives of 32 never mentally ill (NMI) controls. Informant data were obtained on an additional 126 relatives (total ‘combined’ samples of 263 and 154 respectively). Analyses used best-estimate diagnoses made by consensus of two ‘blinded’ senior clinicians who reviewed all diagnostic materials including proband informant data about relatives.

Results. Significantly higher risk for OCD but not other anxiety disorders was found in relatives of OCD probands compared to relatives of controls in both the directly interviewed and combined samples. There was no relationship between proband age at onset of OCD and strength of familial aggregation.

Conclusions. These data indicate moderate familial aggregation of OCD, but do not support increased transmission by early onset probands, or a familial relationship between OCD and other anxiety disorders with the possible exception of generalized anxiety disorder.
Annual review of research
Authors: Johnstone Richard
Published: July 2005

The present review refers to studies published in leading international research journals in 2003. It gives priority to published research on learning, teaching and policy in respect of second, modern foreign or additional languages. The aim is not simply to describe or summarise the studies which have been selected for comment, but rather to identify key features which seem to be significant. Since in each case only a few brief and not fully representative words can be devoted to any one article, a further aim of the review is of course to point readers in the direction of the original articles themselves. As usual, I have broken the review down into a number of key themes, beginning this year with Affective Factors. However, this does not imply that an article deals exclusively with the theme into which I have assigned it. An article appearing in the theme of Acquisition and Learning for example will in many cases have relevance to other themes such as Proficiency, Teaching, Strategies or Curriculum. As in previous years reference is made to the abstracts. Thus, MacIntyre, Baker, Clément & Donovan (2003: 03-463) refers to an article by these four authors published in 2003 and reflected in the 2003 series of this journal as abstract 463.
Signatures of Alfvén‐cyclotron wave‐ion scattering: Advanced Composition Explorer (ACE) solar wind observations
Authors: Gary S. Peter , Smith Charles W. , Skoug Ruth M.
Published: July 2005

Theory and simulations predict that Alfvén‐cyclotron fluctuations of sufficiently short wavelengths and at propagation approximately parallel or antiparallel to the background magnetic field Bo in collisionless plasmas scatter ions so as to increase their energies in the directions perpendicular to Bo. Linear Vlasov theory for a homogeneous, isotropic plasma of electrons, protons, and alpha particles predicts that alpha particle cyclotron resonance properties and ion cyclotron damping of such fluctuations are sensitive functions of the alpha/proton relative velocity. If a strong ion resonance corresponds to strong ion pitch‐angle scattering, linear theory implies observable signatures in the anisotropies of solar wind alphas and protons. Statistical analyses of proton and alpha particle anisotropies measured in the solar wind near 1 AU by the plasma and magnetic field instruments on the Advanced Composition Explorer (ACE) spacecraft are reported which are largely consistent with such signatures.
Anomalous and classical diffusion of cosmic rays due to nonlinear two‐dimensional structures and random magnetic fields
Authors: Verkhoglyadova O. P. , le Roux J. A.
Published: July 2005

Magnetic field turbulence in the heliosphere is modeled by two‐dimensional coherent vortex structures and random‐phase linear wave fields added to a background magnetic field. Energetic particle trapping and acceleration by interaction with the turbulent fields are studied numerically. The corresponding radial and field‐aligned diffusion coefficients are estimated. Different diffusion regimes (subdiffusion, superdiffusion, classical diffusion) are controlled by the following parameters: the ratio between amplitudes of the random component and the regular vortex field, ε1, and the ratio between the average particle gyroradius and the magnetic field correlation length, ε2. The anomalous diffusion regime occurs when the correlation length of magnetic field disturbances is about the same or larger than the particle gyroradius (ε2 ≤ 1). Applications of our results to cosmic ray transport are discussed.
Comparison of intense nightside shock‐induced precipitation and substorm activity
Authors: Meurant M. , Gérard J.‐C. , Blockx C. , Coumans V. , Hubert B. , Connors M. , Lyons L. R. , Donovan E.
Published: July 2005

Sudden variations of the solar wind dynamic pressure frequently induce dayside enhancements of auroral activity with features such as high‐latitude arcs, low‐latitude proton flashes, and enhancement of auroral precipitation propagating dawnward and duskward from noon to the night sector. In some cases, these shocks also induce enhanced activity during which the power precipitated into the night sector may reach values as high as observed during substorms. Several studies have shown that the triggering of nightside‐enhanced precipitation is more likely during periods of southward interplanetary magnetic field (IMF) components. Early works showed that substorm‐like activity is not frequent after a shock and suggested that shocks may not be considered as substorm triggers. We examine up to what point substorm‐like nightside activity triggered by a shock is comparable to an isolated substorm. For this purpose, we analyze three events morphologically similar to substorms and occurring within less than 20 min after the arrival of a pressure pulse on the front of the magnetosphere. Different features of these events such as the mean energy of precipitated electrons, the latitudinal motion of boundaries before and after onset, and the power precipitated into the nightside sector are compared with isolated substorms. We conclude that the characteristics of shock‐induced substorms appear very similar to those of isolated substorms. Shocks are able to trigger substorms when they hit an unstable magnetosphere. The interpretation is that the perturbation due to the shock induces a substorm by closure of the plasma sheet magnetic field. For the events presented in this study, the instability result from a period of southward IMF or stretching of the magnetic tail induced by a previous shock.
On the dynamics of NaCl‐H2O fluid convection in the Earth's crust
Authors: Geiger S. , Driesner T. , Heinrich C. A. , Matthäi S. K.
Published: July 2005

Numerical simulations of transient porous media thermohaline convection including phase separation into a high‐density, high‐salinity brine phase and a low‐density, low‐salinity vapor phase at pressures and temperatures well above the critical point of pure H2O are presented. Using a novel finite element–finite volume (FEFV) solution technique and a new equation of state for the binary NaCl‐H2O system, convection of a NaCl‐H2O fluid in an open top square box of 4 × 4 km is studied at geologically realistic pressure p, temperature T, and salinity X conditions. In the simulations, the basal temperature and salinity are varied systematically from 200 to 600°C and from 3.2 to 40 or 60 wt % NaCl, for permeabilities of 10−15 or 10−14 m2 and hydrostatic pressure conditions. Resulting flow patterns are diffusive, steady convective, or oscillatory. Single‐phase thermohaline convection occurs at temperatures below 400°C. Between 400 and 450°C, phase separation can occur during the buoyant rise of heat and salt if the permeability is high or the salinity low. Above 450°C, the fluid at the basal boundary is a vapor phase coexisting with a brine phase. In this case, convection is dominated by heat and salt transport during the buoyant rise of vapor. Convection sets in almost instantaneously at these conditions. Above 570°C, a nearly pure H2O vapor phase coexists with solid salt at the basal boundary. Convection is driven exclusively by the applied temperature gradient. Since fluid properties change by highly nonlinear functions of p, T, and X, parameters such as the Rayleigh number and buoyancy ratio, which are classically used to quantify the different regimes of thermohaline convection, are not meaningful in this context. This implies that parametric studies that make use of the Boussinesq approximation and assume incompressibility are not representative of thermohaline convection in geologic environments. We use the concept of a local Rayleigh number and a fluxibility parameter to provide a better insight into the onset and evolution of thermohaline convective systems.
Water weakening of clinopyroxenite in diffusion creep
Authors: Hier‐Majumder Saswata , Mei Shenghua , Kohlstedt David L.
Published: July 2005

We performed triaxial compressive creep tests to study water weakening of clinopyroxenite in the diffusion creep regime. All tests were carried out on fine‐grained samples at confining pressures between 100 and 300 MPa at temperatures of 1321 to 1421 K for water‐saturated and 1398 to 1508 K for anhydrous conditions. Samples were prepared by hot‐pressing ground powder of Sleaford Bay clinopyroxenite. Water was added to the sample during the run by dehydration of a talc sleeve. Water‐saturated aggregates crept ∼30 times faster than aggregates under anhydrous conditions at a temperature of 1400 K and a pressure of 300 MPa. The stress exponent in both cases was ∼1, and the activation energies under water‐saturated and anhydrous conditions were 340 ± 30 and 760 ± 20 kJ/mol, respectively. Under water‐saturated conditions creep rate increased with increasing water fugacity to the power 1.4 ± 0.2 with an activation volume for creep of 14 ± 6 × 10−6 m3/mol. Comparison of the water weakening in aggregates of clinopyroxene, olivine, and anorthite deformed in the diffusion creep regime indicates that the creep strength of clinopyroxene has a stronger dependence on the water fugacity than do the creep strengths of olivine and anorthite. In water‐rich environments, clinopyroxene will be the weakest component in polycrystalline rocks composed of these phases.
A high‐resolution simulation of the ocean during the POMME experiment: Simulation results and comparison with observations
Authors: Paci A. , Caniaux G. , Gavart M. , Giordani H. , Lévy M. , Prieur L. , Reverdin G.
Published: July 2005

A modeling study of physical processes occurring in an area of the northeast Atlantic (21.33°–15.33°W, 38.00°–45.00°N) that was extensively sampled during the Programme Océan Multidisciplinaire Méso Echelle (POMME) (October 2000–September 2001) is carried out. The model is a mesoscale version of the ocean general circulation model OPA developed at the Laboratoire d'Océanographie Dynamique et de Climatologie in Paris. It is used in a three‐dimensional limited area domain with a high‐resolution grid (approximately 5 km horizontal spacing, 69 vertical levels) and realistic boundary conditions (initial state, air‐sea fluxes, open boundary fluxes, and bottom topography). The objectives of the study are to properly simulate the upper ocean dynamics, particularly mesoscale activity and mixed layer evolution, during a key period (restratification) of the POMME experiment (POMME 1 and POMME 2, from February to May 2001) and to compare model results with oceanographic observations collected during the experiment in order to establish confidence in the model. Some results provided by the high‐resolution simulation, in particular features related to mixed layer depth and vertical velocities, are also presented. There is no pronounced north‐south mixed layer depth gradient, but strong filament‐shaped structures associated with stirring at the periphery of eddies are present. Mixed layer restratification is simulated. It is associated with submesoscale mixed layer depth structures and intense vertical velocity filaments in the upper ocean correlated with the relative vorticity gradient field.
Impact of rain cell on scatterometer data: 2. Correction of Seawinds measured backscatter and wind and rain flagging
Authors: Tournadre J. , Quilfen Y.
Published: July 2005

Rain can strongly modify the normalized radar cross section (NRCS) measured by Ku‐band scatterometers and alter the wind vector retrieval. Part 1 of this paper (Tournadre and Quilfen, 2003) presented a theoretical model of interaction between rain and scatterometer signal and used it to quantify the effect of rain on the backscatter and on wind vectors. Their results showed that the scatterometer data are strongly affected by rain, that they are extremely sensitive to the rain distribution within scatterometer resolution cells, and that the normalized radar cross section (NRCS) variability induced by rain could be a good indicator for rain flagging. The model is further tested and validated on a tropical cyclone case using colocated high resolution rain and Seawinds NRCS data. The model is used to compute attenuation and volume scattering from Tropical Rainfall Mapping Mission Precipitation Radar (TRMM PR) rain data. The comparison of the high‐resolution (4 km) NRCS to synthetic NRCS computed from National Hurricane Center (NHC) winds and modeled rain terms shows a good qualitative agreement. The rain terms are used to correct the measured NRCS, to infer corrected winds which are significantly improved compared to NHC winds, especially for high winds. The wind correction using low‐resolution rain data (such as Special Sensor Microwave Imager (SSM/I) ones) is also investigated using rain data averaged over wind scatterometer cells. This can also significantly improve the rain retrieval. A new rain flag based on the NRCS variability within wind vector cells is presented and shown to perform better than the operational one.
Odin/SMR limb observations of stratospheric trace gases: Level 2 processing of ClO, N2O, HNO3, and O3
Authors: Urban J. , Lautié N. , Le Flochmoën E. , Jiménez C. , Eriksson P. , de La Noë J. , Dupuy E. , Ekström M. , El Amraoui L. , Frisk U. , Murtagh D. , Olberg M. , Ricaud P.
Published: July 2005

The Sub‐Millimetre Radiometer (SMR) on board the Odin satellite, launched on 20 February 2001, observes key species with respect to stratospheric chemistry and dynamics such as O3, ClO, N2O, and HNO3 using two bands centered at 501.8 and 544.6 GHz. We present the adopted methodology for level 2 processing and the achieved in‐orbit measurement capabilities of the SMR radiometer for these species in terms of altitude range, altitude resolution, and measurement precision. The characteristics of the relevant level 2 data versions, namely version 1.2 of the operational processor as well as versions 222 and 223 of the reference code, are discussed and differences are evaluated. An analysis of systematic retrieval errors, resulting from spectroscopic and instrumental uncertainties, is also presented.
Correlations of spectral intensity fluctuations: Application to radio frequency interference mitigation
Authors: Deshpande Avinash A.
Published: July 2005

This paper describes a technique based on correlating fluctuations in spectral intensities. When applied to intensity data recorded as a function of time and frequency, the result can be viewed in the form of a correlation map, wherein the temporal correlation between fluctuations in every possible pair of spectral channels is represented. In addition to serving as a useful diagnostic tool for the measuring system itself, such a correlation map offers a wealth of information on spectral channels affected by radio frequency interference (RFI) and intermodulation products, if any. Although such estimations are inherently less sensitive than those using voltage correlations, the technique promises much broader applicability since intensity data are more commonly available. The strengths and weaknesses of this technique with respect to RFI mitigation are discussed and are illustrated with real examples. An extension of this analysis to polarization data is also explored. A promising way to isolate RFI on the basis of its highly polarized nature is proposed, and relevant practical issues are discussed. The present study suggests that high‐resolution time‐frequency data for the full Stokes parameters allow effective excision of RFI (by typically more than 20 dB), particularly for observations of unpolarized astronomical sources. This method is exceedingly effective in situations where a large fraction of the data is affected by polarized RFI, where a robust statistics approach fails.
A statistical solar flare forecast method
Authors: Wheatland M. S.
Published: July 2005

A Bayesian approach to solar flare prediction has been developed which uses only the event statistics of flares already observed. The method is simple and objective and makes few ad hoc assumptions. It is argued that this approach should be used to provide a baseline prediction for certain space weather purposes, upon which other methods, incorporating additional information, can improve. A practical implementation of the method for whole‐Sun prediction of Geostationary Observational Environment Satellite (GOES) events is described in detail and is demonstrated for 4 November 2003, the day of the largest recorded GOES flare. A test of the method is described on the basis of the historical record of GOES events (1975–2003), and a detailed comparison is made with U.S. National Oceanic and Atmospheric Administration (NOAA) predictions for 1987–2003. Although the NOAA forecasts incorporate a variety of other information, the present method outperforms the NOAA method in predicting mean numbers of event days for both M‐X and X events. Skill scores and other measures show that the present method is slightly less accurate at predicting M‐X events than the NOAA method but substantially more accurate at predicting X events, which are important contributors to space weather.
A Mesozoic crustal suture on the Gondwana margin in the New Zealand region
Authors: Davey F. J.
Published: July 2005

Marine crustal multichannel seismic data, recorded offshore South Island, New Zealand, are used to provide constraints on the evolution of the Gondwana margin in this region. Lower crustal and upper mantle seismic reflectivity off southeastern Stewart Island, south of South Island, is interpreted in terms of a northeast dipping paleosubduction zone. This inferred suture is considered to be related to the docking of the Brook Street oceanic island arc terrane to the Gondwana margin in the Triassic, the junction of which is now largely covered by the Median Batholith. A similar lower crustal–upper mantle feature has been imaged off western South Island. Both inferred sutures have similar strikes and are approximately collinear after restoration of the region for major Cenozoic horizontal deformation. It is proposed that they are parts of the same paleosuture that was oriented subparallel to the former Gondwana margin and to the present Paleozoic and Mesozoic terranes forming South Island.
Temporal scaling of hydraulic head fluctuations: Nonstationary spectral analyses and numerical simulations
Authors: Zhang You‐Kuan , Li Zhongwei
Published: July 2005

Temporal scaling of the hydraulic head time series,h(t), was found in a previous analysis of hourly measured head data. This issue is further investigated in this paper with nonstationary spectral analyses and numerical simulations. The results show that temporal scaling may indeed exist inh(t), which fluctuates like a fractional Brownian motion in most aquifers. On the basis of a linear reservoir model with a white noise recharge input, we show that the variance and covariance ofh(t) are functions of time: The head variance increases with time and approaches a constant limit as time progresses, while the covariance decreases with the separation time interval for a fixed time and approaches the typical exponential covariance as time increases. The spectra of the simulatedh(t) using a one‐dimensional transient groundwater flow model with a white noise recharge in both homogeneous and heterogeneous aquifers are shown to be proportional tof‐β, wherefis frequency and β ∼ 1.84 (orH= 0.42). Heterogeneity in the hydraulic conductivity may affect the fractal dimension ofh(t) in highly permeable aquifers but not in the low permeable aquifer simulated in this study.
The composition and transport of organic carbon in rainfall: Insights from the natural (13C and 14C) isotopes of carbon
Authors: Raymond Peter A.
Published: July 2005

The dilute nature and compositional complexity of rainwater organic carbon (OC) has made it difficult to determine the role of rainwater OC in regional and global carbon budgets. Here I present the δ13C and Δ14C signatures of OC in rainfall, including two hurricanes, which indicate that OC in rain originates from multiple sources including a significant fraction from fossil fuels and marine OC. These samples demonstrate that atmospheric wet deposition of OC from fossil fuels can supply significant quantities of relic carbon to ecosystems. In addition, rainfall events that originate over the ocean can be dominated by marine OC, arguing for a significant transfer of marine OC to the continents and a large recycled marine OC component to marine rain. A conceptual model of the direct transfers of OC in rainfall concludes that the net transfer of continental OC to the ocean could be close to zero due to a significant marine to continental flux.