bluuebunny/crossref_metadata_2025 huggingface dataset:
Nucleotide sequence of circular DNA molecules homologous to the 240 bp tandem repeats of the intergenic spacer of Drosophila melanogaster ribosomal DNA
Authors: Degroote Fabienne , Renault Sylvaine , Picard Georges
Published: August 2004

Summary—

We have determined the nucleotide sequence of ten 240 bp repeated sequences of the DNA intergenic spacer present in circular DNA molecules purified from D melanogaster embryos. No significant difference was found with the sequence of the chromosomal units. This suggests that most of the circular molecules homologous to the 240 bp repeats are generated by homologous recombination between adjacent chromosomal units.
Analysis of isoactin expression in cultured mouse cells by in situ hybridization
Authors: Nakamura Yohko , Sakiyama Shigeru
Published: August 2004

Summary— The expression of cytoskeletal isoactin genes in NIH 3T3 and L cells was studied by in situ hybridization. Anti‐sense RNA probes specific for β‐ and γ‐actin were prepared by in vitro transcription of the 3′‐untranslated regions of each cDNA which diverge in an isoactin‐specific manner. Both NIH 3T3 and L cells showed a higher expression of β‐and γ‐actin mRNAs in a growing state than in a stationary one. Among these changes, the suppression of γ‐actin mRNA in L cells was most prominent and that of β‐actin in 3T3 cells was least profound.
The stroma‐vascular fraction of rat inguinal and epididymal adipose tissue and the adipoconversion of fat cell precursors in primary culture
Authors: Gre´goire Francine , Todoroff Germaine , Hauser Nadine , Remacle Claude
Published: August 2004

Summary— The stroma‐vascular fraction (SVF) of inguinal and epididymal fat pads of 4 week‐old rats was studied by electron microscopy. Among the various cell types, endothelial cells and preadipocytes were found in both SVF, while mesothelial cells were only detected in the epididymal SVF. The resulting heterogeneity of primary culture and the adipoconversion of the fat cell precursors were studied in a serum‐supplemented medium enriched with insulin (14.5 nM) and exogeneous triglycerides. Despite the heterogeneity of the inoculum, the primary cultures were rather homogeneous, fat cell precursors being the main cell type. Distinctive contaminant fibroblast‐like cells were observed in both cultures, whereas epithelial‐like cells, which correspond most probably to mesothelial cells, were only found in epididymal cultures. Differentiation of fat cell precursors was assessed by the appearance of lipoprotein lipase (LPL) and glycerol‐3‐phosphate dehydrogenase (GPDH). LPL activity was found in the same level in cells of both deposits while GPDH activity was elevated in inguinal vs epididymal derived stroma‐vascular cells. The different adipose conversion pattern of both cultures was confirmed by morphological quantification: the maturation of epididymal fat cell precursors was faster but less extensive. These differences could be related mainly to regional localization rather than to different maturation of the two fat deposits.
Calbindin D28k in mammalian intestinal absorptive cells: immunohistochemical evidence
Authors: Pochet Roland , Blachier François , Gangji Valérie , Kielbaska Viviane , Duée Pierre‐Henri , Résibois Anne
Published: August 2004

Summary—

Calbindin D28k and D9k are two cytosolic calcium‐binding proteins abundant in intestinal absorptive cells which appear to play a role in calcium translocation. Until today, calbindin D28k was found in avian and reptilian absorptive cells but not in mammalian ones. We have described the presence of calbindin D28k‐immunoreactivity in intestinal absorptive cells of pig and jerboa (Jaculus jaculus). Pig calbindin D28k‐immunoreactive absorptive cells were prominent in duodenum, they were scattered along the villi and nearly absent in the crypts. Jerboa labelled absorptive cells were located along the colonic mucosal surface. No calbindin D28k could be detected in mouse, rat and goat absorptive cells. Topography of calbindin D28k absorptive cells was compared with calbindin D9k distribution. Our results confirmed the data of the literature showing a gradient of labelling increasing from the crypt to the top of the villus and no positive endocrine cell. Young (48 h old) pigs did not expressed calbindin D28k in absorptive cells although calbindin D9k was detected. Calbindin D28k was also observed in endocrine cells which were numerous in pig and goat duodenum and very rare in mouse and jerboa. Western blot experiments confirmed the presence of calbindin D28k in the adult pig intestine, in the jerboa colon and the absence of cross‐reactivity between calbindin D28k antibody and calbindin D9k.
Cellular distribution of sea urchin antibacterial activity
Authors: Gerardi Patrizia , Lassegues Maguy , Canicatti Calogero
Published: August 2004

Summary— Paracentrotus lividus circulating coelomocytes could be separated by a discontinuous sodium‐metrizoate gradient. Amoebocytes and red spherule cells were separated in an almost pure population, whereas colourless spherule cells were distributed at different density levels suggesting that several morphological or functional types constitute this cellular category. Vibratile cells co‐occur with amoebocytes, colourless and red spherule cells in a single heterogeneous fraction. Studies with the separated bands indicate that antibacterial activity against gram negative marine bacteria is present in each cellular fraction. However, the highest degree of bacterial growth inhibition was produced by amoebocytes from band A and red spherule cells from band F. Amoebocytes most probably exerted their antibacterial function by lysozyme‐like molecules, while red spherule cells do not possess this enzyme.
Kinetoplast DNA permits characterization of pathogenic plant trypanosomes of economic importance
Authors: Ahomadegbe Jean Charles , Dollet Michel , Coulaud Dominique , Gargani Daniel , Riou Guy
Published: August 2004

Summary— Twelve Phytomonas isolates were obtained from different plants originating from several countries and cultured in vitro in complex media. The kinetoplast DNA (kDNA) was purified and observed by electron microscopy. The structure of kDNA from all isolates appeared as a large network of interlocked minicircles with some maxicircles extruding from the network, as has often been shown for Trypanosomatidae. Topoisomerase II resolved the kDNA network into free minicircles which were then analyzed by electron microscopy and by electrophoresis in agarose gel. The minicircle sizes varied from 1.3 to 2.8 kilobase pairs according to the Phytomonas isolate. The analysis by restriction endonucleases revealed a base sequence heterogeneity in the minicircles of 10 of these Phytomonas isolates. By contrast, in 2 Phytomonas isolates, more than 90% of their minicircle content was found to be homogeneous. Most interestingly, the minicircle cleavage patterns were found to be different between Phytomonas isolates and thus could be used to distinguish them.
Cytogenetic applications of high resolution secondary ion imaging microanalysis: detection and mapping of tracer isotopes in human chromosomes
Authors: Levi‐Setti Riccardo , Le Beau Michelle
Published: August 2004

Summary—

Analytical imaging by secondary ion mass spectrometry (SIMS) using a state‐of‐the‐art scanning ion microprobe enables the detection and mapping of tracer isotopes in human metaphase chromosomes. The stimulated mitosis of cells cultured in media containing labelled nucleosides, typically 14C‐labelled thymidine or adenosine, and BrDU, yields chromosomes that have incorporated the labelled molecule in their constituent DNA. The label is subsequently detected and localized by SIMS imaging. The relative label signal intensities of sister chromatids can be quantified. The occurrence of sister chromatid exchanges (SCE) can be detected. The distribution of specific nucleosides can be directly mapped. This is non‐uniform along the chromatids, giving rise to characteristic banding patterns (SIMS bands) that seem to correspond to the well known G‐ or Q‐bands resulting from conventional staining methods. The study of a number of cytogenetic problems is expected to benefit from the use of this new method of approach, similar in principle, but potentially more sensitive and capable of higher spatial resolution than autoradiography.
Microanalysis and image processing of stable and radioactive elements in ecotoxicology. Current developments using SIMS microscope and electron microprobe
Authors: Chassard‐Bouchaud Colette , Escaig Françoise , Boumati Pierre , Galle Pierre
Published: August 2004

Summary—

Ecotoxicological investigations were performed on two sets of biological models. The first one concerns marine pollution and was composed of invertebrates (molluscs and crustaceans) contaminated by stable or radioactive elements originating from wastes discharged into sea water. The second one concerns freshwater pollution and was composed of vertebrates (fish) contaminated by aluminium which was dissolved in rivers, as a consequence of an atmospheric pollution by acid rain. Mechanisms involved in the uptake, storage and elimination processes of these toxicants were studied, with a special emphasis on cellular and subcellular aspects of concentration sites. Two microanalytical methods were employed: secondary ion mass spectrometry (SIMS), using the ion microscope and the ion microprobe, and X‐ray spectrometry using the electron microprobe (EMP). SIMS, which enables the visualization of trace elements, was associated with an image processing system using a highly sensitive television camera connected to an image computer. Polychromatic images were obtained, allowing to establish the cellular distribution of metal contaminants. In marine organisms, the target organs and tissues of Al, rare earth elements (Tm and La) and radionuclides (U, Pu, Am) were shown to be mainly digestive gland and exoskeleton. The target organelles were shown to be spherocrystals and lysosomes where the enzymatic lysosomal coprecipitation with phosphorus was observed. Amoebocytes, which are enzymatically equipped with lysosomal phosphatase, were involved in the phagocytic clearance of metal pollutants. In trout, two processes appeared to be involved in Al accumulation. The first one corresponds to the well known insolubilisation of Al phosphate, within lysosomes of organs devoted to uptake and excretion such as gill and kidney. The second one demonstrates that organs and tissues which cannot eliminate, such as bone, heart and brain, retain Al, exhibiting a high intracellular metal concentration; moreover, large Al deposits inducing nervous tissue destruction have been observed. Data have been discussed in connection with the relationship between man and his environment.
Subcellular localization of two neurotropic drugs in three varieties of central nervous system cells by secondary ion mass spectroscopy (SIMS) microscopy
Authors: Zhang Li Li , Tardy Marcienne , Berry Jean‐Pierre , Escaig Françoise , Galle Pierre
Published: August 2004

Summary—

The intracellular localization of two neurotropic drugs, flunitrazepan (benzodiazepine) and triflupromazine (phenothiazine), was studied by secondary ion mass spectrometry microscopy (SIMS) in three varieties of cells. The images of the intracellular distributions of the two drugs are easily obtained by selecting the fluorine atom of the molecules. These images show that the drug from the benzodiazepine group is mainly located in the nuclei, whereas the phenothiazine is exclusively located inside the cytoplasm.
Immunogold localization of photosystem I and photosystem II light‐harvesting complexes in cryptomonad thylakoids
Authors: Lichtle´ Christiane , McKay R Michael L , Gibbs Sarah P
Published: August 2004

Summary— The molecular organization of the thylakoids of Cryptomonas rufescens was studied by immunoelectron microscopy employing antibodies against photosystem (PS)‐I and two PS‐II antenna proteins. The PS‐I complex and the 19‐kDa chlorophyll a/c light‐harvesting (LH) protein are both localized along the length of the thylakoid membranes. The external membranes of the paired thylakoids are enriched in PS‐I whereas the chlorophyll a/c LH protein is more concentrated in the internal or appressed membranes. However, unlike the situation in higher plants and Chlamydomonas, there is not a marked asymmetry in the concentration of PS‐I and chorophyll a/c LH protein in the two types of membranes. Double labelling studies of sections and isolated PE‐PS‐II particles with anti‐phycoerythrin and anti‐LH confirmed that phycoerythrin is localized in the thylakoid lumen and that this pigment exists in two forms, a fraction closely associated with the thylakoid membranes and another fraction free in the lumen. These results confirm the uniqueness of cryptomonad thylakoids.
Calcium‐induced acetylcholine release and intramembrane particle occurrence in proteoliposomes equipped with mediatophore
Authors: Brochier Guy , Gulik‐Krzywicki Tadeusz , Lesbats Bernard , Dedieu Jean‐Claude , Israel Maurice
Published: August 2004

Summary— Proteoliposomes obtained from the mediatophore, a purified Torpedo electric organ nerve terminals protein, and endogenous lipids were used for a study of calcium‐induced release of acetylcholine and freeze‐fracture electron microscopy. Large intramembrane particles were induced by the influx of calcium into proteoliposomes, as previously observed for synaptosomes or stimulated electric organ nerve terminals. The involvement of mediatophore in a calcium dependent acetylcholine translocation seems therefore to be related to the occurrence of a category of intramembrane particles in the course of the release process.
Kinetoplast DNA from plant trypanosomatids responsible for the Hartrot disease in coconut trees
Authors: Ahomadegbe Jean‐Charles , Dollet Michel , Riou Guy
Published: August 2004

Summary— Phytomonas parasites were isolated from crude sap of coconut trees affected with Hartrot disease in French Guyana (Hart 1 and Hart 2) and Brazil (Hart 3) and cultured in vitro. Two Phytomonas isolates obtained from weeds belonging to the Euphorbiaceae family and growing in an infected coconut tree plantation were also cultured (E hys and E hir). The kinetoplast DNA (kDNA) was purified and incubated with topoisomerase II which decatenates the huge network into free minicircles of 1.6 kilobase (kb) pair for Hart 1, Hart 2 and Hart 3 and 1.3 kb for E hys and E hir. Restriction endonuclease analysis showed that more than 90% of Hart 1 and Hart 2 minicircle content was homogeneous in base sequence while minicircles from Hart 3, E hys and E hir were heterogeneous. Minicircles exhibited restriction cleavage patterns characteristic of each Phytomonas isolate allowing their identification, except for the major class of Hart I and Hart 2 minicircles whose restriction maps were identical. Cross‐hybridization experiments were performed by Southern blot. A high sequence homology was found between minicircies from Hart 1, Hart 2 and Hart 3 on one hand and those from E hys and E hir on the other. In contrast, minicircles from the Hartrot Phytomonas and those from the two Euphorbiaceae Phytomonas present little sequence homology. These data showed that minicircles from Phytomonas infecting coconut trees displayed biochemical properties different from those of other Phytomonas. This could lead to the elaboration of new molecular tools aimed to help to epidemiological studies, to an early diagnosis and to a better control of the disease.
Lymphocyte calmodulin and its participation in the stimulation of T lymphocytes by mitogenic lectins
Authors: Nakabayashi Hiroshi , Komada Hiroshi , Yoshida Toshimichi , Takanari Hideki , Izutsu Kosaku
Published: August 2004

Summary— Calmodulin was purified from human tonsillar lymphocytes utilizing calcium‐dependent binding of calmodulin to fluphenazine‐Sepharose. The molecular weight and phosphodiesterase activation of the lymphocyte calmodulin were very similar to those of purified bovine brain calmodulin. Trifluoperazine (TFP), a calmodulin inhibitor, suppressed lymphocyte stimulation as assessed by 3H‐thymidine incorporation into DNA of lectin‐stimulated lymphocytes. TFP had no effect on the early 45Ca2+ uptake induced by mitogenic lectins, although this latter was inhibited by verapamil which also suppressed the 3H‐thymidine incorporation. The results are in keeping with the interpretation that the inhibition of T cell stimulation by TFP was not due to suppression of Ca2+ uptake, but due to inactivation of Ca2+‐calmodulin complex which might be formed subsequent to Ca2+ entry into the cell.
Higher eucaryotic cdc25 proteins are structurally related to phosphoseryl/threonyl protein phosphatases
Authors: Bellé Robert , Ollivier Emmanuelle , Guerrucci Marie‐Anne
Published: August 2004

Summary—

cdc25 proteins are universally involved in the control of cell division. Using an original method of sequence analysis, cdc25 proteins from different sources were compared to protein phosphatases. Protein phosphatases could clearly be characterized as two distinct protein families, the phospho‐seryl/threonyl phosphatases, and the phospho‐tyrosyl phosphatases. None of the cdc25 proteins analyzed fitted with the phospho‐tyrosyl phosphatases, indicating that if they indeed possess this biochemical activity, they form a distinct phosphatase protein group. Unexpectedly, higher eucaryotic cdc25 proteins (from human and fly) were found to be structurally related to phospho‐seryl/threonyl phosphatases. These results fit well with the expected function of the proteins, associated solely in higher eucaryotes, to dephosphorylation of threonine in the cell cycle control protein cdc2.
Localization of the enzyme geranylgeranylpyrophosphate synthase in Capsicum fruits by immunogold cytochemistry after conventional chemical fixation or quick‐freezing followed by freeze‐substitution. Labelling evolution during fruit ripening
Authors: Cheniclet Catherine , Rafia Fatima , Saint‐Guily Agnes , Verna Alain , Carde Jean‐Pierre
Published: August 2004

Summary—

The enzyme geranylgeranylpyrophosphate synthase (GGPPS), which plays a key role in the synthesis of diterpene compounds, carotenoids and higher terpenoids, has been localized in Capsicum fruit cells by ultrastructural immunogold cytochemistry, after conventional chemical fixation of tissues and quick‐freezing followed by freeze‐substitution of isolated chloroplasts and chromoplasts. In agreement with previous biochemical studies on cell fractions, the enzyme seems restricted to the plastid compartment. Together with the phenotypic changes of the fruit and the ultrastructural modifications of the plastids during the transition of chloroplasts to chromoplasts, the amount of immunolabelling over plastid sections increases more than a ten‐fold factor in the course of fruit ripening. In chemically fixed tissues, the gold labelling of chloroplasts is very faint and erratically localized whereas in further transition stages, and in chromoplasts, most of the gold particles surround the developing plastoglobuli, which are the characteristic carotenoid‐bearing structures. Because of the very low and inconstant labelling of chloroplasts in green fruits after chemical fixation, cryofixed and acetone freeze‐substituted purified plastids were used as a model system for an accurate localization of the enzyme in these organelles. Quick‐freezing in buffered sucrose by slam‐freezing on a cold copper block results in optimal preservation of the plastids and improved labelling of GGPPS. The enzyme is not scattered at random throughout the stroma. Gold particles are concentrated in distinct stroma regions, and especially at the sites of initiation of stroma globuli which are the early structural event of carotenoid accumulation. A few gold particles are also present on the margins of thylakoids and, presumably, on the plastid envelope. This paper reports further evidence of the central role of the plastid compartment in the production of C20 isoprenoid intermediates in the plant cell, shows the spatial relationship of the enzyme geranylgeranylpyrophosphate synthase with the plastid substructures and the existence of several GGPPS pools within the plastids. It demonstrates the interest of cryo‐methods for an accurate localization of various enzymes in plant cells.
Flow cytometry and RNA studies
Authors: Grunwald Didier
Published: August 2004

Summary— RNA was less studied by flow cytometry (FCM) in comparison to other cellular components. Moreover, most of these studies were applied to the measurement of total RNA. Nevertheless, such a quantification, essentially by the use of acridine orange, but also other dyes or dye combinations, permitted the acquisition of important information about the general metabolism, and the characterization of different tumoral cell types. More recently, FCM has been used to quantify specific mRNA, in two different approaches: the first one employes the sorting followed by RNA extraction and/or detection by specific radiolabeled probes; in the second approach, the use of fluorescence in situ hybridization (FISH) on cells in suspension allowed the direct quantification of specific mRNA by FCM.
Flow cytometry: A useful technique in the study of multidrug resistance
Authors: Léonce Stéphane , Burbridge Michael
Published: August 2004

Summary— Flow cytometry has recently become a very important tool in the study of the mechanisms of multidrug resistance (MDR). This technique allows rapid access to information regarding two characteristics related to the MDR phenotype: i) the level of overexpression of the P‐glycoprotein; and ii) its functional aspect in expulsion of the cytotoxic agents to which the cell is exposed. In pharmacology, flow cytometry also allows evaluation of the capacity of modulating agents to reverse this resistance, and contributes a deeper insight into the mechanism of action of new molecules.
Timing the phases of the microtubule cycles involved in cytoplasmic and nuclear divisions in cells of undisturbed onion root meristems
Authors: Utrilla Lourdes , Giménez‐Abián M. Inmaculada , De la Torre Consuelo
Published: August 2004

Summary—

The duration of the different phases of the microtubule and chromosome cycles were estimated in the native diploid cell populations of Allium cepa L root meristems proliferating undisturbed, under steady state conditions, at the physiological temperature of 15°C. The cycles were coupled by considering their fitting in relation to the short process of nuclear envelope breakdown. In the cycle related to cytoplasmic division, the preprophase band which predicts the future position of the phragmoplast made its appearance, as a wide band, 16 mm before the G2 to prophase transition, ie it was only present during the final 5% of the total G2 timing (5 h 30 mm). The band became narrow only 6 mm after prophase had started and it was present in this form for the remaining prophase time (2 h 24 mm). Its disappearance occurred strictly coinciding with nuclear envelope breakdown, at the end of prophase. No microtubules related to cytoplasmic division were apparent until 9 mm after telophase had initiated. The two initial stages of phragmoplast formation which followed occupied, respectively, 27 mm and 54.5 mm of the 2‐h long telophase. On the other hand, the third and last stage in phragmoplast formation covered both the final 35 mm of mitosis and the 6 initial mm of the G1 of the next interphase. A very short (less than 4 mm) stage of microtubular nucleation around the nuclear envelope took place immediately afterwards, before the cortical array of microtubules appeared. The microtubule cycle related to nuclear division started with the apparent activation of the future spindle poles 7.4 mm before prophase was over. The mitotic spindle developed in the 5.6 mm long prometaphase. The spindle functioned in metaphase for the 42 mm it lasted, half spindles being separated for the 37 mm anaphase occupied in these cells.
Trichostatin A activates p18INK4cgene: differential activation and cooperation with p19INK4dgene
Authors: Yokota Tomoya , Matsuzaki Youichirou , Sakai Toshiyuki
Published: August 2004

We have reported that histone deacetylase (HDAC) inhibitors activate a member of the INK4 family, the p19INK4dgene, causing G1 phase arrest. We report here that HDAC inhibitor, Trichostatin A, activates another member of the INK4 family, the p18INK4cgene, through its promoter in Jurkat cells. Interestingly, the activation patterns of the p18INK4cgene were different from those of p19INK4d. Furthermore, mouse embryo fibroblasts lacking p18Ink4cor p18Ink4c/p19Ink4dwere resistant to the growth inhibitory effects of TSA as compared to their wild‐type counterpart. Our findings suggest that p18INK4cis involved in TSA‐mediated cell growth inhibition and cooperates with p19INK4d.
Altering the course of neurodevelopment: a framework for understanding the enduring effects of psychotropic drugs
Authors: Andersen Susan L. , Navalta Carryl P.
Published: August 2004

Childhood is a time filled with wondrous changes, as brain plasticity permits experiences to shape the immature brain to meet the demands of the environment. Change occurs at various levels—from neuroanatomy, including within a given region and its connectivity to other regions, to the function of neurotransmitter systems and their reactivity to pharmacological agents in the short‐ and long‐term. The nature and degree to which drug exposure influences the final adult topography is influenced greatly by the maturational phase of these critical factors. Moreover, evidence is slowly emerging that suggests that the long‐term effects of drug exposure are delayed and expressed once the vulnerable system reaches maturation (i.e., typically during adulthood). This phenomenon is known as neuronal imprinting and occurs when the effects of drug exposure outlast the drug itself. Thus, understanding the persistent effects critically depends on the window of observation. Embracing this concept should influence how we conduct preclinical assessments of developmental drug exposure, and ultimately how we conduct clinical assessments of drug efficacy, effectiveness, and safety for the treatment of childhood psychiatric disorders. In this article, we present a model to provide a heuristic framework for making predictions about imprinted effects of childhood drug exposure. We then review epidemiological data on attention deficit hyperactivity disorder (ADHD) and childhood depression, prescription practices, and what is known regarding the long‐term consequences of drug exposure in these populations. We conclude with a discussion of the current status of preclinical studies on juvenile stimulant exposure.
Hydrosonography in screening for intracavitary pathology in infertile women
Authors: Guven M.A. , Bese T. , Demirkiran F. , Idil M. , Mgoyi L.
Published: August 2004

Objectives: We evaluated the value of hydrosonography in screening for intracavitary pathologies in infertile patients. Methods: A total of 93 infertile women with suspected intracavitary lesions on transvaginal ultrasonography (TVS) underwent hydrosonography. Specimens obtained either by dilatation and curettage or hysteroscopic resection were compared with findings on TVS and hydrosonography. Results: Pathology confirmed the presence of sonographically diagnosed intracavitary lesions in 40 out of 66 (60%) women. The sensitivity, specificity, positive predictive value, and negative predictive value of TVS for the detection of endometrial cavity lesions were 78%, 38%, 61%, and 59%, respectively. Forty‐six out of 71 (65%) women who were found to have intracavitary lesions on hydrosonography were pathologically confirmed. The sensitivity, specificity, positive and negative predictive value of hydrosonography in the detection of endometrial cavity lesions were 90%, 40%, 65%, and 77%, respectively. Conclusions: Hydrosonography is a useful procedure in screening for intracavitary pathologies and allows differentiation of intracavitary, endometrial, and submucosal abnormalities.
Psychology in Europe: Developments, Challenges, and Opportunities *This article is based on the EFPPA Presidential Address held at the Vth European Congress of Psychology, Dublin, Ireland, July 1997.
Authors: Lunt Ingrid
Published: August 2004

The paper considers the development of psychology in Europe with a focus on the role of the EFPPA in these developments. It describes some of the challenges and opportunities for the future for psychology in Europe by considering the present circumstances for psychology and psychologists, the current situation in Europe, and the overall context of changes within the society in which we work and live. The paper concludes by addressing the future role and relevance of psychology in the rapidly changing context in which we live.
The measurement of climate change using data from the Advanced Very High Resolution and Along Track Scanning Radiometers
Authors: Lawrence S. P. , Llewellyn‐Jones D. T. , Smith S. J.
Published: August 2004

Global sea‐surface temperature is an important indicator of climate change, with the ability to reflect warming/cooling climate trends. The detection of such trends requires rigorous measurements that are global, accurate, and consistent. Space instruments can provide the means to achieve these required attributes in sea‐surface temperature data. Analyses of two independent data sets from the Advanced Very High Resolution and Along Track Scanning Radiometers series of space sensors during the period 1985 to 2000 reveal trends of increasing global temperature with magnitudes of 0.09°C and 0.13°C per decade, respectively, closely matching that expected due to current levels of greenhouse gas exchange. In addition, an analysis based upon singular value decomposition, allowing the removal of El Niño in order to examine areas of change other than the tropical Pacific region, indicates that the 1997 El Niño event affected sea‐surface temperature globally. The methodology demonstrated here can be applied to other data sets, which cover long time series observations of geophysical observations in order to characterize long‐term change. The conclusion is that satellite sea‐surface temperature provides an important means to quantify and explore the processes of climate change.
Transmission of convoluted periodic loop element with selective reflection
Authors: Teo P. T. , Luo X-F , Lee C. K.
Published: August 2004

The transmission and reflectivity of electromagnetic energy across a planar layer consisting of periodic arrays of convoluted loop elements (with interelement spacing of 6.08cm) is investigated in the lower microwave spectrum at 1.575GHz(λ=19cm). This relatively close spacing is achieved by convoluting the conventional 1λ square loop element at its four corners. The close interelement spacing provides a stable passband frequency response over wide angles of wave incidence, while the convoluted segment provides a short circuit response when the segment length is λ∕4 long. The short circuit will provide a reflection to the electromagnetic energy at the selected band-stop frequency range. Various design considerations have been adopted to meet the challenge of ensuring a common passband bandwidth of 22.47% (1.5–1.95GHz), with a transmission loss of less than 0.5dB for scan angles up to 45° in both TE and TM polarization.
Surface morphology of AlN buffer layer and its effect on GaN growthby metalorganic chemical vapor deposition
Authors: Zhao D. G. , Zhu J. J. , Liu Z. S. , Zhang S. M. , Yang Hui , Jiang D. S.
Published: August 2004

The in situ optical reflectivity measurements are employed to monitor the GaN epilayer growth process above low-temperature AlN buffer layer on c-plane sapphire substrate by metalorganic chemical vapor deposition. It is found that the lateral growth of GaN islands and their coalescence is promoted in the initial growth stage if the AlN buffer layer is treated with a long annealing time and has an optimal thickness: As confirmed by atomic force microscopy observations, the quality of GaN epilayers is closely dependent on the surface morphology of AlN buffer layer, especially the grain size and nuclei density after the annealing treatment.
Measurements of helium metastable density in an atmospheric pressure glow discharge
Authors: Nersisyan G. , Morrow T. , Graham W. G.
Published: August 2004

The density of metastable helium atoms in a dielectric barrier discharge operating in helium with some impurities present has been measured using laser-collisional-induced fluorescence and absorption techniques. Time-resolved measurements indicate that helium metastables contribute to the production of impurity ions, in this case N2+, in the postdischarge current phase of a glow discharge. In our particular discharge environment, the helium metastable density is (1.5±1.4)×1010cm−3, a result consistent with failure to observe absorption by metastables in a multipass absorption measurement.
Tuning of emission color for blue dendrimer blend light-emitting diodes
Authors: Markham Jonathan P. J. , Namdas Ebinazar B. , Anthopoulos Thomas D. , Samuel Ifor D. W. , Richards Gary J. , Burn Paul L.
Published: August 2004

We demonstrate efficient tunable blue electroluminescence from blends of two solution-processible light-emitting dendrimers. These materials can be blended to form optical quality thin films with no phase-separation effects, irrespective of the blend ratio. External quantum efficiencies of 1% have been measured for the blend systems and the emission color can be tuned from deep blue (emission peak 401nm) to blue green (477nm) by blend composition. A power efficiency of 1.5lm∕W (at 200Cd∕m2 and 5.4V) is measured for a single layer, first-generation blue-green fluorene-thiophene dendrimer. These results show that by choice of a dendrimer structure with common branching units and surface groups, dissimilar cores can be blended with excellent miscibility. This provides a simple way of tuning the color of organic light-emitting diodes.
Multistable switching due to magnetic vortices pinned at artificial pinning sites
Authors: Rahm M. , Stahl J. , Wegscheider W. , Weiss D.
Published: August 2004

Magnetic vortices form the ground state in micron and submicron ferromagnetic disks. By inserting artificial defects (antidots) into a submicron ferromagnetic disk, magnetic vortices can be pinned controllably thus enabling a different way for magnetic switching. We show that by inserting n antidots into a disk magnetization reversal takes place via n-1 jumps of the vortex core between neighboring antidots. This cannot only be used to establish stable two-state switching for n=2, but also to realize a multilevel remanent state with low switching fields.
Magnetostriction of stress-induced martensite
Authors: Cui J. , Shield T. W. , Wuttig M.
Published: August 2004

The magnetostriction of stress-induced Fe7Pd3 martensite has been investigated. The striction reaches a value 1980ppm if this martensite is induced by a compressive stress of −12MPa in the small temperature interval Ms⩽T⩽Ms+10°C. It is proposed that the observed magnetostriction reflects the formation and response of metastable adaptive orthorhombic martensite to the externally applied magnetic field.
Electron scattering study within the depletion region of the GaN(0001) and the GaAs(100) surface
Authors: Liu Zhi , Machuca Francisco , Pianetta Piero , Spicer William E. , Pease R. F. W.
Published: August 2004

The energy distribution curves (EDCs) of photoelectrons emitted from the GaN(0001) negative electron affinity (NEA) surfaces are investigated along with GaAs(100) NEA surfaces. These experiments are performed at room temperature using 3.82eV laser excitation for GaN and 1.96eV laser excitation for GaAs. We find the main contribution to the total emitted current is the electrons that have lost an average energy of 310meV and 140meV, respectively, in the bandbending region (BBR). We propose that the origin of the energy loss as the electrons exit the solid is due to intervalley phonon scattering in the BBR (scattering of Γ electrons into the L–M valleys for GaN and L valley for GaAs). EDC studies on semiconductor NEA surfaces enable us to investigate the semiconductor electron transport property in the high-field region, which is established internally by the bandbending voltage at the surface.
Transparent low-work-function indium tin oxide electrode obtainedby molecular scale interface engineering
Authors: Osikowicz W. , Crispin X. , Tengstedt C. , Lindell L. , Kugler T. , Salaneck W. R.
Published: August 2004

A redox reaction between a monolayer of electron–donor molecules, tetrakis(dimethylamino)ethylene, and the indium tin oxide (ITO) surface results in a decrease of the ITO work function down to 3.7eV. The modified ITO surface may be used as electron injecting electrode in polymer light-emitting devices. Photoelectron spectroscopy measurements show that the low-work-function of the modified electrode remains upon exposure to air or gentle annealing; thus, making it a good candidate for inexpensive fabrication of organic/polymeric (opto)electronic devices.
Spin injection across (110) interfaces: Fe∕GaAs(110) spin-light-emitting diodes
Authors: Li C. H. , Kioseoglou G. , van ’t Erve O. M. J. , Hanbicki A. T. , Jonker B. T. , Mallory R. , Yasar M. , Petrou A.
Published: August 2004

We report electrical spin injection from an Fe contact into a (110)-oriented light-emitting diode (LED) structure, and compare results with data obtained from (001)-oriented structures to address the dependence of spin injection on interface and orientation. Fe∕AlGaAs∕GaAs LEDs were grown by molecular-beam epitaxy, and processed to form surface emitting structures. Electroluminescence results obtained using a reverse-biased Fe Schottky tunnel barrier injector show that a 13% electron spin polarization is achieved in the GaAs(110) quantum well due to injection across the Fe∕AlGaAs(110) interface. Analysis of the transport data indicates that tunneling is a significant transport mechanism at low temperatures. The temperature dependence of the spin polarization is similar to that of (001)-oriented spin LEDs, and is dominated by the GaAs electron spin lifetime.
Efficient large-area polymer solar cells on flexible substrates
Authors: Al-Ibrahim Maher , Roth H. Klaus , Sensfuss Steffi
Published: August 2004

Polymer solar cells based on poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylene vinylene]:[6,6]-phenyl-C61-butyric acid methyl ester (1:3wt%) were fabricated using flexible 5×5cm2 polyester foils. These cells show a white-light power conversion efficiency of 3% comparable to smaller cells on glass published by other authors. Ten cells were arranged on one substrate with an active area of 25 and 175mm2 demonstrating a remarkably high reproducibility. It was found that the open-circuit voltage does not depend on the device area. An increase of the cell area caused a slightly lower short-circuit current, lower fill factor, and lower white-light power conversion efficiency.
Planar optical waveguides in β-BaB2O4 produced by oxygen ion implantation at low doses
Authors: Wang Xue-Lin , Chen Feng , Wang Ke-Ming , Lu Qing-Ming , Shen Ding-Yu , Nie Rui
Published: August 2004

The planar waveguides have been fabricated in z-cut β-BaB2O4 crystal by 2.2MeV O+ ion implantation at doses ranging from 5×1012 to 5×1014ions∕cm2 at room temperature. The waveguides were characterized by the prism-coupling method. Monomode, nonleaky planar waveguides at λ=633nm in β-BBO single crystals were fabricated at doses from 5×1012 to 2×1013ions∕cm2, and two mode and three mode waveguides were fabricated at doses from 4×1013 to 5×1014ions∕cm2, respectively. The refractive index profiles of the waveguides are reconstructed using reflectivity calculation method. The propagation loss of the measured ion implanted waveguide was about 1.6dB∕cm. It was found that positive changes of extraordinary refractive indices happened in the guiding regions, and such changes increased with the doses, which were different from most of the observed ion-implanted waveguides.
Room-temperature continuous-wave operation of GaInNAs∕GaAs quantum dot laser with GaAsN barrier grown by solid source molecular beam epitaxy
Authors: Sun Z. Z. , Yoon S. F. , Yew K. C. , Bo B. X. , Yan Du An , Chih-Hang Tung
Published: August 2004

We present the results of GaInNAs∕GaAs quantum dot structures with GaAsN barrier layers grown by solid source molecular beam epitaxy. Extension of the emission wavelength of GaInNAs quantum dots by ∼170nm was observed in samples with GaAsN barriers in place of GaAs. However, optimization of the GaAsN barrier layer thickness is necessary to avoid degradation in luminescence intensity and structural property of the GaInNAs dots. Lasers with GaInNAs quantum dots as active layer were fabricated and room-temperature continuous-wave lasing was observed. Lasing occurs via the ground state at ∼1.2μm, with threshold current density of 2.1kA∕cm2 and maximum output power of 16mW.
Structure and relationships of basal relictual angiosperms
Authors: Endress Peter K.
Published: August 2004

A review of the present perspective of basal angiosperms and the steps that led to this perspective is provided. Major steps of progress over the past century can be seen with the discovery of new extant plants (Degeneria), new fossils and the advent of new research methods, especially molecular cladistic studies, which catalysed new waves of research. A spectacular result in 1999 was the identification of the well-supported basalmost clades of the angiosperms, forming the ANITA grade, with Amborella, Nymphaeales and Austrobaileyales, by several research groups. This provided a new framework in which basal angiosperms can be discussed in evolutionary terms. In this review basalmost angiosperms (ANITA grade and Chloranthaceae) and other basal angiosperms (eumagnoliids and Ceratophyllaceae) are addressed, with a focus on the different major clades and on general traits and evolutionary tendencies. A short outlook for future avenues is also provided.
Accelerated folding in the weak hydrophobic environment of a chaperonin cavity: Creation of an alternate fast folding pathway
Authors: Jewett A. I. , Baumketner A. , Shea J.-E.
Published: August 2004

Recent experiments suggest that the folding of certain proteins can take place entirely within a chaperonin-like cavity. These substrate proteins experience folding rate enhancements without undergoing multiple rounds of ATP-induced binding and release from the chaperonin. Rather, they undergo only a single binding event, followed by sequestration into the chaperonin cage. The present work uses molecular dynamics simulations to investigate the folding of a highly frustrated protein within this chaperonin cavity. The chaperonin interior is modeled by a sphere with a lining of tunable degree of hydrophobicity. We demonstrate that a moderately hydrophobic environment, similar to the interior of the GroEL cavity upon complexion with ATP and GroES, is sufficient to accelerate the folding of a frustrated protein by more than an order of magnitude. Our simulations support a mechanism by which the moderately hydrophobic chaperonin environment provides an alternate pathway to the native state through a transiently bound intermediate state.
Nuclear body movement is determined by chromatin accessibility and dynamics
Authors: Görisch Sabine M. , Wachsmuth Malte , Ittrich Carina , Bacher Christian P. , Rippe Karsten , Lichter Peter
Published: August 2004

Promyelocytic leukemia (PML) and Cajal bodies are mobile subnuclear organelles, which are involved in activities like RNA processing, transcriptional regulation, and antiviral defense. A key parameter in understanding their biological functions is their mobility. The diffusion properties of PML and Cajal bodies were compared with a biochemically inactive body formed by aggregates of murine Mx1 by using single-particle tracking methods. The artificial Mx1-yellow fluorescent protein body showed a very similar mobility compared with PML and Cajal bodies. The data are described quantitatively by a mechanism of nuclear body movement consisting of two components: diffusion of the body within a chromatin corral and its translocation resulting from chromatin diffusion. This finding suggests that the body mobility reflects the dynamics and accessibility of the chromatin environment, which might target bodies to specific nuclear subcompartments where they exert their biological function.
Intracellular actin-based transport: How far you go depends on how often you switch
Authors: Snider Joseph , Lin Francis , Zahedi Neda , Rodionov Vladimir , Yu Clare C. , Gross Steven P.
Published: August 2004

Intracellular molecular motor-driven transport is essential for such diverse processes as mitosis, neuronal function, and mitochondrial transport. Whereas there have been
in vitro
studies of how motors function at the single-molecule level, and
in vivo
studies of the structure of filamentary networks, studies of how the motors effectively use the networks for transportation have been lacking. We investigate how the combined system of myosin-V motors plus actin filaments is used to transport pigment granules in
Xenopus
melanophores. Experimentally, we characterize both the actin filament network, and how this transport is altered in response to external signals. We then develop a theoretical formalism to explain these changes. We show that cells regulate transport by controlling how often granules switch from one filament to another, rather than by altering individual motor activity at the single-molecule level, or by relying on structural changes in the network.
Tetra-
O
-methyl nordihydroguaiaretic acid induces growth arrest and cellular apoptosis by inhibiting Cdc2 and survivin expression
Authors: Chang Chih-Chuan , Heller Jonathan D. , Kuo Jennifer , Huang Ru Chih C.
Published: August 2004

We previously reported that Sp1-dependent Cdc2 gene expression is inhibited by tetra-
O
-methyl nordihydroguaiaretic acid (M
4
N) and that M
4
N is likely responsible for causing growth arrest in M
4
N-treated transformed C3 cells. Here, we show that after M
4
N treatment and cell-cycle arrest, expression of the Sp1-dependent survivin gene, a member of the inhibitor of apoptosis family, is also suppressed, and the mitochondrial apoptotic pathway is activated. To confirm that inhibition of Cdc2 and survivin gene expression is necessary for M
4
N-induced growth arrest and apoptosis, we tested the effect of adding Cdc2 and survivin back to M
4
N-treated cells. Cell division was transiently restored in the presence of M
4
N after transfection of an exogenous Cdc2 gene copy under the control of the Sp1-independent cytomegalovirus promoter. Caspase-3 activation was also reduced by 50% and 75% in transiently and stably survivin-transfected C3 cells, respectively. The results suggest that M
4
N induces growth arrest and apoptosis by suppressing Cdc2 and survivin expression, which constitutes the cellular basis of its antitumoric action.