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  • Springer  (193)
  • Institute of Physics  (63)
  • 1995-1999  (255)
  • 1950-1954  (1)
  • 1
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    High-performance GaN p-n junction photodetectors for solar ultraviolet applications (1998)
    Institute of Physics
    Details
    Publication Date: 1998-09-01
    Print ISSN: 0268-1242
    Electronic ISSN: 1361-6641
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Published by Institute of Physics
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    PAPER CURRENT
  • 2
    Electronic Resource
    Electronic Resource
    Spatial congruence between exine pattern, microtubules and endomembranes in Vigna pollen (1995)
    Springer
    Sexual plant reproduction 8 (1995), S. 147-151 
    Details
    ISSN: 1432-2145
    Keywords: Microtubules ; Cytoskeleton ; Endoplasmic reticulum ; Pollen ; Exine ; Pattern formation ; Vigna vexillata ; DiOC6
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The role of microtubules and endomembranes in pollen wall pattern formation in Vigna vexillata L. was examined using fluorescence laser scanning confocal microscopy. Indirect immunofluorescence using anti-β-tubulin antibodies revealed that the arrangement of the cortical microtubular cytoskeleton in microspores resembled the reciprocal of the reticulate ektexine ornamentations of mature V. vexillata pollen. Patches of microtubules in cortical cytoplasm corresponded in location with the lumina of the exine reticulum and with apertural sites. Microtubules were absent from cytoplasm under muri (ridges) of the exine reticulum. Labeling of microspores during the mid-tetrad stage with the endomembrane-specific fluorochrome DiOC6 produced a pattern similar to that of the microtubules; i.e., DiOC6 staining was localized in cytoplasm underlying lumina and absent from cortical cytoplasm underlying sites of muri. This report represents the first observation of congruence of the pattern of occurrence of any subcellular organelles with exine pattern and, in particular, the congruence of both microtubules and endomembranes in cortical cytoplasm with the lumina of the reticulate exine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00242259
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  • 3
    Electronic Resource
    Electronic Resource
    The geology of the Taparko gold deposit, Birimian greenstone belt, Burkina Faso, West Africa (1998)
    Springer
    Mineralium deposita 33 (1998), S. 591-605 
    Details
    ISSN: 1432-1866
    Keywords: Key words Early Proterozoic ; Birimian ; Shear zone ; Gold ; Quartz veins ; Burkina Faso ; West Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The Taparko gold deposit, located in the eastern branch of the Proterozoic Birimian Bouroum-Yalogo greenstone belt (Burkina Faso) consists of a network of quartz veins developed in a N 170° trending shear zone (250 m wide, 4 km long) superimposed on the regional Birimian structural pattern. The quartz vein network is composed of: (a) a dominant array of quartz veins (type 1), parallel to the shear zone and comprising strongly deformed dark quartz exhibiting foliation, layering, ribbon, tension gashes, etc.; (b) oblique and subparallel related veins (type 2) of gray to white weakly deformed quartz crosscutting the dominant quartz veins resulting in breccia structures; and (c) shallow dipping veins (type 3), cross-cutting veins types 1 and 2 and filled by undeformed white buck structure quartz. Cross-cutting relationships and different quartz types in different veins and within individual veins imply a concomitant filling of the veins during the progressive deformation. Initial sinistral transcurrent shearing evolved with time to sinistral reverse shearing. Metallic minerals occur only in type 1 and 2 veins and were deposited in two stages, with native gold being related to second stage sulfides. Gold (and chalcopyrite) precipitated preferentially upon the surfaces of fractured pyrite grains in low-pressure sites (pressure shadow zones) around and/or within the sulfide grains (along subsequently annealed fractures). The formation of the South Taparko deposit can be divided into a succession of events: (a) during the first event, N 170°-directed sinistral transcurrent shearing resulted in a N 20° mylonitic foliation and fractured rock which allowed H2O-, CO2- and SiO2-rich fluids to circulate and deposit quartz with buck texture; (b) during the second event, type 1 quartz was strongly deformed and type 2 veins formed with sigmoidal shapes as viewed on a horizontal plane; and (c) during the third event, the sinistral transcurrent shearing evolved to sinistral reverse shearing and the deformation style evolved correspondingly from ductile to brittle-ductile. During the last phase of deformation gold nucleated and deposited in low-pressure zones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001260050175
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  • 4
    Electronic Resource
    Electronic Resource
    Use of random amplified polymorphic DNA (RAPD) markers in the study of the parasitic weed Orobanche (1996)
    Springer
    Theoretical and applied genetics 93 (1996), S. 367-372 
    Details
    ISSN: 1432-2242
    Keywords: Key wordsRAPD markers  ;  DNA fingerprinting  ; Orobanche  ;  Broomrape  ;  Parasitic weed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Despite the tremendous economic impact of broomrapes (Orobanche spp.) on agriculture in many countries little is known of the pattern of genetic variation within this group of parasitic weeds. The present paper describes the use of RAPD markers for the study of five Orobanche species in agricultural fields in Israel. Pronounced genetic differentiation was found between the species, and RAPD markers were raised for the identification of each of them. Southern-hybridization patterns of RAPD products of the various species were used to confirm the interpretation. The same markers were valid both for broomrapes collected in agricultural fields and for those collected in natural habitats. The validity of the markers found for O. cumana and O. crenata was confirmed on plants of the same species that were collected in Spain. Parsimony analysis of 86 RAPD characters produced a tree that clearly distinguishes between the five studied Orobanche species, separates the two Orobanche species belonging to sect. Trionychon from those belonging to sect. Osproleon, and supports the separation of O. cumana from O. cernua and of O. aegyptiaca from O. ramosa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050290
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  • 5
    Electronic Resource
    Electronic Resource
    Guild structure of carnivorous intertidal fishes of the Chilean coast: implications of ontogenetic dietary shifts (1998)
    Springer
    Oecologia 114 (1998), S. 563-573 
    Details
    ISSN: 1432-1939
    Keywords: Key words Guilds ; Intertidal fishes ; Ontogenetic dietary shifts ; Chilean coast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although ontogenetic changes in resource use within species are common in animals, these changes have not been widely considered in studies of guild structure within communities. The occurrence of one or more shifts in resource use in an individual of a given species during its life should mean that it would also belong to different guilds at different life stages. We specifically addressed this issue by describing the feeding habits of ten species of carnivorous fishes occurring in tidepools in rocky intertidal areas along the coast of central Chile. Most of these species undergo clear ontogenetic dietary shifts and a feeding guild structure of this group of fishes was established that takes these dietary shifts into account. Each species was divided into a number of size classes. Dietary overlap values between both intraspecific and interspecific size-class pairs in the entire group of ten species were used to construct a phenogram of dietary similarity through an UPGMA cluster analysis. Numbers of guilds and their memberships were established objectively by applying a bootstrapping procedure. Four “ontogenetic” feeding guilds (OFGs), each consisting of size-classes of species, were recognized. The majority of species belonged to more that one guild. Interestingly, when the bootstrapping procedure was applied to a phenogram based on the diets of “taxonomic” or complete species, only one significant guild was found. The implications of these ontogenetic dietary shifts for interspecific interactions are substantial because the identity of the species with which each fish species shares resources change through their lives. The usefulness of taxonomic species for investigating potential competitive interactions in this assemblage is greatly undermined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050481
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  • 6
    Electronic Resource
    Electronic Resource
    Anatomical and ultrastructural studies of chemical defence in the sponge Dysidea fragilis (1998)
    Springer
    Marine biology 131 (1998), S. 639-645 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The marine sponge Dysidea fragilis from El Mar Menor, a hypersaline coastal lagoon (Murcia, Spain), contains the furanosesquiterpenoid ent-furodysinin as the major secondary metabolite. D. fragilis emits a defensive white fluid when it is disturbed. Electron micrographs of this fluid revealed intact vesiculated cells together with other amorphous material. Dissociated cells are more rounded in shape but maintain the same ultrastructural features as cells observed in ultra-thin sections of the whole sponge. The defensive secretion is composed mainly of sponge cells with abundant light vesicles. Sometimes these light vesicles appear to open into the intercellular space; this correlates with surface blebs on these cells observed under scanning electron microscopy. The intracellular location of ent-furodysinin was confirmed by Erlich staining. In laboratory assays, we examined the role of ent-furodysinin as a feeding deterrent to generalist fish predators. It was isolated from D. fragilis and incorporated into a carrageenan-based artificial diet. The addition of ent-furodysinin to the artificial diet reduced feeding by the fish Thalassoma pavo. Similarly, fish did not feed on artificial diet above which defensive secretion of D. fragilis had been ejected with a small syringe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050356
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  • 7
    Electronic Resource
    Electronic Resource
    Evidence for Horizontal Transfer from Streptococcus to Escherichia coli of the kfiD Gene Encoding the K5-Specific UDP-Glucose Dehydrogenase (1998)
    Springer
    Journal of molecular evolution 46 (1998), S. 432-436 
    Details
    ISSN: 1432-1432
    Keywords: Key words: Lateral gene transfer — UDP-glucose dehydrogenase — Capsular polysaccharides — Pneumococcus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Capsular polysaccharides are important virulence factors both in Gram-positive and Gram-negative bacteria. A similar cluster organization of the genes involved in the synthesis of bacterial exopolysaccharides has been postulated in both cases, suggesting that these clusters evolved by module assembly. Horizontal gene transfer has been postulated to explain the polymorphism found in these cellular polymers. The cap1K and cap3A genes coding for the pneumococcal type 1 and type 3 UDP-glucose dehydrogenases, respectively, have been compared with other UDP-sugar dehydrogenases. We have observed that the evolutionary distance between Cap1K and Cap3A is approximately equal to that found between Cap1K (or Cap3A) and other UDP-GlcDH of families evolutionarily distant like KfiD, the dehydrogenase from Escherichia coli K5. On the basis of comparisons of G + C content, patterns of synonymous and nonsynonymous substitutions, dinucleotide frequencies, and codon usage bias, we conclude that the kfiD gene has been introduced into E. coli from an exogenous source, probably from a streptococcal species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006322
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  • 8
    Electronic Resource
    Electronic Resource
    Bone mass in androgen-insensitivity syndrome: Response to hormonal replacement therapy (1995)
    Springer
    Calcified tissue international 57 (1995), S. 94-96 
    Details
    ISSN: 1432-0827
    Keywords: Androgen insensitivity syndrome ; Hormone replacement therapy ; Bone mineral density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The response of bone mass to long-term treatment with estrogen and progesterone in patients with complete androgen-insensitivity syndrome (AIS) is unknown. We report a 17-year-old female patient (karyotype 46 X, Y) with AIS studied during a 4-year period. Bone mineral density (BMD) measured by dual X-ray absorptiometry in lumbar spine and proximal femur was sharply reduced at the initial visit, and remained unchanged during long-term follow-up on hormone replacement therapy with estrogens and progestin. Bone metabolism markers were all in the normal range. The lack of significant increase in BMD highlights the importance of androgens on bone physiology that cannot be balanced in spite of an appropriate estrogenic milieu.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298426
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  • 9
    Electronic Resource
    Electronic Resource
    Vertebral fractures and osteopenia in chronic alcoholic patients (1995)
    Springer
    Calcified tissue international 57 (1995), S. 111-114 
    Details
    ISSN: 1432-0827
    Keywords: Osteoporosis ; Alcoholism ; Ethanol ; Vertebral fractures ; Bone fractures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract To assess whether vertebral fractures are associated with osteopenia in chronic alcoholic patients, a transversal study was carried out in 76 chronic alcoholic males and 62 age-matched healthy males. Lumbar bone mineral density (BMD) by dual photon absorptiometry and spinal chest X-ray films were done in all patients. Twenty-seven patients (36%) had vertebral fractures, but only 5 of them had a BMD below the fracture threshold. Twenty-two patients (29%) had osteoporosis by densitometric criteria. There were no significant differences in lumbar BMD between alcoholic patients with and without vertebral fractures (1.11±0.2 versus 1.13±0.2, P=ns). Previous trauma was recorded in 24 of the 27 patients with vertebral fractures and in 28 of the 49 patients without vertebral fractures (P〈0.001). Moreover, patients with vertebral fractures had more peripheral fractures than patients without vertebral fractures (81% versus 49%, P=0.01). Only one patient was aware of a previous episode of traumatic vertebral fracture. In conclusion, chronic alcoholics frequently have traumas and vertebral fractures, the latter despite having a lumbar BMD above the fracture threshold, suggesting a frequent but unrecognized association between both processes. These results suggest that both spine films and BMD measurements should be obtained for diagnosis of osteoporosis in alcoholic patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298430
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  • 10
    Electronic Resource
    Electronic Resource
    Bone Mineral Density in Children and Adolescents with Diabetes Mellitus Type 1 of Recent Onset (1998)
    Springer
    Calcified tissue international 62 (1998), S. 31-35 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Bone mineral density — Insulin-dependent diabetes mellitus — Auxological parameters.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. There is still controversy over the impact of diabetes control and duration on bone mass and growth parameters in children and adolescents with insulin-dependent diabetes mellitus (IDDM). The aim of this study was to assess bone mineral density (BMD) at axial and appendicular sites, in children with noncomplicated IDDM of recent onset, and its relation to metabolic control and auxological parameters (weight, height, and puberal stage). Fifty-five young Spanish IDDM, otherwise healthy patients (26 males, aged (SD 9.7 ± 4.3 years) and 29 females, aged (SD 11.2 ± 3.8 years) were studied. Duration of diabetes was 1–13.8 years. Two hundred eighty-two age-matched, healthy, Spanish children served as controls. HbA1 was assayed by high pressure liquid chromatography (HPLC) and BMD was measured using dual X-ray absorptiometry (DXA) densitometry at the spine and forearm. Results showed a Gaussian BMD distribution of patients according to sex and age, without sexual-stage differences. There was no correlation between BMD and glycated hemoglobin (average life disease or last HbA1 values) or duration of the disease; moreover, no differences in bone mass were found between 〈3 and ≥3 years of disease duration. Diabetes impact index (mean HbA1× duration of disease in months) showed no significant influence of diabetes control on BMD. We could not demonstrate any impact of diabetes on BMD and growth parameters in children with IDDM of short duration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900390
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