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  • Articles  (225)
  • Coleoptera  (94)
  • 42.55
  • 42.80
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  • Springer  (225)
  • Annual Reviews
  • Blackwell Publishing Ltd
  • Wiley
  • 2005-2009
  • 1990-1994  (150)
  • 1980-1984  (75)
  • 1991  (65)
  • 1990  (85)
  • 1981  (75)
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  • Articles  (225)
Publisher
  • Springer  (225)
  • Annual Reviews
  • Blackwell Publishing Ltd
  • Wiley
Years
  • 2005-2009
  • 1990-1994  (150)
  • 1980-1984  (75)
Year
  • 1
    ISSN: 1572-8889
    Keywords: Coleoptera ; Scarabaeidae ; Cotinis nitida (L.) ; beetle flight ; pheromone bioassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 2
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    Entomologia experimentalis et applicata 59 (1991), S. 75-78 
    ISSN: 1570-7458
    Keywords: Leptinotarsa decemlineata Say ; Coleoptera ; Chrysomelidae ; female sex pheromone ; screening method ; mating behaviour ; tactile stimuli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 3
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    Entomologia experimentalis et applicata 54 (1990), S. 219-224 
    ISSN: 1570-7458
    Keywords: Diabrotica virgifera virgifera ; Coleoptera ; Chrysomelidae ; corn ; life-stage occurrence ; planting date
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Dans les conditions de l'est du Sud Dakota (USA), 3 dates de semailles de maïs et 3 dates de contamination avec des œufs de D. virgifera virgifera LeConte ont servi à imposer ou à empêcher la synchronisation des éclosions des œufs et par conséquent des développements ultérieurs. Les dates médianes d'apparition de chacun des 3 stades larvaires et des imagos ont été déterminées en relation avec les unités de température et le nombre de jours depuis la contamination. Aucune différence significative entre les dates médianes d'apparition n'a été mise en évidence par utilisation des unités de température; par contre, ces différences deviennent significatives lorsque l'on utilise le nombre de jours depuis la contamination. Des paramètres fiables sont nécessaires pour prédire la présence des différentes stades de cet insecte. En dépit des différentes conditions imposées pour cette étude, la méthode la moins capricieuse pour prédire l'apparition d'un stade larvaire et l'émergence des adultes est la somme de températures avec une base de 11°C.
    Notes: Abstract Under field conditions in eastern South Dakota, USA three different planting dates of corn and three times of egg infestation were used to imposed synchronous and asynchronous timing of corn growth and Diabrotica virgifera virgifera LeConte egg hatch and subsequent development. Median occurrence of each of the three larval stages and of the adult stage for each of the infestation-planting treatments was determined by relating occurrence to thermal units and to days after infestation. No significant differences were found among the treatments for median occurrence of each life stage when the thermal unit approach was used. However, significant differences were found among treatments for median occurrence when the day after infestation approach was used. Consistent parameters are needed for prediction of the occurrence of life stages of this insect. Despite the various imposed conditions, this study indicates that the least variable method of predicting life stage occurrence and adult emergence of D. v. virgifera was the use of thermal unit accumulations (base 11°C).
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  • 4
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    Cellular and molecular life sciences 46 (1990), S. 700-704 
    ISSN: 1420-9071
    Keywords: Coleoptera ; Tenebrionidae ; Tribolium confusum ; defesive secretion ; biosynthesis of 1-alkenes ; oxidative decarboxylation ; anti-elimination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The terminally unsaturated hydrocarbons of the defensive secretion ofTribolium confusum are biosynthesized from fatty acids by oxidative decarboxylation. The process involves an enantiospecific cleavage of the C−H bond of thepro-(S) C(3)−H atom and simultaneous decarboxylation of the acid into an 1-alkene and carbon dioxide via ananti-periplanar transition state geometry (anti-elimination). The stereochemistry of this biotranformation is identical in all respects with the same reaction in higher plants. The mechanism seems to be of general importance for the biosynthesis of many vinylic substructures of natural products from oxygen-containing precursors.
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  • 5
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    Entomologia experimentalis et applicata 30 (1981), S. 151-156 
    ISSN: 1570-7458
    Keywords: Xyleborus ferrugineus ; pupae ; ecdysteroids ; pharate adult ; radioimmunoassay ; Coleoptera ; Scolytidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Der Ecdysteroidtiter weiblicher Puppen von Xyleborus ferrugineus (Fabr.) wurde geschätzt, indem ganze Tiere homogenisiert und radioimmunologisch untersucht wurden. Ein ausgeprägtes Maximum an Ecdysteroiden wurde bei 36 Stunden Puppenent-wicklung beobachtet (743 pg/mg Körpergewicht). Der Titer nahm ab auf 299 pg/mg im Pharatstadium und auf 193 pg/mg unmittelbar vor Schlüpfen der Adulten. Qualitative Studien mit HPLC ergaben in frischen Puppen ein Verhältnis von 3:1 Ecdyson zu 20-Hydrooxyecdyson. Pharatstadien enthielten vor allem 20-Hydrooxyecdyson. Das beobachtete einzige Maximum im Titer stimmt überein mit den Resultaten bei andern untersuchten Coleopteren.
    Notes: Abstract Ecdysteroid titers were estimated on the whole body homogenates of Xyleborus ferrugineus (Fabr.) female pupae during development by radioimmunoassay. A distinct peak of ecdysteroids was observed at 36-hr pupal development (743 pg/mg body wt). Titer declined to 299 pg/mg by the pharate adult stage and to 193 pg/mg body wt just before adult emergence. Qualitative studies by HPLC revealed a ratio of 3:1 ecdysone to 20-hydroxyecdysone in the initial pupal stage. Pharate adults had mainly 20-hydroxyecdysone. The observed single peak in ecdysteroid titer agrees with findings in other studied coleopteran species.
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  • 6
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    Entomologia experimentalis et applicata 56 (1990), S. 15-21 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Chrysomelidae ; corn rootworms ; age-specific survival ; age-specific fecundity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé D. virgifera virgifera LeConte a été placé sur des régimes nutritifs mimant l'évolution des tissus du maïs disponsibles dans le champ lorsque les insectes éclosent est aux stades suivants du maïs: 1) après émergence de l'épi mâle, mais avant l'apparition des barbes et l'émission du pollen; 2) lors de la présence de barbes et de l'émission de pollen; 3) après la pollinisation et quand les barbes ont bruni. Un quatrième régime a été fourni pendant toute l'expérience comprenant des barbes vertes, du pollen et des feuilles. Les pontes moyennes des femelles pendant les 12 semaines de l'étude on été 125, 235, 179 et 441 pour les régimes 1, 2, 3 et 4. Les dates de mort de la moitié des adultes a été 7,2, 7,2, 6,7 et 8,8 semaines pour respectivement les mêmes régimes. Les femelles du régime 1 pondent à un âge plus avancé que les femelles des régimes 2 et 3. L'influence des changements de la qualité alimentaire du maïs au fur et à mesure du vieillissement des plantes et deDiabrotica, a été déterminée par la survie au bout de 48 heures d'insectes éclos depuis peu et d'autres maintenus en cage sur des lots de maïs à différents stades poussant en serre depuis des temps plus ou moins longs. Plus les plantes sont âgées, plus la survie des 2 groupes deDiabrotica diminue, mais plus vite chez les lots d'insectes âgés.
    Notes: Abstract Adult corn rootworm beetles,Diabrotica virgifera virgifera LeConte, were maintained on three dietary regimes which mimicked the progression of corn tissues that would be available in the field for beetles eclosing when corn was in the following growth stages: (A) after tassels had emerged but prior to silking and pollen shed; (B) while plants were silking and shedding pollen; and (C) after pollination was complete and silks had turned brown. A fourth regime (D) was established in which green corn silks, pollen, and leaves were provided throughout the study. The mean number of eggs laid per female over the 12-week duration of the study was 125, 235, 179, and 441 for regimes A, B, C, and D, respectively. Median length of life was 7.2, 7.2, 6.7, and 8.8 weeks for regimes A, B, C, and D respectively. Beetles in regime A laid a greater proportion of their eggs at an older age than did beetles from regimes B and C. To further investigate the influences on survival of changes in food quality of corn as plants and beetles aged, newly-eclosed beetles and beetles that had been maintained in caged plots of corn growing in a greenhouse for various lengths of time were caged on corn at different stages of growth, and the proportion of beetles surviving for 48 h was determined. Survival decreased as plants aged for both groups of beetles, but decreased at a faster rate for old than for young beetles.
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  • 7
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    Entomologia experimentalis et applicata 61 (1991), S. 255-263 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Bruchidae ; Bruchidius atrolineatus ; larval crowding ; post-embryonic development ; intracotyledonary mortality ; weight of emerging adults ; reproductive diapause
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Chez Bruchidius atrolineatus, l'accroissement de la densité larvaire à l'intérieur de la graine entraîne une augmentation de la mortalité alors que la réduction de poids des individus à l'émergence est relativement limitée. L'accroissement de la densité larvaire provoque une augmentation du taux d'adultes en diapause reproductrice, dans certaines conditions thermopériodiques. Dans d'autres conditions, permenttant l'émergence d'un fort taux d'adultes diapausants, l'effet de la densité larvaire est nul. Lorsque l'on analyse l'effet de la densité chez les individus d'une souche ne présentant pas de phénomène de diapause, il n'y a pas de corrélation entre la durée de développement et le poids des adultes. Par contre, lorsqu'il y a émergence d'adultes sexuellement actifs et diapausants, il existe une corrélation entre la durée de développement et le poids des adultes émergeants. Cette corrélation est due au fait que les adultes diapausants, qui présentent les durées de développement les plus longues, sont ceux qui ont les poids les plus faibles.
    Notes: Abstract In Bruschidius atrolineatus (Pic), an increase in larval density inside the seed led to a reduction in the survival rate during post-embryonic development, with only a limited decrease in the weight of adults. A high larval density increased the proportion of adults in reproductive diapause under certain thermoperiodic conditions. Under other conditions that already promote the emergence of a high proportion of diapausing beetles, an increase in larval density had no effect on diapause. There was no correlation between the larval developmental time and the weights of adults in a strain with a very low incidence of diapause. However, such a correlation was observed when both sexuallyactive and diapausing beetles emerged. This correlation was explained by the longer developmental times and lower weights of diapausing beetles.
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  • 8
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    Applied physics 50 (1990), S. 101-114 
    ISSN: 1432-0649
    Keywords: 42.40 ; 42.65 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We describe the principles of holographic storage and reconstruction of ultrashort light pulses using spectrally nonselective media. This can be achieved by the application of a 3-D recording medium and by the holography of waves produced by spatial spectral decomposition of light pulses. We also describe various transformations of optical temporal signals based on holographic spectral filtering and nonlinear interaction of spectral decomposition waves.
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  • 9
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    Applied physics 51 (1990), S. 71-74 
    ISSN: 1432-0649
    Keywords: 42.60 ; 42.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have found a simple analytical expression which describes the relation between amplified spontaneous emission (ASE) and small-signal gain in short-pulse amplifiers. It is also shown that the contrast of the short pulse to the ASE is weakly dependent on the saturation of the ASE, and influenced mainly by the saturation of the short pulse. The theoretical considerations were verified by measurements.
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  • 10
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    Applied physics 51 (1990), S. 153-164 
    ISSN: 1432-0649
    Keywords: 42.30 ; 42.80
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    Topics: Physics
    Notes: Abstract A generalized optical correlator is used to analyze the performances of the Vander Lugt and the joint transform architectures. Noise performance and the effects caused by the differences between the input and the reference functions are analyzed. It is found that the modulation index of the joint transform filter decreases due to the presence of noise as well as the differences between the input and the reference functions. However, it is found that, in general, the joint transform correlator would perform better than the Vander Lugt correlator and certainly has the advantage for real-time implementation.
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  • 11
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    Applied physics 51 (1990), S. 292-294 
    ISSN: 1432-0649
    Keywords: 42.55 ; 42.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The conditions for optimum 611.8 nm laser operation are obtained and a convenient method for indicating 3.39 µm suppression is proposed. Single longitudinal mode 611.8 nm generation is obtained using higher gas-mixture pressure and application of an axial magnetic field. Several milliwatt monomode output power and 0.75 multimode-to-monomode power conversion coefficients are obtained without an internal iodine cell. A comparison of the experimental results with a single-mode laser theory is given.
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  • 12
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    Applied physics 51 (1990), S. 421-426 
    ISSN: 1432-0649
    Keywords: 42.50 ; 42.55 ; 42.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A comprehensive control system has been developed for the stabilization of internalmirror He-Ne lasers to their power envelopes. It is designed particularly for use with lasers emitting at 552, 505, or 490 THz (543, 594, 612 nm). The aim has been to combine convenience in routine operation with good day-to-day resettability and minimal frequency drift during a day. The lasers are observed to emit in up to four modes simultaneously and their tuning behaviour is highly alignment-sensitive. They also tend to flip between modes having orthogonal linear planes of polarization. Reliable control of polarization and mode frequency are possible using permanent magnets and active length control through thermal expansion. The stabilized single-frequency outputs have frequency drifts of about 2×10−8 per year, and powers of between 150 μW and 850 μW.
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  • 13
    ISSN: 1432-0649
    Keywords: 42.55 ; 42.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Improvements in output pulse energy and efficiency of a conventional capacitor-transfer-type discharge excimer laser with automatic preionization have been achieved by extending the discharge volume and resulting moderate pumping of the active medium. The discharge laser produces a pulse energy of more than 1 J for XeCl, KrF, and ArF lasers in square beams of about 2×2 cm2, and the maximum overall efficiency observed is 2.9% for XeCl, 3.2% for KrF and 1.8% for ArF. The laser device has been involved in a picosecond (∼ 32 ps) XeCl laser amplification system, and was operated as an amplifier at a repetitive frequency of 10 Hz. Saturation fluence for XeCl laser was measured to be 1.4 mJ/cm2, and the picosecond pulse energy of ∼40 mJ was extracted from the amplifier.
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  • 14
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    Applied physics 52 (1991), S. 22-26 
    ISSN: 1432-0649
    Keywords: 42.55
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    Topics: Physics
    Notes: Abstract The excimer vibtational relaxation have been studied in the diffusional approximation, and stationary substantially non-equilibrium populations of high vibrational levels have been found. New formulae have been derived for quantum yield of UV lasing. Taking into account the vibrational relaxation the new effect of far-IR radiation amplification in the active media of excimer lasers is predicted.
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  • 15
    ISSN: 1432-0649
    Keywords: 42.55
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    Topics: Physics
    Notes: Abstract We report new FIR laser lines from 13CH2F2 molecules optically pumped by a waveguide CO2 laser. The increased tunability (300 MHz) with respect to a conventional CO2 laser allows the pumping of 13CH2F2 vibrational transitions of large offset. 34 new laser lines have been discovered, ranging from 113.1 μm to 491.4 μm in wavelength, thus increasing the number of known FIR laser lines from this important molecule to 99. For all the new lines and many (36) of those known previously, precise offset measurements through the transferred Lamb-dip technique were performed. The frequency of six new laser lines was also directly measured by heterodyne detection with known laser lines.
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  • 16
    ISSN: 1432-0649
    Keywords: 42.55
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    Topics: Physics
    Notes: Abstract In this work we report new FIR laser lines from CD3OD optically pumped by a CO2 waveguide laser. The wide tunability of this laser (290 MHz) makes it possible to pump absorption lines with large frequency offset relative to the CO2 laser line center, which are not possible by using conventional CO2 lasers. As a consequence 19 new laser lines have been discovered, ranging from 38.0 μm to 455.2 μm in wavelength. For all lines, precise frequency offset measurements between the CO2 line center and the center of the absorber CD3OD line were performed using the transferred Lamb-dip technique. We also present direct Doppler-free offset measurements of infrared absorption, obtained within the FIR laser cavity itself, using optoacoustic detection.
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  • 17
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    Applied physics 52 (1991), S. 96-101 
    ISSN: 1432-0649
    Keywords: 42.65 ; 42.55
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    Topics: Physics
    Notes: Abstract We analyze a nonlinear mirror based on Raman interactions. The mirror is a combination of a Raman-active medium and a tetrachroic mirror. The reflections of the nonlinear mirror at two input frequencies differing by the Raman shift are calculated and its properties and possible applications are discussed.
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  • 18
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    Applied physics 52 (1991), S. 158-162 
    ISSN: 1432-0649
    Keywords: 42.65 ; 42.55
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    Topics: Physics
    Notes: Abstract A nonlinear mirror is used to provide a passive negative feedback in an actively mode-locked pulsed Nd:YAG laser. Trains of 250 ps pulses with a total length of up to 50 microseconds were generated. The train duration is limited only by the flashlamp pump pulse length.
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  • 19
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    Applied physics 52 (1991), S. 234-243 
    ISSN: 1432-0649
    Keywords: 42.55 ; 52.65 ; 52.80
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    Topics: Physics
    Notes: Abstract The results of a comprehensive study of a compact UV-preionized XeCl laser are presented. The subjects of this study were: discharge voltage and current measurements, dye laser probing of the active medium, and the mass spectrometry of gas mixture degradation products. It is shown that the gas lifetime was significantly improved when the laser was operated with BCl3 as a halogen donor instead of commonly used HCl. By the dye laser absorption and gain probing, the temporal and spatial dependences of the densities for several plasma components, Ne*, Xe*, Xe+*, Cl−, XeCl* and of ground state boron atoms were measured. Some aspects of plasma kinetics for uniform and constricted phases of the discharge are discussed. By the mass spectrometry of gas mixture degradation products on long-term operation of the laser device several gaseous (N2, O2, CO2, H2O, C2H4) and solid (NiCl2, H3BO3) products were detected in the laser chamber. NH4Cl was determined to be a stable fraction of the deposits on optics surfaces. The reasons for the improvement of gas lifetime for BCl3-containing gas mixtures are discussed.
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  • 20
    ISSN: 1432-0649
    Keywords: 42.55 ; 52.25
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    Topics: Physics
    Notes: Abstract Simultaneous oscillation of UV (248–270 nm) and IR lines (773–785 nm) in the copper ion laser with helical hollow cathode has been observed using high reflectivity combination mirrors. The output power characteristics of these laser lines are measured as functions of the discharge current and fill-gas pressure. A total laser power of about 100 mW with equal UV and IR contributions was obtained.
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  • 21
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    Applied physics 53 (1991), S. 148-152 
    ISSN: 1432-0649
    Keywords: 02.50 ; 42.60 ; 42.80
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    Topics: Physics
    Notes: Abstract This paper deals with a theoretical and experimental study of the picosecond synchronization of a streak camera used in conjunction with a cw actively mode-locked laser system. The temporal resolution of two synchronization set-ups, a passive device (sweep obtained directly from the mode-locker oscillator) and an active arrangement (deflection derived from the recurrent laser pulses through a photodiode and a tunnel diode) has been examined. On the basis of the stochastic analysis it has been possible to interpret the experimental results for both configurations: in particular, it has been demonstrated that even in the presence of phase noise in the laser signal, perfect synchronization can be achieved.
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  • 22
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    Applied physics 26 (1981), S. 161-167 
    ISSN: 1432-0649
    Keywords: 52.80 ; 42.55
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    Topics: Physics
    Notes: Abstract A new magnetic discharge stabilization technique for coaxial laser systems is described. The approach utilizes crosses electric and magnetic fields to create and maintain a large and rapidly rotating plasma volume which does not experience glow-to-arc transitions. Very high cw specific discharge power loadings have been achieved even without the benefit of external gas cooling or circulation. Performance is insensitive to gas composition and pressure such that high power coaxial discharges have been run in CO2 laser gas mixtures up to several hundred torr. Stable cw discharges have also been obtained in mixtures containing several torr of SF6. The technique appears to be readily scalable to give very large excited volumes in systems with comparatively small overall physical dimensions.
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  • 23
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    Applied physics 26 (1981), S. 73-76 
    ISSN: 1432-0649
    Keywords: 07 ; 42.55
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    Topics: Physics
    Notes: Abstract A liquid nitrogen cooled cw CO-Laser is described, with which laser action up to 8.18 μm (v=36→35) has been achieved.
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  • 24
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    Applied physics 26 (1981), S. 89-98 
    ISSN: 1432-0649
    Keywords: 42.80 ; 42.82 ; 42.10
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    Topics: Physics
    Notes: Abstract The two-dimensional analysis of a recently reported thick grating Bragg diffraction focussing device is carried out using Solymar's coupled-wave approach. It is shown that the device is capable of operating as a non-divergent lens with beam contraction ratios of better than 100:1, and conversion efficiencies of nearly 100%. It is also shown that it can operate as a novel kind of Fourier spectrum analyser, the focussed diffracted intensity being proportional (as a function of Bragg condition violation) to the modulus squared of the Fourier transform of the incident finite beam. The focussing properties are studied as functions of incident beam profile, width and position, grating strength and Bragg condition violation. Poynting vector optics is used successfully to predict (in conjunction with the dispersion surfaces of x-ray dynamical theory) the off-Bragg behaviour in the focal plane. It is likely that the device could be used as avariable ratio beam contractor in integrated optics, where the grating strength could be controlled (interdigital electrode system) electrooptically.
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  • 25
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    Applied physics 26 (1981), S. 141-146 
    ISSN: 1432-0649
    Keywords: 42.55
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    Topics: Physics
    Notes: Abstract We have designed and tested a pulsed single-mode dye laser for spectroscopy experiments. The dye laser is pumped by a 6 kHz copper vapor laser to produce up to 230 mW average power at over 5% efficiency in a nearly diffraction limited beam. The dye laser pulse closely resembles the 30 ns pump pulse. Using an electronic servo loop, the 60 MHz wide line can be scanned, without mode hopping, through the 16 GHz permitted by the travel on the piezo driven mirror mount.
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  • 26
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    Applied physics 26 (1981), S. 31-32 
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    Topics: Physics
    Notes: Abstract A 4 J XeCl (308 nm) laser has been used to produce ∼ 1 J of dye laser output from selected dyes whose lasing wavelengths sample the spectral range from 330 to 600 nm.
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  • 27
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    Applied physics 26 (1981), S. 33-36 
    ISSN: 1432-0649
    Keywords: 42.55 ; 33 ; 34
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    Topics: Physics
    Notes: Abstract A far-infrared (FIR) NH3 laser was resonantly pumped with a line-tunable infrared (IR) NH3 laser. The number of the observed FIR laser lines amounted to 33. Most of them belonged toaR(J,K) rotation-inversion transition in (0, 1, 0, 0) vibrational state. The line tunability of sealed-off FIR NH3 laser was almost achieved in 90, 115, 150, and 220 μm wavelength regions by the selective line tuning of the pumping IR NH3 laser.
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    Applied physics 50 (1990), S. 409-413 
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    Keywords: 42.65 ; 42.55
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    Topics: Physics
    Notes: Abstract The theory of active-passive mode-locked solid-state lasers is developed where the passive mode-locking is achieved by a nonlinear mirror. Steady-state cw numerical solutions are analyzed in detail for the case of a Nd: YAG laser. The steady-state pulse duration can be reduced by an order of magnitude as compared to the pure active mode-locking regime.
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  • 29
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    Applied physics 50 (1990), S. 355-359 
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    Keywords: 42.65 ; 42.80
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    Notes: Abstract The interaction between two strong pump beams and two signal beams is investigated both theoretically and experimentally. It is shown that the frequencies of the beams need to satisfy the relation that the sum of the pump beam frequencies should be equal to the sum of the signal beam frequencies. The gain is shown to depend on the detuning of the pump beams relative to the incident signal beam and on the direction of the signal beam. Maximum gain is obtained when the signal beams bisect the pump beams.
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    Applied physics 50 (1990), S. 393-404 
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    Keywords: 42.65k ; 42.80 ; 42.82
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    Notes: Abstract We study optical second harmonic generation (SHG) in planar waveguide structures composed of several layers with different dielectric constants. We develop a general formalism for the calculation of mode generation by a planar antenna embedded in the waveguide. As an application we consider a monolayer of high second-order susceptibility adsorbed at the interface between two layers of the waveguide structure. Periodic modulation of the nonlinear susceptibility allows phase matching leading to dramatically enhanced second harmonic intensities. We investigate the SHG-efficiency of various experimentally realizable geometries.
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    Applied physics 50 (1990), S. 441-454 
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    Notes: Abstract An overview is provided of the planar laser-induced fluorescence (PLIF) method, which currently allows simultaneous combustion measurements at more than 105 flowfield points. Important advantages of the method include its relatively high signal strength, ease of interpretation, and applicability for determining several flowfield variables (including concentration, temperature, velocity, pressure and density). Example results are shown for a turbulent non-premixed flame, a spray flame, a rod-stabilized premixed flame, and a diffusion flame from a fuel jet in cross-flow.
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    Applied physics 26 (1981), S. 49-56 
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    Keywords: 42.55 ; 52.80
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    Notes: Abstract The cw output power of the uv CuII laser has been optimized with respect to the hollow cathode geometry, the discharge current, the fill gas pressure and the resonator mirror parameters. A maximum laser output power of 900 mW for multiline operation at 248.6, 259.1, 260.0, and 270.3 nm was achieved with 100 A discharge current, 260 V voltage and 16 mbar fillgas pressure, when a hollow cathode of 1.2 m length and 2×6 mm2 cross section was employed. The single-pass pain gl has been estimated to 7%. A hollow cathode cross section of 1.5×4.5 mm2 is suggested as an optimum geometry. In addition, some investigations on the mechanism of the laser power decay in Ne−Cu-discharges are presented.
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    Applied physics 26 (1981), S. 239-242 
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    Notes: Abstract A mode-locked Nd-glass laser oscillator with intra-cavity pulse selection by a Pockels cell shutter is described. A regenerative amplifier system with a saturable absorber is used to shorten the selected light pulses from the master oscillator. Pulses were shortened from 8 ps to 1 ps.
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    Applied physics 51 (1990), S. 219-221 
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    Notes: Abstract In this paper we describe a phase-conjugate scheme in which the pump waves are derived from a distorted optical beam by a spatial filtering technique. Experimental demonstration of this scheme is given for phase-distortion correction. To avoid the problem of back reflection a quasi-real-time reconstruction scheme is adopted. The read out is done with a direct beam from the laser.
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    Applied physics 53 (1991), S. 119-120 
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    Notes: Abstract A colliding-pulse-mode-locked dye ring laser was mounted on a rotary stage and the beat frequency of the two output pulse trains was measured as a function of the rotation rate. The measurements are in good agreement with the Sagnac theory.
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    Applied physics 50 (1990), S. 133-136 
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    Notes: Abstract It is shown analytically that for a pulsed dye laser amplifier, transversely pumped by a short duration pulsed laser, there exists an optimum gain length of the amplifier at dye laser wavelengths at which ground state absorption does not vanish. Thus, if the available pump power is distributed over this gain length, the extraction efficiency and the saturated gain of the amplifier reaches a maximum. The dependence of the extraction efficiency and gain on the amplifier length is strongly affected by the nonlinear absorption of the dye laser arising from excited state absorption, subsequent to ground state absorption.
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    Applied physics 50 (1990), S. 319-322 
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    Notes: Abstract A new type of anisotropic scattering with ring-and-line structure is observed for the first time from a BaTiO3 crystal illuminated by a linearly polarized laser beam. The analysis presented herein is based on the photorefractive four-wave interaction of the incident, reflected, and scattered beams. The experimental results agree well with the theoretical analysis.
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  • 38
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    Notes: Abstract Color phase-conjugate imaging is demonstrated using a multi-colored laser beam. Speed of response, size of the image, clarity of the image, and the intensity of the image are investigated. Color images are stored and recalled without crosstalk between different colors.
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    Applied physics 53 (1991), S. 350-352 
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    Notes: Abstract We report an experimental measurement, based on an interferometric technique, for the determination of the temperature dependence of the refractive index n L of a liquid suspension of dielectric spheres in the thermal range 20–52° C. In this range we have measured values of ∂n L /∂T of order of magnitude 10−4° C−1. The observed values are compared with those obtained for water.
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    Applied physics 51 (1990), S. 258-262 
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    Notes: Abstract We present some new experiments on self-diffraction in nematic liquid crystals and an extended static theoretical description of this effect. Our model gives some new insights and improvements to calculations carried out before. Using these calculations it was, e.g., possible to determine elastic constants in a pure optic way. For the static and dynamic measurements we designed a computer-controlled optical setup. It allows determination of the most interesting nonlinear optical properties of liquid crystals under variation of many parameters. The layout even allows application for any other nonlinear material. Especially modulation sensitivity, modulation transfer function and distribution of noise measured with just one setup are interesting for later application in optical signal or image processing. Furthermore, we present measurements one some new commercial nematic mixtures which show promising behaviour for future application in nonlinear optics. It was possible to verify our theoretical model with the experimental results.
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    Applied physics 26 (1981), S. 197-202 
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    Notes: Abstract A theoretical treatment of the influence of a saturable absorber in close contact with a highly reflecting mirror on a light pulse is given. The shaping of a Gaussian pulse during a single passage through such an absorber is calculated for various absorber lengths. The influence of absorber position and length on the pulse parameters and the stability of a continuously pumped dye laser are investigated. The shortest pulses and the most favourable operation conditions of the laser are to be expected in the case of a short contacted saturable absorber.
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  • 42
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    Applied physics 26 (1981), S. 213-216 
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    Notes: Abstract Fluctuating pulse durations considerably influence the time resolution of probing experiments. The commonly used arithmetic averaging the experimental data changes the shape of the signal curves and gives longer decay times in the wings. Methods are presented to reduce the effect of fluctuating pulse durations.
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    Applied physics 51 (1990), S. 238-241 
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    Keywords: 42.60 ; 42.80 ; 85.60
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    Notes: Abstract When a laser is focused by a lens or mirror array the field acquires a longitudinal component. Under certain conditions this longitudinal laser field could be used to accelerate an injected particle to high energies.
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    Applied physics 51 (1990), S. 254-257 
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    Notes: Abstract We present a very compact and very reliable laser system formed of two discharge sections both with lateral UV preionization. The discharge electrodes are contained in a single vessel and form an oscillator-amplifier system. A single spark gap switches on both circuits. By applying a generalized self-filtering unstable resonator to the oscillator and injecting the laser beam into the single pass amplifier, an output beam of 105 mJ, with a brightness of 5.5×1013 W cm−2Sr−1 has been obtained. Moreover, by applying a pulse-forming network in one discharging circuit, the duration of the discharge breakdown has been increased and output laser pulses of 40 ns FWHM, and 80 ns base width duration (at 10% points) and of energy 100 mJ are obtained.
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    Applied physics 52 (1991), S. 371-375 
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    Keywords: 42.55 ; 82.40
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    Notes: Abstract Laser-induced fluorescence from carbon atoms, excited at the two-photon resonances around 280 nm, has been detected in fuel-rich hydrocarbon flames together with Swan band emission from the C2 radical, which was non-resonantly excited at the same wavelengths. The emission from the C atom and from the C2 molecule exhibited several similarities, indicating a possible common photo-chemical origin.
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  • 46
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    Applied physics 53 (1991), S. 14-18 
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    Notes: Abstract This paper reports on the results of an experimental study of a XeCl laser having two independent preionizators which generated UV radiation into the active medium in the perpendicular and parallel directions to the electrode surfaces. Output energy and other parameters were measured using a single preionizator and two preionizators, changing the power supply polarity and varying the delay time between the preionization and the main discharge. When the preionization system generated photons only in the direction perpendicular to the electrode surfaces, a high discharge current and a high output laser energy were obtained. Besides, the diffusion coefficient of the photo-preionized electrons, played an important role in the laser behaviour, particularly when a consistent delay time between the onset time of the preionization and the main discharge was present.
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  • 47
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    Applied physics 53 (1991), S. 314-318 
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    Notes: Abstract We report the observation and study of optical bistability in the power transmitted by a twisted nematic liquid crystal bounded by crossed dichroic polarizers. A detailed study of the dependence of the phenomenon on the sample initial temperature has been performed. The effect is a good test for a simple theoretical model which describes the isotropic droplet formation in a nematic sample under laser illumination. A good agreement is found between experimental results and theoretical predictions. Applications of the effect to realize temperature sensors are envisaged.
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  • 48
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    Applied physics 26 (1981), S. 133-140 
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    Notes: Abstract Single-mode selection with Michelson selectors in cw standing-wave dye lasers is analyzed. The application of single and double Michelson mode selectors for compensation of spatial hole burning effects is described in detail. Upper limits for the pumping are considered. It is shown that with spatial hole burning compensation, even the single Michelson selector provides sufficient selectivity for high power single-mode operation in linear cavities.
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    Applied physics 26 (1981), S. 203-210 
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    Notes: Abstract A series of experiments are carried out by current modulating a tunable diode laser, and slowly ramping the wavelength to scan weak absorption lines in gases at pressures ranging from 2 to 60 Torr. A lock-in amplifier detects the second harmonic (2f) of the modulation frequency, and the experimental 2f signals are compared with theory. Detailed measurements are made on Lorentzian, Voigt, and Gaussian line profiles, over a wide range of modulation amplitudes. Excellent agreement between experiment and calculation is obtained in all cases. This quantitative understanding enables one to derive true lineshapes and linewidths of very weak absorption lines from measurements of 2f lineshapes only. Results are applicable to trace gas detection using tunable diode lasers, and to other areas of spectroscopy and magnetic resonance where harmonic detection techniques are routinely employed to monitor weak signals.
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  • 50
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    Applied physics 26 (1981), S. 37-42 
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    Keywords: 42.80 ; 42.82 ; 42.10
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    Notes: Abstract Novel thick grating focussing and de-focussing devices are described which employ uniform phase gratings with special boundary shapes. The analysis used is based upon an eigenmodal approach to Kogelnik's coupled-wave equations, akin to the dynamical theory of x-ray diffraction. The relationship between the direction of phase progression of the coupled-waves at Bragg incidence, and the direction of the Poynting vector is carefully delineated. As a consequence, a new technique-Poynting Vector Optics — is suggested as potentially an important means of designing thick gratings to fulfil certain beam processing roles, especially in integrated optics applications. The two-dimensional coupled-wave equations are briefly employed to illustrate the effectiveness of a particular focussing device.
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    Applied physics 26 (1981), S. 193-195 
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    Notes: Abstract A simple method for single-frequency operation and stabilization of a low power He−Ne laser has been described and used. With a proper resonator length very weak sideband modes on each side of the strong mode produce a feedback signal to a piezoelectric pusher which controls the resonator length. The long-term frequency stability was estimated to be about ±10 MHz.
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  • 52
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    Applied physics 24 (1981), S. 13-20 
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    Notes: Abstract Simultaneous laser operation at the wavelengths of λ1=637 and λ2=717 in Pr0.5La0.5P5O14 single crystals was observed. The crystals were excited by nanosecond publses from a Coumarin 2 dye laser (λ=450 nm). Laser emissions and their interdependence were studied both in crystals without an external resonator and in crystals placed within a plane parallel resonator. The energetic, time and frequency characteristics for both laser actions were examined. The effect of bifrequential emission was also found in crystals of different ratios of Pr and La ions concentration and in pure praseodymium pentaphosphate.
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  • 53
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    Applied physics 24 (1981), S. 55-59 
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    Keywords: 78.20 ; 42.80 ; 85.60
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    Notes: Abstract The fundamental absorption edge of evaporated WO3 films is investigated. The optical gap of the virgin film is estimated to be 3.41 eV at room temperature and it decreases with increase of annealing temperature up to 200°C. Annealing at 300°C leads to change in the spectral shape, which is caused by crystallization. For the films annealed at 200°C, temperature coefficient of the optical gap is estimated to be −2×10−4 eV/K and the slope of Urbach's tail is found to be independent of measuring temperature up to 200°C. With electrolytic coloration, shift of the optical gap toward higher energy is observed. Magnitude of this shift is estimated to be 0.05 eV at the color center concentration of 7.5×1021 cm−3 when H+ electrolyte is used. If Li+ electrolyte is used, the magnitude of this shift is about three times larger than in the case of H+ electrolyte. This fact is interpreted by a small change in the host matrix structure owing to the injection of proton or Li+ during coloration.
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  • 54
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    Notes: Abstract An analytical treatment of the thermal phenomena during free-running ruby laser annealing of boron implanted silicon is presented. The heat equation was solved for a simplified shape of the pulse train consisting of a uniform succession of triangular spikes, identical in energy. During one spike the optical and thermal parameters of the sample were taken constant, but for each new spike, new values of these parameters were calculated taking into account their temperature dependence. Such a model predicts the melting of the top surface before the laser pulse has ended, for energy densities higher than 9×104 J/m2. RHEED confirms the presence of recristallization at about the same value of the laser-pulse energy densities.
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    Applied physics 50 (1990), S. 425-430 
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    Keywords: 42.70 ; 42.80 ; 61.40 ; 78.60
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    Notes: Abstract Insensitive bulk samples of poly-(methyl methacrylate) (PMMA) may be sensitized by in-diffusion of monomers and photoinitiators. Different methods for the fabrication of refractive index profiles in the PMMA surface for lightguiding are demonstrated. The photolocking procedures are suitable for recording 2 dimensional patterns as well.
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    Applied physics 24 (1981), S. 331-340 
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    Notes: Abstract A full-automatic wavelength controled pulsed dye laser has been developed. With the control system, dye laser oscillations of nanosecond pulses are tuned to any wavelength in the visible or scanned in any sweep mode keeping the nearly transform-limited bandwidth of 0.45 GHz. A mechanical tuning of the wavelength is employed, such that the motion of three wavelength selectors is synchronized to give a smooth and precise wavelength control. The basic principle underlying the tuning scheme, various requirements to be met in system construction, and the practical performance of automatic wavelength control are described in this paper.
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    Applied physics 24 (1981), S. 33-38 
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    Notes: Abstract We report infrared laser emission in the region of 3 to 5 μm from sodium vapour optically pumped by a pulsed dye laser with wavelengths ranging from 585 to 610nm. Twophoton excitation processes are believed to be responsible for the primary excitation. Both molecular transitions (4 to 5 μm) between high lying states, and atomic transitions (52 S 1/2−42 P 3/2,1/2 at 3.41 μm) have been identified.
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    Applied physics 24 (1981), S. 267-272 
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    Notes: Abstract Detailed data of the minimum preionization electron density (MPED)n 0 necessary to initiate a homogeneous discharge mode in transverse gas discharges are computed. An upper limit for the inductance of the discharge circuit is set by the power balance during breakdown. The results are presented as functions of generalized parameters. Applicability of the computations is proved by experimental observations.
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    Applied physics 24 (1981), S. 341-348 
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    Notes: Abstract The presented theoretical model for a mode-locked Nd-glass laser simultaneously takes into account dynamics of the mode-locking dye, amplification saturation and radiation background. A systematic variation of laser parameters gives insight into the pulse formation process and allows to improve the laser design. The calculations show that it should be possible to decrease considerably the duration of light pulses of a mode-locked Nd-glass laser. Using a new mode-locking dye with a switching time of τ=2.7×10−12 s we obtained stable laser operation and a pulse duration of 1.7×10−12s.
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    Applied physics 25 (1981), S. 31-34 
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    Keywords: 35 ; 42.55 ; 42.65
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    Notes: Abstract The decay rates of the3 D 1 level of I–II and the 3s 2 level of neon have been measured by the magnetic-field power dip method. The decay rate at the zero-pressure limit is found to be 7.1 MHz/2π for the3 D 1 level. The collision cross-section for excited I ions with helium atoms equals 0.19×10−15 cm2.
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    Applied physics 25 (1981), S. 17-22 
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    Notes: Abstract The characteristics of near uv dye lasers pumped with short duration, 308 nm pulses from a XeCl laser are described with particular emphasis on the parameters influencing high average power operation. The solvent is shown to effect the operation of all dye lasers studied, particularly the photochemical stability. Measurements of the efficiency, as a function of the integrated pump energy have been made for a series of dye-solvent combinations. With the best combinations, average output powers in excess of 1W and conversion efficiencies greater than 25% were obtained at a repetition rate of ∼100 Hz.
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    Applied physics 25 (1981), S. 273-274 
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    Notes: Abstract Near-infrared laser action of atomic carbon was obtained using a hollow cathode discharge tube. Besides the known 1.4543 μm and 1.0691 μm laser lines, cw laser operation at 1.0683 μm, 0.9658 μm, and 0.9406 μm wavelength was observed for the first time. The source of carbon was due to dissociation of CO, CO2 or CH4 added to the He buffer gas.
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    Applied physics 25 (1981), S. 311-316 
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    Notes: Abstract A high precision wavelength meter in the visible is described, which is based on a Fabry-Perot interferometer with several etalons of different resolution. The interference fringe pattern projected on a photo-diode array detector is computationally processed to give a stepwise refinement of the wavelength value to any adjusted accuracy. The present model intends to provide digital and real-time values of high precision wavelength for dye-laser spectroscopy, and to serve as a monitor or as a pilot for wavelength control of a dye-laser source of nanosecond pulses. The model is, therefore, designed with particular emphasis on its short-pulse capability and on-line mode of operation as well as on its high sensitivity and resolution. Some arrangements of essential necessity are involved therein, such as to avoid an errorneous wavelength readout for a noisy incidence of pulsed field. The ultimate accuracy of wavelength measurement is prescribed by the resolving power of the thickest etalon employed. As applied to the pulsed source, the model determines the wavelength to the accuracy of ±one part in 107 for even a single shot nanosecond incidence of a fraction of μJ energy. The design and performance are described in connection to pulsed dye-laser incidence.
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    Applied physics 25 (1981), S. 329-336 
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    Notes: Abstract This work was an experimental investigation of a potential large-scale excimer laser system, in which a high-pressure KrF gas mix was pumped by the 4-MeV electron beam from an available linear accelerator. As a function of the mix and the pressure, fluorescence from KrF* and/or Kr2F* were produced with good efficiency. Comparing measured data with a kinetic model, it was found that the kinetics followed the “normal” patterns seen in low-energy electron pumping. The data fitting process also resulted in a new value for the three-body quenching rate constant for reactions involving Ar. A critical factor in the development of this laser will be an improvement in beam control over that afforded by a simple solenoidal magnet. The conditions necessary for lasing are predicted; no inherent limitations on scaling of the device were found.
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  • 65
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    Applied physics 52 (1991), S. 7-9 
    ISSN: 1432-0630
    Keywords: 78.55 ; 78.60 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The matching between the spectral distribution of the light emitted from a light source and the spectral distribution of the sensitivity of a light detector is characterized by the “matching factor”. In the paper we present a table of 500 matching factors for the combination of various phosphors with the most common photodetectors.
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  • 66
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    Applied physics 24 (1981), S. 45-48 
    ISSN: 1432-0630
    Keywords: 42.55 ; 42.65 ; 64
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We investigated time-dependent effects related to the bistable operation of a CO2 laser with an intracavity nonlinear absorber (SF6). The response of the system to small perturbations was sensitively dependent on the operating laser line [P(12)→P(30)] of the 10.6 μm band. The narrow bistable region forP(12), due to a very narrow hysteresis loop, can be effectively utilized for optical switching, because of its pronounced sensitivity to variations in operational parameters. The maximum admissable beam blocking time (intracavity) for spontaneous return to lasing was measured forP(16), for a range of absorber pressures. This τm is related to the relaxation time of the upper level in the absorber.
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  • 67
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    Applied physics 26 (1981), S. 143-149 
    ISSN: 1432-0630
    Keywords: 42.80 ; 42.82
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The exposure-development process for the fabrication of holographic diffraction gratings for integrated optics in the positive photoresist Shipley AZ-1350 is theoretically and experimentally investigated. An analysis of the light intensity distribution is carried out, taking into account the reflectivity at the photoresist-substrate interface and the attenuation in the photoresist for two holographic exposure arrangements. The influence of the exposure energy, the development time for a fixed concentration of the developer and the initial photoresist thickness are described. Various grating profiles are calculated for photoresist films, coated on matched and reflective substrates. Scanning electron micrographs demonstrate very good agreement between the actual and calculated gratings profiles.
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  • 68
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    Applied physics 51 (1990), S. 350-353 
    ISSN: 1432-0630
    Keywords: 07.60 ; 42.80 ; 61.80
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    Notes: Abstract It is shown that optically excited surface plasmons can be used for measurements of the surface temperature of a metal with nanosecond time resolution. This method is closely related to transient thermoreflectance, but its sensitivity is considerably higher. We give a survey on the mechanisms involved, briefly discussing the dependence on the sample properties. Experimental confirmation of the proposed sensitivity enhancement as well as the time resolution is presented.
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  • 69
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    Applied physics 53 (1991), S. 282-283 
    ISSN: 1432-0630
    Keywords: 61.80 ; 42.55 ; 74.70
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Projection patterning of Y-Ba-Cu-O films on (100) SrTiO3 and (100) MgO substrates using femtosecond KrF-excimer-laser pulses is reported
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  • 70
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    Applied physics 24 (1981), S. 381-386 
    ISSN: 1432-0630
    Keywords: 33 ; 42.55
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    Notes: Abstract A tunable diode laser and a multipass optical cell are used to investigate the feasibility of performing radiocarbon dating by means of infrared spectroscopy. We show that the detection of14CO2 at concentrations of14C/12C≲10−12 is not limited by interferences from the background of normal CO2 molecules, provided the gas sample is cooled. Using short-time constants, the present sensitivity of the infrared technique is comparable to that of an ideal disintegration counter. The experimental results are extrapolated to long time constants to demonstrate that radiocarbon dating by infrared spectroscopy is feasible, and that carbon samples with a mass of less than 1 gm can be dated by this technique.
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  • 71
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    Applied physics 24 (1981), S. 7-9 
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    Keywords: 42.55
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    Notes: Abstract Newly found reflection properties of the Fizeau wedge interferometer are shown to be of particular advantage in obtaining efficient multi-wavelength operation of dye lasers. Use is made of the fact that the reflecting Fizeau wedge can ensure at once a selective feedback for a given wavelength and quasi-total reflection in an other direction for all other wavelengths. Fully independent tuning of two 0.02 nm lines is obtained with short pulse (2 ns) N2-laser pumping using a single Fizeau wedge.
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  • 72
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    Applied physics 24 (1981), S. 201-203 
    ISSN: 1432-0630
    Keywords: 42.10 ; 42.80 ; 42.50
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    Notes: Abstract A laser signal propagating in an optical fiber is amplified by the evanescent field interacting with the excited Rhodamine 6 G solution surrounding the fiber. A small signal gain of 430 at 600 nm has been measured in a long fiber with a 2 cm long fiber optic amplifier.
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  • 73
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    Applied physics 24 (1981), S. 233-238 
    ISSN: 1432-0630
    Keywords: 42.55
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    Notes: Abstract A synchronously mode-locked, cavity-dumped picosecond dye laser is described. The structure and intensity of the picosecond pulses measured under different conditions are reported. It was found that the structure of the pulses from the synchronously pumped dye laser depends critically on the length of the Ar+ laser pulses. At the shortest Ar+ laser pulses of about 70 ps the dye pulses are as short as 1.1 ps. With Ar+ laser pulses of 200 ps the dye laser pulses contains a broad satellite pulse which contains a large fraction of the total intensity. When a cavity dumper is added to the system one gets dye laser pulses 15–20 ps long with a substructure, which indicates incomplete mode-locking. Well mode-locked 1.5–2.0 ps pulses were obtained in the red part of the dye laser action spectrum, i.e. 620–650 nm for R6G, 595–608 nm for R 110 and 657–662 nm for RB, respectively. Addition of mode-locking dyes also improved the pulse quality at some wavelengths.
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  • 74
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    Applied physics 50 (1990), S. 565-572 
    ISSN: 1432-0630
    Keywords: 78.40 ; 78.55 ; 42.55
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This paper describes measurements of the R-line emission from Cr3+ ions in Y3Ga5O12, Gd3Sc2Ga3O12, and Gd3Sc2Al3O12. Discrete splittings of the lines are interpreted as due to disorder on the cation sublattices. Assuming statistical distributions of the cations on the different cation sublattices enables estimates to be made of the degree of non-stoichiometry in the crystals.
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  • 75
    ISSN: 1423-0445
    Keywords: toxin sequestration ; predation ; human dietary hazard ; cantharidin ; Coleoptera ; Meloidae ; Epicauta vittata ; Rana ; Hirudo ; Nerodia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Frogs(Rana pipiens) fed on blister beetles (Meloidae) or cantharidin, retain cantharidin systemically. After cessation of feeding, they void the compound relatively quickly. Systemic cantharidin does not protect frogs against ectoparasitic feeding by leeches(Hirudo medicinalis) or predation by snakes(Nerodia sipedon). As suggested by our data, and from reports in the early literature, ingestion of cantharidin-containing frogs can pose a health threat to humans.
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  • 76
    ISSN: 1423-0445
    Keywords: pheromone ; attractant ; triene ; tetraene ; hydrocarbon ; Insecta ; Coleoptera ; Nitidulidae ; Carpophilus freemani
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    Topics: Biology
    Notes: Summary Males ofCarpophilus freemani Dobson (Coleoptera: Nitidulidae) produce an aggregation pheromone to which both sexes fly in a wind-tunnel bioassay. The major pheromone component (ca. 30 ng per male per day in volatile collections) was identified as (2E,4E,6E)-5-ethyl-3-methyl-2,4,6-nonatriene. A minor component, (2E,4E,6E,8E)-7-ethyl-3,5-dimethyl-2,4,6,8-undecatetraene, was 3–10% as abundant as the major triene and was 5–20% as active when compared at relative doses ranging from natural proportions to 1:1. These compounds act synergistically: a mixture of major and minor components in natural proportions attracted more than twice as many beetles as the major component alone, and the mixture fully accounted for the activity of male-derived volatile collections. Six other male-derived conjugated hydrocarbons, ranging from 2% down to 0.04% as abundant as the major component, were also identified. These are (in order of decreasing bioassay activity when compared on an equal-weight basis): (3E,5E,7E)-6-ethyl-4-methyl-3,5,7-decatriene, (2E,4E,6E)-5-ethyl-3-me-thyl-2,4,6-octatriene, (3E,5E,7E,9E)-8-ethyl-4,6-dimethyl-3, 5,7,9-dodecatetraene, (2E,4E,6E,8E)-3,5,7-trimethyl-2,4,6, 8-undecatetraene, (3E,5E,7E)-5-ethyl-7-methyl-3,5,7-undecatriene, and (2E,4E,6E)-3,5-dimethyl-2,4,6-nonatriene. All structure identifications were confirmed by synthesis. In the wind tunnel, the pheromone acted synergistically with “host”-type volatiles such as propyl acetate, valeric acid, and ethanol. This concept was verified by fields tests in California, in which there was dramatic synergism between the pheromone and fermenting host materials. Pheromone biosynthesis is discussed.
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  • 77
    ISSN: 1423-0445
    Keywords: secretion-grooming ; pygidial glands ; chemical defence against microorganisms ; respiration ; aquatic beetles ; Coleoptera ; Hydradephaga ; Gyrinidae ; Haliplidae ; Noteridae ; Hygrobiidae ; Dytiscidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary All Hydradephaga investigated so far crawl onto land when exposed to an increase in water temperature and light intensity and spread the secretion from their pygidial glands over the body surface (“secretion-grooming”). The secretions have antimicrobial properties and are mainly applied to hydrofuge body regions important for aquatic respiration. Experimental prevention of secretion-grooming leads to the loss of the respiratory air bubble and a significant increase in mortality. These findings support the view that the secretion-grooming of adephagous aquatic beetles, like in some aquatic Heteroptera, inhibits the growth of microor-ganisms, thus preventing the contamination and wetting of the cuticular respiratory structures. Thus it keeps functional the air-retaining hydrophobous body regions essential for aquatic respiration. A model is presented on how secretion-grooming may have evolved in the Hydradephaga. Other possible functions of the pygidial gland secretions are discussed.
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  • 78
    ISSN: 1423-0445
    Keywords: chemical defence ; mimicry ; reflex bleeding ; variation ; alkaloid ; coccinelline ; Coleoptera ; Coccinellidae ; Coccinella septempunctata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 7-spot ladybirds secrete alkaloid (coccinelline)-rich fluid (reflex blood) from leg joints as a defence mechanism against predators. A technique is described that enables the collection and accurate quantification of reflex blood produced, and the amount of coccinelline therein. Coccinelline was found distributed throughout the body, although concentrated in the reflex blood. Reflex blood was collected from a large set of beetles at several time points. Significant variation was found among beetles in the amount of reflex blood produced (for males and for females corrected for body weight) and the coccinelline concentration of the reflex blood. The results are discussed in relation to automimicry and the maintenance of variation through energy trade-offs. The relationships between tendency to aggregate, ability to reflex bleed and the possession of aposematic coloration are also considered.
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  • 79
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    Cellular and molecular life sciences 46 (1990), S. 1209-1211 
    ISSN: 1420-9071
    Keywords: Pheromone ; E-myrcenol ; ipsdienol ; Ips duplicatus ; Coleoptera ; Scolytidae ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Males of the Eurasian bark beetleIps duplicatus, when feeding in host Norway spruce (Picea abies (L.) Karst.), produced and released ipsdienol andE-myrcenol, which we show to be aggregation pheromone components. Bioassays using walking beetles indicated thatE-myrcenol in synergistic combination with ipsdienol is essential for attraction. Synergism ofE-myrcenol and ipsdienol released at natural rates in the forest was also demonstrated with a new technique using mechanical slow-rotation of sticky traps.
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  • 80
    ISSN: 1423-0445
    Keywords: chemical defence ; mimicry ; reflex bleeding ; variation ; alkaloid ; adaline ; Coleoptera ; Coccinellidae ; Adalia bipunctata
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    Topics: Biology
    Notes: Summary 2-spot ladybirds secrete alkaloid (adaline)-rich defence fluid (reflex blood) in response to predator attack. Reflex fluid was collected from individual ladybirds and weighed and the alkaloid content measured by GC. The amount of fluid produced built up rapidly following winter hibernation in animals feeding on aphids. The concentration of adaline in the fluid was highest in the first bleeding after winter hibernation. A large sample of beetles was reflex bled several times. Significant among beetle variation was found in the amount of fluid produced and the concentration of the reflex blood. The results are discussed in relation to the possibility that 2-spot ladybirds are Batesian mimics of 7-spot ladybirds and to the possible functions of adaline.
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  • 81
    ISSN: 1423-0445
    Keywords: defensive secretion ; hot secretion ; elytral flanges ; evolution ; benzoquinones ; hydrocarbons ; bombardier beetle ; Coleoptera ; Carabidae ; Paussinae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Australian bombardier beetle,Mystropomus regularis, sprays a mixture of quinones (1,4-benzoquinone, 2-methyl-1,4-benzoquinone, 2-ethyl-1,4-benzoquinone) and hydrocarbons (principallyn-pentadecane). The defensive fluid ist generated explosively in two-chambered glands, and is ejected audibly and hot (maximal recorded temperature = 59°C).Mystropomus is a member of the paussoid lineage of bombardiers. In common with other members of the group, it has a pair of elytral flanges (flanges of Coanda), associated with the gland openings, that serve as launching guides for anteriorly-aimed ejections of spray. It is argued thatMystropomus may be the least derived of flanged paussoids, and the closest living relative of the most primitive of extant bombardiers (Metriini).
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  • 82
    ISSN: 1423-0445
    Keywords: pyrrolizidine alkaloid N-oxides ; alkaloid sequestration ; defensive secretion ; host plant ; Coleoptera ; Chrysomelidae ; Oreina ; Asteraceae ; Adenostyles alliariae ; Senecio fuchsii ; Petasites paradoxus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Oreina cacaliae andO. speciosissima (Coleoptera, Chrysomelidae) sequester in their elytral and pronotal defensive secretions pyrrolizidine alkaloids (PAs) as Noxides (PA N-oxides). The PA N-oxide patterns found in the beetles and their host plants were evaluated qualitatively and quantitatively by capillary gas chromatography/mass spectrometry (GC-MS). Of the three host plantsAdenostyles alliariae (Asteraceae) is the exclusive source for PA N-oxide sequestration in the defensive secretions of the beetles. With the exception of O-acetylseneciphylline the N-oxides of all PAs ofA. alliariae, i.e. senecionine, seneciphylline, spartioidine, integerrimine, platyphylline and neoplatyphylline were identified in the secretion. PA N-oxides typical ofSenecio fuchsii (Asteraceae) were detected in the bodies of the beetles but not in their secretion. No PAs were found in the leaves of the third host plant,Petasites paradoxus (Asteraceae). The results suggest the existence of two distinctive storage compartments for PA N-oxides in the beetle: (1) the defensive secretion, containing specifically PA N-oxides acquired fromA. alliariae; (2) the body of the beetle, sequestering additionally but less selectively PA N-oxides from other sources,e.g. S. fuchsii or monocrotaline N-oxide fed in the laboratory. The concentration of PA N-oxides in the defensive secretion is in the range of 0.1 to 0.3 mol/1, which is more than 2.5 orders of magnitude higher than that found in the body of the beetle. No significant differences exist in the ability of the two species of beetles to sequester PA N-oxides fromA. alliariae, althoughO. speciosissima, but notO. cacaliae, produces autogenous cardenolides. A negative correlation seems to exist between the concentrations of plant-derived PA N-oxides andde novo synthesized cardenolides in the defensive secretion ofO. speciosissima.
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  • 83
    ISSN: 1423-0445
    Keywords: larval frass ; predator ; prey ; biological control ; kairomones ; Rhizophagus grandis ; Dendroctonus micans ; Coleoptera ; Rhizophagidae ; Scolytidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Adults of the predatory beetleRhizophagus grandis are strongly attracted to both adult and larval frass of its specific prey,Dendroctonus micans, in walking bioassays. Spruce bark and resin are relatively unattractive. Solvent extracts of larval frass that were attractive toR. grandis adults in a flight wind tunnel contained a mixture of monoterpenes of host plant origin. A synthetic mixture of these monoterpenes, (+)—α-pinene, (−)—β-pinene, β-phellandrene,dl limonene and 3-carene, was responsible for 70–80% of the activity of the most attractive extract. We suggest that a blend of monoterpenes in frass acts as a kairomone forR. grandis but that attraction to monoterpenes is only the first of a sequence of behavioural responses that ensures successful host location and identification.
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  • 84
    ISSN: 1432-1041
    Keywords: Atenolol ; hypertension ; ß-adrenoceptor blockade ; blood pressure ; heart rate ; ambulatory ; circadian rhythm
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    Topics: Chemistry and Pharmacology , Medicine
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    European journal of clinical pharmacology 39 (1990), S. 435-439 
    ISSN: 1432-1041
    Keywords: co-dergocrine mesylate ; hypertension ; aldosterone ; catecholamines ; nifedipine ; renin side effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Co-dergocrine mesylate (Cod), which inhibits norepinephrine secretion by stimulating presynaptic dopamine receptors, and has no known metabolic side effect, has an additive antihypertensive effect to that of Nifedipine (Nif). Plasma norepinephrine, epinephrine, renin activity and aldosterone have been measured after acute administration of Nif and Cod alone and in combination to 18 patients with a diastolic blood pressure 〉 105 mm Hg in a cross-over, randomized, double-blind study. Every patient received 4 mg Cod then 20 mg Nif, placebo then 20 mg Nif and 4 mg Cod then placebo. The second treatment was always given 1 h after the first medication. Blood pressure was measured before and every 15 min during the study period. Blood for measurement of catecholamines, aldosterone and renin activity was collected before medication, 1 h after the first dose and 90 min after the second treatment. Blood pressure was significantly lower (P 〈 0.05) where Cod preceded Nif. Cod caused a significant decrease in plasma norepinephrine from 293 to 202 pg · ml−1 and in epinephrine from 67 to 55 pg · ml−1. The Nif-induced increase in norepinephrine from a pre-treatment value of 293 pg · ml−1 with preceding Cod to 331 pg · ml−1 was much less than the increase with placebo as premedication, from 284 to 440 pg · ml−1. Nif caused an increase in renin activity but no increase in aldosterone. Nif-related side effects, such as flushing and headache, occurred in 6 patients of whom 5 had no received Cod as premedication. Due to the stabilizing action of Cod on catecholamines and on the side effects of Nif, Cod may be preferable to other antihypertensives in augmenting the antihypertensive action of Nif.
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  • 86
    ISSN: 1432-1041
    Keywords: Insulin secretion ; Nifedipine ; non insulin-dependent-diabetes mellitus- ; hyperglycaemia ; plasma insulin ; hypertension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of 7-days of nifedipine treatment on insulin secretion has been analyzed in hypertensive patients with non-insulin-dependent mellitus (NIDDM). Pancreatic β-cell function was assessed as insulin release following stimulation with arginine after potentiation by hyperglycaemia. Two groups of 5 patients with NIDDM (fasting blood glucose 139.2 mg·dl−1), on the same controlled diet, were compared; one was treated with nifedipine 30 mg per d and the other was the control. The mean blood pressure in the nifedipine group decreased (110 vs 102 mm Hg). Fasting blood glucose and basal plasma insulin were not affected by nifedipine. The acute insulin response (AIR) to 5 g arginine after potentiation by hyperglycaemia (clamped at 240 and 350 mg/dl for 30 min) was significantly (P〈0.05) decreased, as well as the potentiation slope (line relating AIR and plasma glucose level) in those patients, and were unchanged in the control group. Thus, nifedipine may impair insulin secretion at high glucose levels in patients with NiDDM.
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  • 87
    ISSN: 1432-1041
    Keywords: arrhythmia ; hypertension ; LVH ; holter monitoring ; BP monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary To evaluate the relationship among supraventricular and ventricular arrhythmias with blood pressure and heart rate (HR) values, we studied 2 groups of 20 hypertensive men with (group I) and without (group II) left ventricular hypertrophy. Ambulatory electrocardiographic tracings were recorded continuously, together with ambulatory arterial pressure. Systolic (SBP) and diastolic (DBP) blood pressure values measured over 24 h showed no difference between the two groups, but we found greater variability in SBP in group I. The incidence of ventricular and supraventricular arrhythmias was significantly higher in patients of group I; moreover, we found a strong correlation between the incidence of ventricular extrasystoles (VPCs) and SBP, DBP, and HR values in group I, whereas in group 11 the incidence of supraventricular extrasystoles (APCs) was higher during peaks of SBP and HR values. The relationship between APCs and SBP observed in group II may be attributable to the pressure stimulus on a normal atrium, and the significant correlation between VPCs and SBP, DBP, and HR values may be due to episodes of subendocardial ischemia or to the influence of adrenergic stimulation on previously compromised myocardial tissue.
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  • 88
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    European journal of clinical pharmacology 38 (1990), S. 209-211 
    ISSN: 1432-1041
    Keywords: Isradipine ; hypertension ; pharmacokinetics ; pharmacodynamics ; clinical trial
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In conjunction with a multicentre clinical trial of the calcium antagonist isradipine in hypertension, pharmacokinetic and pharmacodynamic studies were conducted in 9 subjects. An initial dose of 5 mg (capsule formulation) of isradipine was given orally. The mean Cmax, tmax and AUC(0–8) were 6.0 ng · ml−1, 1.5 h and 15.1 h · ng · ml−1 respectively. Seven subjects repeated the study at steady state after 10 week's dose titration with isradipine. Cmax, tmax and AUC(0–8) were 3.7 ng · ml−1, 1.2 h and 12.2 h · ng · ml−1 respectively indicating that the drug does not accumulate over time. Control of blood pressure paralleled plasma isradipine concentrations which suggested that the drug should be given at least twice daily. Pharmacokinetic studies performed in conjunction with clinical trials can provide valuable information about the patterns of drug response.
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  • 89
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    European journal of clinical pharmacology 40 (1991), S. 131-134 
    ISSN: 1432-1041
    Keywords: trimazosin ; hypertension ; alpha1-adrenoceptor blocker ; essential ; exercise ; extracellular fluid volume ; haemodynamics ; plasma volume ; side effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The long-term haemodynamic effect of sustained-release trimazosin (mean daily dose 418 mg) at rest and during exercise has been examined in 14 male patients (age 30–61 y) with previously untreated mild or moderate essential hypertension. Cardiac output (dye dilution), heart rate and intra-arterial blood pressure were measured supine and sitting at rest, and during bicycle exercise. After 11 months of trimazosin treatment the mean casual blood pressure was reduced from 165/106 mm Hg to 147/92 mm Hg. The intra-arterial systolic and diastolic pressure was reduced by 3–7% at rest and during 50, 100 and 150 W exercise. Total peripheral resistance was reduced by 8–14% and cardiac output was slightly higher (2–8%) in all situations. Stroke volume and heart rate remained unchanged, as did body fluid volumes (isotope dilution) and body weight. Side effects were minor and transient. Thus, the haemodynamic responses to trimazosin are similar to but weaker than those of other alpha1-adrenoceptor blockers. The efficacy of the sustained-release formulation of trimazosin was low and daily doses above 600 mg are likely to be needed by many patients.
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  • 90
    ISSN: 1432-1041
    Keywords: Fibrinolysis ; hypertension ; atenolol ; doxazosin ; tissue plasminogen activator ; plasminogen activator inhibitor ; cholesterol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Disturbances in the fibrinolytic system have been associated with cardiovascular disease and its risk factors. In the present study the effects of an alpha1-adrenoceptor inhibitor (doxazosin) and a selective beta-adrenoceptor blocker (atenolol) on the fibrinolytic system have been evaluated. Eighty four subjects with previously untreated mild to moderate hypertension and elevated serum cholesterol were randomized to receive atenolol or doxazosin in a double-blind study over 6 months. Tissue plasminogen activator(tPA) and plasminogen activator inhibitor (PAI-1) were measured in citrated plasma samples before and after venous occlusion before and at the end of the study period. tPA activity after venous occlusion and tPA capacity were significantly increased after doxazosin as compared to pretreatment values. The fibrinolytic variables did not change in the atenolol group. Thus, doxazosin but not atenolol, improved the activity of the fibrinolytic system in patients with hypertension and an elevated serum cholesterol level. This effect of doxazosin warrants consideration when selecting a first-line antihypertensive drug.
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  • 91
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    European journal of clinical pharmacology 19 (1981), S. 19-24 
    ISSN: 1432-1041
    Keywords: hypertension ; guanfacine ; central antihypertensives ; withdrawal ; catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary 1. Guanfacine (2–6 mg/day) a centrally acting antihypertensive drug, was effective in controlling blood pressure in 5 essential hypertensives and lowered plasma noradrenaline and urinary catecholamine excretion. 2. Withdrawal of guanfacine by blind substitution of identical placebo tablets under observation in hospital led to a gradual recovery of blood pressure over 2–4 days. 3. Salivary flow, which was reduced on guanfacine, returned to pretreatment levels by 2 days after withdrawal and significantly exceeded control for the next two days. 4. Urinary catecholamine excretion returned to pretreatment levels by 3 days but did not exceed control levels during the period of study. 5. Plasma noradrenaline returned gradually to pretreatment levels, and by day 4 significantly exceeded them. 6. No patient experienced symptoms suggesting catecholamine excess although four out of five reported a headache from the second day onwards. 7. Guanfacine, a centrally acting drug which pharmacologically resembles clonidine, has a slow offset of hypotensive effect over 2–3 days. Symptoms or biochemical evidence of catecholamine excess were not encountered within 48 h of withdrawal, possibly reflecting the longer duration of action and plasma half-life of guanfacine.
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  • 92
    ISSN: 1432-1041
    Keywords: guanfacine ; methyldopa ; hypertension ; rebound hypertension ; withdrawal symptoms ; plasma noradrenaline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Nine patients with essential hypertension completed a clinical trial designed to study the effects and side effects of administration and withdrawal of guanfacine (2 mg tds) and methyldopa (250 mg tds) on blood pressure, heart rate, and plasma noradrenaline. The study was of randomised doubleblind crossover design with two active therapy phases of eight weeks each, preceded by an initial 4 week placebo phase, separated by an intermediate 2 week placebo phase, and followed by a final 2 week placebo phase. Patients took bendrofluazide 5 mgs daily throughout the entire trial, during both active and placebo periods. Each patient was admitted to hospital at the end of the 8 week active treatment phases, so that the effects of drug withdrawal on blood pressure, heart rate, plasma noradrenaline and side reactions, could be closely observed and monitored. The main conclusions from analysis of the results were that: 1. The hypotensive efficacy of guanfacine and methyldopa was very similar in the doses used, each of the two drugs lowering the supine mean arterial pressure by about 15 mm Hg and the supine diastolic pressure by about 10 mm Hg. 2. The frequency of side effects was greater with guanfacine than with methyldopa. 3. There was no signficant early rebound phenomenon after withdrawal of either methyldopa or guanfacine. 4. There was tendency for the blood pressure to rise slowly and marginally above initial placebo values, 2 weeks after cessation of guanfacine treatment though this was not significant. It was however, accompanied by a significant increase in plasma noradrenaline at 2 weeks. This was not seen 2 weeks after cessation of methyldopa. There was no single incidence of worrying rebound hypertension or withdrawal symptoms either early or late in any patient following cessation of methyldopa or guanfacine.
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  • 93
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    European journal of clinical pharmacology 20 (1981), S. 163-168 
    ISSN: 1432-1041
    Keywords: hypertension ; captopril ; cardiac output ; extracellular fluid volume ; renin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effects of captopril 450 mg/day for 4 weeks on blood pressure, heart rate, cardiac output and extracellular fluid volume were compared in severe, often drug-resistant hypertension (n=23), mild to moderate hypertension associated with renal artery stenosis (n=10) and mild to moderate essential hypertension (n=20). Plasma renin in the three groups was 52±19, 58±17 and 20±4 µU/ml (mean ± SEM), respectively. Blood pressure fell by 18±4%, 21±2% and 18±1%. The pressure drop was mainly due to a fall in peripheral vascular resistance. Addition of the diuretic hydrochlorothiazide (25–100 mg/day) caused a further fall in resistance. Despite the vasodilator effect of captopril, reflex cardiostimulation and reactive fluid retention were not observed. In severe hypertension, captopril alone was more effective in lowering blood pressure than combined diuretic-betablocker-vasodilator therapy. Moreover, cardiac output in these patients was higher and resistance was lower after captopril than during combined treatment. Thus, captopril was capable of normalising the abnormal haemodynamic state in patients with essential hypertension, and in hypertension associated with renal artery stenosis. Despite marked differences in pre-treatment plasma renin, the effects of captopril on systemic haemodynamics were similar in all the patients.
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  • 94
    ISSN: 1432-1041
    Keywords: vasodilator ; hypertension ; haemodynamic effects ; renal plasma flow ; renal tubular function ; plasma renin activity ; aldosterone ; Ro 12-4713
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Selected cardiovascular and endocrine effects of the new oral vasodilator Ro 12-4713 have been evaluated in an acute single dose study. In five patients with essential hypertension, Ro 12-4713 caused a dose-dependent decrease in supine and upright blood pressure and an increase in heart rate. Initial effects occurred one to 2 h after drug ingestion and maximal effects were noted after five hours and persisted for at least 8 h. Blood pressure was normalized, and the antihypertensive and chronotropic effects persisted for 24 h after a dose of about 300 mg/1.73 m2. Plasma and urinary norepinephrine and plasma renin levels tended to be raised, whereas plasma and urinary epinephrine and plasma aldosterone did not change. Changes in supine heart rate were inversely correlated with changes in mean blood pressure (r=−0.60; P〈0.02), and positively with those in plasma norepinephrine (r=0.55; P〈0.05) and renin (r=0.62, P〈0.01); changes in supine plasma renin level were also inversely correlated with those in mean blood pressure (r=−0.65; P〈0.01), and positively with those in plasma norepinephrine (r=0.58; P〈0.05). 24 h-urinary sodium excretion was significantly (P〈0.001) decreased; it was positively correlated with mean blood pressure (r=0.51; P〈0.05) and inversely with supine plasma renin activity (r=−0.63; P〈0.01). In six normal subjects and six patients with essential hypertension, effective renal plasma flow and the renal clearance of sodium, potassium, calcium and uric acid were not significantly altered five hours after a dose of Ro 12-4713 of about 250 mg/1.73 m2; glomerular filtration rate tended to be slightly decreased, and filtration fraction was significantly (P〈0.05) reduced in the hypertensive patients. At the same time blood pressure was decreased and plasma norepinephrine (P〈0.01) and renin (ns) were slightly increased in both groups. Ro 12-4713 in a single oral dose of about 300 mg appeared to be a potent, long acting, hypotensive vasodilator.
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  • 95
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    European journal of clinical pharmacology 19 (1981), S. 25-32 
    ISSN: 1432-1041
    Keywords: clonidine ; hypertension ; baroreceptor reflex ; mode of action ; sympathetic activity ; urinary catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Acute studies of clonidine suggest that it lowers blood pressure by central enhancement of baroreflex sensitivity coupled with diminished evidence of sympathetic outflow, but longterm clonidine data have not been conclusive. We examined effects of one month of low dose clonidine (0.4 ± 0.15 mg/day) alone in 13 essential hypertensive men, assessing several biochemical indices of sympathetic function, as well as physiologic parameters, including baroreflex sensitivity, the cold pressor test, and the hypotensive response to alpha adrenergic blockade. Clonidine diminished mean arterial pressure (from 104±5 to 84±3 mmHg;p〈0.01), without associated changes in several biochemical parameters of sympathetic outflow (urinary excretion of catecholamines, metanephrines, and vanillylmandelic acid; allp〉0.1). Circulatory baroreflex function was not enhanced by clonidine, during either the amylnitrite test or the phenylephrine test, before or after parasympathetic blockade with atropine. The cold pressor test, an index of efferent sympathetic pressor function, was also unaltered. The enhanced mean arterial pressure response to phentolamine during clonidine therapy (from a fall of 14.8±4.3 to 39.4±5.2 mmHg,p〈0.01), suggested an increase in alpha adrenergic vascular tone, perhaps mediated by clonidine's alpha agonist properties in vascular smooth muscle. The antihypertensive mechanism of longterm low dose clonidine cannot reliably be ascribed either to baroreflex enhancement or to suppression of sympathetic outflow.
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  • 96
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    European journal of clinical pharmacology 19 (1981), S. 113-118 
    ISSN: 1432-1041
    Keywords: tolmesoxide ; vasodilators ; hypertension ; side-effects ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics, hypotensive effect and tolerability of a new vasodilator, tolmesoxide (T), have been studied in 6 uncontrolled hypertensive patients receiving atenolol and a diuretic. After a 50 mg oral dose mean (± SD) peak plasma concentration of T was 1.13±0.29 µg/ml−1 and occurred 0.79±0.40 h after the dose; mean peak plasma concentration of its sulphone metabolite (M) was 0.37±0.09 µg/ml−1 at 1.92±1.32 h after the dose. Following peak plasma concentrations there was a monoexponential decline in T and M concentrations with half-lives of 2.78±0.77 h and 10.78±7.85 h respectively. There was a linear increase in plasma concentration of T and M during incremental dosing with 50–200 mg t. i. d. During in-patient administration of 600–900 mg T daily (n=6) there was no significant change in blood pressure, pulse rate or body weight. Out-patient administration of 900 mg T daily (n=4) was associated with a significant fall in mean systolic but not diastolic bp (lying −15/+1 mm Hg. standing −25/−8 mm Hg). A further fall was observed in 2 subjects receiving 1200 mg and 1500 mg daily. Supine pulse rate increased (mean ± SD) significantly from 55±5/min to 66±8/min following 900–1500 mg T in 4 out-patients. Severe nausea and other gastro-intestinal side-effects in all subjects receiving 600–900 mg daily eventually necessitated drug withdrawal. In its present from T is not recommended for the treatment of hypertension.
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  • 97
    ISSN: 1432-1041
    Keywords: carteolol ; hydrochlorthiazide ; amiloride ; hypertension ; double-blind clinical trial
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The antihypertensive effect of carteolol, a new β-blocking agent, added to basal diuretic treatment (hydrochlorthiazide 50 mg and amiloride 5 mg) has been assessed in a controlled trial in 17 patients with mild-to-moderate hypertension. The trial was divided into 4 stages: 1) run-in period with no antihypertensive treatment, 2) diuretic period (the diuretic being continued as basal treatment during the two following periods), 3) carteolol titration period, and 4) double-blind cross-over period comparing carteolol with placebo, which lasted 2 times 4 weeks. Although the diuretic effectively reduced the blood pressure, 17 of the 20 patients originally studied still had an elevated diastolic blood pressure (≧ 95 mmHg) after the diuretic period, thus fulfilling the inclusion criteria for the study. During the titration period carteolol 5 to 20 mg b. i. d. significantly reduced the elevated blood pressure. The blood pressure was reduced to normal in all 17 patients, although in two patients this occurred only during the double-blind period. During the double-blind period, the dose of carteolol was used which had given a satisfactory response during the titration period. The blood pressure in the 14 patients who completed the trial remained low both with carteolol and placebo during the double-blind stage, and was only slightly lower with carteolol than with placebo. This is probably due to a “carry-over” effect. Three patients discontinued the trial due to side effects (1 urticaria, 1 insomnia and 1 nausea) while on carteolol. There was no other difference between carteolol and placebo in the number or severity of side effects.
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  • 98
    ISSN: 1432-1041
    Keywords: vasodilator ; hypertension ; antihypertensive treatment ; catecholamines ; renin ; aldosterone ; blood volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The antihypertensive efficacy and endocrine profile of the new antihypertensive agent, Ro 12-4713, were evaluated in 23 patients (17 men and 6 women) with moderate to severe arterial hypertension. Following addition of Ro 12-4713 to pre-existing therapy with diuretics and beta-blockers or sympatholytics, blood pressure in most of the patients was normalized within one month by a daily dose of 60 to 120 mg. Heart rate was only slightly increased. Orthostatic hypotension was not observed. Weight gain or oedema formation occurred in 14 patients within the first four weeks, but could be controlled satisfactorily by intensified diuretic therapy. Increased hair growth occurred in most of the patients. After a mean duration of treatment of 2.8 months, plasma volume and plasma and urine sodium were unaltered, and plasma potassium was slightly decreased. Plasma renin activity was doubled, whereas plasma aldosterone concentrations were unaltered. Plasma norepinephrine levels were high before and increased only slightly during chronic Ro 12-4713 treatment, whereas urinary norepinephrine excretion was unchanged. Plasma and urinary epinephrine were unaltered by Ro 12-4713. Ro 12-4713 appears to be a potent vasodilator for the combination treatment of hypertension in men.
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  • 99
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    European journal of clinical pharmacology 20 (1981), S. 335-338 
    ISSN: 1432-1041
    Keywords: atenolol ; atherosclerosis ; hypertension ; serum lipoproteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Serum lipoproteins were determined in 15 patients before and during antihypertensive treatment with atenolol 0.1–0.2 g/day for a mean of 8 months. The mean blood pressure fell from 171/103 to 154/93 mm Hg (p〈0.05). Significant lipoprotein changes were an increase in very low density triglycerides (VLDL-TG) from 1.21±0.95 (SD) to 1.62±1.24 mmol/l (p〈0.01) and in low density (LDL) TG from 0.46±0.12 to 0.51±0.12 mmol/l (p〈0.05). Together, these TG increases resulted in development of hypertriglyceridaemia in 7/15 patients during atenolol treatment. No effect on whole serum cholesterol or on the high density lipoprotein cholesterol concentrations were found. Thus, some patients on long term treatment with atenolol seem to receive the benefit of normotension at the cost of hypertriglyceridaemia. This may have practical implications, since hypertriglyceridaemia constitutes an important risk factor for atherosclerosis.
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  • 100
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    European journal of clinical pharmacology 20 (1981), S. 347-349 
    ISSN: 1432-1041
    Keywords: reserpine ; syrosingopine ; prolactin secretion ; hypertension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In 20 mild hypertensive women, reserpine induced a significant increase in mean plasma PRL, both under basal conditions (from 6.6±0.9 to 17.9±2.9 ng/ml), and on repeated determinations during the day. In contrast to reserpine, the administration of syrosingopine, a synthetic compound derived from reserpine, to the same subjects was not followed by a significant change in prolactin level. Beyond their pharmacological interest, these results are of clinical importance when considering that rauwolfia alkaloids are used for long term treatment, and that an increase in PRL levels is important in pathology, both in relation to the function of the hypophyseogonadal axis and in view of its possible facilitation of the growth and development of mammary cancer.
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