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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 7 (1975), S. 21-28 
    ISSN: 1432-0630
    Keywords: Dye laser ; Single mode operation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This paper describes an investigation of the special problems of single mode operation in cw dye lasers. Single mode operation in homogeneously broadened lasers can be obtained, if the gain due to spatial hole burning is compensated by dispersive elements, as prisms, Fabry-Pérot etalons and single dielectric interfaces within the resonator. The gain and the influence of the dispersive elements were calculated for two commonly used types of resonators. The calculations make it possible to design simple continuously tunable single-mode systems.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 764 (1995), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Der Nervenarzt 68 (1997), S. 459-465 
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Neuroendoskopie ; Ventrikulostomie ; Verschlußhydrocephalus ; Arachnoidalzysten ; Syringomyelie ; Key words Neuroendoscopy ; 3rd ventriculostomy ; Non-communicating hydrocephalus ; Arachnoid cyst ; Syringomyelia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The trend in recent neurosurgery is going toward further reduction of invasiveness and avoidance of traumatization of the brain, spinal cord, and peripheral nerves to reduce the risk of neurological and mental deficit. In this way, the duration of hospital stay and disablement can be shortened. An important „minimally invasive” technique is neuroendoscopy. The ventricular system and the sub- arachnoid space of the brain give suitable conditions for the use of an endoscope. Non-communicating hydrocephalus is the most frequent indication for an endoscopic ap- proach. However, arachnoid cysts, cystic tumors, and intraventricular lesions may also effectively be treated with an endoscope. Using special instruments, laser devices, and bipolar diathermy, even highly vascularized lesions, such as cavernomas, may be completely resected. Moreover, endoscopes are used in the treatment of various spinal diseases and carpal tunnel syndrome, as well as in endoscopy-assisted microsurgery.
    Notes: Zusammenfassung Auch in der Neurochirurgie geht der Trend zu immer weniger invasiven Operationstechniken, um große Trepanationen zu vermeiden, die präparative Traumatisierung von Hirn, Rückenmark und Nerven zu minimieren und damit das Risiko neurologischer und psychischer Störungen so gering wie möglich zu halten. Der Krankenhausaufenthalt und die Arbeitsunfähigkeit können so häufig verkürzt werden. Wesentliches „minimal invasives” Verfahren ist die Neuroendoskopie. Das Gehirn bietet mit seinen präformierten Hohlräumen, den Hirnkammern und dem Subarachnoidalraum gute Voraussetzungen für den Einsatz des Endoskopes. Die häufigste Indikation für einen neuroendoskopischen Eingriff stellt der Verschlußhydrozephalus dar. Aber auch Arachnoidalzysten, zystische Tumoren und kleinere intraventrikuläre Raumforderungen können effektiv endoskopisch über ein kleines Bohrloch behandelt werden. Durch Einsatz spezieller Instrumente, Laser und bipolarer Elektroden können selbst stark vaskularisierte Prozesse, z.B. Kavernome, komplett entfernt werden. Daneben werden Endoskope auch bei einer Reihe von spinalen Erkrankungen und dem Karpaltunnelsyndrom sowie adjuvant bei der mikrochirurgischen Operation eingesetzt.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 1 (1973), S. 343-348 
    ISSN: 1432-0630
    Keywords: Dye laser ; Linewidth ; Stability
    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 linewidth of a cw-single-mode tunable dye laser has been investigated. It was found that the linewidth is determined by microscopic velocity fluctuations of the turbulent flow within the dye cell of the laser and by fluctuations of the pump power. The linewidth is further influenced by mechanical disturbances and by temperature fluctuations of the dye solution. The results of the investigations made it possible to achieve a reduction of the velocity fluctuations. It is shown that under adequate operating conditions the free-running dye laser has a linewidth of 2 MHz.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 11 (1976), S. 97-101 
    ISSN: 1432-0630
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract An efficient conversion of the tunable cw dye laser radiation to the UV region was achieved by intracavity SHG. The conversion efficiency depends strongly on the total cavity loss. This paper gives a survey on conventional and thermally induced loss mechanisms and discusses ways of loss reduction. A system is described that yields 50 mW and 4 mW of tunable UV radiation in multimode and single mode operation, respectively, where the wavelength can be varied from 285–315 nm.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 14 (1977), S. 377-380 
    ISSN: 1432-0630
    Keywords: 42.55 ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Due to spatial hole burning, standing-wave dye lasers require a large amount of selectivity inside the cavity for single-mode operation. The output power of these lasers is limited by losses caused by the frequency selecting elements. In a travelling-wave laser, on the other hand, spatial hole burning does not exist, thereby eliminating the need for high selectivity. A travelling-wave cw dye laser was realized by unidirectional operation of a ring laser, yielding single mode output powers of 1.2 W at 595 nm and of 55 mW in the UV-region with intracavity frequency doubling.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1437-2320
    Keywords: Key words Focal cerebral ischemia ; Programmed neuronal death ; Nimodipine ; Mannitol ; Cerebroprotection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The present study was conducted to evaluate the effects of nimodipine and mannitol on infarct size and on the amount of apoptosis after transient focal cerebral ischemia. Focal cerebral ischemia was induced in male Sprague-Dawley rats (weight 300–380 g) by transient occlusion of the right middle cerebral artery (MCAO) using an intraluminal thread model. All animals underwent ischemia for 2 h, followed by 24 h of reperfusion. Group I (n=16) was untreated. Group II (n=16) received 15% mannitol (1 g/kg as bolus) and group III (n=9) received 15 µg/kg/h nimodipine intravenously beginning 15 min prior to MCAO. Twenty-four hours after reperfusion, the brain was taken and sectioned in coronal slices. The slices were stained with H&E and with the transferase dUTP nick-end labeling (TUNEL) technique. Histopathological analysis revealed a significant (P〈0.05) decrease in infarct size in the striatum with both drugs: mannitol (group II) 25.4±5.9% and nimodipine (group III) 21.5±11.0% versus control (group I) 34.9±7.0% and in the cortex 2.7±2.0% (group II) and 6.3±2.4% (group III) versus control 14.4±9.0% (group I). The number of apoptotic cells was statistically lower in the therapy groups (group III 9.6, group II 25.8) versus control (group I 57.9) (Mann-Whitney-Wilcoxon U-test Z〉1.96, P〈0.05). This study indicates that mannitol and nimodipine provide neuroprotection by preventing both the necrotic and apoptotic components of cell death after transient focal cerebral ischemia and may be effective as neuroprotective drugs for cerebrovascular surgery.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Mycopathologia 57 (1975), S. 77-78 
    ISSN: 1573-0832
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Fusarium roseum f. sp.gibbosum andF. roseum f. sp.semitectum were isolated from blighted culms of grain sorghum. Zearalenol and 8′-hydroxyzearalenone were produced by these isolates cultured on grain sorghum or cracked yellow field corn. Zearalenol is reported to have uterotropic activity and might be an important mycotoxin in sorghum.
    Type of Medium: Electronic Resource
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