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  • 1
    Digitale Medien
    Digitale Medien
    Accumulation and localization of aluminium in root tips of loblolly pine seedlings and the associated ectomycorrhiza Pisolithus tinctorius (2005)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 28 (2005), S. 0 
    Details
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Evidence from past studies suggests that loblolly pine may be tolerant of Al. The experiments described in this manuscript were initiated to examine Al tolerance and Al accumulation in the pine root and the degree of Al accumulation in fungal hyphae when pine roots were colonized with the ectomycorrhiza Pisolithus tinctorius. The experiments used lumogallion staining and confocal microscopy to localize Al in root and fungal structures. The results clearly showed that loblolly pine seedlings were highly resistant to Al. A decrease in primary root extension could not be detected until Al+3 activities approached 40 µmol L−1, and extension was suppressed only 30% at an Al+3 activity of 580 µmol L−1. This contrasted with the response of the Al-sensitive ‘check’ species soybean, where primary root extension was severely restricted at Al+3 activities lower than 5 µmol L−1. Tissue Al measurements and lumogallion fluorescence of longitudinal sections of the pine root tip indicated that tolerance was associated with both Al exclusion from the tip region and compartmentalization of absorbed Al in peripheral cell areas outside of the meristem. In lateral roots colonized with ectomycorrhizae, lumogallion fluorescence showed that large amounts of Al accumulated at the fungal mantle and in areas with the Hartig net. At higher magnification, lumogallion indicated substantial Al accumulation inside hyphae. Little Al could be detected in lateral root cells. The results show that pine possesses multiple mechanisms that can contribute to Al tolerance in acid field soils.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-3040.2004.01240.x
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  • 2
    Digitale Medien
    Digitale Medien
    On the high energy proton spectrum measurements (1977)
    Springer
    Astrophysics and space science 52 (1977), S. 415-427 
    Details
    ISSN: 1572-946X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Beschreibung / Inhaltsverzeichnis: Résumé L'accroissement avec l'énergie de l'albedo dû au calorimètre peut expliquer l'augmentation de la pente du spectre primaire de protons au-delà de 1000 GeV et la croissance des sections efficaces inélastiques entre 20 et 600 GeV observés lors des expériences en satellite PROTON 1, 2 et 3.
    Notizen: Abstract The steepening of the proton spectrum beyond 1000 GeV and the rise in inelastic cross sections between 20 and 600 GeV observed by the PROTON 1-2-3 satellite experiments may be explained by systematic effects of energy dependent albedo (back-scatter) from the calorimeter.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01093876
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  • 3
    Digitale Medien
    Digitale Medien
    Liver MR imaging: comparison of respiratory triggered fast spin echo with T2-weighted spin-echo and inversion recovery (1996)
    Springer
    Abdominal imaging 21 (1996), S. 433-439 
    Details
    ISSN: 1432-0509
    Schlagwort(e): Key words: Magnetic resonance—Fast spin echo—Liver.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Background: The purpose of this study was to compare a fast spin-echo sequence combined with a respiratory triggering device (R. trig. FSE) with conventional T2-weighted spin-echo (CSE) and inversion recovery (STIR) sequences for the detection of focal hepatic lesions. Methods: We performed a prospective study of 33 consecutive patients with known or suspected hepatic tumors. All patients underwent R. trig. FSE, CSE, and STIR imaging at 1.5 T. Acquisition times were 10.7 min for the CSE sequence and ranged from 12 to 15 min for STIR and from 5 to 7 min for R. trig FSE. For each sequence, liver–spleen contrast-to-noise ratio (CNR) and liver–lesion CNR were determined quantitatively. Image artifact and sharpness were graded by using a four-point scale on each sequence by two independent readers. Both readers also independently identified hepatic lesions (up to a maximum of eight per patient). For patients with focal lesions, the total number of lesions detected (on each sequence) and the minimum size of detected lesions were also determined by each reader. Results: No significant difference was detected between R. trig. FSE and CSE or STIR in either liver–spleen CNR or liver–lesion CNR. R. trig. FSE images were equivalent to CSE and superior to STIR in sharpness (p 〈 0.01) and presence of artifact (p 〈 0.01). R. trig. FSE detected a higher number of lesions (reader 1: n = 92, reader 2: n = 86) than CSE (reader 1: n = 70, reader 2: n = 69) and a significantly higher number than STIR (reader 1: n = 71, reader 2: n = 76). Lesion structure was significantly better defined with R. trig. FSE than with STIR (p 〈 0.01) and CSE (p 〈 0.05). Conclusions: Compared with CSE and STIR, R. trig. FSE produces hepatic images of comparable resolution and detects an increased number of focal hepatic lesions in a shorter period of time.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002619900098
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  • 4
    Digitale Medien
    Digitale Medien
    MRI in venous thromboembolic disease (1993)
    Springer
    European radiology 3 (1993), S. 53-61 
    Details
    ISSN: 1432-1084
    Schlagwort(e): MR venography ; Pulmonary embolism ; Pulmonary MR angiography ; Venous thromboembolic disease
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We evaluated the ability of magnetic resonance (MR) imaging to detect deep venous thrombosis (DVT) and pulmonary embolism (PE). MR venography was performed on 217 patients suspected of having DVT. Cine-MR imaging of the pulmonary arteries was performed in 14 other patients who were thought to have PE based on other imaging studies. In a third group of 5 patients, MR pulmonary angiograms were performed in the sagittal and coronal planes with a multislice fast gradient recalled echo technique. All but one of the 217 MR venograms were technically adequate. In 72 patients with correlative imaging studies (venography and ultrasound) MR venography was 99% sensitive and 95% specific. On the basis of follow-up (mean 8.3 months), no false-negative MR venograms were detected in an additional 64 patients. In 11 other patients MR revealed a diagnosis other than DVT. Cine-MR showed PE in all 14 patients evaluated. MR pulmonary arteriography demonstrated filling defects consistent with acute PE in 2 of 3 patients with acute PE; in the third patient only a questionable filling defect was seen. Coarctations or webs were found in the pulmonary arteries of both patients with chronic PE. These preliminary data suggest that MR imaging may be able to evaluate both the peripheral venous and the pulmonary arterial component of venous thromboembolic disease. Further technical refinement and more extensive clinical experience will be required to establish the role of this method in diagnosing pulmonary embolism, but MR venography is now used routinely in our hospital for the diagnosis of deep venous thrombosis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173525
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  • 5
    Digitale Medien
    Digitale Medien
    Practical choices of fast spin echo pulse sequence parameters: clinically useful proton density and T2-weighted contrasts (1992)
    Springer
    Neuroradiology 35 (1992), S. 38-41 
    Details
    ISSN: 1432-1920
    Schlagwort(e): Fast spin echo ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary With the development of fast spin echo (FSE) MRI techniques, T2-weighted images of the brain may be obtained much more quickly than when using conventional spin echo techniques (CSE), because made the individual echoes on the FSE pulse sequence are phase encoded, allowing acquisition of the same spatial information as in CSE with less excitations. The pulse sequence parameters (echo train length, bandwidth echo spacing) are discussed. Images were obtained on four volunteers using both CSE and FSE while varying repetition time, echo time and matrix. Comparison for signal intensity gray-white differentiation, fat and CSE signal, arifacts and vascular resolution showed that FSE images comparable in quality to those of CSE can be obtained in less than half the time. A practical choice of FSE parameters is recommended for clinical use. However, artifacts, possibly related to CSF and vascular pulsation, of which the radiologist should be aware, were identified on the FSE images.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00588276
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