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  • 1
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    German Medical Science GMS Publishing House; Düsseldorf
    In:  Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2017); 20171024-20171027; Berlin; DOCPO20-422 /20171023/
    Publication Date: 2017-10-23
    Keywords: Wirbelsäule ; Simulator ; Virtual Reality ; Training ; Assessment ; ddc: 610
    Language: German
    Type: conferenceObject
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  • 2
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Bifidobacterium adolescentis was grown anaerobically in medium enriched with α-D-galactosides. α-Galactosidase (EC 3.2.1.22) was released from the cells by ultrasonic treatment and purified 36-fold by ultrafiltration, ammonium-sulphate precipitation, anion-exchange chromatography, and size-exclusion chromatography. Two protein bands were consistantly observed after sodium-dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE). Electrophoretically homogeneous α-galactosidase was only obtained by electroelution. The enzyme had an apparent molecular mass of 344 kDa and 79 kDa as judged by size-exclusion chromatography and SDS-PAGE, respectively. Activity-staining after nondenaturing SDS-PAGE indicated an apparent molecular mass of 145 kDa. Thus, a tetrameric structure of the protein is suggested. The α-galactosidase showed optimal activity at pH 5.5 and 55°C. Lower pH values and higher temperatures rapidly inactivated α-galactosidase. The enzyme hydrolyzed specifically α-galactosidic linkages, and α-(1-3)-linkages were hydrolyzed at a higher rate compared to α-(1-6)-linkages. Hydrolysis of galactosides followed normal saturation kinetics; KM-values for p-nitrophenyl-α-galactopyranoside (p-NPG) and raffinose were calculated with 0.957 mM and 4.12 mM, respectively.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1619-7089
    Keywords: Left ventricular volumes ; Left ventricular function ; Positron emission tomography ; Gating
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To date cardiac positron emission tomography (PET) studies have focussed on the measurement of myocardial blood flow, metabolism and receptors while left ventricular (LV) function and dimensions have been derived from other modalities. The main drawback of this approach is the difficulty of data co-registration, which limits clinical interpretation. The aim of this study was to evaluate whether it is possible to measure absolute cardiac volumes, and consequently LV function parameters such as ejection fraction, and wall motion with gated PET. Nineteen patients underwent a PET scan and planar radionuclide ventriculography (MUGA) within 9±9 days. A 9-min scan (16 gates/cardiac cycle) was acquired after inhalation of 3 MBq/ml of oxygen-15 labelled carbon monoxide at the rate of 500 m1/min over 4 min using a multislice PET camera. Noise reduction was performed on the gated image to enhance the definition of the ventricles before reslicing to the short-axis view. A threshold value was used to detect the edge of the LV at each gate. LV volumes at each gate were estimated by summing the volume of voxels within the LV boundary. PET measurements of LV volumes were as follows: LV end-diastolic volume ranged from 72 to 233 ml and LV end-systolic volume ranged from 24 to 203 ml. Phantom experiments supported the validity of this approach for estimating volumes. LV ejection fraction measured with MUGA was 38.4%±16.3% (range 15%–71%) and that measured with PET was 39.6%±17.7% (range 9%–72%) (P=NS). The LV ejection fraction measurements were highly correlated (r 2=0.824). These results indicate that: (1) absolute enddiastolic and end-systolic volumes can be quantified using gated PET and (2) LV ejection fraction can be accurately measured by gated PET simultaneously with the other physiological PET parameters.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1619-7089
    Keywords: Key words: Fluorine-18 fluorodeoxyglucose – Positron emission tomography – Medullary thyroid cancer – Calcitonin – Compartment-orientated microdissection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The early detection of metastases from medullary thyroid cancer (MTC) is important because the only curative therapy consists in surgical removal of all tumour tissue. There is no single sensitive diagnostic imaging modality for the localization of all metastases in patients with MTC. Therefore, in many cases several imaging modalities (e.g. ultrasonography, magnetic resonance imaging, computerized tomography and scintigraphy using pentavalent technetium-99m dimercaptosuccinic acid, thallium-201 chloride, indium-111 pentetreotide, anti-CEA antibodies or metaiodobenzylguanidine) must be performed consecutively in patients with elevated calcitonin levels until the tumour is localized. In this prospective study, we investigated the value of fluorine-18 fluorodeoxyglucose positron emission tomography ([18F]FDG PET) in the follow-up of patients with MTC. [18F]FDG PET examinations of the neck and the chest were performed in 20 patients with elevated calcitonin levels or sonographic abnormalities in the neck. Positive [18F]FDG findings were validated by histology, computerized tomography or selective venous catheterization. [18F]FDG PET detected tumour in 13/17 patients (nine cases were validated by histology, four by computerized tomography). Five patients showed completely negative PET scans (of these cases, one was true-negative and four false-negative). One patient with [18F]FDG accumulation in pulmonary lesions from silicosis and one patient with a neck lesion that was not subjected to histological validation had to be excluded. Considering all validated localizations, [18F]FDG PET detected 12/14 tumour manifestations in the neck, 6/7 mediastinal metastases, 2/2 pulmonary metastases and 2/2 bone metastases. In two patients with elevated calcitonin levels, no diagnostic modality was able to localize a tumour. The sensitivity of [18F]FDG PET in the follow-up of MTC was 76% (95% confidence interval 53%–94%); this is encouraging. [18F]FDG PET promises to be a valuable diagnostic method, especially for the detection of lymph node metastases, surgical resection of which can result in complete remission.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-2568
    Keywords: dogs ; gastric ulcer ; ornithine decarboxylase ; polyamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Ornithine decarboxylase (ODC) activity has been associated with mucosal growth and injury, yet, little information is available on ODC activity during gastric ulcer healing. We measured ODC activity in the ulcer base submucosa and the surrounding mucosa at 1 cm and 2 cm and assessed ulcer surface healing and a histologic score in experimentally induced ulcers (Quinton ulcer-maker) at 0 and 5 hr and at one, two, three, four, and seven days. A total of 26 dogs were studied, eight of which received 2% difluoromethylornithine (DFMO, a specific inhibitor of ODC) in drinking water. Ulcer healing was assessed by digitizing initial (plug size), and final ulcer surface area and was expressed as percent ulcer surface reduction. A histologic score was assessed by two independent pathologists unaware of the treatment. ODC induction was observed in the submucosa of the ulcer base but not in the surrounding mucosa. The baseline submucosal ODC activity was measured at 0.2±0.1 pmol (14CO2)/mg protein/hr, and at one day the ODC activity increased to 4.0±0.7, at three days to 15.2±5.5, and at seven days to 2.6±1.0 (P〈0.001). DFMO treatment delayed GU healing significantly up to three days, but no difference was noted at seven days. The assessed histologic parameters did not correlate with ODC activity, and DFMO treatment did not alter the histologic score. These data suggest that polyamine biosynthesis occurs in the ulcer base submucosa during the first seven days of experimentally placed gastric ulcers. Suppression of ODC activity with DFMO delays ulcer surface reduction during the first three days, but the significance of ODC induction and polyamine biosynthesis during early ulcer healing remains in question.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 309-311 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed in situ transmission electron microscopy studies of abnormal grain growth in electroplated copper films at room temperature and 55 °C, starting minutes after the plating process by electroplating directly onto electron-transparent membranes. A kinetic analysis indicates that the grains that grow abnormally, reject impurities as they grow, so that the impurities accumulate in (and must diffuse through) the untransformed matrix. This suggests that while impurities impair normal grain growth, impurity rejection contributes to the energetics that drive abnormal grain growth. This result also indicates that removal of impurities from the film can control the kinetics of the transformation to large-grained structures. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 2599-2603 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new heterostructure field effect transistor is proposed consisting of a pseudomorphic TlGaAs channel combined with an AlGaAs charge supply layer, the whole structure grown on a GaAs substrate. The properties of TlGaAs from previously published calculations and some simple scaling rules for the effective mass, mobility, and conduction band separation are predicted. The expected charge density in a realistic channel is calculated self-consistently and the expected critical thickness is discussed. The results suggest that a marked improvement in device performance can be expected over similar structures containing InGaAs. © 1998 American Institute of Physics.
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 403-405 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Adsorption and desorption of C60 molecules on GaN{0001}-1×1 surfaces as well as the surface decomposition by heating were investigated with Auger electron spectroscopy. The first monolayer of C60 forms strong chemical bonds to the substrate atoms. A seven-step annealing procedure at temperatures up to 1275 K is presented which completely removes the adsorbed carbon without decomposing the surface. If the process is applied to clean, uncovered GaN{0001}-1×1 surfaces thermal etching with a significant Ga atom loss is observed. The results indicate that adsorbed C60 increases the thermal stability of the surfaces considerably and that thermal etching begins at defects or steps at the surface where the molecules are most strongly bound. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present results of photoluminescence studies of Al0.5Ga0.5As1−xSbx grown by molecular beam epitaxy on GaAs substrates. We compared the photoluminescence (PL) peak position as a function of composition with the band gap prediction using the established formalism developed for other quaternaries. We found a discrepancy of up to 0.2 eV indicating that an extra bowing factor needs to be included in the band gap composition equation for this material system. InGaAs/AlInAs structures grown on top of the Al0.5Ga0.5As1−xSbx were also characterized and compared with similar structures grown on InP and were shown to exhibit similar PL intensities and Hall mobilities, indicating that the quaternary buffer layer can be used for growth of high-In concentration InGaAs device structures on GaAs. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this article we analyze the combined effects of the deterministic nonuniform flux distribution in a molecular-beam epitaxy system, and the random variations in device parameters induced by processing. As a case study, the distribution of the saturation current (Idss) before gate metallization of a high-electron mobility transistor is investigated. The magnitude of the observed statistical variations has been compared to calculated values given by a theoretical expression for the saturation current. Using a semiempirical method to describe the radial dependence of a device parameter and its variation, simple expressions describing the shape of the wafer distribution, mean value, standard deviation, yield, and radial probability of finding devices within set limits, have been derived. The expressions can be used to relate the layer properties in the wafer center to the mean value of the same properties as obtained from a map of the whole wafer. The expressions for radial probability of finding a working device can be easily added to the software of an automatic wafer tester in order to speed up the screening procedure of wafers.
    Type of Medium: Electronic Resource
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