Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Accuracy and the influence of marrow fat on quantitative CT and dual-energy X-ray absorptiometry measurements of the femoral neck in vitro (1996)
    Springer
    Osteoporosis international 6 (1996), S. 25-30 
    Details
    ISSN: 1433-2965
    Keywords: Absorptiometry ; Accuracy ; Bone ; Comparative study ; Dual-energy X-ray ; Femur ; In vitro ; Marrow fat, Quantitative CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Bone mineral measurements with quantitative computed tomography (QCT) and dual-energy X-ray absorptiometry (DXA) were compared with chemical analysis (ChA) to determine (1) the accuracy and (2) the influence of bone marrow fat. Total bone mass of 19 human femoral necks in vitro was determined with QCT and DXA before and after defatting. ChA consisted of defatting and decalcification of the femoral neck samples for determination of bone mineral mass (BmM) and amount of fat. The mean BmM was 4.49 g. Mean fat percentage was 37.2% (23.3%–48.5%). QCT, DXA and ChA before and after defatting were all highly correlated (r〉0.96,p〈0.0001). Before defatting the QCT values were on average 0.35 g less than BmM and the DXA values were on average 0.65 g less than BmM. After defatting, all bone mass values increased; QCT values were on average 0.30 g more than BmM and DXA values were 0.29 g less than BmM. It is concluded that bone mineral measurements of the femoral neck with QCT and DXA are highly correlated with the chemically determined bone mineral mass and that both techniques are influenced by the femoral fat content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01626534
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Unraveling the Role of Structure and Density in Determining Vertebral Bone Strength (1997)
    Springer
    Calcified tissue international 61 (1997), S. 474-479 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Vertebral strength — Magnification radiographs — Texture — Quantitative computed tomography.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. The strength of bone is determined not only by bone density but also by structure. Therefore, quantification of the structure in radiographs by texture parameters may result in a better prediction of fracture risk. Since in radiographs density and structure are strongly correlated, the predictive power of texture parameters should be corrected for the influence of BMD to determine the additional information conveyed by these parameters. In this study, we evaluated the predictive power of various texture parameters based on the Grey-Level Dependence Method and the Morphological Gradient Method. This study was performed on 67 vertebrae obtained from 20 male and 12 female human cadaver thoracolumbar spines. BMD and area of the vertebral body were determined from QCT images and texture parameters were derived from direct magnification (DIMA) radiographs. The fracture force, measured under conditions simulating the in vivo situation, was corrected with the area of the vertebra to yield the fracture stress (FS). Results of the study indicate that BMD correlates significantly with FS r= 0.82 (P 〈 0.001, n= 24) and r= 0.94 (P 〈 0.001, n= 43) for female and male vertebrae, respectively. Correlation coefficients of the investigated texture parameters were as high as 0.80 (P 〈 0.001) and 0.67 (P 〈 0.001) for the female and male vertebrae, respectively. Multiple regression analysis showed that in female vertebrae, the addition of one texture parameter to BMD results in a better prediction of strength. The multiple correlation coefficient was 0.87 (P 〈 0.001) in this case. In male vertebrae, BMD was the best predictor of fracture stress. These results suggest that texture parameters, as measured in magnification radiographs, can predict bone strength. Whereas in all cases BMD is the best single predictor of bone strength, for women texture parameters contain useful additional information.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900370
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Vertebral Dimensions: Influence of X-Ray Technique and Patient Size on Measurements (1998)
    Springer
    Calcified tissue international 62 (1998), S. 214-218 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Vertebral dimension — Correction — Osteoporosis — Technique — Patient size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. In this study a new reference value, ``corrected vertebral dimension,'' is presented for vertebral height measurements. Of 68 females (age 18–88 years; mean 44.2 years) and 40 males (age 16–81 years; mean 55 years) the projected vertebral dimensions (T4–L5) were measured on lateral radiographs. In addition to this, the vertebra-to-film distances (VFD) were measured and a fixed focus-to-film distance (FFD) was used during the study. Corrected dimensions of the thoracic and lumbar vertebrae (T4–L5) were calculated using the FFD and VFD. These corrected dimensions were then used to recalculate projected vertebral dimensions at different focus-to-film distances. The applied geometric corrections were verified in a phantom study representing an in vitro situation. The results indicate that studies using different X-ray techniques for making lateral radiographs of the spine can become comparable when using corrected vertebral dimensions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900420
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Statistical analysis and interpretation of the initial response of cochlear nucleus neurons to tone bursts (1975)
    Springer
    Experimental brain research 23 (1975), S. 407-423 
    Details
    ISSN: 1432-1106
    Keywords: Cochlear nucleus units ; Tone responses ; Latency ; Regularity of firing ; Interval distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Subject of investigation is the initial response of cochlear nucleus neurons and units presumed to be auditory nerve fibres to CF tone burst stimu lation. 2. The initial response is characterized by computing the distribution of the latency of the first spike and of the duration of the first interval in the ensemble of responses to a large number of stimuli. 3. In many of the neurons the properties of both distributions appear to be related. The presumed auditory nerve fibres and spontaneously active cochlear nucleus neurons showing only activation responses to tonal stimuli (A type) exhibit irregularity in both response onset and intervals. Minimum latency and minimum first intervals are short. On the other hand, spontaneously active neurons with both activation and suppression in the response area (AS type) and silent neurons showing only activation (A(S) type) often show a more precisely timed onset of response and narrow interval distributions. In many neurons this leads to oscillations in the PSTH (chopping). In these neurons minimum latency and minimum first interval have higher values. The longer minimum latency cannot be attributed to longer pure time delays in these neurons. 4. The results are interpreted as speaking in favour of temporal integration as an important mechanism in many of the AS and A(S) neurons, particularly those in the DCN. The firing patterns of A neurons are thought to indicate virtual absence of this mechanism. 5. Using pure time delay estimates derived from cross-correlation functions, computed from the responses to stationary noise, an attempt is made to estimate the integration time in the cochlear and in the cochlear nucleus neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238023
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Neurons in the cochlear nucleus investigated with tone and noise stimuli (1975)
    Springer
    Experimental brain research 23 (1975), S. 387-406 
    Details
    ISSN: 1432-1106
    Keywords: Cochlear nucleus units ; Tone and noise responses ; Cross-correlation functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Responses of cochlear nucleus neurons to stationary and amplitude modulated noise stimulation are investigated and compared with responses to tonal stimuli. 2. Cross-correlation functions, computed from responses to stationary noise stimulation, showing a clear oscillation could be most easily obtained from low CF fibres presumed to be auditory nerve fibres and low CF cochlear nucleus neurons showing only activation response and a primarylike temporal pattern of response to tone bursts. This reflects good quality of phase locking in these neurons. 3. The CCF reflects strongly the frequency selectivity of the neuron as revealed in its response area but not the temporal pattern of response to tone bursts. 4. Responses to noise bursts are correlated with the responses to tone bursts of many different frequencies in both their sign (i.e. activation or suppression) and their temporal pattern. 5. The concept of two independently operating mechanisms, one depending on the fine time structure of the stimulus (the carrier) and the other on its amplitude, and determining respectively the fine time structure of the response pattern and its magnitude, is introduced. Experimental data are presented which lend support to the adequacy of the description in the majority of cases and reveal its shortcomings in others.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238022
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Spectral and temporal characteristics of activation and suppression of units in the cochlear nuclei of the anaesthetized cat (1975)
    Springer
    Experimental brain research 23 (1975), S. 367-386 
    Details
    ISSN: 1432-1106
    Keywords: Cochlear nucleus units ; Activation and suppression ; Anatomical subdivisions ; After effects ; Model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The responses are described of cochlear nucleus neurons of anaesthetized cats as a function of time in dependence on intensity and frequency of tonal stimuli. Depending on spectral properties three types are distinguished in the group of spontaneously active units: A type (activation only) AS type (activation and suppression) and S type (suppression only). The A(S) neurons have insufficient spontaneous activity to judge presence or absence of suppression. 2. Four temporal patterns of response are distinguished: transient, sustained, build up and complex. Units of the A type display a sustained time course of activation and have properties similar to those of auditory nerve fibres. S type units show sustained suppression. Temporal patterns of activation other than sustained were found only in the AS and A(S) units. 3. The recordings indicate that on suppression and off suppression are present more frequently in VCN neurons than previously found. The suppression phenomena in the DCN are, however, still more wide spread and more dramatic in appearance. 4. In contrast to earlier findings, off suppression was always observed and never seen to extend beyond the on activation band in A neurons. Data from AS neurons indicate that off suppression is neither simply an after effect of high firing rates nor simply a continuation of on suppression. 5. The relations between off suppression and spectral and temporal characteristics of on activation and suppression can be matched with a model featuring overlapping antagonistic inputs and postexcitatory inhibition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238021
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    What is measured in electrogastrography? (1980)
    Springer
    Digestive diseases and sciences 25 (1980), S. 179-187 
    Details
    ISSN: 1573-2568
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The object of this study was to elucidate what is actually measured in electrogastrography. Comparison of gastric signals simultaneously recorded from serosal and cutaneous electrodes in the conscious dog led to the following findings: 1. In the absence of phasic contractile activity and electrical response activity (ERA), the cutaneous recordings contained a frequency corresponding to the fundamental frequency of the electrical control activity (ECA) of the stomach (about 0.08 Hz). 2. Tachygastrias gave rise to cutaneous signals containing the tachygastric frequency (about 0.25 Hz). 3. The amplitude of the electrogastrogram increased when ERA occurred. It is concluded that both ECA and ERA are reflected in the electrogastrogram. A model is proposed that describes the electrogastrogram as the result of field potentials generated by depolarization and repolarization dipoles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01308136
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Adaptive filtering of canine electrogastrographic signals. Part 1: system design (1981)
    Springer
    Medical & biological engineering & computing 19 (1981), S. 759-764 
    Details
    ISSN: 1741-0444
    Keywords: Adaptive filtering ; Electrogastrography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The study of the relation between gastric myo-electrical activities recorded from serosal and cutaneous electrodes is hindered by the poor quality of the cutaneous signal. This hindrance could be minimised by suitable filtering of the signal. Since it is not yet clear which aspects of the cutaneous signal constitute valuable information, the filter process should not affect phase, amplitude, frequency and waveform of the gastric component, while noise components should be suppressed strongly. The system design of a modified adaptive filter that meets these requirements is described. The filter was implemented on a digital Nova 2 minicomputer. the filter performance is described and tested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441337
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Adaptive filtering of canine electrogastrographic signals. Part 2: filter performance (1981)
    Springer
    Medical & biological engineering & computing 19 (1981), S. 765-769 
    Details
    ISSN: 1741-0444
    Keywords: Adaptive filtering ; Electrogastrography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The modified adaptive filter method described in Part 1 was applied to 16 stretches of (cutaneous) electrogastrographic signal of 17·07 min duration. A signal-to-noise ratio improvement of about 8 dB was achieved. The most characteristic feature of the filter method appeared to be that wave-form and phase of the gastric component of the electrogastrographic signal are preserved. It is concluded that the use of the modified adaptive filter forms a valuable tool in the study of the electrogastrographic signal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441338
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Running spectrum analysis as an aid in the representation and interpretation of electrogastrographic signals (1987)
    Springer
    Medical & biological engineering & computing 25 (1987), S. 57-62 
    Details
    ISSN: 1741-0444
    Keywords: Electrical control activity ; Electrical response activity ; Electrogastrography ; Fast Fourier transform ; Gastric myoelectrical activity ; Running spectrum analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The recording of gastric myoelectrical activity by means of cutaneous electrodes attached to the external abdominal wall is termed electrogastrography. Respiration and motion artefacts hamper the interpretation of electrogastrographic signals. Running spectrum analysis, using the fast Fourier transform, seems to provide a concise spectral representation of electrogastrographic data. In this paper the concept of running spectrum analysis is presented in detail using test signals consisting of frequency modulated sine waves and actual recordings from dog and man. Especially the visual interpretable representation in appropriate plots is emphasised and discussed. It is demonstrated that tachygastrias with a duration of the order of 30s can easily be recognised in the spectra. In most cases the gastric frequency can be recognised in the spectra. It is concluded, therefore, that running spectrum analysis has to be considered an attractive noninvasive method to study gastric myoelectrical activity in dog and man.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02442821
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...