Bibliothek

feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • 1995-1999  (21)
  • 1999  (8)
  • 1997  (13)
  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1684-1687 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The TGV32, a 32-channel preamplifier–multiplicity discriminator chip for the multiplicity vertex detector (MVD) at PHENIX, is a unique silicon preamplifier in that it provides both an analog output for storage in an analog memory and a weighted summed-current output for conversion to a channel multiplicity count. The architecture and test results of the chip are presented. Details about the design of the preamplifier, discriminator, and programmable digital–analog converters performance as well as the process variations are presented. The chip is fabricated in a 1.2 μm, n-well, complementary metal–oxide–semiconductor process. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Annals of noninvasive electrocardiology 2 (1997), S. 0 
    ISSN: 1542-474X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: To test heart rate variability (HRV) in patients with acute myocardial infarction (AMI) for nonlinear deterministic complex behavior and for its dependence on autonomic tone.〈section xml:id="abs1-2"〉〈title type="main"〉MethodsFifteen patients (mean age 55, 14 men) with AMI and 16 healthy individuals (mean age 41, 11 men) with ongoing beta-adrenergic receptor blockade were investigated after intravenouse administration of atropine (0.03 mg/kg). Nonlinear indices for HRV were assessed by local sensitive dependence on initial conditions as quantitated by the Lyapunov exponent, fractal dimension (FD), and correlation dimension. Linear indices for HRV were assessed in the time domain by the standard deviation of the RR interval (SD-RR), the coefficient of variation (CV%), and the mean successive difference (MSD). In the frequency domain, the following indices were used: very low frequency power (VLF), low frequency power (LF), high frequency power (HF), total power (TP), and the ratio between low and high frequency power (LF/HF).〈section xml:id="abs1-3"〉〈title type="main"〉ResultsSurrogate data analysis revealed independent behavior of the Lyapunov exponent, the FD, and the correlation dimension, suggesting the presence of deterministic chaos in HRV. The Lyapunov exponent was positive in both groups at baseline but was significantly lower in the patient group. Following atropine, the value decreased while remaining positive, but no differences between the groups were found. The FD and the correlation dimension reacted similarly to the Lyapunov exponent. All time-domain indices were significantly lower in the patients along with power in LF and HF bands. The differences were abolished by the administration of atropine.〈section xml:id="abs1-4"〉〈title type="main"〉ConclusionsThe heart rate of patients with AMI exhibits characteristics of deterministic chaotic behavior with a positive Lyapunov exponent but with significantly less complex behavior than in healthy controls. The difference was eliminated by atropine, suggesting that vagal tone is a major cause. The nonlinear indices have a discriminating capacity for changes in HRV comparable to linear indices.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 3803-3805 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have induced large elastic strains in ropes of single-wall carbon nanotubes, using an atomic force microscope in lateral force mode. Freely suspended ropes were observed to deform as elastic strings with tension proportional to elongation. Ropes were elastically deformed over 〉10 cycles without showing signs of plastic deformation. The maximum strain observed, 5.8±0.9%, gives a lower bound of 45±7 GPa for the tensile strength (specifically, yield stress) of single-wall nanotube ropes. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK and Boston, USA : Blackwell Publishers Ltd
    British journal of educational technology 28 (1997), S. 0 
    ISSN: 1467-8535
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Pädagogik
    Notizen: Many people from very diverse disciplines have attempted to define the concept of Visual Literacy (VL), but with little general consensus so far. This is probably due to the fact that those representing the different disciplines and paradigms are each wanting to interpret Visual Literacy in a way that reflects and flatters their contribution or way of thinking. As a consequence, a theoretical concept with seemingly little practical value has been created, but cannot be used productively until an agreed definition is established.It is self evident that if a concept does not have a broadly accepted definition, if the theory behind it is confusing, and if its viability on practical terms is a matter of continuing controversy, then the only reasonable way to cope with it is to abandon it. Nevertheless, with the exception of very few and of minor importance cases, no serious attempt has ever been made towards discarding VL altogether.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 11216-11221 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Dynamic light scattering data on a polymer gel electrolyte with a complex relaxation behavior is presented. The electrolyte consists of lithium perchlorate dissolved in an ethylene carbonate and propylene carbonate solution that is immobilized with poly(methyl methacrylate). We attribute the observed relaxation processes to two diffusive and one segmental relaxation processes based on the form of the time decay of the intermediate scattering function and the corresponding temperature and wave vector dependencies. The dynamic light scattering results are compared with the ionic conductivity, which reveals a close connection between the fast diffusive motion of the low molecular weight solvent within the gel and the ionic conductivity. This motion is strongly decoupled from and considerably faster than the segmental motion of the polymer matrix. The results indicate that the ionic transport occurs mainly within the low molecular weight solvent. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of medicine & science in sports 7 (1997), S. 0 
    ISSN: 1600-0838
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin , Sportwissenschaft
    Notizen: Forty-eight hour Holter monitoring was undertaken of 16 male elite middle- and long-distance runners, age 25±3 years, with peak oxygen uptake 4.83±0.43 1 O2/min or 73.0±3.9 ml O2/kg/min. The athletes had pronounced bradycardia during the night-time, with heart rate calculated from four RR intervals 〈30 beats/min in five runners. Twelve of 16 runners had RR intervals 〉2 s. Of those, 10 runners had sinus pauses exceeding 2 s, the longest being 3.06 s. Three runners had AV block II, two with Mobitz type 1, and one with both Mobitz type 1 and 2. Autonomic function was estimated by time domain and power spectral analysis of heart rate variability. The runners were compared with a control group of 13 sedentary or moderately active subjects. The runners had a mean of 14 b.p.m. lower heart rate at night than the controls. The runners had higher heart rate variability in all spectral bands. In the time domain pNN50 and rMSSD, which are considered to reflect strongly vagal tone, were markedly higher in the runners than the controls. The findings suggest that an increased parasympathetic tone might at least partly explain the pronounced resting sinus bradycardias found in endurance-trained runners.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of medicine & science in sports 7 (1997), S. 0 
    ISSN: 1600-0838
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin , Sportwissenschaft
    Notizen: The aim of this study was to follow changes in saliva and serum after strenous prolonged exercise. Twenty individuals, three women and 17 men, 24–62 years old, well-trained but not at elite level, participating in the Stockholm Marathon, were selected for the study. Two of the subjects broke the race after 20 km. Three samples of saliva were collected, i.e. (i) just before the race, (ii) directly after the race, and (iii) 1 h after the race. Paraffin-stimulated whole saliva, resting non-stimulated whole saliva and citric acid-stimulated parotid saliva were investigated. In all three types of saliva, there was a decrease in secretion rate and only 14 of the 18 participants could produce resting non-stimulated whole saliva directly after the race. The salivary concentration of chloride, phosphate, potassium, amylase, hexosamine, sialic acid and salivary peroxidase were significantly higher after than before the race. There were no significant changes in salivary pH and buffer capacity. The total protein concentration was increased in all types of saliva after the race. To conclude, there were several changes in the saliva composition just after the marathon, but most of the values were back to baseline after 1 h of rest. However, the values for sodium, calcium, phosphate, salivary peroxidase, amylase and salivary IgA were still elevated 1 h after the race.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Educational theory 47 (1997), S. 0 
    ISSN: 1741-5446
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Pädagogik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Educational theory 47 (1997), S. 0 
    ISSN: 1741-5446
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Pädagogik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 10
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] During vertebrate development, the specification of distinct cell types is thought to be controlled by inductive signals acting at different concentration thresholds. The degree of receptor activation in response to these signals is a known determinant of cell fate, but the later steps at which ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...