Library

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
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 3426-3428 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Avalanche multiplication and noise in 1.0, 0.5, 0.1, and 0.05 μm GaAs p+-i-n+ diodes have been calculated for both electron and hole initiated multiplication using a simple model which incorporates a randomly-generated ionization path length (RPL) and a hard-threshold dead space. We find that the mean multiplication obtained using this RPL model is in excellent agreement, even for the shortest structure, with that obtained from an analytical-band structure Monte Carlo (MC) model, which incorporates soft-threshold effects. However, it predicts slightly lower avalanche noise in the shorter devices. This difference results from the narrower ionization path length probability distribution and larger dead space of the hard-threshold RPL model at high electric fields as compared to the more realistic distribution function associated with the relatively sophisticated MC model. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 232-234 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We use a Monte Carlo model to investigate the improvement of avalanche noise performance in thin p+-i-n+ GaAs diodes. The model predicts a decrease in avalanche noise as the multiplication length decreases from 1.0 to 0.05 μm, in good agreement with recent experimental measurements. Our simulations suggest that electron initiated multiplication in short devices has inherently reduced noise despite higher feedback from hole ionization, as compared to long devices. This low noise behavior results from the narrower ionization probability distribution and larger dead space effect as a higher operating electric field needed in short devices. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 2963-2965 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of an electric-field gradient on the excess avalanche noise is examined using both a Monte Carlo model and experiment. Nonlocal effects cause the noise to be significantly reduced as the electric-field gradient increases in a p+–n junction. For equal electron and hole ionization coefficients, lower noise is always achieved when carriers are injected into the high field end of these structures. Furthermore, for a constant noise figure and depletion thickness, a higher gain is always achieved in a p+–n junction compared a p+–i–n+. The results are explained in terms of coherence in ionization events. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Commercial serological tests for the detection of Helicobacter pylori infection must be locally validated. We evaluated the accuracy of five commercial tests in the Chinese population.〈section xml:id="abs1-2"〉〈title type="main"〉Methods:Serum samples were collected from patients referred for upper endoscopy. Antral biopsies were taken for histological examination and culture of H. pylori. The gold standard for diagnosing H. pylori infection was positive histological staining and/or positive H. pylori culture. The serum samples were tested for H. pylori antibodies using the following tests: (i) Cobas Core Anti-H. pylori EIA; (ii) GAP IgG; (iii) GAP IgM; (iv) H. pylori microwell EIA (Quidel); and (v) Premier H. pylori. The sensitivity, specificity and accuracy of each test was calculated according to the manufacturers’ instructions or according to a new cut-off value.〈section xml:id="abs1-3"〉〈title type="main"〉Results:A total of 158 patients were recruited amongst whom 114 (72%) were H. pylori-positive. Indeterminate results varied from 7% to 19%. The accuracy of the tests varied from 57% to 85%. By using new cut-off values, the accuracy was much improved, ranging from 73.4% to 86.7%.〈section xml:id="abs1-4"〉〈title type="main"〉Conclusions:By defining new cut-off values for the Chinese population, we were able to improve the performance of some of the serology tests. This illustrates the importance of local validation.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aim : To investigate the efficacy of measurement of Helicobacter pylori stool antigen (HpSA) using stored frozen stool specimens, and to assess whether there were factors affecting efficacy in Hong Kong.Methods : Patients undergoing upper endoscopy at Tuen Mun Hospital were recruited. Stool samples were saved for HpSA testing and questionnaires were completed. Stool samples were frozen immediately upon receipt and stored at − 70 °C until tested. HpSA results were compared with rapid urease test and histology.Results : One hundred and eighty-one patients were recruited. One hundred and seventy-eight patients were suitable for analysis. Eighty-three were H. pylori positive and 95 were H. pylori negative. The mean duration of storage of the stool samples was 120 days (range, 40–225 days). The sensitivity, specificity and positive and negative predictive values were 84.3%, 97.9%, 97.2% and 88.6%, respectively. In patients with a false negative HpSA test, there was a significant delay in collecting the stool specimen after endoscopy when compared with those with a true positive HpSA test (4.2 vs. 2.3 days; P 〈 0.05). However, the duration of storage of the specimens was not longer, and consumption of coffee or tea and smoking habits were similar.Conclusions : HpSA testing showed good sensitivity and specificity, even with frozen stool samples stored for up to 225 days. The efficacy was not affected by coffee, tea or smoking.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Rabeprazole is a new proton pump inhibitor with more potent acid suppressive and anti-Helicobacter effects.〈section xml:id="abs1-2"〉〈title type="main"〉Aim:To compare two different regimens of rabeprazole-based triple therapy vs. 7-day omeprazole-based triple therapy for the eradication of Helicobacter pylori infection.〈section xml:id="abs1-3"〉〈title type="main"〉Method:Patients with proven H. pylori infection were randomized to receive: (i) 7-day rabeprazole, 10 mg, amoxicillin, 1000 mg, and clarithromycin, 500 mg, all twice daily; (ii) 3-day rabeprazole, 20 mg, amoxicillin, 1000 mg, and clarithromycin, 500 mg, all twice daily; or (iii) 7-day omeprazole, 20 mg, amoxicillin, 1000 mg, and clarithromycin, 500 mg, all twice daily. Endoscopy (CLO test, histology) was performed before randomization and 6 weeks after drug treatment.〈section xml:id="abs1-4"〉〈title type="main"〉Results:One hundred and seventy-three patients were randomized. H. pylori eradication rates (intention-to-treat, n=173/per protocol, n=167) were 88%/91% for 7-day rabeprazole-based therapy, 72%/72% for 3-day rabeprazole-based therapy and 82%/89% for 7-day omeprazole-based therapy, respectively. The per protocol eradication rate was significantly better in the 7-day rabeprazole-based therapy and 7-day omeprazole-based therapy groups when compared to the 3-day rabeprazole-based therapy group (P=0.01 and P=0.04, respectively). Compliance was excellent and all three regimens were well tolerated.〈section xml:id="abs1-5"〉〈title type="main"〉Conclusions:The efficacy of seven-day rabeprazole-based triple therapy is similar to 7-day omeprazole-based triple therapy for the eradication of H. pylori infection.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Telecommunication systems 4 (1995), S. 133-149 
    ISSN: 1572-9451
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper provides a view of the next generation switching (NGS) system maintenance operations model based on potential switching technologies. Several potential benefits of the NGS system maintenance over today's switch maintenance are discussed with emphasis on functions but not on costs. A set of maintenance functions required for the NGS system is provided, using the LSSGR and OTGR as guidelines. The definition associated with each maintenance function is also presented. Finally, issues related to the NGS module structure and definition are identified and discussed because the progress of the overall NGS work is largely dependent on the resolution of these issues. The purpose of this work is twofold: (i) to place switch maintenance functions into the NGS operations model; and (ii) to provide a guideline for further defining switch maintenance functions which are/will be unique to NGS.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...