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| 2. |
- Aberg, Jan, et al.
(author)
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Multialphabet coding with separate alphabet description
- 1997
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In: Proceedings. Compression and Complexity of SEQUENCES 1997. - 0818681322 ; , s. 56-65
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Conference paper (peer-reviewed)abstract
- For lossless universal source coding of memoryless sequences with an a priori unknown alphabet size (multialphabet coding), the alphabet of the sequence must be described as well as the sequence itself. Usually an efficient description of the alphabet can be made only by taking into account some additional information. We show that these descriptions can be separated in such a way that the encoding of the actual sequence can be performed independently of the alphabet description, and present sequential coding methods for such sequences. Such methods have applications in coding methods where the alphabet description is made available sequentially, such as PPM.
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| 3. |
- Aberg, J., et al.
(author)
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Towards understanding and improving escape probabilities in PPM
- 1997
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In: Proceedings DCC '97. Data Compression Conference. - 0818677619 ; , s. 22-31
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Conference paper (peer-reviewed)abstract
- The choice of expressions for the coding probabilities in general, and the escape probability in particular, is of great importance in the family of PPM algorithms. We present a parameterized version of the escape probability estimator which, together with a 'compactness' criterion, provides guidelines for the estimator design given a 'representative' set of files. This parameterization also makes it possible to adapt the expression of the escape probability during one-pass coding. Finally, we present results for one such compression scheme that illustrates the usefulness of our approach.
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| 4. |
- Abrahamson, Magnus, et al.
(author)
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Modification of cystatin C activity by bacterial proteinases and neutrophil elastase in periodontitis
- 1997
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In: Molecular Pathology. - 1366-8714. ; 50:6, s. 291-297
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Journal article (peer-reviewed)abstract
- AIM: To study the interaction between the human cysteine proteinase inhibitor, cystatin C, and proteinases of periodontitis associated bacteria. METHODS: Gingival crevicular fluid samples were collected from discrete periodontitis sites and their cystatin C content was estimated by enzyme linked immunosorbent assay (ELISA). The interaction between cystatin C and proteolytic enzymes from cultured strains of the gingival bacteria Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans was studied by measuring inhibition of enzyme activity against peptidyl substrates, by detection of break down patterns of solid phase coupled and soluble cystatin C, and by N-terminal sequence analysis of cystatin C products resulting from the interactions. RESULTS: Gingival crevicular fluid contained cystatin C at a concentration of approximately 15 nM. Cystatin C did not inhibit the principal thiol stimulated proteinase activity of P gingivalis. Instead, strains of P gingivalis and P intermedia, but not A actinomycetemcomitans, released cystatin C modifying proteinases. Extracts of five P gingivalis and five P intermedia strains all hydrolysed bonds in the N-terminal region of cystatin C at physiological pH values. The modified cystatin C resulting from incubation with one P gingivalis strain was isolated and found to lack the eight most N-terminal residues. The affinity of the modified inhibitor for cathepsin B was 20-fold lower (Ki 5 nM) than that of full length cystatin C. A 50 kDa thiol stimulated proteinase, gingipain R, was isolated from P gingivalis and shown to be responsible for the Arg8-bond hydrolysis in cystatin C. The cathepsin B inhibitory activity of cystatin C incubated with gingival crevicular fluid was rapidly abolished after Val10-bond cleavage by elastase from exudate neutrophils, but cleavage at the gingipain specific Arg8-bond was also demonstrated. CONCLUSIONS: The physiological control of cathepsin B activity is impeded in periodontitis, owing to the release of proteinases from infecting P gingivalis and neutrophils, with a contribution to the tissue destruction seen in periodontitis as a probable consequence.
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| 5. |
- Abrahamsson, K, et al.
(author)
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Application of heat pump systems for energy conservation in paper drying
- 1997
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In: International Journal of Energy Research. - 0363-907X. ; 21:7, s. 631-642
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Journal article (peer-reviewed)abstract
- Drying is one of the most energy intensive and common operations in the chemical and process industries. Scope for energy recovery is substantial, particularly from the latent heat of the exhaust moist air. Using real operating data from a major Swedish mill, optimal energy conservation strategies were investigated using different heat pump systems in paper drying. Simulation results are compared for compressor-driven and absorption heat pump systems. An absorption heat transformer was also investigated. A CH3OH-LiBr double-lift cycle would have a low COP value due to the low temperature of the moist air stream and the restricted temperature of the cooling water available. A total of 30 MW thermal equivalent is currently needed in the mill at a temperature of 75 degrees C for mixing-pits, district heating and a log store. Exhaust humid air at a temperature of 54 degrees C from only three of the paper machines was used in this study. SHPUMP simulations revealed that installing a mechanical heat pump unit using HFC 134a would result in a recovery of 22 MW due to the temperature level of this application. On the other hand, 12 MW can be recovered with an absorption heat pump. To optimize the operating conditions, H2O-NaOH was selected as the best of three based on exergy index criteria. Assuming a steam cost of 22 $/MW h and an electricity cost of 32 $/MW h, the pay-off periods would be 3.3 and 2.9 years for compressor-driven and absorption heat pump alternatives, respectively. (C) 1997 by John Wiley & Sons, Ltd.
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| 6. |
- Abrahamsson, P. A., et al.
(author)
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Molecular forms of serum prostate-specific antigen : The clinical value of percent free prostate-specific antigen
- 1997
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In: Urologic Clinics of North America. - 0094-0143. ; 24:2, s. 353-365
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Journal article (peer-reviewed)abstract
- The concept of measuring the proportions of various forms of PSA in serum, particularly the proportion of free to total PSA, represents a new and exciting method of detecting early curable prostate cancers and avoiding unnecessary prostate biopsies in men who have BPH only. Compared with other methods of improving diagnostic specificity, it does not require transrectal ultrasound for determination of prostate volume, as does the use of PSA density, and it does not require multiple blood sampling over a sufficiently long period, as does PSA velocity. Recent findings suggest determination of the proportion of free to total PSA, rather than that of complexed to total PSA, to be the optimal discriminator between patients with prostate cancer and those with BPH in the PSA reflex range of 2.5 or 3 ng/mL to 10 ng/mL, and to improve the clinical accuracy of the PSA test substantially. If the total PSA value is normal, percent free PSA improves the sensitivity (increases cancer detection) of the PSA test; if the total PSA value is slightly elevated, percent free PSA enhances the specificity (eliminates unnecessary negative prostate biopsies) of the PSA test. Both of these outcomes are clinically desirable in attempting to diagnose early, curable prostate cancers in a cost-effective manner among men who also have varying degrees of BPH. Figure 5 contains a diagnostic algorithm for the detection of clinically significant prostate cancers at a curable stage, employing the concept of percent free PSA. As more is learned about percent free PSA, however, it may be necessary to make modifications in how this concept is used clinically.
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| 8. |
- Adler, Jan-Olof, et al.
(author)
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A broad range tagging spectrometer for the MAX-laboratory
- 1997
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In: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 388:1-2, s. 17-26
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Journal article (peer-reviewed)abstract
- A broad range tagging spectrometer together with a new beam transport system for photonuclear experiments at the MAX-laboratory in Lund is described. The spectrometer consists of a quadrupole followed by an Elbek-type dipole and has a large momentum acceptance. It can produce both polarized and unpolarized tagged photons in the energy range 10–80 MeV with an energy resolution of about 300 keV.
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| 10. |
- Afanassiev, Valentin, et al.
(author)
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Fast authentication codes based on random polynomial residue classes
- 1997
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In: Proceedings 1997 IEEE International Symposium on Information Theory. - 2157-8095. - 0780339568 - 9780780339569 ; , s. 175-175
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Conference paper (peer-reviewed)abstract
- The verification of the authenticity of a text document or a datafile is one of the main applications of cryptographic techniques. A common used technique for this purpose is the application of a message authentication code (MAC). Usually the MAC computation has to be done in software. Based on the relationship between error-correcting codes and so-called families of almost universal hash functions, and the error-correcting codes using polynomial residue classes we describe an efficient procedure for a MAC computation which is much faster than the standard MAC constructions using MD5 or SHA and uses much less key bits than the fast MACs based on bucket hashing.
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