Improvement in adaptive noise canceling using a nonlinear filter based on the pontryagin minimum principle

This paper introduces a new nonlinear filter that is used for adaptive noise canceling. The derivation and convergence properties of the filter are presented. The performance, as measured by the root mean square error between the signal and its estimate, is compared with that of the commonly used least mean square (LMS) algorithm. It is shown, through simulation, that the proposed nonlinear noise canceler has, on the average, better performance than the LMS canceler. The proposed adaptive noise canceler is based on the Pontryagin minimum principle and the method of invariant imbedding. The computational time for the proposed method is about 10% of that of the LMS, in the studied cases, which is a substantial improvement.     

Reanalysis procedure for large structural systems

An efficient procedure is presented for repetitive analysis of structures, with large numbers of degrees of freedom and design variables, as they are progressively modified during the automated optimum design process. The three key elements of the procedure are: (a) lumping of the large number of design variables into a single tracing parameter; (b) operator splitting or additive decomposition of the different arrays in the governing finite element equations of the modified structure into the corresponding arrays of the original structure plus correction terms; and (c) application of a reduction method through the successive use of the finite element method and the classical Bubnov-Galerkin technique. The reanalysis procedure is applied to the linear static and free vibration problems of framed structures. Changes in both the sizing and shape (configuration) design variables are considered. For static problems the similarities between the proposed procedure and the preconditioned conjugate gradient technique are identified and are exploited to provide a physical meaning for the preconditioned residual vectors. The effectiveness of the proposed procedure is demonstrated by means of numerical examples.     

Evidence for strain specificity in cytotoxic T-lymphocyte-mediated, major histocompatibility complex class I-dependent killing of Theileria annulata-infected cells

Cattle immunised against Theileria annulata with one parasite strain have been found to be immune to re-challenge with different strains of the parasite. However, recent evidence of apparent strain specificity has been documented in cattle immunised with attenuated parasite-infected cells. In this study the strain specificity of major histocompatibility complex class I-restricted cytotoxic T-lymphocytes (CTL), a major anti-parasite effector mechanism, was examined. CTL generated following challenge with the Hissar (Indian) strain effectively lysed autologous cells infected with this strain of the parasite. However, CTL were less effective against cells infected with the Gharb (Moroccan) strain and showed virtually no reactivity against the Ankara (Turkish) strain, providing the first direct evidence for strain specificity in immune responses against T. annulata.     

Epoxidized polyurethaneamide and polyesteramide as petroleum pipeline coatings

Linseed oil fatty acids were epoxidized by peracetic acid, then reacted with diethanolamine to give epoxidized hydroxy ethyl linseed oil fatty acid amide ( I ). This amide was rejected with toluene diisocyanate to produce epoxidized polyurethane-amide ( II ). Component I was also reacted with phthalic anhydride to give epoxidized polyesteramide ( III ). Resins II and III were evaluated as coating materials. The results obtained were compared with commercial epoxy resin, and show that resins II and III may be suitable to use as petroleum pipeline coatings.     

The ribonucleotide reductase inhibitor (E)-2''-fluoromethylene-2''-deoxycytidine (MDL 101,731): a potential topical therapy for herpes simplex virus infection

Recent advances in diagnosis, treatment, and tumor biology of the lymphoid blastic malignancies have challenged historical concepts and created a need for revised classification of these diseases. The authors review this material and present a classification relevant to current therapeutic protocols and available biological data. Further advances in understanding of these diseases can be anticipated, with possible further evolution of classification. The exact clinical role of sensitive studies to monitor residual disease during and after treatment remains to be established. These diseases may present difficult differential diagnostic problems. The importance of accurate diagnosis cannot be overemphasized, as highly successful but divergent treatments have evolved for these various hematopoietic diseases. Diagnostic problems are usually resolved with systematic analysis including careful morphology, cytochemistry, immunologic analysis, and addition of EM and other studies in selected circumstances.     

PAK promotes morphological changes by acting upstream of Rac

The serine/threonine kinase p21-activated kinase (PAK) has been implicated as a downstream effector of the small GTPases Rac and Cdc42. While these GTPases evidently induce a variety of morphological changes, the role(s) of PAK remains elusive. Here we report that overexpression of betaPAK in PC12 cells induces a Rac phenotype, including cell spreading/membrane ruffling, and increased lamellipodia formation at growth cones and shafts of nerve growth factor-induced neurites. These effects are still observed in cells expressing kinase-negative or Rac/Cdc42 binding-deficient PAK mutants, indicating that kinase- and p21-binding domains are not involved. Furthermore, lamellipodia formation in all cell lines, including those expressing Rac binding-deficient PAK, is inhibited significantly by dominant-negative RacN17. Equal inhibition is achieved by blocking PAK interaction with the guanine nucleotide exchange factor PIX using a specific N-terminal PAK fragment. We conclude that PAK, via its N-terminal non-catalytic domain, acts upstream of Rac mediating lamellipodia formation through interaction with PIX.     

Nasal carriage of staphylococcus aureus and epidemiology of surgical-site infections in a Sudanese university hospital

Surgical site infections (SSI) due to Staphylococcus aureus among 256 male and 158 female patients (mean age, 28 years) undergoing elective surgery at the Soba University Hospital (Khartoum, Sudan) were studied. During an 11-month study period all patients were analyzed for nasal carriage of S. aureus at the time of admission. Follow-up of the development of SSI proceeded until 4 weeks after the operations. In addition, nasal swabs were obtained periodically during the same period from 82 members of the staff. In order to discriminate autoinfection from cross infection, bacterial isolates were typed by random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE) of DNA macrorestriction fragments, and restriction fragment length polymorphism analysis of the protein A and coagulase genes. Preoperative cultures revealed the presence of S. aureus in the noses of 98 patients (24%). The overall number of postsurgical wound infections in the entire group was 57 (14%), 24 of which were due to S. aureus. Only 6 of the 98 nasal S. aureus carriers suffered from wound infections by the same species. In these six cases the infecting strain could not be genetically discriminated from the nasal inhabitant, substantiating autoinfection. However, nasal carriage of S. aureus is not a significant risk factor for the development of SSI in this setting (6 of 98 patients with autoinfection versus 18 of 316 patients [414 - 98 patients] with cross infection; P = 0.81), most probably due to the fact that noncarriers are at a significant and relatively large risk for acquiring an independent S. aureus SSI. The other S. aureus strains causing SSI showed a high degree of genetic heterogeneity, demonstrating that it is not an epidemic strain that is causing the SSI. Among the staff personnel screened, 47.4% did not carry S. aureus in the nose at any time during the study period, whereas 13. 2% persistently carried a single strain in the nose. Another 39.5% could be classified as intermittent carriers. When strains derived from staff personnel were genetically typed, it was demonstrated that most of the strains represented genetic variants clearly differing from the isolates causing SSI. On the other hand, possible cross colonization among staff personnel and even cross infection from staff personnel to patients or from patient to patient were demonstrated in some cases, but epidemic spread of a single strain or a few clonally related strains of S. aureus could be excluded.     

Integrated bandpass filters

The letter presents some new results associated with one bandpass (b.p.) filter configuration of the integrated uniform R0-C0KR0 structure consisting of two rectangular resistive films, one having per-unit-length (p.u.l.) constant series resistance R0 and the other KR0 (where K is a dimensionless constant), separated from each other by a dielectric film having p.u.l. constant shunt capacitance C0. It is shown that the output voltage in the b.p. region may be made almost constant for the load fluctuations in the wide range R0 ? Rt < ? (where Rt = load resistance) by selecting K ? 0.3. The range of variation of Rt producing constant output voltage in the b.p. region is found to be narrower for increasing value of K.