Using output to evaluate and refine rules in rule-based expert systems

The techniques described provide an effective tool which knowledge engineers and domain experts can utilize to help in evaluating and refining rules. These techniques have been used successfully as learning mechanisms in a prototype adaptive diagnostic expert system and are applicable to other types of expert systems. The degree to which they constitute complete evaluation/refinement of an expert system depends on the thoroughness of their use

Using decision-tree classifier systems to extract knowledge from databases

One difficulty in applying artificial intelligence techniques to the solution of real world problems is that the development and maintenance of many AI systems, such as those used in diagnostics, require large amounts of human resources. At the same time, databases frequently exist which contain information about the process(es) of interest. Recently, efforts to reduce development and maintenance costs of AI systems have focused on using machine learning techniques to extract knowledge from existing databases. Research is described in the area of knowledge extraction using a class of machine learning techniques called decision-tree classifier systems. Results of this research suggest ways of performing knowledge extraction which may be applied in numerous situations. In addition, a measurement called the concept strength metric (CSM) is described which can be used to determine how well the resulting decision tree can differentiate between the concepts it has learned. The CSM can be used to determine whether or not additional knowledge needs to be extracted from the database. An experiment involving real world data is presented to illustrate the concepts described

Polyimide processing additives

A process for preparing polyimides having enhanced melt flow properties is described. The process consists of heating a mixture of a high molecular weight poly-(amic acid) or polyimide with a low molecular weight amic acid or imide additive in the range of 0.05 to 15 percent by weight of additive. The polyimide powders so obtained show improved processability, as evidenced by lower melt viscosity by capillary rheometry. Likewise, films prepared from mixtures of polymers with additives show improved processability with earlier onset of stretching by TMA

ADAMTSL3 as a candidate gene for schizophrenia: Gene sequencing and ultra-high density association analysis by imputation

We previously reported an association with a putative functional variant in the ADAMTSL3 gene, just below genome-wide significance in a genome-wide association study of schizophrenia. As variants impacting the function of ADAMTSL3 (a disintegrin-like and metalloprotease domain with thrombospondin type I motifs-like-3) could illuminate a novel disease mechanism and a potentially specific target, we have used complementary approaches to further evaluate the association. We imputed genotypes and performed high density association analysis using data from the HapMap and 1000 genomes projects. To review all variants that could potentially cause the association, and to identify additional possible pathogenic rare variants, we sequenced ADAMTSL3 in 92 schizophrenics. A total of 71 ADAMTSL3 variants were identified by sequencing, many were also seen in the 1000 genomes data, but 26 were novel. None of the variants identified by re-sequencing was in strong linkage disequilibrium (LD) with the associated markers. Imputation analysis refined association between ADAMTSL3 and schizophrenia, and highlighted additional common variants with similar levels of association. We evaluated the functional consequences of all variants identified by sequencing, or showing direct or imputed association. The strongest evidence for function remained with the originally associated variant, rs950169, suggesting that this variant may be causal of the association. Rare variants were also identified with possible functional impact. Our study confirms ADAMTSL3 as a candidate for further investigation in schizophrenia, using the variants identified here. The utility of imputation analysis is demonstrated, and we recommend wider use of this method to re-evaluate the existing canon of suggestive schizophrenia associations

Identification of Functional and Expression Polymorphisms Associated With Risk for Antineutrophil Cytoplasmic Autoantibodyâ Associated Vasculitis

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136726/1/art40034_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136726/2/art40034-sup-0002-suppinfo02.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136726/3/art40034-sup-0001-suppinfo01.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136726/4/art40034.pd

Meta‐analysis of genetic polymorphisms in granulomatosis with polyangiitis (Wegener's) reveals shared susceptibility loci with rheumatoid arthritis

ObjectiveTo examine the association of previously identified autoimmune disease susceptibility loci with granulomatosis with polyangiitis (Wegener's) (GPA), and to determine whether the genetic susceptibility profiles of other autoimmune diseases are associated with those of GPA.MethodsGenetic data from 2 cohorts were meta-analyzed. Genotypes for 168 previously identified single-nucleotide polymorphisms (SNPs) associated with susceptibility to different autoimmune diseases were ascertained in a total of 880 patients with GPA and 1,969 control subjects of European descent. Single-marker associations were identified using additive logistic regression models. Associations of multiple SNPs with GPA were assessed using genetic risk scores based on susceptibility loci for Crohn's disease, type 1 diabetes, systemic lupus erythematosus, rheumatoid arthritis (RA), celiac disease, and ulcerative colitis. Adjustment for population substructure was performed in all analyses, using ancestry-informative markers and principal components analysis.ResultsGenetic polymorphisms in CTLA4 were significantly associated with GPA in the single-marker meta-analysis (odds ratio [OR] 0.79, 95% confidence interval [95% CI] 0.70-0.89, P = 9.8 × 10(-5) ). The genetic risk score for RA susceptibility markers was significantly associated with GPA (OR 1.05 per 1-unit increase in genetic risk score, 95% CI 1.02-1.08, P = 5.1 × 10(-5) ).ConclusionRA and GPA may arise from a similar genetic predisposition. Aside from CTLA4, other loci previously found to be associated with common autoimmune diseases were not statistically significantly associated with GPA in this study

The American College of Rheumatology response criteria for systemic lupus erythematosus clinical trials: Measures of overall disease activity

Objective. Improved standards for the evaluation of therapeutic interventions in systemic lupus erythematosus (SLE) are needed. The purpose of this study by a committee of the American College of Rheumatology was to define clinically meaningful improvement, no change, or worsening in 6 existing clinical measures of SLE disease activity. This represents an important step in a disease in which some organ symptoms get better and others get worse. It is intended to help investigators develop sample size estimates based on meaningful effect sizes and to gauge the clinical relevance of any observed change in disease activity. Methods. Medical records from 310 patients drawn from 3 sources were abstracted into a standard format. Each vignette included clinical and laboratory data obtained during 2-3 visits. Ratings on the following 6 instruments were obtained for the same patients during the visit or retrospectively: the British Isles Lupus Assessment Group (BILAG), the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), the revised Systemic Lupus Activity Measure (SLAM-R), the European Consensus Lupus Activity Measure (ECLAM), the Safety of Estrogens in Lupus Erythematosus: National Assessment (SELENA)-SLEDAI, and the Responder Index for Lupus Erythematosus (RIFLE). From this pool of vignettes, 5 common vignettes and 10 randomly selected vignettes were rated through a secure Web site by 88 international experts on SLE. The experts, who were blinded to the activity measure scores, were asked to rate each patient's clinical condition as worsened, improved, or unchanged relative to the previous visit. These ratings were transformed by statistical procedures into performance characteristic curves that related a change on a particular SLE activity measure to the physicians' agreement on whether that patient had worsened, improved, or remained the same clinically. These were discussed by the committee members, who were blinded to the actual instrument used. The committee then voted on what level of expert agreement would be used to determine clinically meaningful change. Results. The physician ratings on the 5 common vignettes revealed considerable variation in their clinical appraisals. Overall, the 6 SLE activity measures showed excellent separation of clinical conditions as being worsened, improved, or the same. The committee voted to take 70% agreement by physicians as the point on the performance characteristic curves at which meaningful change in a score could be identified. For each instrument, we computed the units of change required to indicate improvement or worsening. Conclusion. To our knowledge, these are the first response criteria in any disease where a clinically relevant change has been determined a priori and mapped to standardized measures. This criterion should aid the clinical evaluation of new therapies, improve comparability between trials, and facilitate innovative trial designs