Matrices generated by semilattices

AbstractWe give a characterization of 0–1 matrices M which are generated by semilattices in the way that Mij = 0 if and only if xi Λ xj = 0̂ where xi,xj, 0̂ are elements in a semilattice

Invertibility of the base Radon transform of a matroid

AbstractLet M be a matroid of rank r on n elements and let F be a field. Assume that either char F=0 or char F. It is shown that the point-base incidence matrix of M has rank n−k+1 over F, where k is the number of connected components. This implies that the Radon transform on the family of bases is invertible if and only if the matroid is connected. If M is loop-free then the Radon transform on the family of m-element independent sets is invertible, for every 0<m<r

Potential for improved retention rate by personalized antiseizure medication selection: A register-based analysis

Objective: The first antiseizure medication (ASM) is ineffective or intolerable in 50% of epilepsy cases. Selection between more than 25 available ASMs is guided by epilepsy factors, but also age and comorbidities. Randomized evidence for particular patient subgroups is seldom available. We asked whether register data could be used for retention rate calculations based on demographics, comorbidities, and ASM history, and quantified the potential improvement in retention rates of the first ASM in several large epilepsy cohorts. We also describe retention rates in patients with epilepsy after traumatic brain injury and dementia, patient groups with little available evidence. Methods: We used medical, demographic, and drug prescription data from epilepsy cohorts from comprehensive Swedish registers, containing 6380 observations. By analyzing 381 840 prescriptions, we studied retention rates of first- and second-line ASMs for patients with epilepsy in multiple sclerosis (MS), brain infection, dementia, traumatic brain injury, or stroke. The rank of retention rates of ASMs was validated by comparison to published randomized control trials. We identified the optimal stratification for each brain disease, and quantified the potential improvement if all patients had received the optimal ASM. Results: Using optimal stratification for each brain disease, the potential improvement in retention rate (percentage points) was MS, 20%; brain infection, 21%; dementia, 14%; trauma, 21%; and stroke, 14%. In epilepsy after trauma, levetiracetam had the highest retention rate at 80% (95% confidence interval [CI] = 65–89), exceeding that of the most commonly prescribed ASM, carbamazepine (p\ua0=.04). In epilepsy after dementia, lamotrigine (77%, 95% CI = 68–84) and levetiracetam (74%, 95% CI = 68–79) had higher retention rates than carbamazepine (p\ua0=.006 and p\ua0=.01, respectively). Significance: We conclude that personalized ASM selection could improve retention rates and that national registers have potential as big data sources for personalized medicine in epilepsy

History of Orthodontic Treatment, Treatment Needs and Influencing Factors in Adolescents in Croatia

Aim: The aim of this study was to assess the orthodontic treatment needs of adolescents in Zagreb, Croatia, in relation to their orthodontic treatment history, caries experience and socio-demographic parameters. Methods: The study sample comprised 1,289 adolescents from 12 randomly selected public schools in Zagreb, Croatia. The subjects were 15-18 years old (mean age 16.3±1.4), and 51% of them were girls. The Dental Aesthetic Index (DAI), the sum of the numbers of decayed, missing and filled teeth (DMFT index), and a questionnaire (covering socio-demographic issues, oral health-related attitudes and behaviours) were employed in this study. The data was analyzed by means of Chi-square test, analysis of variance, and multiple logistic regression models. Results: The DMFT score was higher in adolescents with no orthodontic history (5.2±3.7) than in those who were under orthodontic treatment at the time of the research (4.5±3.2; p=0.043). More than 60% of the adolescents have never undergone any orthodontic treatment, around 24% previously undergone treatment and 15% were under treatment at the time of the research. Overall, 85% of the adolescents' orthodontic appliances were removable, and the girls were more often under orthodontic treatment. One fifth of the studied population had severe or very severe malocclusion. Adolescents with previous orthodontic treatment were more often interested in better teeth alignment, changes in their teeth positioning and continuing orthodontic treatment. Multiple logistic regression model demonstrated that previously treated adolescents, in comparison with their untreated peers, were on average older (p=0.002), were less satisfied with the appearance of their teeth (p=0.001), they had higher malocclusion severity (p=0.046), and fewer dental caries (p<0.001), changed toothbrushes more often (p=0.012), and their mothers attained higher education (p<0.001). Conclusions: Although many adolescents received orthodontic treatment, the severity of their malocclusion was still somewhat high, and they were more often dissatisfied with their treatment outcome. Mothers' educational level was found to be the most important socio-demographic predictor for children's involvement in orthodontic treatment. The caries experience increased in comparison with the Croatian national survey data from 1999

Application of effect-compartment model to bumetanide-indomethacin interaction in dogs

Analyses of bumetanide's dose-response relationship have been complicated by the hysteresis observed between the drug's urinary excretion rate and its sodium excretion. This apparent time lag reflects the disequilibrium between the urine concentration and effect compartment (biophase) which occurs during the early distribution phase. In the present article, an expanded pharmaco-dynamic model has been introduced in which the hypothetical effect compartment is linked, by a first-order process (K ue ), to the urine compartment. Drug dissipation from the effect compartment occurs by means of the first-order rate constant , K eo . This representation accommodates bumetanide's luminal site of action in the kidney tubule as well as the drug's temporal component. Application of this model to the bumetanide-indomethacin interaction in dogs is examined.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45030/1/10928_2005_Article_BF01058955.pd