Effective problem solving using SAT solvers

In this article we demonstrate how to solve a variety of problems and puzzles using the built-in SAT solver of the computer algebra system Maple. Once the problems have been encoded into Boolean logic, solutions can be found (or shown to not exist) automatically, without the need to implement any search algorithm. In particular, we describe how to solve the $n$-queens problem, how to generate and solve Sudoku puzzles, how to solve logic puzzles like the Einstein riddle, how to solve the 15-puzzle, how to solve the maximum clique problem, and finding Graeco-Latin squares.Comment: To appear in Proceedings of the Maple Conference 201

On parallel Branch and Bound frameworks for Global Optimization

Branch and Bound (B&B) algorithms are known to exhibit an irregularity of the search tree. Therefore, developing a parallel approach for this kind of algorithms is a challenge. The efficiency of a B&B algorithm depends on the chosen Branching, Bounding, Selection, Rejection, and Termination rules. The question we investigate is how the chosen platform consisting of programming language, used libraries, or skeletons influences programming effort and algorithm performance. Selection rule and data management structures are usually hidden to programmers for frameworks with a high level of abstraction, as well as the load balancing strategy, when the algorithm is run in parallel. We investigate the question by implementing a multidimensional Global Optimization B&B algorithm with the help of three frameworks with a different level of abstraction (from more to less): Bobpp, Threading Building Blocks (TBB), and a customized Pthread implementation. The following has been found. The Bobpp implementation is easy to code, but exhibits the poorest scalability. On the contrast, the TBB and Pthread implementations scale almost linearly on the used platform. The TBB approach shows a slightly better productivity

One-year adherence to oral antihyperglycemic medication and risk prediction of patient outcomes for adults with diabetes mellitus: an observational study

Medication adherence is essential in preventing adverse intermediate outcomes, but little is known on hard outcomes. The aims of this study were to determine the 1-year adherence to oral antihyperglycemic drugs (OADs) and to predict the risk of subsequent health outcomes among (non)adherent patients with diabetes.Using a large Swiss healthcare claims database from 2011 to 2014, we identified all patients aged ≥18 years with diabetes and treated with at least 1 OAD prescription. Adherence to OADs was measured as the proportion of days covered (PDC) over 1 year and subdivided into 2 categories: adherent (PDC ≥ 80%), nonadherent (PDC < 80%). We estimated the relative risk of hospitalization and mortality at follow-up using multivariate Cox proportional hazard models.Based on a sample of 26,713 patients, adherence to OADs was quite low: 42% of the patients achieved a PDC of ≥80% during the 1-year observation period. A 7% reduction in the hospitalization risk and a 10% reduction in the risk of mortality could be observed in adherent patients compared to nonadherent patients (hazard ratio [HR], 0.93 [95% CI, 0.89-0.97]; HR, 0.90 [95% CI, 0.82-0.99]). Subgroup analysis showed that an intensified diabetes therapy had no significant influence on the risk of both outcomes in adherent patients.Poor medication adherence increases the risk of subsequent hospitalizations and premature mortality in patient with diabetes, regardless of disease severity and comorbidities. This emphasizes the need for an earlier identification of patients with poor medication adherence. The awareness of physicians and patients regarding the importance of adherence in diabetes treatment should be increased

Systematic analysis of annual health resource utilization and costs in hospitalized patients with inflammatory bowel disease in Switzerland.

Real-life data on health resource utilization and costs of hospitalized patients with inflammatory bowel disease are lacking in Switzerland. We aimed to assess health resource utilization and costs during a 1-year follow-up period starting with an index hospitalization. On the basis of claims data of the Helsana health insurance group, health resource utilization was assessed and costs reimbursed by mandatory basic health insurance [in Swiss Francs (CHF); 1 CHF=0.991 US$] were calculated during a 1-year follow-up period starting with an index hospitalization in the time period between 1 January 2013 and 31 December 2014. Of 202 002 patients with at least one hospitalization in 2013-2014, a total of 270 (0.13%) patients had inflammatory bowel disease as main diagnosis [112 (41.5%) ulcerative colitis (UC), 158 (58.5%) Crohn's disease (CD), 154/270 (57.0%) females]. In comparison with patients with UC, patients with CD were significantly more frequently treated with biologics (45.6 vs. 20.5%, P&lt;0.001) and more frequently underwent surgery during index hospitalization (27.8 vs. 9.8%, P=0.002). Compared with patients with UC, those with CD had significantly more consultations [odds ratio (OR): 1.06, 95% confidence interval (CI): 1.01-1.12, P=0.016], higher median annual total costs (OR: 1.25, 95% CI: 1.05-1.48, P=0.012), and higher outpatient costs (OR: 1.33, 95% CI: 1.07-1.66, P=0.011). In the bivariate model, median total costs for patients with CD and those with UC were 24 270 and 17 270 CHF, respectively (P=0.032). When compared with patients with UC, hospitalized patients with CD have during a 1-year follow-up a higher rate of outpatient consultations and generate higher costs

Diet-induced pseudohypoparathyroidism: A hypocalcemia and milk fever risk factor

Subclinical hypocalcemia may affect half of all multiparous cows, and clinical hypocalcemia or milk fever affects approximately 5% of dairy cows each year. This disorder of calcium homeostasis can be induced by several dietary factors. Recent studies implicate high dietary potassium and high dietary cation-anion difference (DCAD) with increased risk of milk fever. The hypothesis tested in this study was that high-DCAD diets fed to prepartum cows reduce tissue sensitivity to parathyroid hormone (PTH), inducing a pseudohypoparathyroid state that diminishes calcium homeostatic responses. Multiparous Jersey cows were fed low- or high-DCAD diets in late gestation, creating a compensated metabolic alkalosis in the high-DCAD cows and a compensated metabolic acidosis in the low-DCAD cows. They then received synthetic PTH injections at 3-h intervals for 48 h. Parathyroid hormone is expected to cause an increase in plasma calcium by increasing renal production of 1,25-dihydroxyvitamin D and increasing bone calcium resorption. Plasma calcium concentration increased at a significantly lower rate in cows fed the high-DCAD diet. Cows fed the high-DCAD diet also produced significantly less 1,25-dihydroxyvitamin D in response to the PTH injections than cows fed the low-DCAD diet. Serum concentrations of the bone resorption marker carboxyterminal telopeptide of type I collagen were numerically lower in cows fed the high-DCAD diet but this difference was not statistically significant. These data provide direct evidence that high-DCAD diets reduce tissue sensitivity to PTH. The metabolic alkalosis associated with high-DCAD diets likely induces a state of pseudohypoparathyroidism in some dairy cows at the onset of lactation, resulting in hypocalcemia and milk fever