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

Real-world data on topical therapies and annual health resource utilization in hospitalized Swiss patients with ulcerative colitis

Objectives: Topical treatment with aminosalicylates and/or budesonide was shown to be highly effective in patients with ulcerative colitis (UC), while reducing the likelihood of systemic adverse effects. However, previous research has shown that topical treatment is clearly underused. We aimed to evaluate the use of topical therapy in the real-world setting. Methods: This is an observational study based on claims data of 201 Swiss adult patients who were hospitalized for UC between 2012 and 2014 and who were then followed for 1 year. A variety of factors presumably associated with topical treatment were examined. Annual health care utilization (UC-related medications, diagnostic procedures, consultations, and rehospitalizations) of patients with versus without topical therapy was compared. Results: Of the 201 hospitalized UC patients, 82 (40.8%) were treated with topical 5-acetylsalicylic acid (ASA) and/or topical rectal steroids. The main factors significantly and positively associated with receiving topical treatment were the use of topical treatment in the year prior to the hospitalization, receiving oral 5-ASA, and living in an urban area. The mode of administration was further related to the language area. Patients with topical therapy significantly more often received other UC-related medications, such as combinations with systemic steroids. They significantly more often underwent colonoscopies and calprotectin measurements, and more often consulted a gastroenterologist in the follow-up, while there was no significant difference regarding rehospitalizations. Conclusions: Topical treatment is underused in patients with UC, which stands in contrast to the current European Crohn's and Colitis Organization guidelines. Patients' preferences and considerations need to be taken into account when prescribing medical therapy

Follow-up ileocolonoscopy is underused in Crohn’s disease patients after ileocecal resection despite higher total and inpatient health-care costs compared to controls

Background: Postoperative recurrence is frequently observed after ileocecal resection in Crohn's disease (CD) patients. Since 2010, endoscopy within 1 year is considered the gold standard for its diagnosis. However, if and how frequent such endoscopies are performed in clinical practice remains unknown. Methods: We analyzed 1-year follow-up data on CD patients who underwent ileocecal resection between 2012 and 2014 and compared them with hospitalized, non-resected CD controls. Data were extracted from the Helsana database. Helsana is one of the largest Swiss health insurance companies providing coverage for 1.2 million individuals. Results: A total of 645 CD patients were identified with ≥1 hospitalization between 2012 and 2014 and a follow-up of 1 year. Of these, 79 (12.2%) underwent ileocecal resection. Although endoscopy rates increased over time and were higher in patients with resection versus controls (p = 0.029), in only 54.4% a 1-year follow-up ileocolonoscopy was performed. Postoperative prophylaxis with anti-tumor necrosis factor or azathioprine was prescribed in 63.3%. Female sex and age >60 years were independent predictors for not receiving prophylaxis (odds ratio [OR] 0.36, p = 0.048, and OR 0.2, p = 0.022). Patients with resection had significantly lower numbers of rehospitalizations (1.2 vs. 1.8, p = 0.021), with resection being an independent negative predictor for number of rehospitalizations in a Poisson regression model (incident risk ratio 0.64, p = 0.029). However, disease-related surgery was more often the cause for rehospitalization after resection versus controls (47.6 vs. 22.1%, p = 0.015). Total and inpatient health-care costs were higher in these patients. Conclusion: Endoscopies are underused after ileocecal resection. This contrasts current guidelines. Physicians should be aware of this underuse and perform follow-up examinations more often

A comparison of the compositional, microstructural, and mechanical characteristics of Ni-free and conventional stainless steel orthodontic wires

Ni-free orthodontic wires were introduced to mitigate concerns associated with the use of Ni-containing alloys in orthodontics. However, limited information is available on their properties and therefore, the aim of this study was to characterize the elemental composition, the microstructure, and the mechanical properties of Ni-free orthodontic wires and compare them with their stainless steel (SS) counterparts. Four Ni-free and four conventional SS wires were included in this study. All the wires were initially imaged with a Scanning Electron Microscopy (SEM) and their elemental compositions were determined by X-ray Energy Dispersive Spectroscopy (EDX). Then, their microstructure was assessed by X-ray Diffraction (XRD) and the indentation modulus, elastic index, Martens Hardness and Vickers Hardness by Instrumented Indentation Testing (IIT). All the wires demonstrated surface cracks and pores oriented parallel to their long axis. The elemental composition of Ni-free alloys showed an increased Mn and Cr content while both SS and Ni-free wires shared the same dominant austenite structure. In conclusion, despite the differences in elemental composition, Ni-free wires demonstrated a similar microstructure and comparable mechanical properties with their conventional SS counterparts and thus may be considered as a promising alternative for patients with Ni supersensitivity. © 2019 by the authors

Are weak or negative clinical recommendations associated with higher geographical variation in utilisation than strong or positive recommendations? Cross-sectional study of 24 healthcare services

Objectives When research evidence is lacking, patient and provider preferences, expected to vary geographically, might have a stronger role in clinical decisions. We investigated whether the strength or the direction of recommendation is associated with the degree of geographic variation in utilisation.Design In this cross-sectional study, we selected 24 services following a comprehensive approach. The strength and direction of recommendations were assessed in duplicate. Multilevel models were used to adjust for demographic and clinical characteristics and estimate unwarranted variation.Setting Observational study of claims to mandatory health insurance in Switzerland in 2014.Participants Enrolees eligible for the 24 healthcare services.Primary outcome measures The variances of regional random effects, also expressed as median odds ratios (MOR). Services grouped by strength and direction of recommendations were compared with Welch’s t-test.Results The sizes of the eligible populations ranged from 1992 to 409 960 patients. MOR ranged between 1.13 for aspirin in secondary prevention of myocardial infarction to 1.68 for minor surgical procedures performed in inpatient instead of outpatient settings. Services with weak recommendations had a negligibly higher variance and MOR (difference in means (95% CI) 0.03 (−0.06 to 0.11) and 0.05 (−0.11 to 0.21), respectively) compared with strong recommendations. Services with negative recommendations had a slightly higher variance and MOR (difference in means (95% CI) 0.07 (−0.03 to 0.18) and 0.14 (−0.06 to 0.34), respectively) compared with positive recommendations.Conclusions In this exploratory study, the geographical variation in the utilisation of services associated with strong vs weak and negative vs positive recommendations was not substantially different, although the difference was somewhat larger for negative vs positive recommendations. The relationships between the strength or direction of recommendations and the variation may be indirect or modified by other characteristics of services. As initiatives discouraging low-value care are gaining attention worldwide, these findings may inform future research in this area