Very large-scale neighborhoods with performance guarantees for minimizing makespan on parallel machines

We study the problem of minimizing the makespan on m parallel machines. We introduce a very large-scale neighborhood of exponential size (in the number of machines) that is based on a matching in a complete graph. The idea is to partition the jobs assigned to the same machine into two sets. This partitioning is done for every machine with some chosen rule to receive 2m parts. A new assignment is received by putting to every machine exactly two parts. The neighborhood Nsplit consists of all possible rearrangements of the parts to the machines. The best assignment of Nsplit can be calculated in time O(mlogm) by determining the perfect matching having minimum maximal edge weight in an improvement graph, where the vertices correspond to parts and the weights on the edges correspond to the sum of the processing times of the jobs belonging to the parts. Additionally, we examine local optima in this neighborhood and in combinations with other neighborhoods. We derive performance guarantees for these local optima.operations research and management science;

CONTRIBUTION OF THE LOWER EXTREMITY JOINTS TO MECHANICAL ENERGY IN ATHLETICS CURVE SPRINTING

The purposes of this study were to identify differences of the three-dimensional joint kinetics between linear and curve sprinting and to quantify the asymmetrical loading of both legs during curve sprinting. Six male sprinters performed three linear and curve sprints. The energies of the ankle, knee and hip joint were determined during the ground contact phase with the aid of an adjusted multibody human model. The ankle joint was the largest energy absorber and generator in the sagittal plane while the hip joint was the largest energy absorber and generator in the frontal and transversal plane. Asymmetric functions of the inside and outside leg were determined during curve sprinting. The hip joint of the inside leg might be highly loaded in sprinting on a bend track

Deutschsprachige Versionen des Tinnitus Functional Index

Hintergrund Es existieren zwei deutschsprachige, validierte Versionen des Tinnitus Functional Index (TFI), eine für die Schweiz und eine für Deutschland. Der TFI gilt als möglicher neuer Standard-Fragebogen für die Evaluation eines Tinnitus-Schweregrads und einer Tinnitus-Therapie. Ziel der Arbeit In Anbetracht der stattfindenden Standardisierung bei der Tinnitus-Evaluation war es unser Ziel, die beiden TFI-Versionen miteinander zu vergleichen und im deutschsprachigem Raum nur eine TFI-Version zu empfehlen. Material und Methoden Die beiden deutschsprachigen TFI-Versionen wurden in einer multizentrischen randomisierten Online-Fragebogenstudie im Cross-over-Design miteinander verglichen. Ergebnisse Die Gesamtscores der beiden TFI-Versionen unterschieden sich in der gesamten Population nicht. Bei weiterer Aufschlüsselung in Bezug auf die Population und Reihenfolge der abgegeben TFI-Versionen zeigten sich allerdings teilweise signifikante Unterschiede mit jedoch nur moderaten Effektstärken. Dies deutet darauf hin, dass sich die beiden Versionen leicht unterscheiden, aber trotzdem miteinander vergleichbar sind. Bei der Faktoranalyse konnten bei der TFI-Version für Deutschland in der gesamten Population wie auch für die schweizerische Population 6 Faktoren extrahiert werden. Hingegen konnten bei der deutschen Population in beiden TFI-Versionen und bei der schweizerischen Population in der schweizerischen TFI-Version nur 5 Faktoren extrahiert werden. Schlussfolgerung Die beiden deutschsprachigen Versionen des TFI sind gut miteinander vergleichbar. Jedoch spricht die Faktoranalyse eher für die Verwendung der TFI-Version für Deutschland im gesamten deutschsprachigen Raum. ------- Background Two validated German-language versions of the Tinnitus Functional Index (TFI) exist, one for Switzerland and one for Germany. The TFI is considered to be a possible new standard questionnaire for evaluation of tinnitus severity and tinnitus treatment. Objective Considering the standardization taking place in tinnitus evaluation, our aim was to compare the two German-language TFI versions and to recommend only one TFI version in the German-speaking area. Materials and methods The two German-language TFI versions were compared in a multicenter and randomized online questionnaire study with a crossover design. Results The total score of the two TFI versions did not differ in the total population. However, when further divided in terms of population and order of presentation of the TFI versions, there were significant differences in some cases, albeit with only moderate effect sizes. This suggests that the two versions are slightly different but still comparable. In factor analysis for the TFI version for Germany, in the entire population as well as in the Swiss population, six factors could be extracted. In contrast, for the German and Swiss TFI versions, only five factors could be extracted in the German population, and for the Swiss TFI version, only five factors in the Swiss population. Conclusion The two German-language versions of the TFI are well comparable with each other. However, the factor analysis rather argues for use of the TFI version for Germany in the entire German-speaking region

Effects of Anacetrapib in Patients with Atherosclerotic Vascular Disease

BACKGROUND: Patients with atherosclerotic vascular disease remain at high risk for cardiovascular events despite effective statin-based treatment of low-density lipoprotein (LDL) cholesterol levels. The inhibition of cholesteryl ester transfer protein (CETP) by anacetrapib reduces LDL cholesterol levels and increases high-density lipoprotein (HDL) cholesterol levels. However, trials of other CETP inhibitors have shown neutral or adverse effects on cardiovascular outcomes. METHODS: We conducted a randomized, double-blind, placebo-controlled trial involving 30,449 adults with atherosclerotic vascular disease who were receiving intensive atorvastatin therapy and who had a mean LDL cholesterol level of 61 mg per deciliter (1.58 mmol per liter), a mean non-HDL cholesterol level of 92 mg per deciliter (2.38 mmol per liter), and a mean HDL cholesterol level of 40 mg per deciliter (1.03 mmol per liter). The patients were assigned to receive either 100 mg of anacetrapib once daily (15,225 patients) or matching placebo (15,224 patients). The primary outcome was the first major coronary event, a composite of coronary death, myocardial infarction, or coronary revascularization. RESULTS: During the median follow-up period of 4.1 years, the primary outcome occurred in significantly fewer patients in the anacetrapib group than in the placebo group (1640 of 15,225 patients [10.8%] vs. 1803 of 15,224 patients [11.8%]; rate ratio, 0.91; 95% confidence interval, 0.85 to 0.97; P=0.004). The relative difference in risk was similar across multiple prespecified subgroups. At the trial midpoint, the mean level of HDL cholesterol was higher by 43 mg per deciliter (1.12 mmol per liter) in the anacetrapib group than in the placebo group (a relative difference of 104%), and the mean level of non-HDL cholesterol was lower by 17 mg per deciliter (0.44 mmol per liter), a relative difference of -18%. There were no significant between-group differences in the risk of death, cancer, or other serious adverse events. CONCLUSIONS: Among patients with atherosclerotic vascular disease who were receiving intensive statin therapy, the use of anacetrapib resulted in a lower incidence of major coronary events than the use of placebo. (Funded by Merck and others; Current Controlled Trials number, ISRCTN48678192 ; ClinicalTrials.gov number, NCT01252953 ; and EudraCT number, 2010-023467-18 .)

Efficiency of Local Search

Local search heuristics are an important class of algorithms for obtaining good solutions for hard combinatorial optimization problems. Important issues for these heuristics are solution quality and computational time. A local search heuristic starts with an initial solution, and iteratively advances to a neighboring solution of the current solution. This is repeated until some stopping criterion is met. The neighborhood is a critical issue in a local search heuristic. It directly influences the local behavior of a local search heuristic, since it restricts the choice of a new solution in a single iteration. This determines the local efficiency of a local search heuristic. On the other side, this local behavior also influences the global behavior, i.e. the sequence of feasible solutions obtained by the local search heuristic. This sequence of solutions represents the navigational behavior of the local search heuristic and determines the global efficiency of a local search heuristic. In the first part of the thesis, we consider neighborhoods of large size that can be explored in a fast manner, in order to reach local optima of good quality in less time. We consider a single machine and a parallel machine scheduling problem. We develop very large-scale neighborhoods for these two scheduling problems. For all the introduced neighborhoods, we explain what solutions they contain and how the neighborhood is efficiently explored to obtain a better neighbor. We also compare their performance to basic neighborhoods regarding solution quality and running time by conducting computational tests. In the second part of the thesis, we examine the global efficiency in terms of solution quality obtained at the end of a local search heuristic. We obtain performance guarantees for local optima of certain neighborhoods for two parallel machine scheduling problems. Although the found performance guarantees are worse compared to constructive heuristics (however, for our cases the differences are quite small), the advantage of giving performance guarantees for local optima is that these guarantees hold for all solutions which are locally optimal and not only for a single solution as for most constructive heuristics

All for One and One for All? – Examining Convergent Validity and Responsiveness of the German Versions of the Tinnitus Questionnaire (TQ), Tinnitus Handicap Inventory (THI), and Tinnitus Functional Index (TFI)

BackgroundMeasurement of tinnitus-related distress and treatment responsiveness is key in understanding, conceptualizing and addressing this often-disabling symptom. Whilst several self-report measures exist, the heterogeneity of patient populations, available translations, and treatment contexts requires ongoing psychometric replication and validation efforts.ObjectiveTo investigate the convergent validity and responsiveness of the German versions of the Tinnitus Questionnaire [TQ], Tinnitus Handicap Inventory [THI], and Tinnitus Functional Index [TFI] in a large German-speaking sample of patients with chronic tinnitus who completed a psychologically anchored 7-day Intensive Multimodal Treatment Programme.MethodsTwo-hundred-and-ten patients with chronic tinnitus completed all three questionnaires at baseline and post-treatment. Intraclass correlation coefficients determined the convergent validity of each questionnaire’s total and subscale scores. Treatment responsiveness was investigated by [a] comparing treatment-related change in responders vs. non-responders as classified by each questionnaire’s minimal clinically important difference-threshold, and [b] comparing agreement between the questionnaires’ responder classifications.ResultsThe total scores of all three questionnaires showed high agreement before and after therapy (TQ | THI: 0.80 [Pre], 0.83 [Post], TQ | TFI: 0.72 [Pre], 0.78 [Post], THI | TFI: 0.76 [Pre] 0.80 [Post]). All total scores changed significantly with treatment yielding small effect sizes. The TQ and TFI yielded comparable (19.65 and 18.64%) and the THI higher responder rates (38.15%). The TQ | THI and TQ | TFI showed fair, and the THI | TFI moderate agreement of responder classifications. Independent of classification, responders showed significantly higher change rates than non-responders across most scores. Each questionnaire’s total change score distinguished between responders and non-responders as classified by the remaining two questionnaires.ConclusionThe total scores of all three questionnaires show high convergent validity and thus, comparability across clinical and research contexts. By contrast, subscale scores show high inconsistency. Whilst the TFI appears well suited for research purposes, the THI may be better suited to measure psychological aspects of tinnitus-related distress and their changes with accordingly focused treatment approaches

An improved deterministic local search algorithm for 3-SAT

We slightly improve the pruning technique presented in Dantsin et al. (Theoret. Comput. Sci. 289 (2002) 69) to obtain an O*(1.473n) deterministic algorithm for 3-SAT

Two very large-scale neighborhoods for single machine scheduling

In this paper, the problem of minimizing the total completion time on a single machine with the presence of release dates is studied. We introduce two different approaches leading to very large-scale neighborhoods in which the best improving neighbor can be determined in polynomial time. Furthermore, computational results are presented to get insight in the performance of the developed neighborhoods

ISSN 0169-2690Matching Based Exponential Neighborhoods For Parallel Machine Scheduling

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